Using solar and ultraviolet light to degrade PCBs in sand and transformer oils.
The present study describes the effect of the operating variables in the sensitized solar photolysis of sandy sediments contaminated by polychlorinated biphenyls (PCBs) in alkaline isopropanol. PCBs were almost completely removed in two weeks with stoichiometric release of chloride and biphenyl (BP) by a mechanism of reductive dechlorination. The concentration of the sensitizer (acetone) was the variable found to have most influence on the process. Under the same conditions, only partial dechlorination of the PCBs (34%) was observed in dielectric fluids without generating biphenyl to any appreciable extent. Direct photolysis (ultraviolet light at 254nm) of dielectric oils dissolved in alkaline isopropanol lead to 92% removal of PCBs in 60min. The observed mechanism was again that of reductive dechlorination, with stoichiometric release of chloride, and the accumulation of biphenyl, quaterphenyl and condensation products of biphenyl with isopropanol.
Department of Chemical Engineering and Environmental Technology, Faculty of Marine and Environmental Sciences, Cádiz University, Polígono Río San Pedro s/n, 11510 Puerto Real, Cádiz, Spain. manuel.manzano@uca.es
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D000096:Acetone / Q000737:chemistry; D019015:Geologic Sediments / Q000032:analysis*; D007219:Industrial Oils / Q000032:analysis; D007700:Kinetics; D010782:Photolysis / Q000528:radiation effects*; D011078:Polychlorinated Biphenyls / Q000737:chemistry*; D013472:Sunlight; D014466:Ultraviolet Rays
D000096:Acetone; D011078:Polychlorinated Biphenyls