Date of Award
Doctor of Philosophy
James S. Fritz
New anion exchange resins, with superior selectivity for nitrate, have been developed. The resins are based on the covalent attachment of a quaternary phosphonium group to a polystyrene-divinylbenzene copolymer. Phosphonium resins of composition resin-R[subscript]3P[superscript]+A[superscript]- where R is varied from methyl to pentyl were evaluated for nitrate/sulfate selectivity, capacity and nitrate decontamination of drinking water. A similar series for the quaternary ammonium exchangers was also evaluated. Phosphonium resins were found to be more nitrate selective and have higher capacities than ammonium resins. A mixed bed process, where nitrate removal and water softening is accomplished in a single column, was also evaluated;A small piece of silver wire, coated with an insoluble silver salt, works well as a selective potentiometric detector for halide ions in ion chromatography. Several coated electrodes were examined by electron microscopy and their response to various anions evaluated by flow injection analysis. A silver-silver chloride electrode was found to be a selective and reproducible detector for chloride, bromide, iodide, thiocyanate and thiosulfate anions separated by ion chromatography. Calibration curves were non-linear and had slopes ranging from 40 to 60 mV/log concentrations. A working range of 0.05 to 2 mM was used. This electrode was also applied to the use of gradient elution in ion chromatography;Two methods for the determination of aluminum by anion chromatography are presented. In the first method, a standard excess of fluoride ion is added to the sample. Evidence is given for the formation of a strong complex of neutral aluminum trifluoride which elutes very quickly from an anion exchange column. The excess fluoride is retained and can be determined. The aluminum concentration can then be related to the difference in fluoride peak height between the sample and standard;In a second method, aluminum(III) is determined directly by anion chromatography when sodium phthalate is used as an eluent. It was found that Al(III)-phthalate complexes thus formed would show some retention on an anion exchange column. The method is uniquely insensitive to the presence of many foreign cations. Aluminum(III) was successfully determined, by this method, in a 40-fold molar excess of iron(III). ftn*DOE Report IS-T-1395. This work was performed under Contract W-7405-Eng-82 with the Department of Energy.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/
James Edward Lockridge
Lockridge, James Edward, "New selective anion-exchange resins for nitrate removal from contaminated drinking water and studies on analytical anion-exchange chromatography " (1989). Retrospective Theses and Dissertations. 9069.