花生油与羟丙基β环糊精对有机氯农药污染场地土壤异位增效淋洗修复研究

Remediation of Organochlorine Pesticides (OCPs) Contaminated Soil by Successive Peanut Oil and Hydroxypropyl-β-cyclodextrin Enhanced Soil Washing

针对长三角典型区域内某废弃有机氯农药(OCPs)污染场地土壤,选择花生油和羟丙基β环糊精(HPCD)作为环境友好的淋洗剂,并嵌合超声强化、升温辅助等增效洗脱技术,研究了其对OCPs污染场地土壤的洗脱修复效果。结果发现,在100 ml/L花生油和50 g/L HPCD、50 C水浴和35 kHz超声30 min、连续淋洗5次条件下,土壤中DDTs、氯丹(Chlordanes)、灭蚁灵(Mirex)和总量OCPs的最大去除率分别为99.6%±2.2%、94.0%±1.3%、91.3%±2.0%和96.0%±2.5%。同时采用Tenax TA树脂连续提取法,监测每次连续淋洗后土壤中各组分OCPs解吸特性,发现随着淋洗次数的增加,土壤中OCPs的400-h Tenax可提取量逐渐减少,OCPs的快速解吸组分(Fr)和慢速解吸组分(Fsl)比例较原始土壤中的相应比例显著下降(P<0.01),OCPs的快速解吸速率常数(kr)、慢速解吸速率常数(ksl)和超慢速解吸速率常数(kvl)也较原始土壤中相应解吸速率常数显著降低(P<0.01)。综合考虑修复效率和土壤修复后潜在环境风险,3次淋洗可以认为较为合理。本研究为OCPs污染场地土壤的异位增效淋洗技术研发和淋洗终点判断提供了一种有效手段。

Problems associated with OCPs-contaminated sites in China have received wide attention.This study investigated the feasibility of using peanut oil solution and hydroxypropyl-β-cyclodextrin （HPCD） solution to enhance ex situ soil washing for extracting OCPs.Elevated temperature （50℃） in combination with ultrasonication （35 kHz,30 min） at 100 ml/L peanut oil and 50 g/L HPCD was effective.99.6％ ± 2.2％ of DDTs、94.0％ ± 1.3％ of Chlordane、91.3％ ± 2.0％ of Mirex and 96.0％ ± 2.5％ of total OCPs were removed from soil after five successive washing cycles.The desorption kinetics of OCPs from contaminated soil was determined before and after successive washings.The 400 h Tenax extraction of OCPs from soil was decreasing gradually with increasing washing times.Furthermore,the Fr,FS1,kr,ks1 and kv1 were significantly lower than that of CK （P＜0.01）.Therefore,considering the removal efficiency and potential environmental risk after soil washing,successive washing three times was selected as a reasonable parameter.These results have practical implications for site risk assessment and cleanup strategies.