Zhao Baowei, Zhu Lizhong, Yang Kun
Department of Environmental Science, Xixi Campus, Zhejiang University, Hangzhou 310028, China.
Chemosphere. 2006 Feb;62(5):772-9. doi: 10.1016/j.chemosphere.2005.04.080. Epub 2005 Jun 20.
Efforts to remediate the dense nonaqueous phase liquids (DNAPLs) by mobilizing them face with risks of driving the contaminants deeper into aquifer zones. This spurs research for modifying the approach for in situ remediation. In this paper, a novel solubilization of DNAPLs by mixed nonionic and anionic surfactant, Triton X-100 (TX100) and sodium dodecylbenzene sulfonate (SDBS), was presented and compared with those by single ones. Given 1:40 phase ratio of DNAPL:water (v/v) and the total surfactant concentration from 0.2 to 10gl(-1), mixed TX100-SDBS at the total mass ratios of 3:1, 1:1 and 1:3 exhibited significant solubilization for the DNAPLs, trichloroethene (TCE), chlorobenzene (CB) and 1,2-dichlorobenzene (1,2-DCB). The solubilization extent by mixed TX100-SDBS was much larger than by single TX100 and even larger than by single SDBS at the ratios of 1:1 and 1:3, respectively. TX100 partitioning into the organic phase dictated the solubilization extent. The TX100 losses into TCE, CB and 1,2-DCB phases were more than 99%, 97% and 97% when single TX100 was used. With SDBS alone, no SDBS partitioned into DNAPLs was observed and in mixed systems, SDBS decreased greatly the partition loss of TX100 into DNAPLs. The extent of TX100 partition decreased with increasing the amount of SDBS. The mechanism for reduction of TX100 partition was discussed. TX100 and SDBS formed mixed micelles in the solution phase. The inability of SDBS to partition into DNAPLs and the mutual affinity of SDBS and TX100 in the mixed micelle controlled the partitioning of TX100 into DNAPL phase. The work presented here demonstrates that mixed nonionic-anionic surfactants would be preferred over single surfactants for solubilization remediation of DNAPLs, which could avoid risks of driving the contaminants deeper into aquifers and decrease the surfactant loss and remediation cost.
通过调动来修复致密非水相液体（DNAPLs）的努力面临着将污染物驱入含水层更深区域的风险。这促使人们对原位修复方法进行改进研究。本文提出了一种由非离子和阴离子表面活性剂混合（Triton X - 100（TX100）和十二烷基苯磺酸钠（SDBS））增溶DNAPLs的新方法，并与单一表面活性剂的方法进行了比较。在DNAPL与水的相比例为1:40（v/v）且表面活性剂总浓度为0.2至10 g·l⁻¹的条件下，总质量比为3:1、1:1和1:3的TX100 - SDBS混合物对DNAPLs、三氯乙烯（TCE）、氯苯（CB）和1,2 - 二氯苯（1,2 - DCB）表现出显著的增溶作用。TX100 - SDBS混合物的增溶程度远大于单一的TX100，在1:1和1:3的比例下甚至大于单一的SDBS。TX100在有机相中的分配决定了增溶程度。当使用单一TX100时，TX100在TCE、CB和1,2 - DCB相中的损失分别超过99%、97%和97%。单独使用SDBS时，未观察到SDBS分配到DNAPLs中，在混合体系中，SDBS大大降低了TX100分配到DNAPLs中的损失。TX100的分配程度随着SDBS量的增加而降低。讨论了TX100分配减少的机制。TX100和SDBS在溶液相中形成混合胶束。SDBS无法分配到DNAPLs中以及SDBS与TX100在混合胶束中的相互亲和力控制了TX100分配到DNAPL相的过程。本文的研究表明，对于DNAPLs的增溶修复，非离子 - 阴离子混合表面活性剂比单一表面活性剂更具优势，这可以避免将污染物驱入含水层更深区域的风险，并降低表面活性剂损失和修复成本。
