Kinetics of the Radiolysis of Chloroform: Combined Effects of Dose Rate and Temperature
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This dissertation has been microfilmed exactly as received 66—1751 ABRAMSON, Fred Paul, 1941- KINETICS OF THE RADIOLYSIS OF CHLOROFORM: COMBINED EFFECTS OF DOSE RATE AND TEMPERATURE. The Ohio State University, Ph.D., 1965 Chemistry, physical University Microfilms, Inc., Ann Arbor, Michigan Copyright by Fred Paul Abramson 1966 KINETICS OF THE RADIOLYSIS OF CHLOROFORM: COMBINED EFFECTS OF DOSE RATE AND TEMPERATURE DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University Fred Paul Abramson> A. B* ****** The Ohio State University 1965 Approved by Adviser Department of Chemistry ACKNOWLEDGMENTS I wish primarily to thank Dr. Richard F. Firestone for his guidance and instruction throughout the past years. It is hoped that this work» as well as future work» will partially repay him for the time and effort which he has put forth on my behalf. The other members of the Radiation Chemistry section are also owed a great debt of gratitude for it has been their assistance and enthusiasm which has made my graduate program more complete and re warding. I also gratefully acknowledge the support of the Department of Healthy Education and Welfare for its award of a National Defense Education Act Title IV Fellowship from 1962 to the present time. This work was also supported by the United States Atomic Energy Com mission (Contract AT(ll-l)-ll6 ) which sponsored my Research Assistant- ship during the summer months. A special acknowledgment is made to Dr. Clinton Foulk and the Numerical Computation Laboratories of The Ohio State University for their support and assistance with the digital computer programs and the award of computer time. ii VITA January 15» 19**1............. «... Born - Columbus * Ohio 1961-1962 ........... ........... N.S.F. Undergraduate Research Participant* Western Reserve University* Cleveland* Ohio 1962 ...... ................... A.B. cum laude* Western Reserve University* Cleveland* Ohio 1962-1965 .........................N.D.E.A. Research Fellow* The Ohio State University, Columbus* Ohio Summers* 1962-196**................. U.S.A.E.C. Research Assistant The Ohio State University Columbus* Ohio PUBLICATIONS Abramson* F. P.* Buckhold, B. K . * and Firestone* R. F., "The Effects of Temperature and Various Solutes on the Radiolysis of CCl^," J. Am. Chem. Soe., 8J*, 2285 (1962). FIELDS OF STUDY Major Fields Radiation Chemistiy Studies in Radiation Chemistry. Professor R. F. Firestone iii CONTENTS Page ACKNOWLEDGMENTS .................................... ii VITA ...................................... iii TABLES ...................................... v ILLUSTRATIONS ...................................... vi CHAPTER I. INTRODUCTION............... 1 II. EXPERIMENTAL PROCEDURE......................... 6 Analytical techniques Sample preparation Irradiation procedure Dosimetry Reagents Data processing III. EXPERIMENTAL RESULTS ........................... 35 Preliminary results Dosage dependence Combined dosage and dose rate Combined dose rate and temperature Hydrogen yield Chlorine yield IV. DISCUSSION.................... 51 Hydrogen production Chlorine production Dosage experiments Mechanism of the radiolysis BIBLIOGRAPHY................... 98 iv TABLES. Table Page 1* 100-ev. Product Yields at Various Dose Rates at 2^ • ••••••••••••»»♦•* 3 2, 100-ev, Yields in Liquid CHCl-j............. • . 4 3» Gas Chromatographic Retention D a t a ............. 8 4, Sample Size vs Relative Response ............. 15 5, G Values at Various Temperatures and Dose Rates .......................... 44 6 , Chlorine Absorbance and Dose ........... 49 7, G Values ................................ ^ 8, Radiochemical Yields .......................... ^2 9* Relative Rate C o n s t a n t s ...................... r,g 10# 100-ev, Yields in Solid Chloroform ............. v ILLUSTRATIONS Figure Page 1. Computer drawn chromatograms................... 10 2. Sample series chromatogram................ 12 3« Chromatograph linearity . 16 4. Vacuum system ...................... 23 5« Dosage study irradiation vessel ......... 26 6. Vessel holder ......... ............... 28 7* Concentration vs. d o s e ........................ 37 8*. Concentration vs. dose at twodose r a t e s ........ 38 9* G vs. T for CH2CI2 and C2H2C1^ ................ 40 10. G vs. T for CgCl^ and CgHCl^ .................. 41 11. G vs. T for CCl^ and C2CI4. ........... 42 12. G vs. T ....................................... 43 1 3 . Chlorine production ........................ 50 14. Log G(CH2C12 ) vs. 1 / T ........................ 62 15. Analog computer output ........................ 66 16. Digital computer program...................... 69 17. Computer results ........ ................ 70 18. CEzC12 yield v s . B ......... .................. 75 19. Log k5 vs. 1 / T .............................. 80 20. X : Y vs. B ................................ 82 vi CHAPTER I INTRODUCTION Radiation chemistry represents that branch of science whose purpose is the investigation of chemical changes induced by par ticles which are capable of ionising the substance of interest. Although the use of radioactive substances to study chemical changes extends throughout this century* only in about 1945 did radiation chemistry start its rapid growth which today finds the number of radiation chemists exceeding the number of photochemists in this 1 country. It has grown so that a number of books have been published 2 ^ in the field. The reader who is unfamiliar with the basic aspects of radiation chemistry “may be referred to the introductory chapters of these texts. The only point of explanation will be of the G value. This is a yield which has units of molecules formed or destroyed per 100 ev of energy deposited into the system. It is exactly analogous 1. Office of Professional and Government Relations* The Ameri can Chemical Society* Chemical & Engineering News* 42, Jan. 20* 1964* p. 56 . 2. A. J. Swallow* "Radiation Chemistry of Organic Compounds," Pergamon Press* Oxford* England* I960. 3* S. C. Lind* "Radiation Chemistry of Gases»" ACS Monograph No. 131, Reinhold Publishing Corp., New York, N. Y., 1962. 4. A. Chapiro* "Radiation Chemistry of Polymeric Systems," Interscience Publishers* London* 1962. I to the M/N ion pair yields of the early radiation chemist or to S» the quantum yield in a photochemical system. A distinction between tracks and spurs might be made here in order to make the discussion easier. A track is the path which a charged high energy particle takes through the system. Along this path the particle will leave small clusters of radicals and ions. It is such a cluster that one calls a spur. The distribution of spurs along a track is a physical phenomenon which one cannot alter but by increasing the temperature the rate of spur expansion may be altered. Further* by increasing the dose rate the distance from one track to another may be reduced. Thus* by combining dose rate and temperature as parameters in a radiolysis* the extent of spur overlap might be expected to vary. Such reasoning led to this thesis. After investigating several workers' results* it was concluded that a combined dose rate and tem perature study should yield some fruitful information. Gardner and Harper^ studied the effects of dose and dose rate on liquid chloroform. Their results are presented in Table 1. They further showed that the yields of products have no dependence on dosage up to doses of 180 Mrad. Other evidence of dose rate dependence was given by Meaburn.^ Using dose rates of 6.6 and 0.11 x 1 0 ^ ev/gm.-hr. he found that 5* J. B. Gardner and B. G. Harper, Paper No. 53» 8th Annual Meeting of the Radiation Research Society, San Francisco* Calif.* May 9-11* I960. 6 . G. M* M e a b u m * Ph.B. dissertation, University of Leeds* Great Britain* 1959* 3 TABLE 1 100-ev. Product Yields at Various Dose Rates at 25° Dose rate (megarads/hr.) 18,000 360 0.25 0.06 ch2ci2 0.03 0.13 2.9 3-6 CCl^ 0.03 0.08 0.23 0.4 C2C14 0.04 0.05 0.13 0.14 C2H2C14 0.5 0.5 0.6 0.7 c2hci5 0.8 0.8 1.0 0.9 c2ci6 0.5 0.7 2.5 2.8 CgCl^ » 1»1»2-C2H^C1^» sym-C^H^Cl,.* C2 C14 and CC1if a11 showed inverse dose rate dependences of some sorti while CgHCl,. and C^H^Gl^ have some positive dependence. CgHgCl^* Hg and HC1 showed no dose rate dependence• 7 Werner* who also presents a fine historical review of the 8 radiation chemistry of chloroform* and Werner and Firestone studied the effects of temperature. Their data are presented in Table 2. Werner and Firestone also used Br2 as a scavenger and they briefly discuss the problems involved in its use. Furthermore* it will be shown that bromide increases the decomposition of chloroform by at least 3*4 G units. For these reasons, the pure system, rather than the scavenged one* was investigated. 7. H. R. Werner* Ph.D. dissertation* Western Reserve University* 1963. 8. H. R. Werner and R. F. Firestone, J. Phys. Ghem.* 69* 840 (1965). TABLE 2 100-ev, Yields in Liquid CHCl^ Temperature C°c) -62 *30 0 20 25 63 Dosage rate (ev/g-hr x lO”1^) 1.74 1.73 1.72 1.65 a 2.01 Dosage (ev/g x 1 0 ) 4.13 4.16 4.14 0.99 a 4.79 C0C12 0.11 0.09 0.17 — 0.15 0.11 c h 2c i 2 0.23 0.66 1*5 2.2 2.4 3*4 GCl^ 0.59 0.68 0.76 0.79 0.80 0.9 c2ci4 0.01 0.02 0.05 0.08 0.08 0.2 W h 0.97 0.92 0.82 0.60 O .58 0.50 C2HC15 1.6 1.8 1.8 1*3 0.91 0.60 c2c16 0.58 1.0 1.9 2.2 2.4 2.8 c h c i 2c c i 2c h c i 2 0.15 0.13 0.10 0.05 0.04 — CHC12CC12CC13 0.17 0.20 0.20 0.08 0.1 MM C^Clg 0.03 0.06 0.04 — — MM —CHCl^ 8.3 10 13 12 12 12 HC1- 4.0 4.6 5.4 5.3 5*3 5.0 - Selected best values at 25° at dosagesgup to 2.6 x 10 ev/g.