| The electrochemistry and solution reactions of two compounds of environmental relevance, chlorine dioxide (ClO2) and nitric oxide (NO), were studied. The standard heterogeneous rate constant, kel, for the ClO2-/ClO2 redox couple was measured using rotating disk and ac voltammetry. At a Au electrode in 1.0 M KNO3 at 25°C, kel was 0.015 +/- 0.001 cm/s, the activation energy for the electron transfer process at Au was 25 +/- 3.3 kJ/mol, and the preexponential factor was 310(+900/-230) cm/s. Marcus theory was applied to understand the sluggish electron transfer kinetics, and the preexponential factor was examined. Nonadiabaticity may explain the slow rate of electron transfer.; Homogeneously, ClO2 was examined as a component in an advanced oxidation process for the removal of MTBE from water. Solutions of 7:1 molar ratio ClO2 to methyl tert-butyl ether (MTBE) were subjected to either solar or UV irradiation from a 1 kW Hg/Xe are lamp. Comparisons were made to the system utilizing the same molar ratio of D2O2 to MTBE. Both systems were effective at removing MTBE and yielded tert-butyl alcohol, tert-butyl formate, acetone, formaldehyde, and formic acid as initially-formed intermediates, but at very different relative concentrations.; The electrochemical oxidation and reduction of NO was studied in acetonitrile. The reversible oxidation of NO to NO+ was gradually eroded by the addition of H2O, and a second oxidation peak grew in at higher potential. Spectroelectrochemical FTIR and bulk electrolysis coupled with gas chromatography revealed that the product of the first oxidation wave was HONO and the product of the second oxidation wave was NO2. The electrochemical reduction of NO was studied at Pt, Au, Ag, and glassy carbon electrodes. The cyclic voltammograms were similar, the main distinguishing feature being the intensity of a high potential reduction peak around -0.700 V vs SHE.; Lastly, metal catalysts, Pt/C, Au/C, Ag/C, Rh/C, Ru/C, and Ni/alumina, were examined for their effectiveness in the disproportionation reaction of NO to N2O and NO2-. The measured rates were 1.5, 0.45, 0.37, 0.23, 0.16, and 0.00066 mol NO/mol metal per min, respectively. General characteristics of reactivity were proposed. |
