Degradation Of Some Organic Pollutants Using A Combination Technique Of Ozone-activated Carbon And Advanced Oxidation

In this study, di(2-ethylhexy)phthalate, a representational environmental hormone pollutant, and chloral, a typical disinfection by-products of drinking water, were degraded using a combination technique of ozone-activated carbon and advanced oxidation ( AC/O₃/TiO₂/UV ) . Their degradation effects, influencing factors, degradation kinetics and degradation mechanisms were investigated. The following main results have been achieved.(1) It was found that the combination technique of ozone- activated carbon and advanced oxidation can efficiently degrade the two organic pollutants, with high reaction rate constants and complete mineralization. The oxidation degradation reactions follow the pseudo first order kinetics.(2) It was found that a few of factors, such as the initial concentration of degraded pollutants, the pH value of the solution, the quantity of T1O2 loaded in the activated carbon, the concentration of added oxidant, the duration of illumination and some anion ions of HCO₃^-, NO₃^- and Cl^- in the solution had a significant effect on the degradation.(3) The measurements of TOC, pH values and targeted pollutants show that the degradation of TOC was obviously slower than that of their parent compounds, and that the variation of pH value in the system indicated the formation of some organic acids during degradation. This implicates that the organic pollutants were not mineralized to CO₂ and H₂O directly, but were converted to some intermediates firstly, and then mineralized completely.(4) The identified intermediates formed during chloral degradation mainly include acetic acid dichloride, formic acid, dichloromethane, dichloride oxide and formaldehyde, and the intermediates of di(2-ethylhexyl)phthalate are 1,2-benzenedicarboxylic acid, mono(2-ethylhexyl)ester, benzoic acid methyl ester, 2-hydroxy benzoic acid, 1,2-benzonodicarboxylicacid, di(butyl)phthalate, benzoic acid, formic acid, acetic acid, fumaric acid and oxalic acid.This result presents a new combination technique of ozone-activated carbon and advanced oxidation system. It has not only developed the theory of heterogeneous advanced oxidation process in some extent, but also will provide a foundation for the application of this combination technique to water deep treatment.