ADSORPTION OF COBALT, BARIUM, AND ZINC

FROM VERY DILUTE SOLUTIONS

Dissertation

Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University

By

ORVILLE JAMES KVAMME, B.S., M.S.

The Ohio State University 1952

Approved by:

C7fji Adviser

dviser Table of Contents Page

I, Introduction...... 1

II. Literature Survey...... 4

A. Properties of Radiocolloids...... 4

1. Dialysis...... 4

2. Electrophoresis and Filtration... 5

3. Hadioautography...... 8

4. Sedimentation and Centrifugation. 9

B. Target Separations by Filtration 12

C. Properties of the Filter Paper...... 16

D. Radiocolloids Interpreted in Terms

of the Diffuse Double Layer Theory... 30

III. Experimental Procedure...... 36

A. Target Chemistry...... 36

B. Experimental Technique...... 42

IV. Experimental Results and Discussion...... 48

A. Adsorption of Divalent Cobalt,

Barium, and Zinc on Filter Paper,.... 48

1. Dependence on...... pH...... 48

a. Cobalt...... 48

b„ Barium...... 64

c. Zinc...... 72

2. Dependence on Concentration.... 80

3. Dependence on Ammonium Chloride

Concentration...... 87

£29772 -ii- Eflgft

4. Dependence on Manganous and Cup-

ric Chloride Concentration...... 96

5. Dependence on Ammonium Sulfate

Goncentra tion...... 104

B. Nature of the Filter Paper Adsorption.. 109

1. Effect of Washing the Adsorbed

Cohalt and Zinc...... 109

2. Titration of the Filter Paper 116

3. Adsorption of Zinc at a Water-

Hexane Interface...... 119

C. Adsorption of Cesium on Filter Paper... 122

V. Summary...... 126

VI. Conclusions...... 134

VII, Bibliography...... 137

VIII. Autobiography...... 140 -iii-

Tables

Page

I. Effect of pH on Cobalt Adsorption after Three-Day Standing...... •>.... 49

II. Effect cf pH on Cobalt Adsorption by Paper and Glass with Filtration Within Ten Minutes after Titration...... 52

III. Adsorption of Cobalt by Successive Filters after Three-Day Standing...... 55 56 57

IV, Effect of pH on the Adsorption of Barium in Concentrations less than 1 x 10-8 g. atoms/30 ml...... 66

V. Effect of pH on Barium Adsoprtion (Stable Barium Added)...... 68

VI, Effect of pH on Adsorption of Zinc...... 73 74

VII. Effect of Concentration of Cobalt on its Adsorption...... 81

VIII. Effect of Concentration of Zinc on its Adsorption...... 84

IX. Effect of Ammonium Chloride Concentra­ tion on Cobalt Adsorption...... 88

X. Effect of Ammonium Chloride Concentra­ tion on Zinc Adsorption....,...... 94

XI. Effect of Manganous Chloride Concentra­ tion on Cobalt Adsorption...... 97

XII. Effect of Cupric Chloride Concentra­ tion on Zinc Adsorption...... 101

XIII. Effect of Ammonium Sulfate Concentra­ tion on Zinc Adsorption...... 105

XIV. Effect of Washing the Adsorbed Cobalt 110

XV. Effect of Washing the Adsorbed Zinc...... 112 £agft

XVI. Effect of Washing the Adsorbed Zinc with Solutions of Various Acidities 114-

XVII. Adsorption of Zinc by a Water-Hexane Interface...... 120

XVIII. Effect of pH on Adsorption of Cesium 123 -V-

Figures P^ge

1. Effect of pH on Adsorption of Cobalt by Paper...... 51

2. Effect of pH on Cobalt Adsorption by Glass and Paper...... 59

3. Effect of pH on Adsorption of Cobalt by Successive Filters...... 60

A. Effect of pH on Adsorption of Cobalt by Glass...... 62

5. Effect of pH on Adsorption of Barium by Paper...... 67

6. Effect of pH on Adsorption of Barium by Paper, Stable Barium Added...... 70

7. Effect of pH on Adsorption of Zinc by Paper...... 75

8. Effect of Ammonia Concentration on Adsorption of Zinc.''..,...... 78

9. Effect of Ammonia Concentration on Adsorption of Cobalt...... 79

10. Effect of Cobalt Concentration on Ad­ sorption of Cobalt by Paper...... 82

11. Effect of Zinc Concentration on Ad­ sorption of Zinc by Paper...... 85

12. Effect of Ammonium Chloride Concentra­ tion on Adsorption of Cobalt by Paper 90

13. Effect of Ammonium Chloride on Cobalt Adsorption...... 92

1/+. Effect of Ammonium Chloride Concentration on Adsorption of Zinc by Paper...... 95

15. Effect of Manganous Chloride Concentra­ tion on Adsorption of Cobalt...... 98 -vi-

Page

16. Effect of Cupric Chloride Concentra­ tion on Adsorption of Zinc...... 102

17. Effect of Ammonium Sulfate Concentra­ tion on Adsorption of Zinc...... 106

18. Titration Curves for the Filter Paper 117 -vii-

ACKNOWLEDGMBNT

The author wishes to take this opportunity to express his appreciation to Professors M. H, Kurba­ tov and J. D. Kurbatov for their excellent instruction and advice in the accomplishment of this work. Besides problems of a technical nature that arose in the course of this study, their consideration of the personal problems of the author was particularly appreciated.

To the United States Air Force, the author ex­ presses his sincere gratitude for making this work possible. INTRODUCTION

It has been known for almost forty years that certain heavy elements, such as radioactive isotopes of lead, bismuth, and polonium, can be filtered at concentrations much below that of so-called “saturated solutions" of their oxides. As these solutions often exhibit properties which are more like colloids than true solutes, they have become known as "radiocolloids".

More recently it has been shown that the elements, yttrium, zirconium, and lanthanum, exhibit the same property, when the concentration of their respective compounds are much lower than their solubilities. In the above examples of radiocolloids, each element had an oxidation state of three or more.

This tendency of some radioactive isotopes to be adsorbed on filter paper has been utilized in separa­ tions of activated target materials, the value of which lies in its speed and simplicity of operation. However, as yet, there is no satisfactory explanation for this phenomenon of filter paper retention. Also, very little is known concerning the factors which influence target separations by filtration.

This work has been conducted, with the following objectives in mind:

(l) To determine whether elements in the plus -2-

two oxidation state are removed from very

dilute solutions by filter paper.

(2) To determine the factors that influence

filter paper retention, for the following

general purposes:

(a) To increase the scope and efficiency

of target separations by filtration.

(b) To attempt to provide a satisfactory

explanation for the phenomenon of fil­

ter paper retention.

(c) To provide a comparative study of ad­

sorption of cobalt, barium, and zinc —6 in concentrations lower than 1 x 10~

mole per liter.

For this study of some divalent cations, radioactive cobalt, barium, and zinc were utilized as tracers, since the experimental conditions of this work were such that the concentrations of the solute were too small to be measured by other quantitative methods. All activity measurements were made on a Geiger counter.

The effect of the following parameters upon filter paper retention were studied: The effect of pH, of concentration of several divalent cations, of ammonium chloride concentration, of ammonium sulfate concentra­ tion, and of washing the filter paper.

In order to determine more of the nature of the filter paper retention, the following studies were made: Titration of the filter paper, determination of the effect of washing the adsorbed cobalt and zinc with wash solutions at different acidities, and comparison of filter paper retention with surface adsorption be­ tween a water-hexane layer.

Filter paper retention of cesium was also measured to determine the possibility of a separation of radio­ active isotopes of the alkaline earth elements from a target material consisting of a compound of an alkali element. —4-—

LITERATURE SURVEY

Properties of Radiocolloids

As a basis for the understanding of filter paper retention, the literature is reviewed according to the properties which distinguish radiocolloids from true

solutes.

Dialysis. F. Paneth (1913) (l) dialyzed a neutral solution of radio-lead nitrate against pure water. The solution contained RaD (Pb2^0), RaE (Bi2-1,0), and polon­ ium (Po2^®). The RaE and polonium were concentrated in Ihe original solution, whereas the lead isotope diffused into the pure water. When a solution of polon­ ium in nitric acid was made alkaline with ammonium hy­ droxide, there was no apparent precipitation; however, the solution which was previously capable of diffusion now did not show any polonium in the dialysate. This behavior was explained on the basis that radiocolloidal hydroxides of metals were present in neutral and basic solution, but not in acid. It was also found that RaE would diffuse through a membrane in acid solution. F.

Paneth (1913) (2) studied the diffusion coefficients of these same radioactive substances in very dilute solutions. It was found that all of the radioelements diffused with normal speed in acid solution, but that the normal diffusion coefficients of polonium, RaE, and thorium B (Pb2^-2) decrease when their solutions are made neutral or basic with ammonium hydroxide. This decrease in diffusion rate was considered an indication of radiocolloid formation.

In more recent times, J. Schubert and E. Conn

(1949) (3) found that in a half formal uranyl nitrate solution containing most of the fission products in the carrier-free state, only the radioactive isotopes of zirconium and niobium failed to diffuse completely.

The addition of sulfuric or nitric acid increased the diffusion of zirconium and niobium.

Ble ctronh ore sis and Filtration. F. Paneth (1913)

(2) found that polonium and thorium B (Pb2-*-2) migrate toward the cathode in acid solution, but toward the anode in ammoniacal solution. This reversal of charge was considered further evidence of the presence of radiocolloids.

The effect of adding different negative colloids, as colloidal As2S^, platinum, and gold, to a water solution of RaA (Po218), RaB (Pb21M , and RaC (Bi21^) was studied by T. Godlewski (1914) (4). Normally, from a water solution, radium A deposited on the anode, radium B on the cathode, and radium C on both the anode and cathode. Upon addition of a negative colloid in small quantities, the quantity of material deposited at the cathode was diminished, and afterwards disappeared

For still greater quantities of negative colloids, the

products that were previously charged positively become

negatively charged, and were deposited at the anode,

and hence, there was adsorption by a negatively charged

colloid when used in excess. In filtering subaqueous

solution of EaA, RaB, and RaC, the filter was found to

retain RaB and RaC. On adding a small quantity of

aluminum sulfate to the solution, which ordinarily

tends to cause a negative hydrosol to become positively

charged, all three of the radioactive materials remained

on the filter. At acid concentrations of one normal or

more, the filter was inactive, at which point there is

no longer a colloidal state, but rather an ionic solu­

tion.

J. Kurbatov and M. Kurbatov (1942) (5) found that,

at pH 8,8, removal of yttrium by filtration was complete

at very dilute concentrations. It was also noted that

filtration through consecutive papers gave a consider­

ably lower percentage removal by the second paper. Since

the solubility product law, therefore, does not hold, and sedimentation of the radioactive yttrium was observed

the existence of radiocolloids was considered plausible by these investigators.

T. Schbnfeld and E. Broda (1950) (6) indicated that adsorption on filter paper may be used as an indication -7- of the presence of radiocolloids. They distinguish between two separate types of adsorption that may take place. Adsorption due to ion-exchange occurs when

10-15 molar thorium-B solution is brought into contact with paper. If the solution is saturated with hydrogen sulfide, radiocolloids are formed, which are adsorbed by the paper by a different mechanism. When ion-exchange adsorption is occurring, the addition of electrolytes decreases the amount adsorbed. However, when colloid adsorption occurs, such electrolyte either has no effect or may increase the amount adsorbed. Thus, whereas

12% of the thorium-B was adsorbed by paper from hydrogen sulfide - saturated solutions of the thorium-B, on the addition of one-hundredth molar potassium chloride or barium chloride, 71-87% of the activity is adsorbed.

Further difference between adsorption by these two mechan­ isms is shown by differences in velocity of exchange be­ tween adsorbed radioactive substances and the correspond­ ing inactive ion. Thus, when paper containing adsorbed radiocolloidal lead sulfide was brought into contact with one-hundredth molar ordinary lead nitrate, the exchange is very slow, whereas when paper containing adsorbed radioactive lead by the ion-exchange mechanism is brought in contact with ordinary lead nitrate, the exchange is very rapid. -8-

Radioautography. C. Chamie (1927) (7,8) was one of the first researchers to utilize the effect of radia­ tion on a photographic plate, in the study of radiocolloids.

The existence of grouping of polonium atoms was shown by placing acid solutions of polonium on a mica sheet and exposing it to a photographic plate. The grouping of the radioactive atoms manifested themselves by ir­ regular exposure or spotting of the film. C. Chamie

(1929) (9) also found that this grouping of radioactive atoms was common to other radioactive elements in dilute solutions. In 1939, C. Chamie and B* Marques (10) utilized radioautographs in the study of the effect of concentration of a radioactive element upon radiocolloid formation. Solutions of various concentrations of polonium in nitric acid were poured on paraffin and examined photographically. It was shown that the per­ centage of polonium deposited as colloidal aggregates on the paraffin from an acid solution thereof was a function of the content of polonium in the solution, the percentage decreasing as the content increased.

In more recent times, E. Broda and F. Epstein

(1950) (1 1) utilized radioautographs as proof of the existence of radiocolloids. Photographic emulsions con­ taining 80% silver bromide were used for the study of colloid formation in highly dilute acidic to neutral solutions of polonium. nStars" formed on the photographic -,9- plate, after exposure to neutral solutions, were taken as evidence of radiocolloids.

Sedimentation and Centrifugation. H. Lachs and

M. Wertenstein (1922) (12) observed that radioactive polonium settled from a neutral solution. From the data of Lachs and Wertenstein, H. Freundlich (1926) (13) was able to calculate the size of the radiocolloids to be of the order of 10 milli-microns, and pointed out that it was impossible, from the amount of radioactive sub­ stance present, for the entire mass of such large particles to consist of the radioactive element. Freund­ lich, therefore, considered the radioelements as adsorbed by dust or other colloidal particles present in solution, and that this makes it appear as if one was dealing with colloidal radioelements.

0. Werner (1931) (14,15), using an ordinary labora­ tory centrifuge, was able to centrifuge as much as 9$% of the thorium-C (Bi^^) from a solution in a half hour. .

This investigator came to the conclusion that radio­ colloids are formed by adsorption of the radioactive ions by solid impurities, which are present accidentally.

In order to test this theory, Werner determined the ef­ fect of the presence or absence of foreign particles upon radiocolloid formation, A solution containing thorium-B (Pb^^) and thorium-C was filtered through a -10- membrane to remove radiocolloids. This solution was then divided into two parts, one part being diluted with water that had been filtered in the same manner, and the other part with ordinary double-distilled water. The resulting solutions were then centrifuged for thirty minutes to remove radiocolloids that had formed on di­ lution. There was definitely less radiocolloid formation in the solutions diluted with filtered water. Similar results were obtained when the water was purified by centrifugation.

J. Kurbatov and M. Pool (1944) (16) found that radiocolloidal cerium settled from solution at high pH values. Samples were titrated to the desired pH value, and allowed to stand eight days in stoppered, graduated cylinders. The top portion of the solution had a lower concentration of the radioactive cerium after standing than the concentration of the original solution,

C. Thurmond (1952) (17) found that centrifugation was the most reliable method of cleaning solutions in the preparation of dust-free solutions. This work fur­ ther demonstrates the possibility that centrifugation removes from solution foreign nuclei with the radio­ activity adsorbed on these nuclei.

Further work in centrifugation of radiocolloids was done by E, King (1949) (18), who found that plutonium in the plus four oxidation state forms a radiocolloid at -11- low acidity and in trace concentration. The plutonium could be centrifuged from solution if the hydrogen-ion concentration was less than one-hundredth molar. The adsorption by glass of plutonium xinder these conditions increased as the hydrogen-ion concentration decreased.

Neptunium in the plus five oxidation state exhibited no radiocolloidal behavior, even at a hydrogen-ion concentration of 10 * molar.

C. Chamie and M. Haissinsky (1934) (19) showed that the amount of polonium that could be centrifuged from solution depended on the age of the solution. For ex­ ample, 35% of the polonium could be centrifuged from an aliquot of a freshly prepared 10"^ molar nitric acid solution, whereas 71% could be centrifuged from solution after standing forty-five days.

Before completion of this section on the properties of radiocolloids, an observation on radiocolloid formation by A. Wahl and N. Bonner (1950) (20) should be included.

Concerning the solubility of the tracer, it was stated that the tendency of a tracer to hydrolyze in a solution or to form an insoluble compound with some component of the solution favors formation of radiocolloids containing the tracer. The presence in such solutions of substances that form soluble complexes with the tracer hinders the formation of radiocolloids. -12-

Target Separations by Filtration

It has already been mentioned that one of the aims of this work was to provide information that would in­ crease the scope and efficiency of target separations by filtration. With this objective in mind, this sec­ tion will be devoted to a brief survey of the use of filtration in target separations.

J. Kurbatov and M. Kurbatov (194.2) (5) were among the first to utilize this unique and simple method of tajrget separation. Strontium oxide was activated with deuterons in the cyclotron at The Ohio State University to obtain radioactive yttrium. The target was then dissolved in hydrochloric acid without addition of stable yttrium. The solution was brought to pH 9 by means of ammonium hydroxide and filtered. The radioactive yttrium was found to be concentrated on the filter, and was re­ moved quantitatively with warm one-normal hydrochloric acid. The experiments showed that the fraction retained on the filter paper decreased with increased concentra­ tion of the electrolyte, and at constant pH and salt concentration, increased with dilution to some limit.

This work demonstrated that even minute concentrations of yttrium could be separated from weighable quantities of strontium, without the use of a carrier.

In 194-5, M. Kurbatov and J. Kurbatov (21) applied filtration in the separation of tetravalent zirconium. -13-

Xttrium oxide was bombarded with deuterons in The Ohio

State University cyclotron, producing radioactive zircon­ ium. The target was then dissolved in acid and titrated to pH 4.0. Upon filtration, 53.7# of the zirconium re- i mained on the paper, this low yield being attributed to the high salt content or tne solution being liltered.

The zirconium was then purified by removing it from the paper with acid and titrating to pH 4.5. The lower salt content and higher pH value in this second filtration resulted in 94.2# retention of the zirconium.

M. Kurbatov, H. Webster, and J. Kurbatov (1950)

(22) studied the properties of an isotope of thorium, with the aim of developing a simple method of extracting

UX^ from uranium solutions. With this objective in mind, a study was made of the effect of concentration of the uranyl ion on the removal of removal being accomp­ lished by filtration of the thorium isotope. It was found that as the uranium was diluted from 2 x 10"^ to

1 x 10“4 gram-ions per 26 ml., at pH 3.8, the separation of UX^ increased from 10 to 60 per cent. At this same pH, 87-93 per cent of the UX^ was removed in the absence of uranyl ions. The presence of uranyl ions, theh, does interfere with separation of HX-^, but this interference is markedly decreased by reduction of the uranyl-ion \ concentration.

E. Broda and J. Erber (1950) (23) used filtration -14-

as a method of separating tetravalent manganese from

solution. Neutron irradiation of crystalline or aqueous

potassium permanganate produced radioactive manganese.

The radioactive manganese was then separated from solu­

tion in the form of the dioxide, by filtration.

In recent years, researchers at the University of

California, Berkeley, have utilized filtration in target

chemistry. In 1950, H. Haymond, W. Garrisoh, and J.

Hamilton (24) were able to separate radioactive scandium

from a titanium target by this method. A titanium tar­

get was bombarded with deuterons in the 60-inch cyclotron

at this institution, producing radioscandiura, along with

long-lived radiocalcium and radiovanadium. The target

was dissolved in a mixture of strong nitric and hydro­

chloric acid, and made basic with an ammonium hydroxide

solution containing hydrogen peroxide. The resulting

solution contained the titanium as the soluble perti-

tanate, radiovanadium as the pervanadate, radiocalcium,

and radioscandium as a radiocolloidal aggregate. This

solution was then passed through two consecutive filter

papers, which retained over 95$ of the scandium activity..

After washing with water, the scandium activity was then

quantitatively removed in ten milliliters of one-normal

hydrochloric acid. This process ^as repeated three times

to assure complete separation of the radioscandium from

the other activities present. -15-

J. Gile, W. Garrison, and J. Hamilton (1951) (25) of the University of California, Berkeley, obtained carrier-free bismuth by filtration. Lead was bombarded with deuterons in the cyclotron. The lead target was dissolved in a minimum amount of sixteen-normal nitric acid and the solution evaporated to dryness. The residue was dissolved in excess 10$ sodium hydroxide to give a clear mixture of sodium plurabate solution and radio- colloidal bismuth. After diluting, this mixture was filtered and 98$ of the carrier-free bismuth remained on the filter paper. The paper was then washed with 5$ sodium hydroxide and water, and the activity removed from the paper by washing with six-normal hydrochloric acid.

These examples show the ease and simplicity of filter paper retention in the separation of carrier-free radioactive isotopes from their target materials. Other methods of target separation are often very time con­ suming in contrast to separation by filtration, and often the half-lives of isotopes are such that the time re­ quired to separate them determines what further studies can be made. -16-

Properties of the Filter Paper

A literature survey of the properties of filter paper was made with the object of trying to relate the retention of elements by the paper with some property of the paper itself.

Although there is still some question as to the exact chemical structure of cellulose (filter paper), an indication of its structure is obtained from the fact that one can obtain a nearly quantitative yield of glucose by the hydrolysis of cellulose with sulfuric acid, as pointed out by H. Gray and C. Staud (1927) (26).

One ordinarily would not consider the chemical groups associated with a glucose-type molecule as being good ion-exchangers. However, another factor to be considered is that it is impossible to obtain cellulose entirely free of ash. P. Eona and L. Michaelis (1920) (27) point out that, even after careful extraction with hydrochloric and hydrofluoric acids, the cellulose always contains some silica (SiO^) and lime (CaO). Filter paper adsorp­ tion according to Eona and Michaelis, is a pure exchange- adsorption. The apolar adsorption of substances such as heptyl alcohol was found to be extremely small. However the adsorption of acid and basic dyes was very distinct.

In the case of methylene blue, the chloride ion remained almost quantitatively in solution, and was neutralized by calcium ion from the paper. It was the inorganic -17- contaminations, therefore, that were considered to inter­ act with the dyes by ion-exchange.

C. Kullgren (194-8) (28) also pointed out that fil­ ter paper has cation-exchanging properties, which origi­ nate from weak acid groups in the paper. Filtering dilute acid and salt solutions through filter paper, therefore, will change the composition of the paper.

In better grades of paper used for analytical work, the ash was found to be almost exclusively from the cations present.

It was found that the physical characteristics of the paper have some interesting implications in relation to this work. H. Lachs and H, Herszfinkiel (1921) (29) suggested that the charge of the filter paper is of influence in the adsorption of radioelements, and that electrolytes exert an influence in the direction in which they change the charge in electrokinetic experi­ ments. To investigate the possibilities of an explana­ tion of this type, information must be available con­ cerning the nature of this charge of the filter paper, and such information aa the sign of the charge, effect of electrolytes upon the charge, and so forth. Perhaps the best method for obtaining ihformation of this type has been experiments in electrosmosis.

Little of special interest and importance with -18- regard to electrosmosis in conducting solutions was known until J. Perrin’s work appeared (1904, 1905)

(31,31). Perrin devised an ingenious and simple electro-osmometer, which permitted the study of many different solid materials. The materials of which the diaphragms were constructed were employed in the form of a layer of a fine powder. The pulverized solid was used in the form of a cylindrical diaphragm in a vertical glass tube, which constituted one arm of a large U-tube. Platinum electrodes were sealed in close to the upper and lower extremities of the diaphragm.

The rate and direction of endosmosis, that is, the movement of the solvent in respect to the diaphragm, were determined from the movement of a liquid meniscus in a calibrated capillary, inclined slightly from the horizontal, and joining the body of the apparatus just above the diaphragm. In the following table of data, the experimental results using diaphragms other than cellulose are included, as they present additional evidence in the interpretation of this work: -19-

Nature of Nature and molar Charge of Rate of the conc. of the the Diaph­ flow of Diaphragm solution used ragm rela­ soln. in tive to soln, mmj/min.

Cellulose 1/50 HC1 neutral 0

1/500 HC1 negative 20

1/500 KOH negative 70

1/500 hno3 positive 110 A12°3 1/2500 HC1 positive 70

1/500 NaOH negative 55

1/250 NaOH negative 90

AgCl 1/500 HC1 positive 9

1/500 KOH negative 7

CrCl3 1/1000 HCl positive 95 (or HBr,HN03 ) 1/500 KOH negative 85 (or LiOH) Carborundum 1/50 HCl positive 10

1/125 HCl neutral 0

1/500 HCl negative 15

distilled HOH negative 50

1/5000 KOH negative 60

1/500 KOH negative 105

From the above table of data, one can observe that the isoelectric point for cellulose occurs at approximately pH 2. At higher pH values the cellulose is negative with respect to the surrounding solution, the degree of electronegativity increasing with the pH. From - 2 0 - consideration of his data, Perrin proposed the following rule: nThe electric potential of any diaphragm towards a solution is always increased by the addition of a univalent base." In addition to the data presented above, Perrin also studied the effect of other ions on the charge of different membranes, the results of which were discussed by L, Michaelis (1926) (32). The data presented below are a continuation of the above table of figures:

Carborundum 1/500 N KOH negative 105

1 /5 0 0 N KOH plus negative 24 0.1 N NaBr CrCl3 1 /1 5 0 U HCl positive 100

1 /1 5 0 N HCl plus positive 35 0.1 N KBr

These figures show that high concentrations of univalent ions decrease the charge of either a positive or nega­ tive diaphragm. This decrease of potential by univalent ions could be explained on the basis that the univalent

Ions added enter into competitive adsorption with the hydrogen and hydroxyl ion for the surface of the mem­ brane. As the concentration of the univalent ions be­ come large in comparison to the hydrogen and hydroxyl ion concentration, the diaphragm potential could then be affected, as indicated in the above figures. This -21- effect is more striking in the case of the much more adsorbable polyvalent ions, as shown in Perrin‘s data:

(a) Al203 1/1000 N HN03 positive 100

1/1000 N HCl positive 100

1/1000 N H2S0^ positive 15

(b) CrCl3 1/1000 N HH03 positive 88

1/1000 H HN03 plus positive 23 1/1000N MgSO^

1/1000 N HNOo plus positive 4 1/100 N CdSO^

(c) CrCl3 faintly alkaline negative 4.6 water

same plus 1/1000 negative 46 M K3Fe(CN) 6

(a) CrCl3 faintly acidified positive 59 water

same plus 1/1000 positive 2 M K3Fe(CN)6

same plus l/50 negative 20 M K3Fe(CN) 6 o o 1 — u (e) i 1/1000 H HCl positive 86

1/1000 N HCl plus positive 1. 1/2000M K4Fe{CN)6

These experiments show the effect of various polyvalent ions on the charge of a membrane. As seen in (c), as long as the diaphragm remains negatively charged, even polyvalent negative ions are without effect. But the same ions exercise, even at low concentrations, a -22-

strongly diminishing effect upon the potential of a positively charged wall, as in (d) and (e), while in greater concentration, they can even reverse the sign of the charge, as in (d). This activity rises markedly with the valence. Bivalent ions are more effective than univalent ions, and trivalent ions have a greater effect than the bivalent ions. The effect of the valence of the anions is also noticeable in experiment (a), where the anion is added, not in the form of a neutral salt, but as a constituent of the acid itself, for hydro­ chloric and nitric acid show the same activity, while sulfuric acid greatly reduces the potential of the membrane. The cations behave in a corresponding manner*

They exert an/influence only upon a negatively-charged wall, as can be seen from the following data from

Perrin’s experiments:

CrCl^ in faintly acidified positive 43 water

same plus l/lOOO positive 43 M MgCl2

CrCl3 1/1000 N KOH negative 76

1/1000 N KOH plus negative 10 1/1000 M MgCl2

AlgO^ in faintly acidified positive 41 water

same plus 1/500 positive 41.5 N Ca(H03) 2 -23-

A1203 1/500 N NaOH negative 85

same plus 1/500 negative 18 N Ca(N03 )2

Mn2°3 in faintly alkaline negative 40 water

same plus 1/500 positive 18 N Ba(N03)2

Carborundum 1/500 N KOH negative 60,

same plus l/lOOO negative 0.7 N La(N03 )3

The example of the manganese oxide membrane showed that the bivalent barium ion could even reverse the charge of the membrane.

Michaelis points out that attempts have been made to relate the sign of the charge of a surface to its dielectric constant. A rule has been formulated, known as Coehn's rule, stating that every substance becomes negatively charged with respect to another sub­ stance of a higher dielectric constant, and it becomes positively charged with respect to substances of lower dielectric constants. This rule has been found, in general, to be valid*

In 1912, J. Barratt and A. Harris (33) worked with diaphragms of parchment. In general, the results ob­ tained confirmed that of Perrin's work. It was found, that in all solutions investigated, in which the con­ centration of the electrolyte was varied from l/lOOO -24-

to l/lO molar, the solution always flowed to the cathode.

The rate of flow decreased through the following list

of electrolytes; Na^PO^, Na2S0^, NaOH, NaCl, HCl,

CuClg, and AlCl^, In the. case of copper and aluminum

chlorides, the first addition of the electrolyte caused

the rate of flow to rise to a slight maximum, but which

soon fell to zero with increasing concentrations of the

salt, even though the actual amount of the salt present

was very small.

T. Briggs, Hi Bennett, and H. Pierson (1918) (34)

devised an apparatus for studying electrical endosmosis, which was an improvement over that used by Perrin. It

consisted of a diaphragm and electrodes horizontally arranged, with the amount of flow determined by ob­

serving the movement of a bubble of air through a hori­

zontal calibrated capillary tube, which was connected

to the system. The rate of electri csl end osmosis was found to be directly proportional to the applied potential, other conditions being kept unchanged. At room temperature and .for moderate temperature changes, the rate of flow was approximately proportional to the fluidity of the liquid, indicating that moderate changes

of temperature have little affect on the charge of the diaphragm, Vfhen powdered glass was used as the diaph­ ragm, there was always a strong flow to the cathode, and no reversal of charge was obtained in acid solution -25- up to one-hundredth normal hydrochloric acid, although as the acid content increased, the flow to the cathode approached zero. In regard to polyvalent ions, the re­ sults obtained Essentially confirmed Perrin's data, and for the particular salts studied, the so-called valence rule held satisfactorily.

A. Gyemant (1921) (35) studied electrosmosis using several different types of diaphragms, including iron oxide:

water positive 10.5

0.001 N HCl positive 67

0.001 N NaOH negative 16

0.001 N NaCl or positive 23 RbCl

0.001 M M CaCl_ or positive 62 BaCl^

0.001 M a i c i 3 positive 103

The isoelectric point of Fe^O^ is# therefore, in a slightly alkaline solution, the charge being made nega­ tive only by hydroxyl-ions. Since studies have been made of the adsorption of the divalent cobalt and barium ions by hydrous iorn oxide, a comparison can be made of the adsorption of these two ions by filter paper and hydrous iron oxide.

F. Fairbrother and H. Mastin (1925) (36) studied electrosmosis caused by a carborundum diaphragm. The -26- carborundum was negative with respect to water, but be­ came positive in acid concentrations higher than N/39 hydrochloric acid. On studying tne effect of various electrolytes on electrosmosis, it was found that cations tend to annul the negative potential of the carborundum against aqueous electrolytes, and in the case of ter- and quadri-valent ions, to reverse the sign of the charge at concentrations of only a few micro-mols per liter. Anions were found to have comparatively little affect upon the potential of the diaphragm. However,- in very low concentrations of KC1 and K^SO^, the car­ borundum became, to a small degree, more negative than in water. Then, as the concentration of the potassium salts were increased, the negative potential decreased towards zero.'

The commonly-accepted explanation of the charge on different diaphragms with respect to their surrounding solutions, as pointed out by Michaells, is the theory of the electric double layer. The charge of a surface is considered to be due to a layer of ions, adsorbed from solution, which is considered to be bound to the surface. To balance this charge, a layer of oppositely- charged ions form at a finite distance from the first layer. The predominant ion of this more mobile layer is known as the counter-ion, since it balances the -27-

charge of the inner layer. Under the influence of an electric field, if the solution is positive with re­

spect to the surface, the solution will migrate towards the cathode, or if the reverse situation is the case, the migration will be towards the anode.

Perrin, due to the influence of the hydrogen and hydroxyl ions in his work, was led to the assumption that the electric double layer is formed only by the ions of the water, one layer consisting of hydrogen ions and the other of hydroxyl ions. He believed that other univalent ions did not participate in the forma­ tion of the double layer. Michaelis interpreted

Perrin's work in terms of the theory of ionic adsorption, and pointed out that the charge upon any solid wall or diaphragm depends upon the fact that it adsorbs hydrogen and hydroxyl ions to different extents. A wall which adsorbs only hydroxyl ions can, therefore, acquire only a negative charge. A wall which can adsorb either of the two ions will be either positive or negative, de­ pending upon the reaction of the adjacent solution.

The isoelectric point, that is, the point of reversal of the charge, occurs when the wall has an equal capa­ city to adsorb hydrogen and hydroxyl ions. If other ions are present, the cations will compete with the hydrogen ions and the anions with the hydroxyl ions.

However, the hydrogen and hydroxyl ions were found to -28-

be among the most adsorbable ions on the surface of

the diaphragm, thereby making up the inner layer.

The more modern concept of the theory of the

electric double layer is to consider it as a diffuse double layer, as pointed out by R. Hartman (194-7) (37).

The inner layer is fixed to the surface by surface forces, but the outer layer is considered to be made up

of mostly free ions, of both positive and negative

charges. The distribution of these ions in the outer layer is such that it balances the charge of the inner layer of ions. If the inner layer is charged negative­ ly, there would be a concentration of positively-

charged ions in the immediate region of the inner layer,

showing a gradual decrease in excess positive charges as the distance from the surface is increased, until finally, the distribution of opposite charges is equal.

Except for those ions that may be in close contact with the inner layer, the ions of the outer layer may move about as a result of thermal forces.

For electrolytes to be able to reduce the charge

of a surface, the added ions of opposite charge must

come in contact with the inner layer, thereby reducing its potential by bonding and neutralizing of the charge^ of the ions of the inner layer. Along this line of thought, Y. Glazman and D, Strazhesko (1950)

(38) have measured the amount of certain negative and -29- positive ions adsorbed by a negative-charged surface. _3 The amount of the negativeiy—charged ions, PO^ and _2 SO^ , adsorbed by the negative hydrosols of Agl,

HgS, and A a 2 ^ ^ f were determined by tagging the anions 32 3 5 with radioactive P^ and Srespectively. Both at the threshold of coagulation, and in the presence of a twofold excess of the electrolyte, the amounts of anion adsorbed were insignificant, and could play no role in coagulation. However, Sr+^ ions (tagged with radioactive Sr^^) were adsorbed to a large extent at the threshold of coagulation. Here, then, is evidence that polyvalent cations are adsorbed by a surface with a negative charge. -30-

Radiocolloidal Behavior Interpreted in Terms of the

Diffuse Double Laver Theory

An attempt will be made, at this point, to deter­ mine the feasibility of interpreting the data on radiocolloid formation and filter paper retention in terms of the theory of the diffuse double layer. The previously presented general properties of radiocolloids will be examined in light of the data which has been given on electrosmosis.

The data on dialysis can be summarized by stating that certain radioisotopes of lead, bismuth, polonium, and thorium diffuse through a membrane in acid solution, but not in neutral and basic solutions. The addition of acid increased diffusion and the addition of base decreased diffusion. This phenomenon can be explained in terms of the diffuse double layer, around foreign material, if one assumes that there is a small amount of foreign nuclei present, such as small dust particles.

This assumption approaches a certainty under normal laboratory working conditions, even though one works with solutions in triple-distilled water. From the data on electrosmosis, one would expect the foreign nuclei to be charged negatively in neutral and basic solution, and positively in acid solution. The cations, then, would not be adsorbed on the foreign nuclei in acid -31- solution, and therefore, will diffuse in a normal manner

However, as the solution is made basic, the nuclei will then become negatively charged. The radioactive cations then are adsorbed by the nuclei, and now will not diffuse through a membrane by virtue of their attach ment to a particle of colloidal dimensions.

The radiocolloidal behavior in electrophoresis experiments can be explained in a similar manner. As described previously, cations tend to migrate toward the cathode in acid solution as normally expected, but that some of the radioactive elements reverse themselves in basic solution, and migrate toward the anode. Here again, foreign nuclei present in solution may become negatively charged in basic solution, due to the diffuse double layer. The cations are then adsorbed by the foreign nuclei, and are carried toward the anode by these negatively charged particles. In acid solution, the foreign nuclei are positively charged. Therefore, the cations are not adsorbed, and migrate towards the cathode. Evidence for this explanation can be seen in

Godlewski's work, which shows that the addition of a negatively-charged colloid to a solution containing radiocolloids increased the amount of radioactivity that was transported to the anode. The addition of a negatively-charged colloid was, in effect, increasing the concentration of foreign nuclei present in solution. -32-

Thia increase resulted in a greater likelihood of ad­ sorption of the radioactive cations present, and sub­ sequently, a greater quantity of the radioactivity was transported to the anode.

Retention of a radioactive isotope by filter paper can be explained by the diffuse double layer. From the data presented on electrosmosis with a cellulose diaph­ ragm, it can be seen that the filter paper would be neutral at approximately pH 2, and would become increas­ ingly negatively charged as the pH of the solution in contact with the paper was increased. Therefore, one would expect cations to be retained on the paper in neutral and basic solution, but not in acid solution at, or below, pH .2, As previously shown, this expectation corresponds to experimental fact. It was found that some radioactive isotopes were retained on the paper in basic solution, but passed through the paper in strongly acid solution. One would expect added electrolytes to compete with the radioactive cations for paper adsorption. This has been shown experimentally. However, if the radio­ active isotope has already been adsorbed on a foreign nucleus before filtration, a different type of retention may occur, perhaps true filtration, depending upon the size of the foreign nuclei. Even if the foreign nuclei were too small for filtration, the particle could poss­ ibly be adsorbed into the diffuse double layer surrounding -33- the filter paper, by virtue of its large charge as com­ pared to other anions in solution* The data of SchBn- feld and Broda make this distinction in filter paper retention of radioactive isotopes. These investigators showed that electrolytes decreased the amount of filter paper retention of a radioisotope, but that the electrolyte did not decrease the retention of the active isotope, when the solution had been previously saturated with hydrogen sulfide.

Kadioautography has been used in the past as evidence of radiocolloids. By means of the charge of a surface, the "stars" on the radioautograph can be explained as concentrations of the radioelement upon foreign nuclei.

In line with .this explanation, there is experimental evidence that these "stars" become larger as the pH of a solution is increased, and tend to disappear as the acidity becomes greater. 0. Hahn (1936) (39) pointed out that the "stars" of a radioautograph increased in size as the acidity of a solution containing a radio­ element was decreased. The data can be explained by a- gain pointing out that foreign nuclei would become more negative as the pH of a solution is increased, resulting in increased adsorption of the radioactive material, and subsequently, increased spotting of a photographic plate.

It should be pointed out that "stars" on a radioauto- graph could result from the presence of a radioisotope -34- in true solution, even though no foreign nuclei were present to adsorb the radioelement. The reason for this statement is that E. Verwey (1935) (40) pointed out that the charge resulting from the diffuse double layer is not uniformly distributed over a surface. Instead, the charge is concentrated at points on the surface due to surface irregularities. The points of concentrated charge would result in greater adsorption of the radio­ active element, and would account for the appearance of

"stars" on the radioautograph.

Of course, sedimentation and centrifugation of radiocolloids fit well into the theory that the radio­ element may become adsorbed on foreign nuclei. Foreign nuclei, such, as dust particles, would settle with stand­ ing, carrying down adsorbed radioactive ions, and one should also be able to remove these particles by centrifugation. This has been demonstrated experiment­ ally. Added evidence for adsorption of the radioelement on foreign nuclei has already been presented, such as

Werner's work, which showed that a decreased amount of foreign nuclei resulted in a decrease in the amount of radiocolloid that could be centrifuged from solution.

Other added evidence for this interpretation is Freund- lich's calculation, showing that the size of the radio­ colloid for a particular set of data precluded the possibility of the radiocolloid consisting of only the -35- radioactive element present, or of one of its compounds.

From the preceding discussion, it appears that radiocolloid formation and filtration can be well ex­ plained in terms of the diffuse double layer. The author wishes, therefore, to propose this theory as the explanation of the above phenomena. Besides the objectives already stated, the experimental sections of this work will aim to provide evidence for or against the diffuse double layer explanation of filter paper retention of cobalt, barium and zinc. —3 6—

EXPERIMENTAL PROCEDURE

Target Chemistry

This work involved the use of several radioactive isotopes as tracers. Tracer methods were necessary as the concentrations of the solutions studied were very low* The following paragraphs list the source, type of radiation, and method of separation of the radioactive isotopes that were used in this study.

Cobalt-60, T^/2 (half-life) = 5.3 years, disinte­ grates by emission of electrons of 0.31 Mev. (upper energy level), and by two gamma rays of 1.1 and 1.3

Mev. The cobalt-60 was obtained from the Oak Ridge

National Laboratories, Oak Ridge, Tennessee, where co­ balt wire was activated with neutrons to produce the cobalt-60. The cobalt sample had a specific activity of 1.8 curies/gram in Dec. 1951. The cobalt, which was used in this study; had been purified by G. Wood (1950)

(43). The purification procedure was reported by M.

Kurbatov, G. Wood, and J. Kurbatov (1951) (41) ’• The sample of cobalt wire was washed to remove surface impurities, weighed, and dissolved in aqua-regia. The solution was diluted, and a fraction removed for deter­ mination of the activity per unit weight of cobalt wire.

The remaining cobalt solution was brought to pH 2 and treated with dithizone to remove any copper impurities -37-

present. Less than 0.1 per cent of the total activity was lost in this purification. The cobalt was precipi­

tated by addition of a solution of acetic acid, which was saturated with alpha-nitroso-beta-naphthol. The precipitate was dissolved in aqua regia, and the solu­

tion freed of nitrate ion by treatment with hydrochloric acid. The cobalt was dissolved in 0.01 N hydrochloric

acid, and diluted so that one milliliter of tracer

contained 1.4 x 10”^ gram atom of cobalt.

Barium-133f T^/2 = 3S.8 hours, disintegrates to

cesium by K-capture and an emission of a gamma ray of

0.3 Mev, The barium-133 was obtained by bombarding cesium chloride with 15 to 20 Mev. deuterons in the cyclotron at the University of California, Berkeley. The

target material was dissolved in hydrochloric acid, and evaporated to dryness to remove excess hydrochloric acid. This residue was dissolved in distilled water* and a small amount of ferric chloride added. The solu­ tion was made basic at pH 10 to 11 with ammonium hydrox­ ide. In this pH range, the hydrous iron oxide, which is formed and precipitated, adsorbs the radioactive barium from solution. The hydrous iron oxide and the adsorbed barium were then filtered from solution. The precipitate was dissolved in hot one normal hydrochloric acid, and brought to pH 5 to 6 by slowly adding ammonium -38- hydroxide until hydrous iron oxide began to form. After allowing the precipitate to coagulate well, the hydrous iron oxide was filtered from solution, leaving carrier- free barium-133 in solution. This process of adsorption of the barium by hydrous iron oxide was repeated two times to insure completeness of the separation. The solution containing the radioactive barium was evaporated to dryness, and the ammonium chloride removed by sub­ limation. The remaining carrier—free barium-133, in the form of the chloride, was dissolved and diluted to fifty milliliters with 0.01 normal hydrochloric acid.

To check on the efficiency of the separation, ten milliliters of the tracer solution was evaporated to dryness. The remaining solid residue weighed less than

0.1 milligram. The decay curve of the remaining activity was followed through several half-lives, and determined to be 39 hours, which compares favorably with the reported value of 38.8 hours for the half-life of barium-133.

Zinc-60f T^ / 2 zs 250 days, decays by K-electron capture, and emits a gamma ray of 1.12 Mev. intensity.

Zinc metal was irradiated with neutrons in the pile at

Oak Ridge, Tennessee. The original shipment consisted of the target dissolved in four milliliters of hydro­ chloric acid, and contained 15 microcuries of activity. -3v-

Prof. Thomas R. Sweet, of the Department of Chemistry,

The Ohio State University, kindly donated a portion of

this activity for use in this study. In making up the

dilution used in this work, 0.1 milliliter of the

original shipment was evaporated to dryness, and found

to weigh 0.0278 gram, or 2.04 x 10“^ mole of zinc

chloride, assuming the residue to be anhydrous ZnCl^.

This residue was then dissolved and diluted with 0.1

hydrochloric acid to a volume of one hundred milliliters.

Other dilutions were made as required from this source

of activity.

Cesium-131, ^ 1 / 2 = 10.2 days, decays to zenon by

K-electron capture, emitting a 0.145 Mev. gamma ray in

the process.- The cesium-131 was obtained by bombarding

solid barium nitrate with neutrons in the pile at Oak

Ridge. Barium-131 is produced from barium-130 by an m,5f reaction. The barium-131 decays by K-electron cap­

ture to produce cesium-131. In the first step of the

separation of the cesium from the barium, advantage is

taken of the fact that barium chloride is only slightly

soluble in hydrochloric acid, whereas cesium chloride is more soluble. The target was dissolved in hot con­

centrated hydrochloric acid, the solution rapidly cooled with dry ice, and the precipitate of barium chloride filtered from solution. The filtrate containing the - 4 0 -

cesium—131 was then evaporated to dryness. The second

step of the separation made use of the fact that cesium

chloride is very soluble in alcohol, whereas barium .

chloride is not. The residue from the evaporation was

dissolved in hot water, the solution cooled rapidly,

and an equal volume of alcohol added. The solid barium

chloride was centrifuged from solution. This second

step was repeated three times to assure efficient re­ moval of the barium from solution. At this point, fifty milligrams of common barium chloride were added to aid in removing radioactive barium. The solution was neutral­ ized with sodium hydroxide, and barium carbonate pre­ cipitated from solution by addition of ammonium carbonate.

The remaining solution was then treated with ferric chloride in the same manner as described for carrier- free barium—133. This procedure of removing the remaining barium from solution by adsorption on hydrous iron oxide was repeated several times to remove last traces of the barium. The solution containing the cesium-131 was then evaporated to dryness, dissolved., and diluted to fifty milliliters with 0 . 0 1 normal hydrochloric acid.

To check the purity with respect to the radioactive isotopes present, the decay curve was followed through several half-lives, and the half-life determined to be

1 0 . 0 days. This value compares favorably with the re­ ported half-life of cesium—131. The amount of inactive — 4.1— foreign substances was determined by evaporating ten milliliters of the tracer solution to dryness. The weight of the solid residue was 1.7 x 10“^ gram/milli­ liter.

Chlorine-36. T^y^ = 2 x 10^ years, was also used in this study. This radioisotope decays by beta- emission, which has an upper energy of 0.65 Mev. This radioisotope was produced by neutron irradiation of potassium chloride at Oak Ridge, and the chlorine iso­ tope was shipped and used in the form of a hydrochloric acid solution. -42-

Experimental Technique

Since this study involved working with solutions

of very low concentrations, extreme care was necessary

in regard to the cleanliness of the equipment used.

All glassware was carefully washed and rinsed in single-

and double-distilled water. Reagents used in this

study were prepared with triple-distilled water. The

water used in the experiments was also triple-distilled.

Samples were prepared by pipetting the tracer into a

container, diluting with triple distilled wqter, and

titrating with ammonium hydroxide to the desired pH

value, as measured by a Leeds and Northrup pH meter.

In each experiment, the total volume of the sample was

thirty milliliters. The container used was an outside

ground weighing bottle. The inside diameter of the bottle

was :30 millimeters, its height was 60 millimeters, and

it had a capacity of 33 milliliters. The containers

with their contents were tightly capped by greasing

the ground-glass fittings with Vaseline, and allowed to

stand three days before filtration. When it became ap­

parent that allowing the solution to stand three days

had no effect upon the retention of the filter paper,

as compared to filtration within ten minutes after

titration, one hundred milliliter beakers were used in place of the ground-glass weighing bottles, as the -43- weighing bottles were found to be difficult to pour from. The samples were filtered within ten minutes after titration.

Samples were filtered through Schleicher and Schttll

blue ribbon analytical filter paper, using three-centi­

meter glass funnels. The grade number of the paper was

589, and paper of this same grade number was used

throughout this work. This particular grade of paper

is designed by the manufacturere for the filtration of

finely divided crystalline materials, such as barium

sulfate and calcium oxalate. The ash content of the

paper was 0.007%. The diameter of each circle of paper

was 4.75 am. In each case, the filter paper was fitted

into the funnel by washing with hot, distilled water.

The paper was then washed with a solution of the same

pH value and salt content as the sample to be filtered.

After filtration of the sample, the paper was transfer-

ed to another glass funnel, and the activity that had

been adsorbed on the paper was washed into a small glass

sample holder by pouring five milliliters of hot six-

normal hydrochloric acid through the paper, which re­

moved essentially all of the activity from the paper.

The sample was then evaporated to dryness under a heat

lamp, and the activity of the dry sample measured by

means of a Geiger counter. In some cases, portions of

the filtrate were also evaporated and their activities "44" measured as a check on the measurements of the activity removed from solution by the paper.

It was found that under certain conditions, the glass container adsorbed a considerable amount of the activity from solution. To determine the extent of the adsorp­ tion in each experiment, the glass container was rinsed with five milliliters of hot six-normal hydrochloric acid, and the acid then poured into a sample container. The sample was evaporated to dryness as previously described, and the activity of the sample measured as before.

The temperature at which the experimental work was conducted was 27 I 1° Centigrade.

The glassware which was used in this work was de­ contaminated by heating it in six-normal hydrochloric acid. This equipment was then thoroughly washed in dis­ tilled water, and it was found that this treatment removed all traces of radioactivity.

In the removal of the cobalt, barium, and zinc from solution by the filter paper, the author was concerned with distinguishing between adsorption and retention by the soaking-up of solution by the paper, which will be henceforth referred to as absorption. To determine the extent of this absorption, several dry filter papertr were weighed, and reweighed after treatment identical to that encountered in a regular experiment. The in­ crease in weight was then the weight of solution absorbed. Experiment Weight of Weight after Weight of ab- No. dry paper filtration sorbed soln.

1 0.152 g 0.490 g 0.338 g

2 0.150 g 0.503 g 0.353 g

3 0.148 g 0.480 g 0.332 g

From the above figures, the average amount of solution

absorbed by the paper is 0.34 gram, or considering the

density of water at 27 degrees Centrigrade, the paper

absorbs 0.34 milliliters of solution. Since the total

volume of solution per experiment is thirty milliliters,

this represents 1.1$ of the total solution. Since this

percentage is well within pipetting and counting error,

absorption of the filter paper is neglected in this work.

In regard to counting technique, the glass dish con­

taining the dry sample to be counted was placed in a

holder, which was so designed that all samples would be

in the same geometrical position with relation to the

Geiger tube window. It is known that the efficiency

of a Geiger tube decreases as the intensity of a radio­

active source increases. To determine if this was a

factor to be considered in the usual counting range of

this work, the following experiment was carried out,

which is also a check on the accuracy of the pipetting

of tracer solution. The samples .were counted for a period

of ten minutes each, and the tracer used was cobalt-60. V olume of counts/min. Average of Ratio tra cer duplicate exp.

2 ml. 2230

2 ml. 2375 2302 1.000

1 ml. 1153

1 ml. 1145 1152 0.500

1/2 ml. 586

1/2 ml. 570 578 0.251

The above figures for two milliliters of tracer solution show that the combined error of pipetting and counting can account for a 6 % difference in two samples of tracer solution. However, the figures for the l/2 ml. and 1 ml. tracer volumes show a difference of less than

3%, A comparison of the averages for the different volumes of tracer solution shows that the counting rate of the 1/2 and 1 ml. volumes of tracer is in good agree­ ment with the expected counting rate, based on the count­ ing rate for the 2 ml. volume. This indicates that counter efficiency is not a significant factor under these experimental conditions. If one considers the average counting rates as the true counting rates per unit volume, the individual measurements of each sample then agree with this average rate within 3%.

To determine the amount of activity that was added to an experimental solution, the same volume of tracer -47- solution was pipetted into a sample holder, evaporated to dryness, and neasured as previously described. The working condition of the Geiger counter was checked be­ fore making any measurements by counting a "standard", which consisted of a sample with a long half-life and a known counting rate. The background was determined at the time of each counting, and was subtracted from each sample measurement. -48-

EXPERIMENTAL RESULTS AND THEIR DISCUSSION

Adsorption of Divalent Cobaltf Barium,, and Zincf on

Filter Paper.

The experimental work of this section was devoted mainly to the study of the effect of pH on filter paper retention of cobalt, barium, and zinc.

Dependence of Cobalt Adsorption on pH. The first series of experiments were carried out by titrating an aqueous solution of cobalt chloride to various pH values, using either hydrochloric acid or ammonium hydroxide.

The concentration of the cobalt was 1.4 x 10*"^ gram atom/30 ml., and the total volume of the solution in each experiment was 30 ml. The solutions were filtered after standing for three days, and the amount of adsorp­ tion by the paper was measured.

The experimental results, listed in Table I, show that cobalt is capable of retention by filter paper ffom very dilute solutions. This point is significant in that previous reports of retention by paper usually con­ cerned radioactive isotopes in an oxidation state of three or more. This work shows that cobalt with an oxidation sta.te of two is also capable of paper retention, which increases the scope of target separations by fil­ tration.

The results of this series of experiments show that neither the addition of hydrochloric acid or ammonium Table I

Effect of pH on Cobalt Adsorption after Three-day Standing

Paper Adsorption Type of Solution pH counts/min % of total water and HC1 3.51 64 6.0 water and HC1 4.71 341 32.0 water 6.58 719 67.5 water and NH^OH 7.20 720 67.5 water a nd NH^OH 8.64 686 64.4 water and HH.OH 9.26 618 58.0 4 water and NH4OH 10.17 29 2.7

Constant Factors: Co, 1,4 x 10"*^ gram atom; 1065 counts/min,

volume, 30.0 * 0,2 ml,; 27°C, -50-

hydroxide is necessary for filter paper retention,

since a large per cent of retention of the activity was

obtained from a water solution.

The results of the preceding series of experiments

are presented in graphic form in Figure 1, in order to

make comparisons more easily with other experimental data

The next set of data using radioactive cobalt chlor­

ide was obtained to determine if filtration within ten

minutes after titration would affect the percentage retention of the cobalt by the paper, as compared with allowing the solution to stand three days before filter­

ing. If the retention of cobalt by the filter paper was due to the formation of colloidal particles, and if time was required after titration for these particles to grow

to colloidal'dimensions, then one would expect a lower per cent adsorption on paper when filtering within ten minutes titrating, as compared to three-day standing.

The concentration of the cobalt used in this experiment

“ 9 was 1.4 x 10 gram atom/30 ml. The walls of the glass beaker were also checked for possible adsorption of radio activity.

The experimental data in Table II show that a con­

siderable amount of the cobalt was adsorbed on the walls

of the beaker at high pH values, even though the time

of contact between the solution and the container was Per Cent Adsorption r 0 9 80 - 0 7 0 4 60 30 50 20 iue Efc o p o Ppr dopin f Cobalt. of Adsorption Paper on pH of Effect I Figure Co, 1.4 x I0"9 g. atom g. I0"9 x 1.4 Co, uain 3“dy standing day “ 3 Duration, ml. 30 Vol., ep, 27°C. Temp.,

pH cn i Table II

Effect of pH on Cobalt Adsorption on Paper and Glass with Filtration within

Ten Minutes after Titration

Paper Adsorption Retention of glass Paper Retention corrected for Tyne of Solution J2& counts/min. % counts/min. % glass retention (%)

Water and HC1 5.40 27 2.5 935 87.8 90.0 CO c°v water 6.51 41 • 1021 96.0 99.8 water and NH OH 7.60 71 6.7 925 86.7 93.0 A water and NH^OH 8.54 157 14.7 747 70.1 82.2 water and WH^OH 9.55 165 15.5 692 65.0 77.0

Constant Factors: Co, 1.4 x 10~^ gram atomj 1065 counts/min.j 30.0 I 0.2 ml.j

27°C. -53- a matter of minutes. In subsequent experiments, the activity adsorbed by the container walls was measured

in each experiment. The measured value for the per cent retention by the paper was then corrected for the amount retained on the beaker walls, in order to obtain per cent retention of the paper in terms of the amount of cobalt that actually came in contact with the paper.

All plotted values for retention of the paper were cor­ rected for beaker adsorption with the exception of Fig­ ure 2. Figure 2 is discussed later.

The experimental fact that the retention by the paper from a water solution at pH 6.5 was close to one hundred per cent indicates that allowing the solution to stand for three days does not increase per cent re­ tention by the paper, as compared to filtration within ten minutes after titration. The comparatively lower values for filter paper retention, when the active solu­ tion was allowed to stand three days before filtering, could be ascribed to higher adsorption by the glass container, due to a longer time of contact with the solution. This point is demonstrated in the next series of experiments, which were similar to the preceding ones except for one modification.

In the next experiments, in which the solution was allowed to stand three days before filtering, the solution was filtered two times, with one funnel placed directly -54- below the other. If radiocolloids are formed, the first paper should remove the particles formed over a period of three days, and the second paper would filter a solu­ tion in which there would be much less time for particle formation. In the following series of experiments, one milliliter of 0.01 N hydrochloric acid was added to the solution in each case, in order to provide constant chloride ion concentrations. Sufficient ammonium hy­ droxide was then added to obtain the required pH value*

The activity of the filtrate was measured in order to determine the accuracy attainable at these low concen­ trations. The radioactivity measured in the filtrate was then added to that of the glass and paper in an attempt to account for all of the activity that was added to a solution. The concentration of the cobalt was increased to 2.8 x 10“^ gram atom/30 ml. in order to facilitate counting under these conditions.

Consideration of the column in Table III titled

"total percentage accounted for" shows that one is able to account for all activity added to the solution, with a maximum error of ten per cent at pH values below eight.

At higher pH values, the amount of activity that is un­ accounted for increases, corresponding to the increase in adsorption by glass. The retention of activity by the two glass funnels was not taken into account in this study. The data for the last part of Table III were Table III

Adsorption of Cobalt by Successive Filtrations after Three-day Standing

ain't, retained ain't, retained ain't, retained am't, in by the glass by 1st paper by 2nd paper filtrate total % counts/rain. % counts/min. % counts/min. % counts/min. % a ccounted

3.66 4 0.2 174 8.2 133 6.3 I960 92.0 106.7

4.87 13 0.6 604 28.4 800 37.5 946 43.9 110.4

5.62 432 20.3 952 44.7 540 25.4 400 18.8 109.2

6.22 70 3.3 1461 68.5 546 25.6 186 8.8 106.2 i Ul 6. 98 141 6.6 1360 64.0 532 25.0 131 6.2 101.8 VJl I 7.70 284 13.3 1050 49.4 490 23.0 253 11.9 97.6

8.50 822 38.6 690 32.4 133 6.3 77 3.6 80.9

9.48 938 44.0 402 18.9 151 7.1 496 23.3 93.3

9.94 951 44* 6 41 1.9 70 3.3 462 21.7 71.5

(continued on next page) Table III (continued)

% on 1st Paper % on 2nd Paper corrected for ain’t corrected for am't. on £H on beaker beaker & 1st Paper X/l-X

3.66 8.2 6.8 0.00201

4.87 28.6 53.0 0.00605

5.62 56.0 72.5 0.255

6.22 70.8 90.8 0.0342

6.98 68.5 85.0 0.0706

7.70 57.0 61.6 0.154

8.50 52.9 21.7 0.630

9.48 33.8 19.1 0.785

9.94 3.4 6.2 0.806

Constant Factors: Go, 2.8 x 10“^ gram atom; HC1, 1 x 10~^ mole;

2130 counts/min.; 30.0 * 0,2 ml.; 27° C. Table III (continued)

Am't retained Am't retained % on Paper on bottle. pH counts/mi n. % counts/min. % bottle reti

9.28 664. 31.6 562 26.8 39.2

9.39 627 29.8 • 537 25.6 36.5

9.60 901 43.0 292 13.9 24.4

9.72 1126 53.6 258 12.3 26.5

9.81 1042 49.7 236 11.2 22.2 i VJl -O 9.96 231 11.0 292 13.9 15.6 1

10.06 218 10.4 283 13.5 15.0

Constant Factors : 2100 counts/min. ; other factors same

as preceding part of table. -58- obtained five months after the data in the first two parts of the table.

A graphical presentation of percentage retention of the glass bottle, filter papers, and filtrate is shown in Figure 2. It is of interest to compare Figure

2 with Figure 1. Maximum retention of the cobalt occurred at pH 6.5 in each case. The curve of Figure 2 drops off more sharply than for Figure 1, which could be caused by interference from the additional salt that is present in the second series of experiments as a result of the addition of one milliliter of 0.01 N hydrochloric acid to each experiment.

In making a comparison of the retention of the first and second papers, it can be seen that the first paper retained the larger amount of cobalt. However, in order to make a significant comparison, the per cent retention of the amount of cobalt that came into contact with the respective papers should be considered. These data a^e in Table III, and are plotted in Figure 3 for purposes of comparison. It can be seen that the two curves are similar in appearance, with the second paper somewhat more efficient in removal of the cobalt. The data show that allowing the titrated solution to stand for three days did not increase the per cent retention of the cobalt, on the first paper, as compared to the second paper, which filtered a solution that had stood 9 0 Co, 2.8 x 10 g. atom Vol., 30 ml. 80 Temp. 27°C. Duration, 3~day standing HCI, 1.0 x I0~5 mole 70

60 —o— glass bottle — 1st paper 2nd paper i 50 — Filtrate cn i 40

30

20

10

0 2 3 4 5 6 7 8 9 10 pH Figure Z Effect of pH on Cobalt Adsorption by Glass and Paper. Per Cent Adsorption of the Cobalt in Contact with Paper 0 9 0 4 0 5 0 3 0 6 0 8 20 0 7 iue Efc o p o Asrto o Cbl b Scesv Filters. Successive by Cobalt of Adsorption on pH of Effect 3 Figure o. 30 ml. atom g. 0 3 9 Vol., 10 x 2.8 Co, ep 27°C. 7 2 Temp. uain 3dy standing 3~day Duration, C, . x 05 mole I0“5 1.0 x HCI, s paper 1st o n paper 2nd •

pH GO- [

-61-

a matter of minutes.

Since the curve for the adsorption of glass in Fig­

ure 2 resembled a mass action curve, special attention

was given these data. In Table III, is per cent ad­

sorption by the glass. In Figure U» l°g]_o is

plotted as a function of pH, and appears to be a straight

line function with a slope of 0.5. An equation can be

written for this straight line in terms of an equili­

brium constant: (brackets are used to indicate concen­

tration)

logX/(l-X) = m(pH) + log Keq m = slope = l/2

Keq = X/(l-X) /-H3 o ; 7 1^

The above equation would result if there were an equili­

brium reaction, as follows:

Cosoln. ^ Coadsorbed + 1>/2 H3° +

This experimental behavior fits in well with the diffuse

double layer theory. Experiments on electrosmosis show

the charge of glass towards an aeqeous solution becomes

negative, and increasingly so, as the pH becomes greater

than approximately two. This increasing degree of

electronegativity was reflected by a greater adsorption

of the positively-charged divalent cobalt ion, as the

pH was increased.

The retention of the paper also fits into the dif­

fuse double layer theory. Paper becomes negative with y / d - y ) iue * fet f H n oat dopin y Glass. by Adsorption Cobalt on pH of Effect 4* Figure o . I" . atomg. I0"9 x 2.8 Co, uain 3-day - 3 Duration, ml. 30 Vol., C , . x I0~5mole x 1.0 HCI, ep, 27°C. Temp., 4 5 6 - 2 3 ( -

pH

8 97 -63- respect to the surrounding aqueous solution at pH values higher than approximately 1.7. The degree of electro­ negativity increases with pH. On examination of Figure

3, it can be seen that the paper begins to retain appreci­ able amounts of cobalt at approximately pH 3, with the amount retained by the paper increasing with pH.

The drop in adsorption by the paper at pH values higher than 6.5 would not be expected from consideration of the charge of the paper. However, it is possible that this drop in adsorption of the cobalt is due to the formation of cobalt-ammonia complexes in solution.

More attention will be devoted to this point after data on barium and zinc have been presented. -64-

Dependence of Barium Adsorption on pK. The first

objective of the next series of experiments was to de­

termine if barium was retained by filter paper. Several interesting comparisons can be made by a study of both barium and cobalt. A comparison can be made between the behavior in very dilute solutions of a strongly- basic and a weakly-basic element with an oxidation state of two. Also, cobalt complexes quite easily with ammonia on a macro-scale, whereas barium has little tendency to complex at the ammonia concentrations util­ ized in this work. From comparisons of this type, one may be able to deduce more about the cause, or nature, of filter paper retention.

One milliliter of tracer solution in 0.01 N hy­ drochloric acid was used in each experiment, and the solution was filtered within ten minutes after titra­ tion. Since the half-life of the barium isotope used was thirty-nine hours, there was appreciable decay of the activity during an experiment. To find the per cent retention by.the beaker and the filter paper, the measured amount of activity added to a given experiment was corrected for decay to the actual counting time of the sample containing the activity retained by the beaker or paper. The correction was made by plotting a decay curve for barium-133, and reading the total count -65- remaining for an experiment at any given time.

In Table IV, the term "tracer" is used to denote the concentrations of barium obtained from the separa­ tion of radioactive barium from a cesium target. The

4 data in Table IV show that, like cobalt, barium was re­ tained by filter paper. It should be pointed out that the preceding experiments were conducted over a period of three days, which resulted in a difference in the total count in each experiment. However, it can be seen by consideration of Figure 5# a plot of per cent reten­ tion of the paper versus pH, that the results appear to be consistent. It appears, then, that per cent reten­ tion was not affected by the changes in concentration which resulted from decay. In order to obtain a further check on the accuracy attainable in this work, the acti­ vity of the filtrate was checked in some of the experiments, the results of which are shown in Table IV, The total per cent accounted for was the combined measured retention of activity by the paper, beaker, and filtrate.

For comparison with the previous work on cobalt, another experiment on barium was performed. In this ex­ periment, stable barium chloride was added giving a barium concentration of 2.8 x 10”^ gram atom/30 ml. This concentration was the same as that of the cobalt in the last experiment on cobalt.

The results obtained are tabulated in Table V. Per Table IV

Effect of pH on the Adsorption of Barium in Concentrations less than 1 x 10 g. atoms/^n m

Am't. retained A m ’t. retained $ on Paper A m ’t. in Total % by beaker by paper corrected for filtrate a ccounte d pH counts/min. % counts/min. % am't. on beaker counts/min. % for

3.26 14 0.4 139 6.2 6.2

3.73 52 0.6 738 8.1 8.1

4.60 16 0.8 639 30.2 30.4

4.68 16 0.8 627 29.6 29.8

5.51 162 1.8 3316 36.4 37.1

6.61 314 3.5 3790 41 * 8 43.4 4460 49.4 94.7

7. 51 69 3.3 905 42.1 43.6 910 43.5 88.9

7.70 71 3.2 856 41.2 42.6 935 45.1 89.5

8.63 605 6.7 3877 43.3 46.4 4340 48.6 98.6

9.69 469 5.3 3317 37.3 39.4

10.13 374 7.8 1081 22.6 24.5

Constant Factors: Ba, 1 ml. of tracer soln.; HC1, 1 x 10”5 mole; 30.0 £ 0.2 ml.;

27°G. Ba, tracer conc. Vol., 3 0 ml. Temp., 27°C. HCI, 1.0 x I0” 5 mole

o o

I_____ i l I______L 6 7 8 9 10 pH Figure 5 Effect of pH on PaperAdsorption of Barium. Table V

Effect of pH on Barium Adsorption (Stable Barium Added)

A m ’t. retained Am't. retained % on Paper on beaker on paper corrected for nH counts/min. % counts/min. % beaker retention

3.94 18 0.6 263 9.2 9.3

4.80 44 1.5 659 23.1 23.4

6.26 30 1.6 836 43.6 44 • 4

6.63 50 2.6 881 45.6 46.9 68

7.89 96 3.4 12 94 45.7 47.3 -

9.23 171 6.1 1141 40.5 43.1

10.33 178 6.3 696 24.8 26.4

Constant Factors: Ba# 2.8 gram atom; HC1, 1 x 10”^ mole;

30.0 * 0.2 ml.; 27°C. -69- cent retention by the paper, which was corrected for beaker adsorption, was plotted versus pH in Figure 6.

Comparison of Figures 5 and 6 shows that they are es­ sentially the same curve. There was no difference, then, in paper retention after the addition of stable barium of a concentration of 2.8 x 10""^ gram atom/30 ml. Com­ parison of the two curves also shows that the results of this type of an experiment are quite reproducible, within the range of error which was previously given.

Some interesting comparisons can now be made be­ tween the adsorption of barium and cobalt. The barium was less adsorbed on both the glass and filter paper.

Under similar conditions, the maximum adsorption by paper for barium and cobalt were 4-7 and 71 per cent respec­ tively. In comparing the per cent adsorption versus pH curves for barium and cobalt as plotted in Figures 3 and 6, it can be seen that adsorption begins and reaches its maximum at the same pH in both cases.

A notable difference between the adsorption of co­ balt and barium was that the adsorption of cobalt drops quite sharply after it reaches its maximum at approxi­ mately pH 6.5. On the other hand, the curve of per cent retention versus pH for barium levels off after it reaches its maximum at this same pH, and only decreases somewhat in the vicinity of pH 10.3. Since barium has little tendency to complex with ammonia, particularly Per Cent Adsorption 90 0 6 0 8 0 7 30 0 4 50 20 iue 6 Figure fet f H n dopin f aim Sal Bru Added. Barium Stable Barium, of Adsorption on pH of Effect 2 3 4 5 6 7 C , . x 05 mole I0"5 x 1.0HCI, Temp., 27°C. Temp., ml. atom g. 30 Vol., 10"9 x 2.8 Ba, *^g". 8 9 10

12 -71-

at the low concentrations of ammonia used in this work, and since cobalt complexes quite readily with ammonia,

the sharp dropping-off of the cobalt adsorption may be attributed to ammonia complexing. The lowering of the adsorption of barium around pH 10.3 may be the result

of interference by ammonium ions. The ammonium ions would be in considerable excess of the concentration

of the barium ions, as one titrates to pH 10.3 with ammonium hydroxide.

Adsorption of the barium by the glass beaker in­ creased with pH, as in the case of cobalt. -72-

Dependence of Zinc Adsorption on pH. Zinc was

the third element with an oxidation state of two to be

studied. The concentration of the zinc was 8.16 x 10 — ft

gram atom/30 ml., and the solutions were filtered within

ten minutes after titration. The results of this series of experiments are listed in Table VI. The last four experiments listed in Table VI were carried out a month after the other data were obtained. The per­ centage retention of the paper, which was corrected for beaker retention, was plotted as a function of pH in Figure 7. Data for this curve were obtained from experiments which were carried out on three successive days.

Again it can be seen that adsorption by the glass increases with pH. Comparison of these data with glass adsorption of cobalt and barium shows that these three elements, arranged in order of increasing adsorption by glass, are barium, cobalt, and zinc. Maximum filter paper retention for these elements also shows this same order. Zinc is more adsorbed, even though the concen­ tration of the zinc in solution was higher than either cobalt or barium. It is of interest to compare this order of filter paper adsorption with the results of T.

Kressman and J. Kitchener (1949) (42), who studied the exchange of these three cations with a synthetic phenol- sulphonate resin. These investigators found the order of Table VI

Effect of pH on Adsorption of Zinc

Am't. retained Am't. retained ^ on Paper on beaker on filter paper corrected for £H Counts/min. % counts/min. % Beaker retention

3.51 3 0.5 , 69 10.1 10.2

4-*49 8 1.3 239 37.4 37.9

5.50 7 1.1 436 68.1 69.0

6.42 19 3.0 547 85.5 88.2

7.20 28 4.4 522 81.5 85.1

7.84 65 10.0 476 74.5 82.8

8.50 195 30.5 351 55.0 79.0

9.08 317 49.5 240 37.5 74.3

9.70 274 42.9 197 30.8 53.9

10.50 248 3 8.8 54 8.5 13.6

Constant Factors: Zn, 8.16 x 10~® gram atom; HC1, 1 x 10“*’ mole

64.O counts/min. j 30.0 1 0.2 ml.; 27° C. Table VI (continued)

Am’t. retained Am’t. retained $ on Paper on beaker on filter paper corrected for £H counts/min. % Counts/min. % Beaker retention

5.00 23 3.3 334 55.0 57.1

9.90 265 43.6 .139 22.9 40.6

10.13 289 47.6 104 17.1 32.7

10.30 260 42.8 77 12.7 22.2

Constant Factors: 607 counts/min.j other factors same as

preceding part of table. Per Cent Adsorption 0 9 0 8 0 6 70 0 4 50 0 3 20 iue fet f H n ae Asrto o Zinc. of Adsorption Paper on pH of Effect 7 Figure n 81 x 08 . atom g. I0"8 x 8.16 Zn, C , . x 05 mole I0“5 x 1.0 HCI, ml. 0 3 Vol., ep 27°C. 7 2 Temp.

PH - 5 7 - 76-

these elements, In terms of increasing exchange with the

resin, to be zinc, cobalt, and barium. These results

show, then, that the order of relative adsorption on

filter paper was the direct reverse of that for a cation-

exchange system, in which a sulfonic acid resin was used.

On the other hand, if one compares the results obtained

in this work with the adsorption of barium and cobalt

on hydrous iron oxide, it is found that the order of

adsorption is the same as for paper retention. G. Wood

(1950) (4-3) found that more cobalt adsorbed on hydrous

iron oxide than barium.

Upon examination of the plot of per cent retention

of the paper versus pH in Figure 7, it can be noted that

the adsorption begins at approximately pH 3 and reaches its maximum at pH 6,5. These same results were obtained with barium and cobalt, which further supports the theory that the pH of maximum retention was due to the charge of the paper, and not to any particular ion-type in solution. According to the diffuse double layer theory, the sign and amount of the charge of the paper is determined by the relative amount of hydrogen and hy­ droxyl ions in solution. Therefore, the percentage retention of the paper would be expected to be a function of pH, which was found to be the case up to pH 6.5. The drop in the curve at higher pH values again can be interpreted as iirfcerference with the paper adsorption -77- by ammonia eomplexing in solution, since it is known that the zinc ion will complex with ammonia.

The adsorption data for zinc and cobalt, obtained between pH 9.3 and 10.5, were plotted as log y/(l-y) versus log ammonia concentration in solution in Figures

8 and 9. The slopes of the curves for the zinc and co­ balt in this pH range were found to be -1 and -0.8 re­ spectively. The K-value calculated from the curves was -3 2 x 10 for both the cobalt and the zinc. J. Bjerrum

(1941) (44) give constants of 9.9 x 10"^ and 6.2 x 10"^ for the followihg reactions in solution:

Co (NH^ ) ++ fesy Co++ +

Zn(NH3 )++ 4 = ^ Zn + + +

It should be noted that the order of increasing maximum adsorption of barium, cobalt, and zinc is the order of decreasing relative solubility of their re­ spective hydroxides. This is also the order of decreas­ ing basicity for these elements. Since the inner layer of the double layer is thought to consist primarily of hydroxyl ions, when a surface is negative with respect to a surrounding aqueous solution, it is possible that adsorbed cations would combine with some of these hy­ droxyl ions* Logloy/(l-y) - 0.4 -0 - - 0.4 H.O 0.2 0.0 0.6 0.8 0.2 0.6 0.8 iue Efc o Amna ocnrto o Ppr dopin f Zinc. of Adsorption Paper on Concentration Ammonia of Effect FigureS 1 - 8 -7 -6 -5 -4 -3 - I 0 -I -2 3 - 4 - 5 - 6 - 7 - -8 -9 -10 Loglo [NH3] Loglo o. 30 ml. atom g. 0 3 I0“8 Vol., x 8.16 Zn, C , . x 0 5 I0~ x 1.0HCI, 27°C. Temp., -o g. mole g.

-\i 00 i 1 Log,0 y/(l~y) - - - 0 . 1 - -0.4 - -1.4 0.6 0.8 02 0.4 0.0 0.2 1.2 iue Efc o Amna ocnrto o Ppr dopin of Adsorption Paper on Concentration Ammonia of Effect 9 Figure -10

-9 Cobalt.

-8 -7 Log -6 ,0 [nhJ -3 4 - 5 - o. 30 ml. 0 3 Vol., o I~ g atom g I0~9 x 8 Co,2 C , . x 05 mole g I0“5 x 1.0 HCI, uain 3-days - 3 Duration, °C. 7 2 Temp. •o -2

O - 9 7 -80-

Effect of Concentration on Adsorption by Paper.

The purpose of the experiments of this section was to determine the effect of concentration on filter paper retention of cobalt. The pH was held constant and the concentration of the cobalt chloride was varied. It was decided to work at pH 6.5, as maximum filter paper adsorption was experienced at this pH for cobalt, barium, and zinc. Another favorable factor in working at pH 6.5 was that loss of activity due to glass adsorption was low. The concentration of the cobalt was varied from

1.4 x 10 ^ to 1.0 x 10 3 gram atom/30 ml. Two milli­ liters of 0,01 N hydrochloric acid were added in each experiment. The solutions were then titrated to pH 6,5 with ammonium hydroxide and filtered.

The experimental results are listed in Table VII.

Per cent adsorption, corrected for beaker adsorption, was plotted in Figure 10, as a function of the logarithm of concentration of the cobalt chloride in mole/30 ml.

Examination of this curve shows that per cent retention by the paper decreased with increasing cobalt concen­ tration, in the concentration range studied. From Fig­ ure 10, it can be seen that per cent adsorption at

1.4 x 10“9 gram atom of Co/30 ml. was sixty per cent.

In the previous work on cobalt, shown in Figure 2, the paper retention at pH 6,5 was nearly one hundred per cent. Table VII

Effect of Concentration of Cobalt on its Adsorption

Cone, of Co Am't. on Am't. on % on Paper in gram atom beaker filter paper corr. for am't. ner 30 ml. counts/min. % counts/min. % on beaker (y)

1.4 X io“ 9 26 2.0 764 58.5 59.7

1.1 X 10-8 22 1.7 714 54.6 55.6

1.0 X 10~7 15 1.2 606 46.5 47.1

2.0 X 10"7 15 1.2 499 38.2 38.7

1.0 X io~6 13 1.0 295 22.6 22.8

2.0 X 10“6 13 1.0 198 15.2 15.4

1.0 X 10” 5 11 0.8 73 5.6 5.6

1.0 X io~4 8 0. 6 21 1.6 1.6

1.0 X 10-3 7 0. 5 20 1.5 1.5

Constant Factors : HC1, 2.0 x 10~5 mole; 30.0 1 °»2 ml.; 27° C;

1305 counts/min. ; pH 6.5. Co, 1.4 x 10“ 9 g. atom 8 0 Vol., 3 0 ml. Temp. 27°C. 70 HCI, 2.0 x I0“ 5 mole pH 6.5

60

50

4 0

3 0

2 0 -

-10 -9 -8 -7 -6 -5 -4 -3 -2 Log mole 0 CCI2/ 3 O ml. Figure 10 Effect of Cobalt Concentration on Adsorption of Cobalt. -83-

However, in that experiment, there was no salt added to the solution, as no hydrochloric acid had been added.

It appears, then, that ammonium chloride in solution does decrease paper adsorption. The effect of a salt on filter paper retention is the subject of another section of this study.

From consideration of Figure 10, it can be seen that the paper was capable of retaining an appreciable amount of the cobalt, even at relatively high concen­ trations of the cobalt chloride. The concentration of a 1 x 10 ^ molal solution of cobalt chloride (3 x 10“^ mole/30 ml. ) would be decreased by approximately twelve per cent, if filtered under the conditions of these experiments.

The effect of concentration on the adsorption of zinc by paper was studied next. Since the ammonium chlor­ ide formed on titration of the acid used in the preceding series of experiments appeared to be a factor in the re­ tention by filter paper, an aqueous solution of zinc chloride was used, to which no hydrochloric acid was added. The pH was 6.5, and the solutions were filtered within ten minutes after titration. The results of this series of experiments are listed in Table VIII.

Per cent adsorption of zinc, corrected for beaker adsorption, was plotted as a function of pH in Figure

11, At a zinc concentration of 8.16 x 10“^ gram atom/ Table VIII

Effect of Concentration of Zinc on its Ads orption

Gone, of Zn Am't on A m ’t on % on Paper in gram atom beaker filter paper corr. for am't. per 30 ml* counts/min. % counts/min. % on beaker (y)

8.16 X 10"8 25 5.6 409 91.3 96.9

1.82 X io-7 13 2.9 389 86.8 89.4

2.82 X io-7 10 2.2 305 69.0 70.5 I 5.82 X 10"7 41 9.1 226 50.5 55.5 fXX I 1.08 X 10“6 3 0.7 14.1 31.4 31.6

1.00 X io"5 11 2.5 34 7.6 7.8

1.00 X IO"4- 8 1.8 30 6.7- 6.8

Constant Factors: 27° C.j 30.0 + 0.2 ml.j 446 count s/min .; pH 6.5. Per Cent Adsorption 100 90 80 50 70 40 30 60 20 iu e I fet f Zinc Concentration of Effect Adsorption on Figure Zinc. of II J L I I I I I I I I I I I I L I -J I 1 - 8 - 6 5 -4 - 2 - 0 -I -2 -3 4 - -5 -6 -7 -8 -9 -10 HI Log mole ZnCl2/30ml. Temp., 27°C. n 8.16Zn, 10x g. atom"8 H 6.5 pH Vol.,ml. 30

99 -86-

30 ml., the adsorption was 97$ in this plot. Referr­ ing back to Figure 7, at this same zinc concentration, the adsorption was 88$, in the presence of 1 x IO*"'* mole of HCl/30 ml. The decrease in adsorption due to the presence of ammonium chloride is more clearly de­ monstrated in the next section. -87-

Dependence of Adsorption on Concentration of Am­ monium Chloride. Since the results of the preceding section have shown that concentrations of ammonium chloride as low as 1 x 10 ^ mole/30 ml. may affect filter paper retention, this section was devoted to the determination of the effect of different concen­ trations of ammonium chloride on the adsorption of zinc and cobalt. It has already been noted by J. Kurbatov and M, Kurbatov (194-2) (5), that for two different con­ centrations of ammonium chloride, per cent removal of yttrium from solution by filtration was lower in the case of the higher salt concentration. This effect is sometimes called the "salt effect" on adsorption of radioactive substances by paper.

For the first series of experiments of this section, an aqueous solution of cobalt chloride was used. The concentration of the cobalt was 1.4 x 10*"^ gram atom/

30 ml., and the pH was maintained constant at 6.5. The solutions were filtered within ten minutes after titra­ tion.

The data of Table IX show that increasing ammonium chloride concentration decidedly decreased the adsorp­ tion of both glass and paper, and that this factor should be taken into consideration in target separations.

A plot of per cent Cobalt adsorption, corrected for Table IX

Effect of Ammonium Chloride on Concentration on Cobalt Adsorption

Gone, of NH/OH A m ’t on Am't. on % on Paper in mole/30 ml. beaker Filter paper corr. for am't, Of counts/min. counts/min. % on beaker

1.00 X 1 0 -7 78 • 6-3 1073 86.7 92.5 12.3

6.00 X 10-7 81 6.5 1059 85.4 92.4 12.5

1.10 X 10~6 86 6.9 1092 88.0 94.5 17.2

5.10 X 10“G 55 982 82.8 4.4 79.1 4.81 CO1 00 1.01 X io' 5 41 3.3 918 74.0 76.5 3.26 *

5.01 X 10"*5 25 2.0 557 45.0 46.0 0.851

1.00 X 10 "4 20 1.6 298 24.0 24.4 0.322

5.00 X 10“4 13 1.0 81 6.5 6.6 0.0707

1.00 X io" 3 9 0.7 41 3.3 3.3 0.0342

Constant Factors: Co, 1.4 x 10“9 gram atom; 27°C.; 30.0 + 0.2 ml. j

124.0 counts/min. j pH 6.5. -89- beaker adsorption, versus log mole of NH.Cl/30 ml., 4 was made in Figure 12. Consideration of this plot shows that if one was making a target separation involv­ ing the adsorption on paper of an element with an oxidation state of two, one should keep the ammonium chloride concentration at, or below, 1 x 10“^ mole/30 ml. in order to obtain maximum efficiency in the separation.

This concentration, in terms of molality, is 4.2 x 10- -*.

In the presence of concentrations of ammonium chloride -2 higher than a 4*2 x 10 molal solution, the adsorption of the cobalt was not observable.

Comparisons can be made between the data plotted in Figure 12 and previous experiments with cobalt. From

Figure 3, the per cent retention of cobalt at pH 6.5 was 70#, at an ammonium chloride concentration of 1.0 x

10-5 mole/30 ml. The corresponding value from Figure 12 was 7656. In another comparison, from Figure 7 at pH 6.5, the per cent adsorption of cobalt was 60$, at a cobalt concentration of 1.4 x 10-^ gram atom/30 ml., and an ammonium chloride concentration of 2.0 x IO-'* mole/30 ml.

From Figure 12, the corresponding value was 66$. The agreement of the experimental data of these different series of experiments, which were conducted months apart, was within 6$.

In Table IX, "y" was the per cent adsorption by the paper corrected for beaker adsorption. A plot of 100

90

80

70

60

50 I CD O 40 I

30 Co, 1.4 x IO- 9 g. atom Vol., 30 ml. Temp. 27°C. 20 pH 6.5

10

Log mole NH4 GI /3 0 ml. 0 ± _L -II -10 -9 - 8 -7 - 6 -5 -4 -3 -2 - 0 Figure12 Effect of Ammonium Chloride Concentration on Paper Adsorption of Cobalt. -91- log y/(l-y) versus log mole of NH^Cl/30 ml. Is presented in Figure 13. From this plot, it can be seen that a

straight line relationship is obtained, with a slope of

-1. The following equation can be written for the ex­ perimental curve, in terms of an equilibrium constant:

log r/(i-y) = -i log /~n h 4ci_7 + log KBq

Keq = r / V _ 7 / C 1-7J

The above equation would result if there were an equili­ brium reaction, as follows:

Go -i Co . , + NH.C1 soln. “ adsorbed 4

The effect of the ammonium chloride on retention of the cobalt was in accord with the diffuse double layer theory. The divalent cobalt would be expected to be ad­ sorbed into the double layer in preference to the ammonium ion, due to its higher charge. However, when the concentration of the ammonium ion becomes much larger than the concentration of the cobalt, then one would ex­ pect competition to occur between the two ion types for adsorption into the double layer. By referring to Fig­ ure 12, it can be seen that the ammonium chloride inter­ feres with the adsorption of cobalt only after its 3 concentration has become 10 times as large as that of the cobalt chloride.

The effect of the concentration of ammonium chloride upon zinc adsorption was also studied. As in the pre­ ceding series of experiments with cobalt, the pH was y / d - y ) i u e / Efc o Amnu Clrd o Cobalt Chloride on Ammonium of Effect Figure /3 6 Adsorption. 4 5 o ml NH4CI moleLog /30ml o - o 1.4Co, x ICT9 g.atom Temp.27°C. ml.Vol., 0 3 H 6.5 pH 92 - 3

2

0 -93- maintained at 6.5, and the solutions were filtered with­ in ten minutes after titration. An aqueous solution of zinc chloride was used, giving a zinc concentration of

8.16 x 10"® gram atom/30 ml.

The data of Table X show, as in the case of cobalt, that as the concentration of the ammonium chloride was increased, the adsorption by both glass and paper was decreased. A plot of per cent adsorption by the paper, corrected for glass adsorption, was made as a function of pH in Figure 14. Upon comparing this plot with the plot of the same nature for cobalt in Figure 12, it can be seen that the curves are very similar. It appears, then, that the effect of the ammonium chloride may be a function of the charge of the cation with which it was competing, since it had the same effect on the adsorp­ tion of cobalt and zinc by paper.

A plot of log y/{l-y) versus log mole of NH^Cl/30 ml. was made. Again "yn was defined as the corrected per cent adsorption by the paper. A straight line re­ lationship was obtained with a slope of -1, which was the value obtained for the slope of the similar plot for cobalt in Figure 13* Table X

Effect of Ammonium Chloride Concentration on Zinc Adsorption

Cone. of NHvOH Am*t. retained Am't retained % on Paper in mole per 30 on beaker on paper corr, for ml. counts/mi n. % counts/min. % am't. on beaker y/(l-y)

1.00 X io“7 35 5.7 513 83.1 88.2 7.48

1.10 X io-6 41 6.6 527 85.5 91.5 10.8

1.01 X 10~5 21 3.4 461 74.7 77.2 3.38

2.01 X 10“5 21 3.4 308 49.9 51.5 1.06

5.01 X 10-5 34 5.5 258 41.3 44.2 0.793

1.00 X 10“4 11 1.8 187 30.3 30.8 0.445

5.00 X 10-4 6 1.0 62 10.0 10.1 0.112

1.00 X 10 9 1.5 52 8.4 8.5 0.0930

Constant Factors: Zn, 8,16 x 10“*^ gram atom; 30,0 * 0,2 ml,; 27°C,;

617 counts/min.; pH 6,5. Per Cent Adsorption 90 r 90 80 60 70 20 30 40 50 iue 4 fet f moim Chloride Ammonium Adsorption Concentration Paper of on Effect 14 Figure Temp. 27°C. o . 0 ml. 30 Vol. n 81 x I0 x 8.16 Zn, H 6.5 pH 1 -9 -10 f Zinc. of

8 ~ g.atom l I l I I l I I I _l 8 - 7 -7

o ml NH Log mole 6 - 5 -4 - -2 -3 4 - -5 4 CI

—96"*

Dependence of Adsorption on Concentration of

Manganous and Cupric Chloride. This section is devoted to a study of the effect on adsorption of varying the cation in solution, using the same anion, namely, the chloride ion. In the section following this one, the anion is varied, using the same cation, namely, the am- monium ion. In this manner, it can be determined whether the "salt effect" upon adsorption is due to competitive adsorption among the cations in solution, or if the anion also plays a part.

The effect of the addition of divalent manganese upon the adsorption of cobalt was first determined.

The manganese was added in the form of the chloride.

It was also of interest to determine the effect of man­ ganese on cobalt adsorption from the point of view of target chemistry, since radioactive cobalt can be pro­ duced by a deuteron bombardment of manganese. In this series of experiments, the cobalt concentration was -9 / 1.4- x 10 gram atom/30 ml. The pH was maintained at

6.5, and the solutions were filtered within ten minutes after titration.

The results of this series of experiments are listed in Table XI. Figure 15 is a plot of per cent adsorption of cobalt, corrected for beaker adsorption, as a function of log mole of MnCl^/^O ml. Comparison of this curve Table XI

Effect of Manganous Chloride Concentration on Cobalt Adsorption

Cone, of MnCl2 Am't. retained A m ’t. retained % on Paper in mole per on beaker on Filter paper corr. for 30 ml. counts/min. % counts/min. % am't. on beaker y/(l-y)

1.00 X 10~8 91 7.3 1061 85.3 92.0 11.5

1.00 X 10-7 27 2.2 1068 85.6 87.6 7.06

2.00 X 10"7 25 2.0 964 77.4 78.9 3.74

5.00 X 10"7 19 1.5 670 53.8 54.6 1.20

1.00 X 10~6 12 1.0 461 37.0 37.4 0.597

2.00 X 10“6 8 0. 6 301 24.2 24.3 0.321

1.00 X 10“5 4 0.3 87 7.0 7.0 0.0753

1.00 X 10"4* 4 0.3 18 1.4 1.4 0.0142

Constant Factors : Co, 1.4 x 1 0 " 9 gram atom; 1244 counts/min.; 27°C •}•

30.0 I 0.2 ml. 5 pH 6.5. 100

f 9 0

80 Co, 1.4 x " I0 9 g. atom Vol., 3 0 ml. 70 Temp. 2 7 °C. pH 6.5

60

50 - 9 6

40

30

20

10 Log mole MnClg/30 ml. 0 J "I ~ l 1 I I _L J -II -10 -9 - 8 -7 - 6 -5 -4 -3 -2 ~l 0 Figure 15 Effect of Manganous Chloride Concentration on Cobalt Adsorption. -99- with that for the effect of ammonium chloride on cobalt adsorption in Figure 12 shows that they are similar curves. However, the manganous chloride shows marked affect on the adsorption of cobalt at manganous chloride concentrations of approximately one-hundredth that of the ammonium chloride.

An interesting comparison can be made between Fig­ ure 15 and Figure 11. It can be seen that these two curves are practically identical. In other words, the effect of manganous chloride on cobalt adsorption was almost identical to the effect of zinc chloride on the adsorption of zinc.

A log y/(l-y) versus log mole of MnCl2/30 ml. plot was made from the data in Table XI. Again a straight line relationship was obtained, with a slope of -1, as in the case of the effect of ammonium chloride con­ centration on zinc adsorption. The term "y” stands for the corrected per cent of cobalt retention by the paper.

An equation can be expressed for the straight line that is obtained in this plot:

log y/(l-y) = -1 log /~MnCl2_7 + log Keq

Keq = y A W ) x f MnCl2„7

Since divalent manganese greatly reduced tne ad­ sorption of cobalt even at low concentrations, the separa­ tion of a radioactive isotope with an oxidation state of two from a target material consisting of a compound -100-

of an element with an oxidation state of two does not appear feasible.

The next series of experiments of this section were conducted to determine the effect of cupric chloride on the adsorption of zinc. An aqueous solution of zinc chloride was used, giving a zinc concentration of *■8 8.16 x 10“ gram atom/30 ml. The pH was maintained at

6.5, and the solutions were filtered within ten minutes after titration.

The results of this experiment a re listed in Table

XII. Per cent adsorption by the paper, corrected for beaker adsorption, was plotted as a function of log mole of CUCI2/3O ml, in Figure 16. This curve was al­ most identical to that of Figure 15, which presented the effect of manganese chloride on cobalt adsorption.

These two curves are, in turn, almost identical to that of the effect of zinc chloride on the adsorption of zinc, as shown in Figure 11. If the concentration of the anion

is of little significance here, the effect of manganous

or cupric chloride on adsorption must be interpreted as

competitive adsorption among the cations in solution,

since they have the same effect as zinc chloride on zinc adsorption. The effect of ammonium chloride on adsorp­

tion of zinc and cobalt is similar to the effect of the above salts of divalent cations, except that the latter

lower adsorption to the same degree as one hundred times Table XII

Effect of Cupric Chloride Concentration on Zinc Adsorption

Cone, of CuCl2 A m ’t. retained Am't. retained % on Paper in mole per on beaker on f ilter paper corr. for am’t, 30 ml* counts/min, % counts/min. % on beaker (y) 7 / (i-y)

1.00 x 10~8 20 3.2 ' 527 85.0 87.9 7.26

1.00 x 10“7 14 2.3 506 81.8 83.6 5.10

2.00 x 10~7 25 4.0 378 61.0 63.5 1,74

5.00 x 10"7 2 0.3 222 35.8 35.9 0.560 101 1.00 x 10~6 19 3.1 187 30.2 31.2 0.454

1.00 x 10“5 5 0.8 28 4.5 4.5 0.0471

1.00 x 10-4 5 0.8 19 3.1 3.1 0.0320

Constant Factors: Zn, 8,19 x 10“® gram atomj 620 counts/min,; 27°C,;

30,0 1 0.2 ml. 5 pH 6.5. Per Cent Adsorption 90 r 60 50 80 40 30 20 iue S fet f urc Chloride Concentration Adsorption. Cupric Zinc on of Effect ISFigure -10 Log mole CuCI2/3 0 ml. 0 CuCI2/3 Log mole -7 -2 3 - 4 - 5 - n 81 x 08 . atom g. 10”8 x 8.16Zn, Vol., 30 ml.Vol., 30 Temp., 27 °C. 27 Temp., H 6.5 pH

zoi -103-

the concentration of ammonium chloride. This indi­

cated that the effect of ammonium chloride on zinc and

cobalt adsorption is also due to competition among the

cations in solution. From this work, it appears that

the charge of the cation in solution was more important

than the slight differences in the characteristics of

the divalent ions used.

A plot of log y/(l-y) versus log mole of OuCl^ was made, in which "y" was defined as per cent zinc reten­ tion by the paper. Again a straight line relationship was obtained, with a slope of -1, as in the case of the similar plot of the effect of manganous chloride on co­ balt absorption. - 1 0 4 -

Dependence of Absorption on Concentration of Am­

monium Sulfate. In the preceding section, the effect

of varying the cation of an added electrolyte was de­

termined. This was done by using the same anion and

Varying the cation. In this section, the same cation was used, namely, the ammonium ion, and the anion was varied, using the divalent sulfate ion in place of the chloride ion. The pH was constant at 6.5, and solu­ tions were filtered within ten minutes after titration.

An aqueous solution of zinc chloride was used, which -8 resulted in a zinc concentration of 8.16 x 10 gram atom/30 ml. The results of this series of experiments are listed in. Table XIII. A plot of per cent adsorption of the zinc versus log mole of ammonium sulfate/30 ml. was made in Figure 17. An interesting comparison can now be made between this plot and the effect of am­ monium chloride on adsorption of zinc in Figure 14*

Comparing some of the figures taken from these two graphs, it can be seen that 0.1 a molar basis, the ammonium sul­ fate has a slightly greater effect on the lowering of the adsorption of zinc than the ammonium chloride. Some representative readings from these two figures are gi\ren in the table below, for the purposes of comparison. Table XIII

Effect of Ammonium Sulfate Concentration on Zinc Adsorption

Cone, of Am't. retained Am't. retained % on Paper in on beaker on paper corr. for beaker mole/30 ml. counts/min. % counts/min. % adsorption

1.00 X 10-7 18 ‘ 4.0 411 91.4 95.1

1.00 X 10”6 16 3.6 409 90.7 94.1

5.00 X 10“6 14- 3.1 393 87.4 90.2

1.00 X 10“5 8 1.8 292 65.0 66.1 105

3.00 X 10"*5 9 2.0 171 38.0 38.8

1.00 X 10“4 7 1.5 78 17.3 17.6

1.00 X 10“3 6 1.3 31 6.9 7.0

Constant Factors: Zn, 8.16 x 10"^ gram atom; 27°G.j pH 6.5;

30.0 * 0.2 ml.; 4-50 counts/min. Per Cent Adsorption 100 90 60 70 80 0 4 30 50 0 2 iue 7 fet f moim uft Concentration Adsorption. Ammonium Zinc Sulfate ofon Effect Figure 17 I -0 6 5 - 2 -I -2 3 - -4 -5 -6 7 - 8 - 9 - -10 -II ep, 27°C. Temp., ml. Vol., 30 g.atom I0~8 x 8.16 Zn, H 6.5 pH

Logml. (NH4)2S04/3Q mole

-107-

Salt cone, % Adsorption % Adsorption % Adsorption in log of Zn in of Zn in of Zn, with mole/30 ml. presence of presence of NH»C1 at a cone, (NH^)2S0 NH^Cl twice column 1

-5.00 66.1 77.2 62

-4.00 17.6 30.8 18

-3.00 7.0 8.5 6

It can be seen that there was good agreement be­

tween per cent adsorption of zinc in the presence of ammonium sulfate and ammonium chloride, when the effects of equivalent concentrations of the ammonium ion are

compared, as in column 4 of the above table. The addi­ tion of the sulfate ion in equivalent amounts, as com­ pared to the chloride ion, has the same effect upon the retention of.zinc by the filter paper.

The data of this section, together with the in­ formation obtained from the section on the effect of the charge of foreign cations, show that the decrease in paper adsorption of cobalt and zinc due to the addition of an electrolyte appeared to be a function of the charge of the added cation.

The data, which show that the charge of the anion has little effect on adsorption, are in accord with the diffuse double layer theory. In the literature survey, it was pointed out from data on electrosmosis that the addition of polyvalent cations reduced the negative charge of a surface, but that the addition of polyvalent -108-

anions had no affect on this negative charge. These

data also agree with the findings of the previous sec­ tion, which show that as the charge of the cation of an added electrolyte became larger, it became more effect­ ive in interfering with the adsorption of cobalt and zinc, presumably by competitive adsorption onto the charged surface of the paper. -109-

Nature of the Adsorption oh Filter Paper

Effect of Washing the Adsorbed Cobalt and Zinc.

The effect of washing the adsorbed cobalt with water was determined. This information would not only give an indication of the conditions necessary for the re­ moval of the adsorbed cobalt from the paper, but would also show whether or not the paper could be washed to remove impurities in a target separation, without loss of the adsorbed radioactive isotope.

An aqueous solution of cobalt chloride was used, giving a cobalt concentration of 1.4 x 10*"^ gram atom/

30 ml. The solution was titrated to pH 6.5, filtered and the paper washed several times with five milliliter portions of water at pH 6.5. The wash water was then collected in a sample holder, evaporated to dryness, and its activity determined.

The data of Table XIV show that the first washing of the paper removed only 1.1# of the adsorbed cobalt, and that successive washings removed none of the acti­ vity. The attachment of the cobalt to the paper was

strong enough, then, to stand thorough washing with water. This information can be utilized in target separations, in order to obtain a more efficient separa­ tion of radioactive material, particularly from non­ volatile salts of monovalent cations. Table XIV

Effect of Washing the Adsorbed Cobalt

Am't of activity % of activity re­ Wash solution removed moved corrected for Adsorbent (5 milliliters) counts/min. ! beaker adsorption beaker hot 6 N HC1 91 7.3 paper water at pH 6.5 12 1.0 1.1 o o paper ii 0 • 0.0 paper it 0 0.0 0.0 paper it 0 0.0 0.0

paper n 0 0.0 090

paper hot 6 N HC1 1101 88.6 95.6

-9 Constant Factors: Co, 1.4 x 10 gram atom; 30 0.2 ml.;

27°C.j pH 6.5; 1243 counts/m I 1 j

-111-

The preceding experiment was repeated, using an

aqueous solution of zinc chloride in place of the co­

balt. The solution was again titrated to pH 6.5, fil­

tered, and washed with successive five-milliliter

portions of water at pH 6.5. The concentration of the

zinc was 8.16 x 10 gram atom/30 ml. The results of

this experiment are listed in Table XV.

In the case of zinc, as with cobalt, washing

with water at pH 6.5 removed an insignificant amount

of the zinc. The second washing of the paper with five

milliliters of hot 6 N HC1 shows that removal of the

activity with one washing of the acid was practically

complete.

In the preceding paragraphs, it was shown that

water would not remove cobalt and zinc from the paper.

Although it was known that the adsorbed cobalt and zinc

were removed from the paper by hot 6 N hydrochloric

acid, it was of interest to determine more exactly the

necessary conditions for their removal from the paper.

Information of this type was obtained by washing the

adsorbed cobalt and zinc with wash solutions of increas­

ing acidity. The wash solutions were then evaporated

in sample holders, and the amount of the activity that

was removed from the paper was determined. For the

next experiment, an aqueous solution of zinc chloride

was used, resulting in a zinc concentration of 8,16 x 10—8 Table XV

Effect of Washing the Adsorbed Zinc

A m ’t. of activity % of activity re­ ’Wash solution removed moved corrected for Adsorbent (5 milliliters) counts/min. % beaker adsorption

Beaker hot 6 N HC1 26 4.2

paper water at pH 6.5 3 0*5 0.5 paper ii 4 0.6 0.6

paper it 6 1.0 1.0 to o paper it 5 • 0.8

paper hot 6 N HC1 551 89.0 93.0 to ii H paper 11 • 1.9

Constant Factors: Zn, 8.16 x 10“^ gram atomj 30,0 * 0.2 ml.;

27°C.$ pH 6.5$ 620 counts/min. -113-

gram atom/30 ml. The solution was titrated to pH 6,5

and filtered. Beaker retention was found to be 13

counts/min., or 2.7% of the activity present.

From Table XVI, it can be seen that the zinc ad­

sorbed by the paper could be removed with wash solutions

of relatively low acid concentration. It was interest­

ing to note that the per cent of the zinc that remained

on the paper, after washing with a solution at a parti­

cular pH, was roughly,, similar to per cent removal from

solution to paper, when filtering zinc solutions at

this same pH value. It would appear, then, that one was

able to return the adsorbed zinc into solution by ad­

justing the pH of the solution in contact with the

paper to a value at which adsorption does not occur.

In terms of the surface charge of the filter paper, washing the paper with solutions of decreasing pH would decrease the negative charge of the paper, in relation to the surrounding solution. This decrease in negative charge would result in a correspondihg decrease in the capacity of the paper for holding the activity which had been adsorbed. Further evidence for the support of this theory was that no cobalt or zinc remained on the paper after being washed with a solution at pH 2. It was shown in the literature survey from data on electros- mosis that the paper was neutral with respect to its surrounding solution at approximately pH 2. Therefore, ftfiMM

Table XVI

Effect of Wa shing the Adsorbed Zinc with Solutions of Various Acidities

Removal from Removal from Paper Per cent pH of Wash paper in in % f- corrected for remaining on solution (5 ml. ) counts/min, beaker adsorption paper______

6.00 8 1.7 98.3 o o tr\

• 263 55.2 43.1

4,00 91 19.0 24.1

3.00 107 22.2 1.9 ~ tt

2.00 7 1.5 0 7 - o o H

• © 0 0

0.00 0 0 0

hot 6 N H61 0 0 0 to i H Constant Factors: Zn, 8.16 x o gram a tom; 490 counts/min.j

30.0 * 0.2 ml.; 27°C. -115- the paper would not be expected to be able to retain the adsorbed cations on its Surface at this pH. -116-

Titration of the Filter Paper. In order to obtain more evidence concerning the nature of filter paper ad­ sorption, a titration curve was obtained for the paper, to determine if it possessed acid or basic characteris­ tics. A titration curve for fifty milliliters of water was first obtained. Secondly, five grams of filter paper in fifty milliliters of water was used, and a titration curve obtained. The third titration was made with one filter paper (0.149 g.) in fifty milliliters of water, which was the amount of paper used in the previous experiments. The paper was washed before titra­ tion in the same manner as the filter paper used in the preceding adsorption experiments.

It can be seen from Figure 18 that the presence of the paper in the water had a marked effect on the titration curve, with the paper displaying acid proper­ ties. From Figure 18, a rough estimate can be made of the change in hydrogen-ion concentration of the solution by the presence of one filter paper. The pH of the 50 cc. volume of triple-distilled water was changed from

6,118 to 6.03 by the addition of one filter paper (0.149 g.).

The difference in the hydrogeii-ion concentration of the two solutions was then of the order of 3 x 10 equivalents/50 ml. This value was of the order of pH

o 50 cc. of 2 HO x 5.00grams of filter paper in 5 0 cc.of h^O • 0.149 gram of filter paper in 50cc.of H^O (one filter paper - 4 .7 5 cm. diam eter)

4

3 1 1 1 0 4 5 6 7 8 10 II Ml. of 0.01 N NH4OH

Figure 18 Titration Curves for the Filter Paper. -118-

magnitude of the adsorption of the zinc, as indicated by the following values from Figure 11:

Cone, of Zn in Per Cent Adsorbed Zn in gram atom/30 ml. Adsorption gram atom/30 ml.

8.16 x l(f8 96.9 7.91 x 10"8

1.82 x lo“7 89.3 1.63 x 10~7

2.82 x 10“7 70.4 1.98 x 10~7

5.82 x 10“7 55.1 3.21 x lo"7

1.08 x 1 0 " 6 31.0 3.35 x lo"7

It can be noted from these values that per cent ad­

sorption of the zinc was decreasing toward zero as its concentration was increasing. -119-

Surface Adsorption of Zinc. It was difficult to

determine just where the adsorption took place in the

case of filter paper, due to its porous nature. As an experiment analogous to paper adsorption, the inter­ face between a water solution of zinc and hexane was

studied, to determine if zinc was adsorbed at the inter­ face. Hexane was chosen because of its low dielectric constant, as compared to water. The charge of the interface should increase with an increasing difference in dielectric constants of two liquids, according to

Coehn's rule, which was based on experimental data from vrork on electrosmosis. Thirty milliliters of an aqueous solution of zinc chloride, with a zinc concentration —& of 8.16 x 10” gram atom/30 ml., and a pH of 6.5, were placed in a buret, along with twenty milliliters of hexane (skellysolve B). The mixture was shaken and al­ lowed to stand for four hours to insure good separation of the two phases. The location of the activity in the column was then determined by slowly running four milli­ liter portions of the liquid into sample holders. The samples were then evaporated to dryness and their acti­ vity measured.

The data in Table XVII show that the hexane phase does not contain any of the zinc, but that there is an abnormally high concentration of the zinc at the inter- -120-

Table XVII

Adsorption of Zinc by a Water-Hexane Interface % of total Sample per ml. No. Content of Sample counts/min % of total of H20

1 4 ml. aqueous phase 44 13.1 3.3

2 44 13.1 3.3

3 46 13.7 3.4

4 46 13.7 3.4

5 42 12.5 3.1

6 35 10.4 2.8

7 29 8.7 2.2

8 2 ml. aqueous phase, 36 10.7 5.4 2 ml. hexane

9 4 ml. hexane 0 0 0

10 0 0 0

11 0 0 0

12 6 ml. hexane 0 0 0

Constant Factors: Zn, 8.16 x 10“^ gram atom; pH 6.5;

27°C.; 335 counts/min. -121- face between the two liquids. Since the concentration of the zinc in the aqueous phase decreases as one ap­ proaches the interface, it appears that the interface was slowly attracting zinc from the surrounding aqueous solution. -122-

Adsorption of Cesium on Filter Paper

The purpose of this experiment was to determine if cesium, with an oxidation state of one, would be adsorbed on paper. This information would give an indication of the importance of oxidation state of an element, in its adsorption by filter paper. Secondly, this in­ formation would show if it was possible to separate radioactive barium from a cesium target, a separation which could presumably be applied to any of the alkaline earth elements from a target material consisting of elements of the alkali group.

A tracer solution of cesium in 0.01 N HC1 was used, which resulted in the addition of 1.0 x 10“^ mole of HCl/

30 ml. in each experiment. Solutions were filtered within ten minutes after titration. A study of adsorp­ tion at different pH values was made.

The results of these experiments are listed in

Table XVIII. Considering that the paper retains approxi­ mately 1.1/6 of the total activity by soaking alone, the per cent retention of the cesium by the paper was almost insignificant. The per cent adsorption of cesium rises, levels out, and drops at the same pH values as in the case of barium adsorption, shown in Figure 5.

The results ohtained with cesium show that the oxi­ dation state of an element is an important parameter Table XVIII

Effect of pH on Adsorption of Cesium

Am't retained Am't. retained % on Paper by beaker by Filter Paper corrected for pH counts/min. % counts/min. % beaker adsorption

3.59 21 0.8 ' 59 2.2 2.2

4.62 16 0.6 105 3.9 3.9

5.73 25 0.9 149 5.5 5.6

6.73 26 1.0 136 5.0 5.1 TO V.O I 7.51 23 0.9 144 5.3 5.4

8.54 30 1.1 162 6.0 6.1

9.65 32 1.2 141 5.2 5.3

10.57 14 0.5 68 2.5 2.5

Constant Factors: Cs, tracer concentrations; 2703 counts/min.;

30.0 1 0.2 ml.; 27°C. — 124."" in its adsorption by paper. This conclusion is in agreement with the diffuse double layer theory, in which the attraction of ions into the double layer would be expected to be a function of the charge of the cation, as indicated by the data on electrosmosis presented in the literature survey. The results obtained with ce­ sium also show that the separation of active barium from a cesium target by filter paper adsorption is a good possibility, assuming that the effect of cesium chloride on barium adsorption is of the same degree as the effect of ammonium chloride on zinc and cobalt adsorption.

In the same manner, since the oxidation state of an ele­ ment seems to be the determining factor in paper reten­ tion, it should be possible to separate any isotope of the alkaline earth elements from a target consisting of an alkali metal.

In the literature survey, it was noted that A. Wahl and N. Bonner (1950) (2D) had stated that the tendency of a tracer to form an insoluble compound with some com­ ponent of the solution favored formation of radiocolloids, which contained the tracer. It should be noted here that an attempt was made to evaluate this solubility factor, as compared to the effect of the oxidation state of the absorbed element, as shown in the previous ex­ periments on cesium. Hydrochloric acid, which contained active chlorine, was added to a solution of silver -125- nitrate, resultihg in a silver chloride concentration of 2.31 x 10-7 mole/30 ml. The solution containing this relatively-insoluble compound was then titrated to various pH values, ranging from 3.5 to 10.5, and the solutions filtered within ten minutes after titra­ tion. Titration was conducted with both sodium hydroxide and ammonium hydroxide. There was no indication of the adsorption of the chloride by the filter paper. This result indicates indirectly that the oxidation state of the adsorbed cation was the determining factor in filter paper retention, with the possibility of insoluble com­ pound formation being of less importance. -126-

SUMMARY

The adsorption of cobalt, barium, or zinc from

very dilute solutions by filter paper was studied.

Radioactive isotopes of cobalt, barium, and zinc were

utilized as tracers, in order to measure the amount of

adsorption.

Cobalt-60, T1/2 = 5.3 years, was obtained by neutron

irradiation of a cobalt wire at the Oak Ridge National

Laboratories. The cobalt-60 was produced by an />v,y re­

action on cobalt-59.

Barium-133, ^±/2 ~ 38.8 hours, was produced in the

cyclotron at the University of California, Berkeley, by

bombardment of a cesium chloride target with deuterons.

The barium was removed from the cesium by adsorption on

hydrous ferric oxide.

Zinc-60, Tj/2 = 250 days, was obtained by neutron

irradiation of zinc metal in the pile at Oak Ridge.

Two other activities were used in this study.

Cesium-13^., T^/2 = 10*2 days, was produced by neutron

irradiation of barium nitrate at Oak Ridge National

Laboratories. Barium-131 was first produced, which de­

cays by K-capture to produce cesium-131. Chlorine-36,

^l/2 = 2 x 10^ years, was produced by neutron irradi­ ation of potassium chloride at Oak Ridge. The chlorine was used in the form of hydrochloric acid. -127-

Throughout this work, a thirty milliliter solution, which contained the radioactive material to be studied, was titrated to various pH values with ammonium hydrox­ ide, filtered, and the material retained by the paper was removed into sample holders by washing the paper with hot six normal hydrochloric acid. The samples were evaporated to dryness by means of a heat lamp, and the amount of activity present measured by use of a

Geiger counter. The adsorption by the glass containers was also studied in a similar manner,

A study of the adsorption of cobalt, barium, or zinc showed that these elements with an oxidation state of two exhibited filter paper retention from very di­ lute solutions. The retention by the paper was found to be a function of pH, Adsorption of cobalt, barium, or zinc began at approximately pH 3, and increased with increased pH to a maximum at pH 6,5. This similar­ ity in the adsorption of these three cations was inter­ preted as meaning that the adsorption was a function of the charge on the paper. Above pH 6.5, cobalt or zinc adsorption dropped off sharply, whereas the barium ad­ sorption remained fairly constant. This difference was interpreted as being due to ammonia complexing with the cobalt or zinc in solution, which interfered with ad­ sorption by the paper.

In order of. decreasing maximiim per cent adsorption -128-

on paper and glass, the three elements studied were zinc,

cobalt, and barium. This order was the reverse of that

for the adsorption of these three by a typical ion-

exchange resin, and agreed with the order of adsorption

of cobalt and barium on hydrous ferric oxide. This

point was interpreted as indicating that adsorption by paper, glass, and hydrous ferric oxide may take place by means of a similar mechanism.

It was noted that the order of decreasing maximum adsorption of zinc, cobalt, and barium was also the order of increasing solubilities of their respective hydroxides.

It was considered possible that adsorbed cations would combine with some of the hydroxyl ions, which make up the inner layer of the diffuse double layer surround­ ing the surface of the paper. In this case, the relative solubility of the hydroxide of an element would affect the tendency of the adsorbed cation to return into solu­ tion .

The effect of allowing a solution containing cobalt to stand for three days before filtering was determined, as compared to filtering within ten minutes after titra­ tion. No appreciable difference was detected in per cent adsorption by the paper. It was found that con­ siderable amounts of the cobalt were adsorbed on glass containers after standing three days with a cobalt con­ centration of 2.8 x 10”9 gram atom/30 ml. With X defined as the per cent adsorption by the glass, a plot

of log X/(l-X) versus pH resulted in a straight line, with aslope of 0.5.

On making successive filtrations with a cobalt solution, which had stood three days, there was not an appreciable difference in per cent retention between the first and the second paper. This point showed that allowing a solution to stand three days did not increase per cent retention by the filter paper.

The effect of concentration on retention by filter paper from very dilute solutions was studied. It was found that cobalt or zinc exhibited appreciable filter _c .paper retention up to concentrations of 1 x 10 gram atom/30 ml. Per cent retention by the paper increased as the concentration of the cobalt or zinc was decreased to 1 x 10”^ gram atom/30 ml.

A study of the "salt effect" was made, using ammonium chloride. As the concentration of the ammonium chloride was increased, the adsorption of cobalt or zinc was de­ creased, for concentrations greater than 1 x 10”^ mole of NH^Cl/30 ml. At 1 x 10~3 mole of NH^Cl/30 ml., the adsorption was not observable.

To determine the cause of the "salt effect", the cation of the added electrolyte was varied, using the same anion, and the anion was varied, using the same cation. In this manner, the effect of manganous chloride, -130- cupric chloride, and ammonium sulfate on the retention of cobalt or zinc by paper was studied. As the con­ centration of manganous chloride or cupric chloride was increased over 1 x 10“® mole/30 ml.,adsorption of cobalt or zinc was decreased, and was not observable at salt concentrations greater than 1 x 10 mole/30 ml. The addition of a salt of a divalent cation, therefore, had a much stronger effect on adsorption of cobalt or zinc by paper than that of a monovalent cation. On the other hand, ammonium chloride or ammonium sulfate had the same effect on adsorption, when compared on an equi­ valent basis. It was concluded that it was primarily the charge of the cation of an added electrolyte that determined the. extent of the "salt effect".

It was found that the addition of zinc chloride or cupric chloride to a zinc solution produced the same effect on retention of zinc by paper. It was concluded, therefore, that the "salt effect" was the result of com­ petition of the different cations in solution for the surface of the paper. This point was also based on the fact that the effect of ammonium chloride on cobalt and zinc adsorption was similar to the effect of the addition of a salt of a divalent cation, except that the effect of the latter was equivalent to a concentra­ tion one hundred times that of the ammonium chloride. -131-

In studying the effect of ammonium chloride, man—

ganous chloride, and cupric chloride on cobalt or zinc

adsorption, it was found that a plot of log y/(l—y)

versus pH resulted in a straight line with a slope of

minus one in each case. The term "y" was defined as

per cent adsorption by the paper, corrected for beaker

adsorption. An equation can be written for the straight

line obtained:

log y/(l-y) = -1 log ,

The above equation would result if there were an equi­ librium reaction, as follows:

soln. ^ adsorbed + salt

M = Co or Zn

It was found that the adsorbed cobalt or zinc could be washed repeatedly with water at pH 6.5, without loosing a significant amount of either one. However, as the pH of the wash solution was lowered below six, there was partial removal of the activity. At pH three, all of the cobalt or zinc was removed from the paper.

The per cent removal of zinc by wash solutions at different pH values was roughly comparable to per cent removal by the paper of zinc from a solution at this same pH. This indicated that the adsorption by paper may be reversible.

A titration curve was obtained for the filter paper. -132-

The paper reacted as an acid to an extent comparable

to the amount of zinc that the paper was capable of adsorbing.

It was observed that a mixture of hexane and water adsorbed active zinc at the interface. No activity was observed in the hexane itself. These data may be con­ sidered to be analogous to the paper retention of zinc.

Paper retention of cesium, with an oxidation state of one, was measured at various pH values. Retention of the cesium was low, with a maximum of approximately five per cent. To determine the effect of relative insolubility of a compound on filter paper retention, a solution of silver chloride, which contained active chloride, was filtered at various pH values. Negative results were obtained, which, together with the data on cesium adsorption, indicated that the oxidation state of a cation was the more important parameter of paper retention. The results obtained with cesium as compared with barium, indicate the possibility of separation by filtration of a radioactive isotope of the alkaline earth metals from a target material consisting of one of the alkali metals.

It was found that the published literature on radio­ colloids could be interpreted in terms of the diffuse double layer theory, which accounts for the charge of -133-

a surface in respect to a surrounding aqueous solution.

This interpretation involved the assumption that there

were foreign nuclei in solution, which adsorbed radio­

active cations as a result of the surface charge of

the foreign nuclei.

The results of this work on the retention of cobalt,

barium, or zinc by filter paper can also be interpreted

in terms of the surface charge of the paper, in respect

to a surrounding aqueous solution. The effect on paper

retention of pH, added electrolytes, concentration

and oxidation state of the adsorbed element, and other factors studied can be explained in terms of adsorp­

tion into the double layer of ions on the surface of

the paper. -134-

conclusions

Zinc, cobalt, and barium exhibited filter paper retention from very dilute solutions. The filter paper retention was a function of pH, with the adsorption beginning at pH 3 and reaching a maximum at pH 6.5 for the zinc, cobalt, and barium.

The sharp decrease in adsorption of cobalt and zinc at high pH values was interpreted as being due to

Interference by ammonia eomplexing In solution.

The order or relative degree of adsorption of the three cations was the same for glass and paper, and was comparable to adsorption on hydrous ferric oxide. How­ ever, the reverse order was the case for these cations for a typical cation-exchange system, in which a sulfonic acid resin was used.

It was found that filtration of a solution after standing three days produced no appreciable difference in paper retention, as compared to filtration within ten minutes after titration.

It was found that the cobalt and zinc were adsorbed -5 on filter paper at concentrations up to 1 x 10 gram atom/30 ml. The per cent retention of the paper increased with decreasing cobalt and zinc concentration down to _ _—8 . 1 x 10 gram atom/30 ml.

It was concluded that the degree of the "salt effect" -135- up on paper retention was a function of the charge of the cation of the added electrolyte, with a larger charge of the cation resulting in a greater decrease in filter paper adsorption. It was concluded that the

"salt effect" was due to cation competition for adsorp­ tion on the surface of the paper, with the added cation entering into the competition on a uni-ionic basis, in the case of the monovalent and divalent cations that were studied.

It was found that washing the paper with solutions below pH 6 removed a percentage of the adsorbed zinc, which was comparable to per cent zinc adsorbed by paper from a solution at this same pH. It was concluded that the adsorption, by paper may be reversible.

In a titration of the filter paper, the paper re­ acted as an acid.

Cesium, a monovalent cation, exhibited almost in­ significant paper adsorption. Also, negative results were obtained when a solution of silver chloride was filtered. It was concluded that the oxidation state of an element was the determining factor in its retention by paper, as compared to the relative insolubility of a compound formed by the element in solution. From these data, it was concluded that it may be possible to separate radioactive barium from a cesium target, a -136- separation that should be applicable to other alkali and alkaline earth metals. For an efficient separa­ tion, a solution at pH 6.5 should be used, ammonium chloride reduced to a minimum, and the paper washed with water. -137 -

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AUTOBIOGRAPHY

I, Orville James Kvamme, was born in Egeland,

North Dakota, on the 16 May 1922. I received my pri­

mary and secondary school education at the Egeland

Public School, Egeland, North Dakota. My undergraduate

training was obtained from Seattle University and the

University of Washington, both of Seattle, Washington,

and North Dakota State College, Fargo, North Dakota.

I was graduated with the degree of Bachelor of Science

from North Dakota State College in 1947. From 1947 to

1949, I was an assistant in the Department of Chemistry, while doing graduate work at North Dakota State College.

I received the degree of Master of Science in Chemistry at this institution in 1949.

I have been on active duty with the Army Air Corps from 1942 to 1945, and with the United States Air Force from 1949 to date. I attended The Ohio State University under the Civilian Institutions Division of the United

States Air Force Institute of Technology, Wright-

Patterson Air Force Base, Ohio.