Degradation and mineralization of diuron and simazine in aqueous solution by advanced oxidation processes

The first part of the thesis consists of experimental studies on removal of pesticides from aqueous solution by advanced oxidation processes (Fenton, photo-Fenton and peroxone oxidation) using Box-Behnken statistical experiment design. Effects of pesticide (diuron or simazine), hydrogen peroxide and ferrous ion concentrations and initial pH on the extent of pesticide and total organic carbon (TOC) removals were investigated. Optimum reagent doses yielding the highest pesticide and TOC removals were determined. Complete removal of pesticides was accomplished within fifteen minutes while complete mineralization was not achieved even within sixty minutes indicating formation of some intermediate compounds. In photo-Fenton treatment, the highest complete pesticide removal and mineralization (eighty-five percent) were obtained for diuron-containing water. In advanced oxidation of simazine ozone/peroxide (peroxone) treatment yielded higher mineralization (ninety-four percent) although there were no differences in simazine removals. The initial rate of pesticide degradation was found to be first-order with respect to the initial pesticide concentration for Fenton and photo-Fenton processes.The second part of the thesis was on treatment of pulp mill effluent by different AOPs. In the treatment of pulp mill effluent, photo-Fenton treatment yielded comparable TOC (eighty-five percent), color (eighty-two percent) and AOX (ninety-three percent) removals within five minutes due to oxidations by UV light in addition to the Fenton?s reagent. When pulp mill effluent from different sources was used, the TiO2-assisted photo-catalysis resulted in the highest TOC (eighty percent) and toxicity (ninety-five percent) removals under alkaline conditions within sixty minutes.