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

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4.81 mg/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. 

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

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 min) 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 263.57mg/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 being heated 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 dispose of the experimental soil samples were 400 ℃ and 20 min.