对柴油污染土壤洗涤修复表面活性剂的筛选及增效机制探究

Experimental Study on Surfactants Used in Soil Washing for Diesel-oil Contaminated Soil Remediation

分别采用5种表面活性剂十二烷基硫酸钠(SDS)、十二烷基苯磺酸钠(SDBS)、皂苷(saponin)、曲拉通X-100(TX-100)、聚氧乙烯月桂醚(Brij35)对柴油污染土壤进行清洗,考察pH、温度、搅拌时间、污染时长及助剂的使用对清洗效果的影响。并用Zeta电位仪对溶液电位,及接触角仪对清洗前后的土壤进行代表值的测定。结果表明:溶液浓度越大,清洗效果越好,对于柴油污染20 d的土壤,升高清洗温度和添加H_2O_2辅助清洗可提高柴油洗脱率;离子型表面活性剂的作用效果类似但存在差异,SDS在pH=10时使用最佳,柴油洗脱率可达65%,并可防止二次污染发生;SDBS则在pH=7时清洗效果最佳,洗脱率达59.3%;实验筛选出皂苷为较理想的清洗剂,与H_2O_2联用,柴油洗脱率最高可以达到75%;对于柴油污染130d土壤,延长清洗搅拌时间,可改善清洗效果。Zeta电位测定表明,表面活性剂与土壤粒子均带负电荷,"同性相斥"作用可防止二次污染。清洗后受柴油污染土壤的接触角变小,亲水性得到恢复。

In a study to select a best cleaner for soil washing in remediation of diesel-oil contaminated soil,five kinds of surfactants（SDS,SDBS,saponin,TritionX-100 and Brij35）were tested,and parameters of p H,temperature,contaminated time, agitation time and auxiliaries were investigated. In addition, Zeta potentials and contact angle variations of contaminated soil before and after washing were measured to probe into the changes of the hydrophilicity of soil particle,interaction of surfactants and soil particles and cleaning-up mechanisms. It was found that the diesel oil removal of 20 dold contaminated soil could be improved by increasing washing temperature or adding H2O2 as an auxiliary;the best result came from the washing using saponin together with H2O2,which removed diesel oil by 75%;and diesel oil removing of 130 d-old contaminated soil could be enhanced by means of increasing agitation time of washing. The Zeta potentials measurement showed that both of soil particles and surfactants were negatively charged,which can prevent the secondary contamination. Furthermore,after washing,contact angle of contaminated soil became small so that hydrophilicity of the soil was improved.