组合液膜对土壤淋洗液中砷(As)的提取效果

Recovery of arsenic from soil leachate by composite liquid membrane

针对土壤淋洗液中重金属传统萃取及液膜提取方法效率低的问题,提出组合液膜来提高提取率.本研究采用双二-乙基已基磷酸(D2EDTPA)和磷酸三丁酯(TBP)互为协同提取剂的组合液膜提取技术对土壤淋洗液中砷(As)进行提取,考察了系统温度、组合池膜溶液提取剂与膜溶剂体积比(M1/M2)、组合相有机相与水相体积比(O/A)、组合相提取剂比例(VD2EDTPA/VTBP)对As3+和As5+提取率的影响.研究结果表明,组合提取剂与As形成络合物在液膜系统中传输,最佳提取条件为:系统温度在28—30℃左右、M1/M2为4∶1、O/A为2∶1、VD2EDTPA/VTBP为4∶3.As3+和As5+起始浓度为5.45×10^(-4)mol·L^(-1)和1.12×10^(-4)mol·L^(-1)时,90 min最佳提取条件下提取率可达93.1%和82.7%.

In order to improve the extraction efficiency of the traditional extraction and liquid film extraction method in soil leaching liquor,this paper proposed a combination liquid membrane to improve the extraction rate. A composite liquid membrane with bis 2-ethyl phosphoric acid（ D2 EDTPA） and tributyl phosphate（ TBP） as synergistic extractant,was used to extract arsenic（ As） in the soil leachate. Effects of the system water temperature,volume ratio of membrane solvent to solvent in the combined receiving pool（ M1/M2）,volume ratio of organic phase to aqueous phase in the composite phase（ O/A） and extractant proportion of composite phase（ VD2 EDTPA/VTBP） on the extraction rate of As3＋and As5＋were investigated. The results showed that the synergistic extractants formed a complex with As and transported in the liquid membrane system. The optimum extraction conditions were the system temperature about 28—30 ℃,M1/M2 4∶1,O/A 2∶1 and VD2 EDTPA/VTBP4 ∶3. At initial concentrations of As3＋and As5＋of 5.45 ×10-4 mol·L-1 and 1.12 × 10-4 mol·L-1,the extraction rate reached 93.1% and 82.7% under the optimum conditions.