title: Effect of temperature and particle size on the thermal desorption of PCBs from contaminated soil.
abstract: Thermal desorption is widely used for remediation of soil contaminated with volatiles, such as solvents and distillates. In this study, a soil contaminated with semivolatile polychlorinated biphenyls (PCBs) was sampled at an interim storage point for waste PCB transformers and heated to temperatures from 300 to 600 °C in a flow of nitrogen to investigate the effect of temperature and particle size on thermal desorption. Two size fractions were tested: coarse soil of 420-841 μm and fine soil with particles <250 μm. A PCB removal efficiency of 98.0 % was attained after 1 h of thermal treatment at 600 °C. The residual amount of PCBs in this soil decreased with rising thermal treatment temperature while the amount transferred to the gas phase increased up to 550 °C; at 600 °C, destruction of PCBs became more obvious. At low temperature, the thermally treated soil still had a similar PCB homologue distribution as raw soil, indicating thermal desorption as a main mechanism in removal. Dechlorination and decomposition increasingly occurred at high temperature, since shifts in average chlorination level were observed, from 3.34 in the raw soil to 2.75 in soil treated at 600 °C. Fine soil particles showed higher removal efficiency and destruction efficiency than coarse particles, suggesting that desorption from coarse particles is influenced by mass transfer.
authors.affiliation: State Key Laboratory of Clean Energy Utilization, Institute for Thermal Power Engineering, Zhejiang University, Hangzhou, 310027, China.
authors.forename: Zhifu
authors.initials: Z
authors.lastname: Qi
authors.forename: Tong
authors.initials: T
authors.lastname: Chen
authors.forename: Sihong
authors.initials: S
authors.lastname: Bai
authors.forename: Mi
authors.initials: M
authors.lastname: Yan
authors.forename: Shengyong
authors.initials: S
authors.lastname: Lu
authors.forename: Alfons
authors.initials: A
authors.lastname: Buekens
authors.forename: Jianhua
authors.initials: J
authors.lastname: Yan
authors.forename: Cora
authors.initials: C
authors.lastname: Bulmău
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Li
mesh_terms: D052918:Environmental Restoration and Remediation / Q000379:methods*; D006358:Hot Temperature; D010316:Particle Size; D011078:Polychlorinated Biphenyls / Q000032:analysis / Q000737:chemistry*; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis / Q000737:chemistry*
chemical_list: D012987:Soil; D012989:Soil Pollutants; D011078:Polychlorinated Biphenyls