Desorption and photodegredation of polychlorinated biphenyls (PCB's) in surfactant solutions

Laboratory-scale studies were conducted to determine the feasibility of using a surfactant washing system for the removal of polychlorinated biphenyls (PCBs) from contaminated soils. Further, photodechlorination was used to destroy the PCBs that were transferred into surfactant micelles. Soils contaminated with PCBs were effectively treated using a combination of surfactant washing with nonionic surfactants and photolysis of the resulting solution. The use of surfactants greatly enhanced the removal of PCBs from soils. The mass loading ratio of surfactant:soil was found to be the key parameter in determining PCB removal efficiency for a given system. Many soil-surfactant system models are based on mass loading ratios in the system, such as the Langmuir isotherm, Freundlich isotherm, and a PCB phase distribution model developed by Jafvert et al. ( 1995) . When using the model developed by Javfert et al., one must consider the source of organic carbon. When significant levels of total petrolem hydrocarbons (TPH) are present, the model can no longer be used to predict contaminant (PCB) removal due to competition. Batch and column systems performed equally well in the methods used. Both systems removed approximately 40% of the available PCBs after one wash cycle. Photolysis of PCBs selectively destroyed congeners that have been shown to cause an estrogenic response in humans. Both the rate and extent of degradation were higher for estrogenic compounds than for non-estrogenic compounds. After 40 minutes, 65% of the initial estrogenic compounds were degraded versus 27% of the non-estrogenic compounds. The TPH in one of the soil wash solutions, primarily contaminated with TPH and Aroclor 1248, reduced the quantum yield of photolysis by more than a factor of 4 when compared to a. solution of only Aroclor 1248. 2, 2' , 4, 4' , 6, 6' CB followed a stepwise reductive dechlorination during photolysis, with the ortho chlorines being preferentially removed. The quantum yield of photolysis for 2,2' ,4,4' ,6,6'CB on POL(l0) was found to be 0.44.