Remediation of polychlorinated biphenyl contaminated soils/sediments by supercritical fluid extraction

Studies of polychlorinated biphenyl (PCB) desorption from soils have been conducted in a laboratory scale supercritical fluid extraction (SFE) unit to provide information for soil remediation. The results demonstrate the effectiveness of SFE as a promising technology for the clean up of PCB contaminated soils/sediments. After 30 minutes of extraction at 40°C and 100 atm, more than 86% of PCBs in real world Hudson River sediment and 92% in St. Lawrence River sediment were removed. The extraction of PCBs from spiked samples showed even higher efficiencies. Various effects such as temperature, pressure, cosolvent, sample water content, and soil/sediment type on PCB desorption have been investigated. The sample water content and the presence of cosolvent were shown to be the most important factors affecting desorption of PCBs. The results show that PCBs in real world samples are more tightly bound than in spiked samples. The desorption behavior of individual PCB congeners in various samples has been investigated. The results demonstrate no relative accumulation of the most environmentally threatening PCB congeners throughout the extraction process.