Photocatalytic degradation of polychlorinated biphenyls in acetonitrile/H2O system using TiO2 thin film

Photocatalytic degradation of polychlorinated biphenyls (PCBs) in a plate-t ype batch recycle photoreactor using a TiO2 thin film is experimentally exa mined in an acetonitrile/H2O system. The concentrations of higher chlorinated biphenyls, hexa-, hepta- and octa- CBs, degrease regularly with irradiation time; those of lower chlorinated b iphenyls, tetra- and penta-CBs, increase in the initial period, and then de crease slowly. It is suggested that some series reactions occur from higher chlorinated biphenyls to lower ones. Based on the analysis of mass fragmen tograms, various PCBs decomposition/production reactions are found to occur . The extend of dechlorination rate of total PCBs from tetra- to octa-CBs i s approximately 35 % after 12 hours of irradiation through providing oxygen gas.