Date of Award
Doctor of Philosophy (PhD)
Because of increasing concern over global pollution by the energy production industry, especially large, centralized utility complexes, the quantitation and speciation of heavy metals have taken on great importance. These metals are emitted with coal fly ash and may be subsequently deposited in natural waters. Complications arise when certain inorganic compounds undergo biomethylation by microbial action in these waters. Therefore, procedures must be developed to analyze and differentiate the mixture of inorganic and organometallic compounds present. This work is a study of the electrochemical properties of inorganic and organothallium compounds. The toxicological significance of thallium compounds is known, and their presence in coal fly ash and natural waters indicates a need for study of their mixtures. Environmental concentrations are thought to be in the ppb range so that very sensitive quantitation procedures must be developed. After discussions of the current literature and the theory pertinent to this work are presented, the experimental procedures for electrochemical analyses are described. Cyclic voltammetry experiments allowed the determination of the irreversible nature of the electron transfer reactions of organothallium compounds used, (CH(,3))(,2)TlI and (CH(,3))(,2)TlNO(,3), and described the transfer coefficients and rate constants for them. The similarity of these respective coefficients as well as the diffusion coefficients found by normal pulse polarography confirmed their ionic nature, appearing as (CH(,3))(,2)Tl('+), in aqueous solutions. Also, its was shown that they undergo a three-electron reduction to Tl(DEGREES). Routine analytical methods were developed for mixtures of TlNO(,3) with (CN(,3))(,2)TlI and (CH(,3))(,2)TlNO(,3) using differential pulse polarography (DPP) and differential pulse anodic stripping voltammetry (DPASV). Direct speciation and quantitation of these solutions were accomplished with DPP at the ppm level. DPASV allows the same analyses at the ppb level by making use of the different electrolysis potentials of the compounds. This method is applicable to other metal systems and is adaptable to field analyses.
Hoeflich, Linda Katherine, "Application of Electroanalytical Techniques to Environmental Thallium Compounds." (1982). LSU Historical Dissertations and Theses. 3720.