Removal of PCDD/Fs and PCBs from sediment by oxygen free Pyrolysis  

作　　者：HU Zhan-bo Saman Wijesekara R.G. Ronald R. Navarro WU De-yi ZHANG Da-lei Masatoshi Matsumura KONG Hai-nan 

机构地区：[1]School of Environmental Science and Engineering, Shanghai Jiaotong University, Shanghai 200240, China [2]Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba-shi 305-8572, Japan [3]Guangxi University, Nanning 530004, China

出　　处：《Journal of Environmental Sciences》2006年第5期989-994,共6页环境科学学报（英文版）

基　　金：The New Energy and Industrial Technology Development Organization of Japan

摘　　要：Few studies have dealt on the evaluation of volatilization and decomposition reactions of dioxins from sediment by oxygen free pyrolysis. In this study, the performance of pyrolysis on the removal of dioxins from sediment was investigated. Dioxin concentrations of the raw sediment and the solid residues after pyrolysis were analyzed at different conditions. Results showed a removal efficiency of 99.9999% for total dioxins at 800℃ and retention time of 30 min. All the polychlorinated dibenzo-furans （PCDFs） have been removed and were not formed in the solid residues at the retention time range of 30-90 min at 800℃. Close to 100% removal of polychlorinated dibenzo-p-dioxins （PCDDs） was also achieved. Only trace PCDDs were detected in the solid yields at a retention time of 60 min. The highest removal efficiency of polychlorinated biphenyls （PCBs） was more than 99.9994% at a retention time of 30 min. During cooling period following pyrolysis, however, the concentration of total dioxins in solid residues increased 130 times as compared to that of the raw sediment under air atmosphere. This confirmed that some complex reactions do occur to form PCDD/Fs and PCBs from 800 to 400℃ in the presence of oxygen. Oxygen-free atmosphere therefore can prevent formation of dioxin during thermal process thus generating clean solid residues.Few studies have dealt on the evaluation of volatilization and decomposition reactions of dioxins from sediment by oxygen free pyrolysis. In this study, the performance of pyrolysis on the removal of dioxins from sediment was investigated. Dioxin concentrations of the raw sediment and the solid residues after pyrolysis were analyzed at different conditions. Results showed a removal efficiency of 99.9999% for total dioxins at 800℃ and retention time of 30 min. All the polychlorinated dibenzo-furans （PCDFs） have been removed and were not formed in the solid residues at the retention time range of 30-90 min at 800℃. Close to 100% removal of polychlorinated dibenzo-p-dioxins （PCDDs） was also achieved. Only trace PCDDs were detected in the solid yields at a retention time of 60 min. The highest removal efficiency of polychlorinated biphenyls （PCBs） was more than 99.9994% at a retention time of 30 min. During cooling period following pyrolysis, however, the concentration of total dioxins in solid residues increased 130 times as compared to that of the raw sediment under air atmosphere. This confirmed that some complex reactions do occur to form PCDD/Fs and PCBs from 800 to 400℃ in the presence of oxygen. Oxygen-free atmosphere therefore can prevent formation of dioxin during thermal process thus generating clean solid residues.

关 键 词：DIOXINS PYROLYSIS oxygen free SEDIMENT PCBS 

分 类 号：X703[环境科学与工程—环境工程]