还原增溶强化EGTA淋洗修复重金属污染土壤  

Remediation of Heavy-Metal-Contaminated Soil by EGTA Washing Enhanced with Reduction Solubilization

作　　者：张金永 朱玉婷 王明新 韩莹 葛嘉琦 ZHANG Jin-yong;ZHU Yu-ting;WANG Ming-xin;HAN Ying;GE Jia-qi(College of Environmental and Safety Engineering,Changzhou University,Changzhou 213164,China)

机构地区：[1]常州大学环境与安全工程学院,常州213164

出　　处：《环境科学》2020年第5期2390-2397,共8页Environmental Science

基　　金：国家自然科学基金项目(41772240,21906009);江苏省“六大人才高峰”培养对象项目(JNHB-003)。

摘　　要：采用还原剂调控土壤中重金属的活性,旨在强化其对乙二醇双(2-氨基乙基醚)四乙酸(EGTA)洗脱土壤重金属的洗脱效果.分析了EGTA投加量、还原剂类型、液固比、淋洗时间等对土壤重金属的影响,以及不同淋洗条件下土壤重金属浸出浓度与化学形态的差异,采用SEM-EDS和FTIR对处理前后土壤样品进行表征.结果表明,硫代硫酸钠(Na2S2O3)可显著提高EGTA对重金属的洗脱率,当液固比为7.5∶1、淋洗时间为2 h、EGTA与Na2S2O3投加量均为5 g·L^-1时,Cu、Zn、Pb和Cd洗脱率分别达85.0%、 60.7%、 88.6%和66.4%.与EGTA单独处理相比,EGTA/Na2S2O3联合处理后, 4种重金属的浸出浓度均降低,Pb的降幅最大,土壤颗粒变小,团粒结构被破坏,O和Al含量减少,Si含量增加,降低了土壤矿物组分的吸附性;土壤有机质含量大幅降低,-OH振动显著减弱,配位能力较强的有机官能团减少,降低了土壤有机组分的吸附性.土壤中吸附性较强组分含量的降低是Na2S2O3强化EGTA洗脱重金属的重要机制.This study used a reducing agent to regulate the activity of heavy metals in soil, with the aim of enhancing the washing efficiency of heavy metals in soil by ethylene glycol bis(2-aminoethyl ether) tetraacetic acid(EGTA). The effects of EGTA dosage, reductant type, liquid-solid ratio, and leaching time on washing efficiency were studied. The heavy metal concentrations in the washing solution and the chemical specification under different washing conditions were analyzed. Scanning electron microscopy/energy-dispersive X-ray spectroscopy and Fourier-transform infrared spectroscopy were used to characterize the soil samples under different treatments. The results showed that the washing efficiencies of Cu, Zn, Pb, and Cd were 85.0%, 60.7%, 88.6%, and 66.4%, respectively, when the liquid-solid ratio was 7.5∶1, the leaching time was 2 h, and the dosage of EGTA and sodium thiosulfate(Na2S2O3) was 5 g·L^-1. Compared with single EGTA treatment, the leaching concentration of the four heavy metals all decreased, with the Pb decreasing most significantly. The soil particles became smaller, the aggregate structure was destroyed, the O and Al content decreased, the Si content increased, and therefore the adsorption capacity of soil mineral components was supposed to decrease. The soil organic matter content decreased significantly, and the -OH vibration was significantly weakened, indicating that the organic functional groups with stronger coordination ability were reduced, and the adsorption of organic components in the soil was reduced. The decrease in content of strongly adsorbed components in soil is an important mechanism for Na2S2O3 to enhance heavy metal elution by EGTA.

关 键 词：乙二醇双(2-氨基乙基醚)四乙酸(EGTA) 重金属 螯合剂 土壤淋洗 土壤表征 

分 类 号：X53[环境科学与工程—环境工程]