温度和停留时间对十溴联苯醚在污染土壤中热脱附的影响

Effects of Temperature and Residue Time on Remediation of Decabromodiphenyl Ether-Contaminated Soil by Thermal Desorption Technology

采用自配十溴联苯醚污染土壤开展热脱附试验研究,试验温度分别为200、300、325、350、400和450℃,停留时间为10、20、30、40、50和90 min.分析多溴联苯醚(PBDEs,包括BDE28、BDE47、BDE66、BDE99、BDE100、BDE138、BDE153、BDE154、BDE183、BDE190、BDE196、BDE197、BDE203、BDE205、BDE206、BDE207、BDE208和BDE209)热脱附前后污染物在土壤中的浓度及总脱附率.试验用土样中w(PBDEs)为1 136.69 mg/kg.低温段(200和300℃)污染物去除率较低,在300℃、停留时间90 min时,残留w(PBDEs)为263.57 mg/kg,去除率为76.81%;中温段(325和350℃)污染物大量减少,350℃、停留时间40 min时,残留w(PBDEs)为114.01 mg/kg,去除率达90%;高温段(400和450℃),温度为450℃、停留时间20 min时,残留w(PBDEs)为4.81mg/kg,去除率达99%以上.结果表明,PBDEs去除率随温度或停留时间的增加而增大,处置试验用土样比较合理的热脱附操作条件:温度为400℃、停留时间为20 min.

Soil artificially contaminated with DecaBDE was used in this study for thermal desorption. Six temperatures （200, 300, 325, 350, 400 and 450 ℃ ） and six levels of residue times （10, 20, 30, 40, 50 and 90 rain） were set in the experiment. The removal rates and residual concentrations of polybrominated diphenyl ethers （PBDEs, including BDE28, BDE47, BDE66, BDE99, BDE100, BDE138, BDE153, BDE154, BDE183, BDE190, BDE196, BDE197, BDE203, BDE205, BDE206, BDE207, BDE208 and BDE209） were tested. The PBDEs concentration of the sample was 1136. 69 mg/kg. In the low temperature ranges, 200 ℃ and 300 ℃ , the removal rates of PBDEs were lower than those under higher temperatures. At 300 ℃ , the removal rate was 76.81% , and the concentration of PBDEs in the soil was 263.57 mg/kg after being heated for 90 min. In the middle temperature ranges, 325 ℃ and 350 ℃ , the PBDEs residues were much less than those in the low temperature ranges. The concentration of PBDEs in the soil was 114. 01 mg/kg after beingheated at 350 ℃ for 40 min, representing a removal rate of about 90%. In the high temperature ranges, 400 ℃ and 450 ℃ , the PBDEs concentration was 4. 81 mg/kg after 20 minutes of heating at 450 ℃ , representing a removal rate exceeding 99%. The results showed that the removal rates of PBDEs increase with temperature and/or residence time. According to the results of the experiment, the optimal temperature and residue time to disposeof the experimental soil samples were 400 ℃ and 20 min.