Supercritical Fluid Extraction of 1,2,4-Trichlorobenzene from DOE Job Control Wastes

Abstract

At U.S. Department of Energy (DOE) sites, significant amounts of job control waste (JCW) need to be disposed. This JCW is generated and contaminated with polychlorinated biphenyls (PCBs) during cleanup operations. A commercial, plant-based absorbent material, “Toxi-dry,” is used extensively for decontamination and decommissioning of DOE waste sites and is classified a hazardous JCW after use. In this investigation, 1,2,4-trichlorobenzene (TCB) was chosen as the surrogate for PCBs. As a promising separation technology, supercritical fluid extraction (SFE) was investigated for removing and recovering PCBs from contaminated of JCW. TCB was extracted from Toxi-dry using both pure and modified supercritical carbon dioxide. It was found that at constant pressure, increasing temperature from 40 to 80°C greatly improved the recoveries, while the pressure effect of SFE was not as clear as the temperature effect. With 5wt% acetone or ethanol added as cosolvent, the efficiency of SFE of TCB was also significantly improved.

Keywords:

• Supercritical fluid extraction
• Job control waste
• Polychlorinated biphenyls
• 1,2,4-Trichlorobenzene

Acknowledgments

This study was supported by the U.S. Department of Energy (EMSP Project #64979-SC). The authors thank Mark C. Thies and David A. Bruce (Clemson University) for providing the reference material Toxi-dry and constructive comments during the research.