Effect of Process Parameters on the Degradation of Polychlorinated Biphenyls in Water Matrix using UV/H2O2

Abstract

In this study, the degradation of polychlorinated biphenyls (PCBs), Aroclor 1260, using the UV/H2O2 system was investigated. The effects of initial H2O2 concentration, initial pH of the solution and initial PCB concentration were studied using a batch tubular reactor equipped with a 254 nm low-pressure Hg lamp. PCB concentration was analyzed using GC-ECD as total aroclor.Results show that there is an optimum H2O2 concentration that maybe used beyond which no significant increase in the degree of degradation was achieved. The highest PCB degradation efficiency of 87.58% after 60 minutes was obtained at a peroxide concentration of 24.71mM and PCB concentration of about 40 ppm. The initial pH of the solution also proved to have an effect on PCB degradation. Highest oxidation efficiency of 87% was obtained at pH 7 after 60 minutes at a peroxide concentration of 24.71 mM. For the effect of initial concentration of PCBs, up to a certain concentration, degradation was found to increase with increasing PCB concentration. Highest degradation efficiency of 68% and 86% after 30 and 60 minutes, respectively, were obtained at a PCB concentration of 40 ppm. A decrease in degradation efficiency was, however, observed at 80 ppm which gave a lower degradation efficiency of 79% after 60 minutes of reaction In all the runs conducted, dechlorination is the main mechanism verified by GC-MS analysis.The use of UV/H2O2 for PCB degradation seems very promising in the treatment of wastewater containing PCBs. The results of this study are highly significant in performing a kinetic analysis on PCB degradation. Current efforts involves improvement of the process.