铅蓄电池厂污染土壤中重金属铅的清洗及形态变化分析

以我国西南某铅蓄电池厂区内不同污染负荷的铅污染土壤为研究对象,对其中铅含量和形态进行分析,并利用不同清洗剂清洗进行筛选.对不同pH条件下铅的清洗效率和铅形态进行分析,并对不同粒径土壤进行不同时间清洗以确定最佳清洗时间.结果表明,厂区内A和B点土壤污染严重,分别达到15 703.22 mg.kg-1和1 747.78 mg.kg-1,活动态铅比例较大,残渣态仅占17.32%、11.64%、14.6%和10.2%.EDTA、盐酸、柠檬酸、鼠李糖脂和SDS这5种清洗剂中EDTA和盐酸的提取效果最好.酸性条件下的清洗不仅能有效地提取铅总量并能有效地减小铅活动态的环境风险,建议pH 4～7最为合适.粗沙粒和细沙粒的清洗效果较好,清洗粉黏粒建议改进工艺,清洗时间定为240 min效果最好.

Analysis of Washing Efficiency and Change in Lead Speciation in Lead-contaminated Soil of a Battery Factory

Lead-contaminated soil with different pollution load in a lead battery factory in the southwest of China was chosen as the research object, the lead content and speciation were analyzed, and different washing agents were screened. The lead washing efficiency and lead speciation were analyzed under different pH conditions, and the soil of different particle size was washed using different duration to determine the best washing time. The results showed that the soil of sites A and B in the factory was severely contaminated, the lead concentration reaching 15703.22 mg ·kg^-1 and 1747.78 mg ·kg^-1, respectively, and the proportion of the active-state lead was relatively high, while the residue state accounted for only 17.32%, 11.64%, 14.6% and 10.2%. EDTA and hydrochloric acid showed the best extraction effect in the 5 washing agents tested, which included EDTA, hydrochloric acid, citric acid, rhamnolipid and SDS. Cleaning under acidic conditions could not only effectively extract the total amount of lead but also effectively reduce the environmental risk of active-state lead. pH 4-7 was suggested as the most appropriate condition. The cleaning effect of coarse sand and fine sand was good, while for washing powder clay, it is better to improve the process, with the optimal washing time determined as 240 min.