摘要
乙二胺四乙酸(EDTA)是目前重金属污染土壤修复中常用的高效淋洗剂,但其难以降解,对环境存在二次污染风险。该研究以EDTA为对照,选取谷氨酸N,N-二乙酸(GLDA)和亚氨基二琥珀酸(IDS)两种易降解材料为螯合淋洗剂,通过振荡模拟淋洗试验研究了4种典型条件下两种材料对土壤Cd、Cu的洗脱率,探讨了Cd、Cu复合污染土壤的淋洗修复技术中两种材料复配替代EDTA的可行性。结果显示,采用单一淋洗剂时,GLDA利于洗脱土壤Cd,而IDS利于洗脱土壤Cu;在试验的各条件下GLDA对土壤中Cd的洗脱率为47.64%—66.32%,IDS对土壤中Cu的洗脱率为25.44%—34.65%,均不及EDTA对土壤中Cd、Cu的洗脱率(分别为71.49%—74.11%和27.07%—39.12%);降低淋洗剂pH有利于提高土壤Cd、Cu的洗脱率;重金属与IDS、GLDA的物质的量比分别为1:5、1:10时土壤Cd、Cu的综合淋洗效果较优。IDS与GLDA混配的物质的量比为4:6时,土壤Cd、Cu的洗脱率分别为71.75%和33.61%,Cd洗脱率比同等用量的EDTA高出3.40个百分点,而Cu洗脱率仅比EDTA低5.89个百分点。综合考虑重金属洗脱率、螯合剂用量及淋洗时间等因素,建议在重金属污染土壤的淋洗修复中,调节重金属与螯合剂总量的物质的量比为1:10,淋洗体系固液比为1:10,淋洗时间为8 h,IDS和GLDA以物质的量比4:6复配,并分2次淋洗,该参数条件下土壤中Cd、Cu的洗脱效果与等量的EDTA相当。以上结果可为可生物降解螯合剂提升重金属污染土壤的淋洗修复效率提供理论参考。
Ethylene Diamine Tetraacetic Acid(EDTA) is widely used in the remediation of heavy metal contaminated soils because of its efficient leaching effect, but its low biodegradability, and toxic effect prohibits practical applications in the field. In this study, two biodegradable substances including N, N-bis(carboxymethyl)glutamic acid(GLDA) and iminodisuccinic acid(IDS) were selected as chelating agents with the contrast treatment of EDTA. The removal rates of Cd and Cu in soil with two materials under four typical conditions were studied by oscillating simulated leaching test. It was discussed that the mixture of two materials might replace EDTA in the leaching remediation technology of Cd and Cu contaminated soil. The results showed that the GLDA addition was conducive to Cd remove, while the IDS addition facilitated the removal of Cu in the individual treatment. The removal rates of soil Cd with the GLDA ranged from 47.64% to 66.32%, and those of soil Cu with the IDS were in the range of 25.44%–34.65%. All of the above removal rates were lower than the corresponding ones with EDTA. Low pH was beneficial to increase the removal rates of Cd and Cu in the soil. The comprehensive leaching effects on Cd and Cu in the soil were optimal in the treatment with the ratios of amount of substance of heavy metals to IDS and GLDA at 1:5 and 1:10, respectively. The removal rates of Cd and Cu in the soil were 71.75%and 33.61% with the ratio of amount of substance of IDS to GLDA at 4:6 in the chelating mixture. Compared with the EDTA addition,the removal rate of Cd was increased by 3.40 percentage points while the removal rate of Cu was only reduced by 5.89 percentage points. Based on the removal rate of heavy metals, the amount of chelating agents, and the leaching time, the leaching parameters were suggested in the remediation of heavy metal contaminated soil. The details are as follows: the ratio of amount of substance was 1:10for total heavy metals to the total amount of chelating agent;the mass ratio was 1:10 for solid to liquid in the leaching system;the ratio of amount of substance was 4:6 for IDS to GLDA in the mixture, 8 hours for the leaching time, and twice for leaching times. Therefore,we suggested that the removal effects of Cd and Cu in the IDS and GLDA treatment were probably equivalent to those of the EDTA addition. These results could provide a theoretical reference for the application of biodegradable chelating agent to enhance the leaching remediation of heavy metal contaminated soil.
作者
黄敏
赵晓峰
梁荣祥
王鹏忠
戴安然
何晓曼
HUANG Min;ZHAO Xiaofeng;LIANG Rongxiang;WANG Pengzhong;DAI Anran;HE Xiaoman(School of Resources and Environmental Engineering,Wuhan University of Technology,Wuhan 430070,P.R.China;City Environment Protection Engineering Limited Company,Wuhan Iron&Steel Design&Research Institute,Wuhan 430205,P.R.China)
出处
《生态环境学报》
CSCD
北大核心
2022年第6期1244-1252,共9页
Ecology and Environmental Sciences
基金
“十三五”国家重点研发计划(2018YFD0800502)。