MnOx/生物炭复合材料对土壤重金属的固化效果及其机理研究  

Immobilization of heavy metals in contaminated soils using MnOx/biochar composites

作　　者：吕宏虹 张慧 刘颖[1] 沈伯雄[1,2] 王旭东 杨伟[1] 包丽 曹椿杨 迟艳琛 LYUHonghong;ZHANG Hui;LIU Ying;SHEN Boxiong;WANG Xudong;YANG Wei;BAO Li;CAO Chunyang;CHI Yanchen(School of Energy and Environmental Engineering,Hebei University of Technology,Tianjin,300401,China;Tianjin Key Laboratory of Clean Energy and Pollution Control,Tianjin,300401,China;Tianjin Eco-City Environmental Protection Co.Ltd,Tianjin,300467,China)

机构地区：[1]河北工业大学能源与环境工程学院,天津300401 [2]天津市清洁能源利用与污染物控制重点实验室,天津300401 [3]天津生态城环保有限公司,天津300467

出　　处：《环境化学》2021年第9期2704-2714,共11页Environmental Chemistry

基　　金：中国博士后科学基金(2019M660967);国家自然科学基金(41807363);河北省优秀青年基金(D2019202453)资助。

摘　　要：为了探究高锰酸钾改性生物炭(MnOx/生物炭)对土壤重金属的固化效果与生物炭的差异,本文采用高锰酸钾溶液改性小麦秸秆生物炭,研究不同MnOx负载浓度、复合材料添加量和固化时间对MnOx/生物炭复合材料固化土壤重金属Cd、Pb、Zn和Cu性能的影响及其机理.结果表明,锰氧化物负载能够显著增加生物炭表面的羟基、羧基和酚羟基等官能团的数量.土壤毒性浸出液(TCLP)中重金属浓度变化表明,当固化剂添加量为1%时,MnOx/生物炭对土壤中Cd、Pb、Zn、Cu固化效果是未改性生物炭的2—4倍;在相同固化时间内,MnOx/生物炭复合材料对重金属固定化效果随着添加量和MnOx负载的浓度升高而增大. MnOx/生物炭复合材料的添加可促进重金属Cd、Pb、Zn和Cu由可交换态(EX)和碳结合态(CB)向更加稳定的锰氧化物结合态(OX)、有机物结合态(OM)和残渣态(RS)转化,从而降低污染土壤重金属的活性态比例. MnOx/生物炭主要通过吸附和氧化的共同作用,实现对土壤中重金属的高效固定.固化处理后土壤TCLP浸出液中Mn浓度均低于1.52 mg·L^(-1),说明使用复合材料不会造成土壤锰污染. MnOx/生物炭复合材料在修复重金属污染土壤中具有较大的应用潜力.In this work,potassium permanganate solution was used to modify wheat straw biochar to explore the difference between manganese-modified biochar(MnOx/biochar)and biochar in the immobilization of soil heavy metals.The effect of different MnOx loading concentration,MnOx/biochar dosage,and reaction time on the heavy metals(Cd,Pb,Zn,and Cu)immobilization ability of MnOx/biochar composites and its mechanism were studied.The results showed that manganese oxide loading could significantly increase the number of functional groups on the surface of biochar.The changes in the concentration of heavy metals in the soil toxicity leachate(TCLP)showed that,the immobilization rate of MnOx/biochar on Cd,Pb,Zn,and Cu in the soil was 2—4 times that of unmodified biochar at a MnOx/biochar dosage of 1%.The immobilization ability of MnOx/biochar composite materials on heavy metals increased with the increase of the MnOx/biochar dosage and the concentration of MnOx loading.The addition of MnOx/biochar composite materials promoted the conversion of more accessible Cd,Pb,Zn and Cu(EX and CB)into the less accessible forms(OX,OM,and RS)to reduce the activeness of Cd,Pb,Zn and Cu.Surface sorption and oxidation were dominant mechanisms for heavy metals immobilization.After solidification,the Mn concentration in the soil TCLP leaching solution was lower than 1.52 mg·L-1,indicating that the application of MnOx/biochar would not cause soil manganese pollution.The MnOx/biochar composite material has great application potential in the remediation of heavy metal contaminated soils.

关 键 词：生物炭 锰氧化物 土壤 重金属 

分 类 号：TB332[一般工业技术—材料科学与工程] X53[环境科学与工程—环境工程]