Wet peroxide oxidation of sediments contaminated with PCBs

Wet peroxide oxidation is investigated as a method of treating Hudson River sediments contaminated with polychlorinated biphenyls (PCBs). Aqueous slur ries containing 2.5% or 10% (w/w) sediment were oxidized with oxygen and hy drogen peroxide in a 1-L, high-pressure, semibatch reactor at temperatures up to 275 degrees C. Effluent concentrations of PCBs adsorbed on the sedime nt and dissolved in the water and gas phases were determined by high-resolu tion gas chromatography. The rates of oxidation of PCBs were highly depende nt on pH, temperature, and the rate of addition of hydrogen peroxide. The a ddition of hydrogen peroxide significantly increased the rates of oxidation of PCBs over those for conventional wet air oxidation. At 225 degrees C an d a pH of 2.6, addition of hydrogen peroxide at a mass ratio of hydrogen pe roxide to sediment of 3:10 resulted in greater than 99% removal of the PCBs as compared to 73% removal for conventional wet air oxidation. The destruc tion of PCBs increases with decreasing pH over the pH range from 7.5 to 2.6 . The optimum temperature for oxidation of PCBs using wet peroxide oxidatio n was ca. 225 degrees C. Above this temperature, destruction efficiencies d ecreased appreciably.