高浓度DDTs污染土壤机械化学球磨试剂筛选

为了筛选DDTs(包括DDT及其衍生物——DDE、DDD)高污染土壤无害化处理的机械化学球磨试剂,以某退役DDT生产场地高污染土壤为研究对象,将不添加任何球磨试剂处理作为对照,分析添加不同球磨主剂(CaO、CaO₂和Fe粉)、球磨助剂(SiO₂、Al₂O₃)组合以及双金属(Fe-Ni、Fe-Zn)试剂对土壤中DDTs的去除效果. 结果表明:①对照处理下土壤w(DDTs)随球磨时间的延长而不断降低,8 h后降至404.0 mg/kg,仍远超过GB 5085.6—2007《危险废物鉴别标准 毒性物质含量鉴别》标准限值〔w(DDTs)为50 mg/kg〕；单一添加CaO₂处理球磨8 h后,土壤及球磨剂混合物中w(DDTs)仍为118.0 mg/kg；而单一添加CaO和Fe粉处理分别于球磨4和6 h后,土壤及球磨剂混合物中w(DDTs)低于GB 5085.6—2007标准,因此,CaO和Fe粉是较好的DDTs机械化学球磨主剂. ②与单一添加CaO处理相比,在CaO中加入球磨助剂SiO₂或Al₂O₃球磨4 h后,土壤及球磨剂混合物中 w(DDTs)由28.55 mg/kg分别显著降至18.70或17.57 mg/kg,DDTs去除率由99.16%升至99.45%或99.48%. 与单一添加Fe粉处理相比,在Fe粉中加入SiO₂或Al₂O₃球磨4 h后,土壤及球磨剂混合物中w(DDTs)由193.0 mg/kg分别显著降至54.25或69.98 mg/kg,虽然仍略超过GB 5085.6—2007标准限值,但却显示出SiO₂或Al₂O₃对机械化学去除土壤DDTs具有显著的促进作用. ③Fe-Ni和Fe-Zn双金属球磨处理4 h后,土壤及球磨剂混合物中w(DDTs)分别为27.00和4.00 mg/kg,DDTs去除率分别达到99.21%和99.88%. 因此,Fe-Zn双金属作为去除土壤DDTs的机械化学球磨试剂,具有潜在的应用前景. 

Selection of Milling Reagents for Mechanochemical Degradation of High Concentrations of DDTs in Contaminated Soil

Abstract: With a goal to screen highly efficient milling reagents for mechanochemical treatments of soil heavily contaminated with DDTs (including DDT and its derivatives-DDE, DDD), this study tested the effectiveness of ball milling reagents (CaO, CaO₂ and Fe), additives (SiO₂ and Al₂O₃) and bimetallic reagents (Fe-Ni and Fe-Zn) with no additives as blank treatment on soil taken from a former DDT production site. The results showed that the residual DDTs concentration w(DDTs) in the blank treatment declined with time. After 8 h of ball milling, w(DDTs) was 404.0 mg/kg, which was still much higher than GB 5085.6-2007, the Identification Standard For Hazardous Waste, (w(DDTs):50 mg/kg). w(DDTs) in the CaO and Fe treatment was lower than GB 5085.6-2007 after 4 and 6 h, respectively. However, w(DDTs) in the CaO₂ treatment was still at 118.0 mg/kg after 8 h of milling. Therefore, CaO and Fe were better milling reagents for mechanochemical treatment of DDTs. After 4 h of ball milling, w(DDTs) was reduced significantly from 28.55 mg/kg in the CaO treatment to 18.70 mg/kg in the CaO-SiO₂ treatment and 17.57 mg/kg in the CaO-Al₂O₃ treatment. The removal rate of DDTs increased from 99.16% to 99.45% and 99.48%, respectively. After 4 h of ball milling, w(DDTs) was reduced significantly from 193.0 mg/kg in the Fe treatment to 54.25 mg/kg in the Fe-SiO₂ treatment and 69.98 mg/kg in the Fe-Al₂O₃ treatment, slightly exceeding GB 5085.6-2007. SiO₂ or Al₂O₃ have a significantly stimulative effect on mechanochemical treatment of DDTs in soil. 3) w(DDTs) in the bimetallic Fe-Ni or Fe-Zn treatment were reduced to 27.00 and 4.00 mg/kg, with removal rates of 99.21% and 99.88%, respectively. In conclusion, bimetallic Fe-Zn has the potential to be used as a highly efficient milling reagent for mechanochemical treatment of DDTs-contaminated soil.