中链支化非离子型表面活性剂对石油污染土壤的清洗性能及机理

Cleaning performance and mechanism of medium-chain branched nonionic surfactant to petroleum-contaminated soil

采用一系列(8种)中链支化非离子型表面活性剂N-长链碳酰基-L-苯丙氨酸单甲基聚乙二醇酯(记为Rn-L-MPEGm,n为烷基碳数,m为合成时所用聚乙二醇单甲醚的相对分子质量)清洗石油污染土壤。清洗实验结果表明,R12-L-MPEG1000的清洗性能最佳。含油率20.35%土壤的最佳清洗条件为:R12-L-MPEG1000加入量2.5%(w),固液比1∶4,50℃下以400 r/min的转速搅拌水洗40 min。在此条件下,除油率可达92.29%,土壤残油率仅为1.57%。通过研究原油乳化性能和原油吸附热力学,并将R12-L-MPEG1000与主链分子结构相似的OP-10进行比较,推断出R12-L-MPEG1000清洗石油污染土壤的机理为滚落-乳化机制和吸附-顶替机制。

The petroleum-contaminated soil was cleaned using a series of medium-chain branched nonionic surfactants N-long-chain carbonyl-L-phenylalanine monomethyl polyethylene glycol ester(denoted as Rn-L-MPEGm,n is the number of alkyl carbon,m is the relative molecular weight of polyethylene glycol monomethyl ether used in synthesis).The results of cleaning experiment show that R12-L-MPEG1000 has the best cleaning performance.For the petroleum-contaminated soil with oil content of 20.35%,the optimal cleaning conditions are as follows:R12-L-MPEG1000 addition of 2.5%(w),solid-liquid ratio of 1∶4,stirring speed of 400 r/min,washing time of 40 min and washing temperature of 50℃.The oil removal rate can reach 92.29%and the residual oil rate in soil is 1.57%.It is found that the cleaning mechanism of R12-L-MPEG1000 is the roll-emulsifying mechanism and the adsorption-displacement mechanism.