Dissertation
Dissertation > Environmental science, safety science > Environmental pollution and its prevention > Marine pollution and its prevention

Studies on Organic Pollutants’ Oxidative Degradations by Photo-assisted Fenton Method and Their Sorption Behaviors on Marine Sediments

Author ZhaoXueKun
Tutor YangGuiPeng
School Ocean University of China
Course Marine Chemistry
Keywords Organic pollutants Fenton Degradation UV Marine sediment Sorption
CLC X55
Type PhD thesis
Year 2004
Downloads 549
Quotes 5
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In the dissertation, we systematically investigated five kinds of organic pollutants (dimethyl phthalate (DMP), diethyl phthalate (DEP), 4-amino-bezenesulfonate (ABS), 4-methyl-bezenesulfonate (MBS) and 1-naphthol) as the main aimed objects in the following four fields: (1) to examine the factors affecting the oxidative degradation of the five aimed organic compounds in Fenton/UV system; (2) to investigate the Fenton/UV oxidative degradation kinetics of the five aimed organic compounds; (3) to study the degradation mechanism of DMP and DEP in Fenton/UV system; (4) to research the sorption behaviors of DMP and DEP on marine sediments. Through the thorough simulation experiments, a train of study results, which would definitely provide valuable evidence for the scientific investigation on environmental science, especially for the degradation of organic pollutants and their removal/transformation in marine environment, were obtained.I. The oxidative degradation possibility of DMP, DEP, ABS, MBS and 1-naphthol in Fenton/UV system was first investigated and an emphasis was made on how the original concentration of H2O2 (and Fe2+) and the acidity of solution influenced the degradation of them.1. The studies proved that the oxidation capacity of Fenton reagent was greatly improved by irradiation of UV light and therefore the oxidative degradations of DMP, DEP, ABS, MBS and 1-naphthol were vigorously enhanced. In Fenton/UV system, the maximal degradation percentages of DMP, DEP, ABS, MBS and 1-naphthol within 120 min were 81.1 %, 75.8 %, 86.0 %, 70.0 % and 88.2 %, respectively.2. The original concentration of H2O2 significantly influenced the degradation of DMP, DEP, ABS, MBS and 1-naphthol. When the original concentration of H2O2 was higher or lower than the optimal concentration, the degradation percentages of DMP,DEP, ABS, MBS and 1 -naphthol would decrease at different degrees.3. The degradations of DMP, DEP, ABS, MBS and 1-naphthol were also influenced significantly by the original concentration of Fe2+. The degradation percentages of DMP, DEP, ABS, MBS and 1-naphthol would decrease at different degrees with the decreasing or increasing of original concentrations of Fe2+.4. The solution acidity had a great impact on the degradation of DMP, DEP, ABS, MBS and 1-naphthol. The degradations of DMP, DEP, ABS and MBS were maximal at the optimal pH values and decreased with the deceasing or increasing of pH value. However, between pH 3.5 and pH 4.5, the degradation percentages of 1-naphthol were beyond 80.0 % and outside the pH range, the degradation percentage of 1-naphthol would decrease.II. The Fenton/UV oxidative degradation kinetics of DMP, DEP, ABS, MBS and 1-naphthol were first investigated and an emphasis was made on the effect of temperature on their oxidative degradation and their reaction activation energies in the specific experimental conditions.1 The results demonstrated that the photo oxidative degradation of the five compounds by Fenton/UV system could be described very well by pseudo first order reaction model.2. The first rate constants increased by 3.7-5.3 times and the half lives decreased by 3.7-5.3 times when temperature varied from 25 to 50 . The temperature dependence of aimed compounds was in good agreement with that predicted by the kinetic formulation.3. The high dependence of Fenton/UV system reactivity on the reaction temperature was attributed to the high temperature dependence of decomposition of H2O2 to hydroxyl radicals.4. The activation energies (obtained by Arrhenius equation) of DMP, DEP, 1-naphthol, ABS and MBS on specific experimental conditions were 48.1 kJ-mol-1, 49.1 kJ mol, 54.6 kJ mol, 56.4 kJ mol and 56.8 kJ mol respectively.III. The degradation mechanisms of DMP and DEP in Fenton/UV system were first investigated. Particularly, many intermediate products were identified by GC-MS and the probable degradation pathways of DEP and DMP by Fenton/UV system wereproposed.1. GC-MS analysis indicated that the major degradation i

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