1Photochemical Dechlorination of Highly Chlorinated PCBs

This paper presents the results of a laboratory investigation to dechlorinate and degrade Aroclor 1254 using UV photolysis with and without a photosensitizer. Some experiments using Fenton’s reagent as a pretreatment, prior to UV photodegradation, were also conducted. The impact of various solvents including hexane, alkaline isopropanol and neutral and alkaline acetonitrile on PCB photodechlorination, was studied. The results indicated that the rate of dechlorination was dependent on the solvent and the presence of alkalinity. Whereas dechlorination was observed in all solvents, it was most rapid in alkaline isopropanol. The dechlorination was marked by a chromatographic shift, observed in GC plots. The concentration of chloride ions released as a result of dechlorination was measured, in one instance, and found to increase with time. Irradiation with 254 nm UV light without any photosensitizer surfaced as the most effective method for dechlorinating Aroclor 1254. The biphenyl formed as a result of PCB dechlorination also degraded by photolysis. The treatment of PCBs with Fenton’s reagent prior to subjecting them to UV irradiation, led to a decrease in Aroclor 1254 concentration. Polychlorinated biphenyls (PCBs), which consist of 209 different congeners, are thermally stabl