Optimized Thermal Desorption-Catalytic Technology For Remediation Of Polybrominated Diphenyl Ethers Contaminated Soils

Polybrominated diphenyl ethers is a new kind of persistent organic pollutants (POPs), because of its persistence, bioaccumulation and biotoxicity, potential harming to environment and biological, therefore, the fourth conference of the parties will be commercial five bromine biphenyl ethers and eight bromine biphenyl ether included in annex A attached to the Stockholm convention in the control list in 2009. Based on thermal analysis principle, this study uses the optimized thermal desorption-degradation catalytic combustion technology to remediate PBDEs contaminated soil.Based on the traditional thermal desorption technology, in order to lower cost of disposal and heat energy loss, optimized thermal desorption technology complete the whole combustion process spontaneously in the context of ventilation after the charcoal fire. Charcoal not only as a source of combustion, but also can be used as adsorbent in this experiment, reusing material and avoiding to producing secondary pollution. Remediating BDE209 contaminated soils of three concentration level, the result showed that the removal rate of PBDEs is 63%、81%、94% respectively. Analysing the degradation products of PBDEs, the experiment result expressed that the high bromine biphenyl ethers mainly took the form of debromination step by step in the process of remediate PBDEs contaminated soils by optimized thermal desorption technology. In the optimized thermal desorption process, PBDD/Fs can detected in the offgas, but conform to the standard, indicating that higher temperature (>650℃)controls PBDD/Fs.In order to further degrade PBDEs homologue of the offgas, this study degrades PBDEs homologue by the means of the optimized thermal desorption-catalytic combustion technology. This experiment selects three kinds of catalyst (Pt/γ-Al2O3/Al, Cu/γ-Al2O3/Al and Fe/Cu/γ-Al2O3/Al) to explore the degradation efficiency at 200℃ and 300℃. The experimental results show that Pt/γ-Al2O3/Al catalyst is not applicable to the degradation of PBDEs; Cu/γ-Al2O3/Al catalysts at 200℃ and 300℃ removal rates were 50% and 80% respectively; Fe/Cu/γ-Al2O3/Al catalysts at 200℃ and 300℃ PBDEs removal rates ball were 70%, little affected by temperature.