EDTA在铅污染土壤治理中的优化处理方法
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摘要
为了探究EDTA在土壤重金属污染治理中的优化处理方法,采用湿筛和水中重力沉降的方法,从人工Pb污染土壤(原土)中分离提取砂土、粉土和粘土,分析讨论了EDTA对土壤中Pb的去除效果,并从EDTA清洗前后土壤中Pb的BCR形态分布出发,分析了EDTA对不同粒径土壤中各形态Pb的去除效果。研究发现,实验用土壤中砂土、粉土和粘土含量分别为11.2%、75.6%和13.2%,EDTA浓度越高,土壤中Pb去除效果越好,且砂土中Pb最易被去除(~100%),粉土与原土其次(88.66%~96.50%),粘土最难被去除(64.78%~79.60%),但随着EDTA浓度增加,粒径对去除Pb的影响减弱。在土壤修复实践中,可通过利用不同浓度EDTA处理不同粒径土壤的方法达到优化效果。BCR形态分布说明外源性Pb进入土壤后主要以弱酸提取态和可还原态存在,EDTA清洗主要去除弱酸提取态和可还原态,粘土中的各形态去除率均最小。
To determine an optimized EDTA washing method for heavy metal contaminated soil remediation,the methods of sieving and gravity sedimentation of water were used to extract sand,silt,and clay from man-made contaminated soils,and then EDTA was used to remove Pb from the contaminated soils. Fractionation was used to analyze the removal efficiency of each of four fractions of soils. The results indicated that the contents of sand,silt,and clay were 11. 2%,75. 6%,and 13. 2%,respectively,and the removal efficiencies increased when the EDTA concentration increased. In addition,the Pb in the sand was the easiest to remove( ~ 100%),followed by silt and original soils( 88. 66%-96. 50%),and finally,the Pb in the clay was the hardest to remove( 64. 78%-79. 60%). The effect of soil size on removal efficiency was reduced when the EDTA concentration increased. In actual practice,the best removal efficiency could be achieved by using different EDTA concentrations to treat soils with different particle sizes. A BCR fraction test showed that F1-Pb and F2-Pb accounted for the largest proportion of Pb in soil,and the EDTA washing removed a majority of F1-Pb and F2-Pb from the soils. The removal efficiencies by clay aggregates were the lowest.
To determine an optimized EDTA washing method for heavy metal contaminated soil remediation,the methods of sieving and gravity sedimentation of water were used to extract sand,silt,and clay from man-made contaminated soils,and then EDTA was used to remove Pb from the contaminated soils. Fractionation was used to analyze the removal efficiency of each of four fractions of soils. The results indicated that the contents of sand,silt,and clay were 11. 2%,75. 6%,and 13. 2%,respectively,and the removal efficiencies increased when the EDTA concentration increased. In addition,the Pb in the sand was the easiest to remove( ~ 100%),followed by silt and original soils( 88. 66%-96. 50%),and finally,the Pb in the clay was the hardest to remove( 64. 78%-79. 60%). The effect of soil size on removal efficiency was reduced when the EDTA concentration increased. In actual practice,the best removal efficiency could be achieved by using different EDTA concentrations to treat soils with different particle sizes. A BCR fraction test showed that F1-Pb and F2-Pb accounted for the largest proportion of Pb in soil,and the EDTA washing removed a majority of F1-Pb and F2-Pb from the soils. The removal efficiencies by clay aggregates were the lowest.
引文
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[20]许妍哲,方战强.生物炭修复土壤重金属的研究进展.环境工程,2015,33(2):156-159XU Yanzhe,FANG Zhanqiang.Advances on remediation of heavy metal in the soil by biochar.Environmental Engineering,2015,33(2):156-159(in Chinese)
[2]张涛,邹华,王娅娜,等.铅污染土壤电动修复增强技术的研究.环境工程学报,2013,7(9):3619-3623ZHANG Tao,ZOU Hua,WANG Ya'na,et al.Experimental study on enhancement technology for electrokinetic remediation of lead contaminated soil.Chinese Journal of Environmental Engineering,2013,7(9):3619-3623(in Chinese)
[3]KIM C.,LEE Y.,ONG S.K.Factors affecting EDTA extraction of lead from lead-contaminated soils.Chemosphere,2003,51(9):845-853
[4]李璐娟,夏建国,刘朗.紫色土有机质对团聚体吸附-解吸Pb2+的影响.生态学杂志,2014,33(5):1274-1283LI Lujuan,XIA Jianguo,LIU Lang.Effect of purple soil organic matter on adsorption and desorption of Pb2+by aggregates.Chinese Journal of Ecology,2014,33(5):1274-1283(in Chinese)
[5]WANG Jianxu,FENG Xinbin,ANDERSON C W N,et al.Remediation of mercury contaminated sites-A review.Journal of Hazardous Materials,2012,221-222:1-18
[6]MEERS E.,RUTTENS A.,HOPGOOD M.J.,et al.Comparison of EDTA and EDDS as potential soil amendments for enhanced phytoextraction of heavy metals.Chemosphere,2005,58(8):1011-1022
[7]LETAN D.,LUO Chunling,LI Xiangdong.The use of chelating agents in the remediation of metal-contaminated soils:A review.Environmental Pollution,2008,153(1):3-13
[8]FINGAR N.,LETAN D.Multi-step leaching of Pb and Zn contaminated soils with EDTA.Chemosphere,2007,66(5):824-832
[9]ZHANG Weihua,HUANG Hao,TAN Fenfang,et al.Influence of EDTA washing on the species and mobility of heavy metals residual in soils.Journal of Hazardous Materials,2010,173(1/2/3):369-376
[10]WEI Binggan,YANG Linsheng.A review of heavy metal contaminations in urban soils,urban road dusts and agricultural soils from China.Microchemical Journal,2010,94(2):99-107
[11]STEELE M.C.,PICHTEL J.Ex-situ remediation of a metal-contaminated Superfund soil using selective extractants.Journal of Environmental Engineering,1998,124(7):639-645
[12]PTISTIEK N.,MILA CI CR.,VEBER M.Use of the BCR three-step sequential extraction procedure for the study of the partitioning of Cd,Pb and Zn in various soil samples.Journal of Soils and Sediments,2001,1(1):25-29
[13]ZOU Zeli,QIU Rongliang,ZHANG Weihua,et al.The study of operating variables in soil washing with EDTA.Environmental Pollution,2009,157(1):229-236
[14]ELLIOTT H.A.,BROWN G.A.Comparative evaluation of NTA and EDTA for extractive decontamination of Pbpolluted soils.Water,Air,and Soil Pollution,1989,45(3/4):361-369
[15]YOO J.C.,LEE C.D.,YANG J.S.,et al.Extraction characteristics of heavy metals from marine sediments.Chemical Engineering Journal,2013,228(28):688-699
[16]PAPASSIOPI N.,TAMBOURIS S.,KONTOPOULOS A.Removal of heavy metals from calcareous contaminated soils by EDTA leaching.Water,Air,and Soil Pollution,1999,109(1/2/3/4):1-15
[17]郭文娟,梁学峰,林大松,等.土壤重金属钝化修复剂生物炭对镉的吸附特性研究.环境科学,2013,34(9):3716-3721GUO Wenjuan,LIANG Xuefeng,LIN Dasong,et al.Adsorption of Cd2+on biochar from aqueous solution.Environmental Science,2013,34(9):3716-3721(in Chinese)
[18]DERMONT G.,BERGERON M.,RICHER-LAFLCHE M.,et al.Remediation of metal-contaminated urban soil using flotation technique.Science of the Total Environment,2010,408(5):1199-1211
[19]ZHANG Haibo,LUO Yongming,MAKINO T.,et al.The heavy metal partition in size-fractions of the fine particles in agricultural soils contaminated by waste water and smelter dust.Journal of Hazardous Materials,2013,248-249:303-312
[20]许妍哲,方战强.生物炭修复土壤重金属的研究进展.环境工程,2015,33(2):156-159XU Yanzhe,FANG Zhanqiang.Advances on remediation of heavy metal in the soil by biochar.Environmental Engineering,2015,33(2):156-159(in Chinese)