两种有机膦酸对砷、铅、锑污染土壤的淋洗研究

Study on the Washing of Arsenic, Lead and Antimony Contaminated Soil by Two Organophosphonic Acids

土壤淋洗技术操作简便、快速高效,被广泛应用于重金属复合污染土壤修复中。筛选绿色、高效的淋洗剂是这一技术的研究热点。文章以多氨基多醚基甲叉膦酸(PAPEMP)和二乙烯三胺五甲叉膦酸(DTPMPA)为供试淋洗剂,探讨其在不同淋洗条件下对某铅酸蓄电池厂内高浓度砷(As)、铅(Pb)、锑(Sb)污染土壤的淋洗情况,并探究淋洗前后供试土壤理化性质及重金属状态变化情况,最后基于强度系数(IR)和迁移系数(MF)综合评估供试土壤中残留重金属的环境生态风险。结果表明:在最佳淋洗条件下,经PAPEMP和DTPMPA三次淋洗后As、Pb、Sb去除率分别达到86.35%、90.07%、48.89%和78.07%、98.36%、42.51%。淋洗过程虽带走土壤部分速效养分,但增加了土壤中碱解氮、有机质含量、阳离子交换量、全磷、速效磷等的含量。同时,土壤中重金属的形态发生了改变。重金属的IR和MF值表明淋洗后的土壤中Pb和Sb的迁移性和生物可利用性减弱,As的迁移性和生物可利用性增加。Soil washing technology is easy to operate, fast and efficient, and is widely used in the remediation of heavy metal composite contaminated soil. Screening of green and efficient washing agents is a research hotspot of this technology. In this paper, polyamino polyether methylphosphonic acid (PAPEMP) and diethylenetriaminepenta-methylphosphonic acid (DTPMPA) were used as the test washing agents to investigate the washing of soil contaminated with high concentrations of arsenic (As), lead (Pb), and antimony (Sb) in a lead-acid battery factory under different washing conditions, and to explore the changes in the physicochemical properties of the test soil and the status of heavy metals before and after the washing, and then to investigate the changes of heavy metal status before and after the washing, and then to explore the changes of heavy metal status before and after the drenching. Finally, the environmental and ecological risks of the residual heavy metals in the test soil were evaluated based on the intensity coefficient (IR) and migration factor (MF). The results showed that, under the optimal washing conditions, the removal rates of As, Pb and Sb reached 86.35%, 90.07%, 48.89%, 78.07%, 98.36% and 42.51% after three washing processes of PAPEMP and DTPMPA, respectively. Although the washing process took away some of the soil’s quick-acting nutrients, it increased the content of alkaline dissolved nitrogen, organic matter content, cation exchange, total phosphorus, quick-acting phosphorus, etc. in the soil. Meanwhile, the morphology of heavy metals in the soil was changed. The IR and MF values of heavy metals showed that the mobility and bioavailability of Pb and Sb decreased and the mobility and bioavailability of As increased in the washed soil.