十二烷基硫酸钠和Triton X-100淋洗菲污染砂土研究

Flushing of Phenanthrene in Sandy Soils by Triton X-100 and Sodium Dodecyl Sulfate

比较研究了阴离子表面活性剂十二烷基硫酸钠(SDS)、非离子表面活性剂辛基酚聚氧乙烯醚Triton X-100(TX100)及其混合表面活性剂(SDS-TX100)对菲污染砂土的柱淋洗作用.表面活性剂质量浓度为1000、1750、2500和3250mg·L-1,混合表面活性剂的质量配比SDS∶TX100(S∶T)分别为1∶1、1∶2和1∶4.结果表明,单一SDS对土柱中菲的淋洗曲线规律不明显,呈锯齿状波动;TX100和SDS-TX100对土柱中菲淋洗规律明显,随淋洗液孔隙体积数增大,淋洗液中菲浓度呈先增大,达到峰值,然后逐渐降低的趋势,且随表面活性剂浓度的增大,淋洗液中菲浓度峰值增大,所需淋洗液的累积孔隙体积数减小.在淋洗液累积孔隙体积数相同时,同种表面活性剂对菲的去除率与表面活性剂浓度呈正相关;TX100和SDS-TX100对土柱中菲的去除效果与表面活性剂浓度和配比有关,且均远远大于SDS.当表面活性剂浓度为1000、1750和2500mg·L-1时,TX100和SDS-TX100对菲的累积去除率均可达95%以上,但SDS-TX100所需的累积孔隙体积数小于TX100;当表面活性剂浓度为3250mg·L-1时,5种表面活性剂(SDS、TX100、S∶T=1∶1、S∶T=1∶2和S∶T=1∶4)对菲的累积去除率均达到最大,分别为70.8%、99.9%、99.9%、98.7%和99.2%,而TX100所需的累积孔隙体积数最小.在表面活性剂淋洗修复有机污染土壤时,表面活性剂种类、浓度和配比等因素对修复效果影响显著.

A comparison of column flushing for phenanthrene-contaminated sandy soils was made by using an anionic surfactant,sodium dodecyl sulfate （SDS）,a nonionic surfactant,Triton X-100 （TX100）,and their mixed surfactants （SDS-TX100）.The tested concentrations of surfactants were 1 000,1 750,2 500 and 3 250 mg·L-1 while the mass ratios of SDS to TX100 （S：T） in the mixed surfactants were 1：1,1：2 and 1：4.It was shown that the elution curves （phenanthrene concentration in elutant versus porous volume number） by SDS were zigzag fluctuating rather than regular patterns while those by TX100 and SDS-TX100 were regular ones in which the phenanthrene concentrations in elutant increased,achieved maximum and then decreased with the porous volume numbers of eluting solutions.Moreover,the maximum phenanthrene concentrations increased and the total porous volume numbers decreased with surfactant concentration increasing.Given the surfactant and total porous volume number,the removal efficiencies of phenanthrene were positively related to surfactant concentrations.The removal efficiencies by TX100 and SDS-TX100 depended on concentration and ratio of surfactant and were much larger than those by SDS.Given 1 000,1 750 and 2 500 mg·L-1 of the surfactant concentrations respectively,the removal efficiencies by TX100 and SDS-TX100 were more than 95% but the total porous volume numbers by SDSTX100 were less than those by TX100.Given 3 250 mg·L-1 of the surfactant concentration,the total removal efficiencies by five surfactants （i.e.SDS,TX100,S：T=1：1,S：T=1：2 and S：T=1：4） achieved their maximum values as 70.8%,99.9%,99.9%,98.7% and 99.2%,respectively,but the needed porous volume numbers by TX100 were the least among those by all surfactants.The results illustrates that the factors such as type,concentration and ratio of surfactant play important roles in surfactant-enhanced flushing remediation for soils contaminated by organics.