Hydroxyazo Compounds As Reagents for Beryllium Laurie Murray Grennan Iowa State University
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Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1966 Hydroxyazo compounds as reagents for beryllium Laurie Murray Grennan Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Analytical Chemistry Commons Recommended Citation Grennan, Laurie Murray, "Hydroxyazo compounds as reagents for beryllium " (1966). Retrospective Theses and Dissertations. 5367. https://lib.dr.iastate.edu/rtd/5367 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. This dissertation has been microfilmed exactly as received g7_gggg GRENNAN, Laurie Murray, 1920- HYDROXYAZO COMPOUNDS AS REAGENTS FOR BERYLLIUM. Iowa State University of Science and Technology, Ph.D., 1966 Chemistry, analytical University Microfilms, Inc., Ann Arbor, Michigan HIDSOXYAZO COHPOMDS AS HSAGEKTS FOR BEHYLLIIE^ by Laurie Murray Grennan A Dissertation Submitted to the Graduate Faculty in Partial Fulfillment of The Requirements for the Degree of DOrOR C? ZEIICSCPKY Major Subject: Analytical Chemistry Approved : Signature was redacted for privacy. In Charge of Major Work Signature was redacted for privacy. [eadAof Major Department Signature was redacted for privacy. D'r^r"o?~GraauateC ollege lo'-ra State University Of Science and Technology Anes, I&wa 1966 TA3L3 0? C0NT2TTS rags I. ISTEODHOTIOE 1 A. The 3162eut Beryllium 1 C. Survey of Methods for the Determination 4 of Beryllium G." Survey of Hydroxyazo Compounds as Reagents 16 and Review of Immediately Related :fork II. P0TSTG?I0M3TRIC TITRATION PROCEDURE FOR THE 19 DSTERMIMIOH OE FOEMATIOÏI CONSTANTS A. Experimental Procedure 19 3. Mathematical Treatment 22 III. EXPERIMSI^TTAL IfORK 30 A. Preparation and Purification of Azo 30 Compounds B. Absorption Spectra of Azo Compounds and 53 Beryllium Derivatives C. Titration Data and Curves from Potentio- 64 metric Titration Procedure D. The Use of Beryllon III and IV for the 92 Determination of Beryllium IT. RESULTS MD COKCLUSIONS 109 Y. SUl'DIART 117 VI. LITERATURE CITED 122 VII. A0IŒ0?7LEDGEim\T ' 126 1 I. INTRODUCTION A. The Elenent Beryllium Before Yorld War II, beryllim was of limited interest to mineral technologists and its chemistry was relatively unde veloped. Since 1942, however, the applications of beryllium have increased enormously; the remarkable metallurgical proper ties of metallic beryllium make it likely this trend will con tinue. Pujre beryllium is both light in weight and high in tensile strength, properties which make it a favorite in the construction of space vehicles. Beryllium copper has the properties of mild steel and does not work harden. Beryllium compounds are poisonous and thus, widespread use of beryllium chemicals is precluded. Beryllium is a poor absorbent of X-rays and has a low cross section for neutrons. It is comparable to deuterium or graphite as a moderator or reflector in atomic piles and pro duces neutrons more easily than any other element when excited with y rays or other radiation (1): ^Be + Y > 1.65 Mev. -* ®Ee + n Sse sec. 2 . Although thirty-second in abundance of the elements in the earth's crust, beryllium is actually more prevalent than arsenic, gold, silver, and molybdenum. However, it is widely dispersed in the crust of the earth, and its recovery is 2 difficult. Because of its small ionic radius, strong electro positive character and low coordination number, high concen trations of beryllium in minerals are rare. The element tends to be dissipated by weathering and sedimentation and is prob ably more widely distributed in rooks than has been assumed. It is estimated at 6 p.p.m. in igneous rocks and 3.5 p.p.m. in shales (2). Beryllium tends to form its owi minerals and substitution in the crystal structure of other minerals is slight, although in silicates, beryllium may replace aluminum and silicon to a small estent. The most stable beryllium minerals are beryl (Be^AlgSigOig), helvite ((Hn.Pe.ZnJ^Be^Si^OigS), chrysoberyl (SeAlgO^), phenakite (BegSiO^), and bertrandite (Ee^SigOg'EgO)* Beryl, which is classed as a cyclosilicate because the crystal structure contains rings of six linked SiO^ tetrahedra, is by far the most important of the beryllium minerals. It is estimated that as high as eighty percent of beryllium in pegmatite, is in this form. The mineral contains roughly four percent beryllium and is easily mistaken for quartz or apatite. Emerald and aquamarine are transparent, gem varieties of beryl. In the late 15*0's, in a joint effort, the U.S. Geological Survey and the U.S. Atomic Energy Commission began a compre hensive survey of the beryllium resources of the U.S. (1). An attempt was made to locate and evaluate deposits of beryl lium, particularly of non-pegmatite origin. The study turned up no commercial value deposits, but set certain criteria for 3 future prospecting. Fluorine appears to be abundant in ores containing beryllium. At present, the only economically important concentrations are found in pegmatites associated with feldspars, micas, and lithium minerals. Pegmatites (3) are usually coarse grained, often tabular, deposits resulting from the fractional crystallization of a magma and are commonly associated with granite. Many pegma tites contain rare elements and unusual minerals. Igneous rocks also resulted from the same crystallization process but in general are much less varied in composition. Pegmatites in the Black Hills, S.D., southwestern Africa, northeastern Brazil and parts of Madagascar are rich in beryl, while the pegmatites in southern ÎTorway and southeastern U.S., excepting the "tin-spodumene belt" of North Carolina, are poor in beryl (4). in ^brth Carolina the beryl and spodumene (a lithium mineral) bearing pegmatites are fine grained and a suitable flotation operation has been devised for the recovery of the beryl. In Brazil, beryl is a by product in the mining of sheet mica. It is important to note that beryllium is a highly toxic material and can produce a variety of maladies in humans. Berylliosis (2) Is considered a distinct disease; it can be identified by various clinical tests which distinguish it from other lung diseases. Apparently, individuals vary in their sensitivity to beryllium and cases have been cited of delayed reactions to exposure to the oxide dust. All beryllium 4 compounds and solutions must be handled with care. Because of all these activities, there exists a strong interest in the analysis of this minor, but important element. B. Survey of Methods for the Determination of Beryllium At a 1953 symposium on the Analytical Chemistry of the Less Familiar Elements, Vinci (5) reviewed the state of beryl lium chemistry and described the information available as "generally scattered and somewhat controversial". Sandell (6, p. 218) in Colorimetric Determination of Traces "of Metals has also sujnmarized the available methods for beryllium and pointed out inadequacies. In the qualitative analysis scheme, beryllium falls with aluminum, iron and chromium in "Group III". It is amphoteric, the hydroxide dissolving in excess alkali to form a beryllate ion. There is considerable question as to the actual species that exist in aqueous solution. A basic beryllium ion, (EeOH)^*^, is a possibility in as much as beryllium is known to form Be-OH-Be and Be-O-Be bridges (7, p. 168). Beryllium salts are extensively hydrolyzed and this has proven a major difficulty in alkalimetric titration procedures in which a neutral solution is required for reaction of beryllium with a reagent. The fact that beryllium salts seem to hydrolyze in completely in the presence of pyridine has been used by Przheval'skii (8) in his study of the precipitation of beryl lium with p-diketones and this may explain why color develop- 5 ment is more rapicL in the presence of pyridine when beryllium is added to a reagent. Any beryllium solution above pH 7 is quite likely to coat the glassware with a thin film of hydroxide which is difficult to remove unless acid is used for cleaning. Beryllium hydrox ide is quite insoluble compared with hydroxides of other di valent metals. Sill (9) in his fluorometric determination of submicrogram quantities of beryllium with morin checked his procedure vdth a "^Be tracer and found that the precision of the instrumental measurements far surpassed that of the chemi cal operations. He recommended coating glassware end pipets used for beryllium solutions with a silicone such as Beckman Desicote. In macro methods and when high accuracy is required, beryllium hydroxide is ignited to beryllium oxide for weighing or beryllium ammonium phosphate is precipitated and ignited to beryllium pyrophosphate for weighing, Vlncl (5) lists ten reagents used for the detection or quantitative "estimation" of beryllium as of 1953: 1. p-îîitrobenzeneazoorcinol (known also as "Zenia") 2, Quinalizarin 5, Curcumin 4. Alkanin (Uaphthazarin) 5. îîaphthachrome Green G (îTaphthachrome Azurine 2B) 6. Aluminon (Aurintricarboxylic acid) 7. Quinizarin-2-sulfonic acid 6 8. Morin (3,4,7,2',4'-Pentaîiydroxyflavone) 9. l,4-Dihydrox7anthraquinone 10. l-Amlno-4-hydrox7anthraquinone. The last three reagents produce fluorescence with an alka line solution of beryllium in ultraviolet light. Vinci (5)