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Thermal desorption of PCBs contaminated soil with calcium hydroxide in a rotary kiln

Liu, Jie, Zhang, Hao, Yao, Zhitong, Li, Xiaodong, Tang, Junhong
Chemosphere 2019 v.220 pp. 1041-1046
calcium hydroxide, dechlorination, desorption, electrical equipment, polluted soils, polychlorinated biphenyls, synergism, toxicity
In this study, thermal desorption was combined with the addition of calcium hydroxide to remediate polychlorinated biphenyls (PCBs) contaminated soil, collected from a storage point for PCB-contaminated capacitors and transformers. The thermal desorption test conditions were varied from 300 to 600 °C, both with blank soil and with 1% Ca(OH)2 added. The results showed that the synergistic thermal desorption was effective to removal most of PCBs. At 600 °C, the removal efficiency (RE) reached 94.0% in presence of Ca(OH)2, higher than that of 90.9% in blank soil. The dechlorination was significant when compared with blank soil. Ca(OH)2 effectively decreased both the sum and the toxic equivalence quantity (TEQ) value of the 12 dioxin-like PCBs, with the RE based on TEQ of 90.0%. Ca(OH)2 strengthened the removal, dechlorination and detoxication of PCBs. The synergistic effect factor proved the promotion did exist in the presence of Ca(OH)2.