化学强化洗脱修复铜、菲及其复合污染黄土

Remediation of Cu/Phenanthrene and Combined Contaminated Loess Soil by Chemical-enhanced Washing

采用批平衡法研究了乙二胺四乙酸二钠(EDTA)或/和十二烷基硫酸钠(SDS)强化洗脱铜(Cu2+)或/和菲(PHE)污染的甘肃黄土.结果表明,EDTA或/和SDS能有效地去除单一或复合污染黄土中的Cu2+或/和PHE,当EDTA浓度<0.1 mol/L时,共存PHE对Cu2+的去除有明显的促进作用,而当EDTA浓度>0.1 mol/L时,共存PHE对Cu2+的去除有轻微的抑制.至于EDTA对PHE的去除,在所研究的浓度范围内,共存Cu2+促进了PHE的去除,在EDTA为0.01 mol/L时,复合菲的去除率比单一菲的高20.94%.在SDS强化洗脱中,在SDS<4 000 mg/L时,Cu2+对PHE的去除有轻微抑制,而在SDS>5 000 mg/L时,Cu2+对PHE的去除有促进作用.相反,在低浓度SDS时,PHE对Cu2+的去除有促进作用,而在高浓度时,PHE对Cu2+的去除有抑制作用.EDTA-SDS复合极大提高了污染物的去除率,在先EDTA后SDS、先SDS后EDTA和EDTA-SDS同时添加顺序中,Cu2+去除率分别为91.40%、95.10%和96.50%,比单独用EDTA对复合污染Cu2+的洗脱率62.94%分别高28.46%、32.16%和33.56%,PHE的去除率分别为68.30%、85.40%和84.95%,比单独用SDS对复合PHE的洗脱率52.16%分别高16.14%、33.24%、32.79%.因此,对PHE和Cu2+去除来说,试剂最佳添加顺序是先加SDS后加EDTA,或SDS-EDTA同时加入.

The chemical-enhanced washing of Cu2＋ or/and phenanthrene（PHE） single or combined contaminated loess soil in Gansu Province was investigated with disodium ethylene diamine tetraacetate（EDTA） or/and sodium dodecyl sulfate（SDS） by the batch equilibrium experiments.The experimental results showed that EDTA or /and SDS could remove efficiently Cu2＋ and/or PHE in single-contaminated or combined contaminated loess soils.The Cu2＋ removal was significantly promoted by coexisting PHE with low concentration of EDTA（EDTA0.1 mol/L）,however,the removal was slightly hindered with high concentration of EDTA（EDTA0.1 mol/L）.As for the PHE removal by EDTA,it was founded that coexisting Cu2＋ could enhance the PHE removal in the investigated ranges of the concentrations of EDTA.When concentration of EDTA was 0.01 mol/L,the removal of combined PHE was 20.94% higher than that of single PHE.The experimental results of the removal of contaminations by SDS showed that coexisting Cu2＋ could suppress slightly the removal of PHE at a concentration of less than 4 000 mg/L SDS,but could assist the removal of PHE in 5 000 mg/L or higher SDS concentration.On the contrary,the influence of coexisting PHE for the removal of Cu2＋ by SDS was that it facilitated Cu2＋ extraction by low concentrations of SDS,however,it inhibited the removal of Cu2＋ at high concentrations of SDS.The removal efficiencies of PHE and Cu2＋ were improved greatly as using combined EDTA-SDS.Beside,there are some differences in the removal efficiency of the both contaminants with the different sequence of EDTA and SDS added in the washing solution.In EDTA washing followed by SDS,SDS washing followed by EDTA and mixture of SDS-EDTA washing concurrently,the removal of Cu2＋ is 91.40%,95.10% and 96.50%,respectively,which is 28.46%,32.16%,33.56% higher than that of combined,62.94%,by single EDTA.For PHE,the removal is 68.30%,85.40%,84.95%,respectively,which is 16.14%,33.24%,32.79% higher than that of combined PHE,52.16%,by single SDS.Thus,SDS washing followed by EDTA or mixture of SDS-EDTA washing concurrently is considered as the optimal washing sequence for PHE and Cu2＋ removal.