三种表面活性剂对高浓度DDTs污染土壤的洗脱作用

以高浓度滴滴涕(DDTs)污染场地土壤为研究对象,采用表面活性剂洗脱试验,比较研究了聚氧乙烯山梨糖醇酐单硬脂酸酯(Tween60)、辛基酚聚氧乙烯醚(TritonX 100)、十二烷基硫酸钠(SDS)对污染土壤中DDTs的洗脱效率.试验结果表明,三种表面活性剂对污染土壤中DDTs均具有一定的洗脱作用,去离子水对DDTs几乎没有洗脱效果.随着洗脱液中Tween60和SDS质量浓度的逐渐升高,土壤中DDTs的总洗脱效率逐渐增大,一次性洗脱时最大洗脱效率分别为43.60%和34.62%.随着洗脱液中TritonX 100质量浓度的逐渐升高,土壤中DDTs的总洗脱效率出现先增大后降低再升高的变化现象,最大为15.46%.土壤中六种DDT组分的洗脱效率不完全一样,其中Tween60对2,4'-DDD的洗脱效率可达55.12%,对4,4'-DDD的洗脱效率为54.09%;SDS对2,4'-DDD的洗脱效率为59.99%,对4,4'-DDD的洗脱效率为57.10%.试验结果可为筛选适宜的表面活性剂及质量浓度,研发高浓度DDTs污染场地土壤表面活性剂洗脱修复技术的工程应用提供理论依据.

Effects of three surfactants on washing remediation of DDTs contaminated site soil

Surfactant washing experiment was carried out for three surfactants with highly contaminated soil by DDT and its metabolites(DDTs) from an industrial site. Removal rates of DDTs from the soil by Tween60(Polyoxyethylene sorbitan monostearate), TritionX 100(Polyoxyethylene octylphenol ether) and SDS(Sodium dodecyl sulfate), respectively, were compared in this study. The results showed that all the three surfactants were effective on desorption of DDTs from the soil, and little effect of deionized water on desorption of DDTs was observed in this study. Removal rates of DDTs from the soil increase gradually with the increase in concentrations of Tween60 and SDS. The highest removal rates were 43.60% and 34.62% for Tween60 and SDS, respectively. Removal rates of DDTs from soil increase firstly when TritionX 100 concentration increase from 0 to 750 mg·L~(-1), then decrease when TritionX 100 concentrations increase from 750 to 1 500 mg·L~(-1) and finally increase rapidly when TritionX 100 concentration increase from 1500 to 3 000 mg·L~(-1). The highest removal rate of 15.46% was observed for TritionX 100 at 3 000mg·L~(-1). All the three surfactants . show higher efficiency for desorption and removal of 2,4'-DDD and 4,4'-DDD than the other metabolites, and the least efficiency is observed for 4,4'-DDT. Removal rates of 2,4'-DDD and 4,4'-DDD are as high as 55.12% and 54.09% as extracted by Tween60, and 59.99% and 57.10% as extracted by SDS, respectively. Results of this study will provide a theoretical basis for selection of suitable surfactants and engineering applications of surfactant enhanced washing for DDTs contaminated site soil.