摘要
固化/稳定化技术已广泛应用于重金属污染场地修复,而二氧化碳碳化作用会改变水泥固化重金属污染黏性土中污染物的化学溶出行为。以铅污染土为对象,采用酸/碱滴定试验和pH相关溶出试验测得浸出液中铅的浓度与pH值的关系,通过连续提取试验确定铅的5种化学赋存形态,研究碳化作用下水泥固化重金属污染黏性土化学溶出特性的变化以及重金属污染物的溶出与pH值的关系。结果表明:碳化作用下,固化污染土的酸/碱缓冲能力减弱18.5%~72.4%;固化污染土中铅的溶解度与pH值的关系展现了两性物质的行为特征,pH值介于7~11之间时,铅的溶解度相对较小,pH值小于7或大于11时,铅的溶解度较大;固化污染土中铅的化学赋存形态均以铁锰氧化物结合态为主,碳化作用下,水泥固化土中可交换态和碳酸盐结合态所占比例分别增加4.3%和3.5%,而铁锰氧化物结合态、有机结合态和残余态所占比例分别减小2.1%、0.9%和4.8%;酸雨和碳化共同作用下水泥固化土中的铅更易溶出。
Solidification/stabilization technology is widely used in remediation of heavy metal contaminated sites.Carbon dioxide carbonation can change the chemical dissolution behavior of pollutants in heavy metal contaminated clayey soil solidified.Taking the lead-contaminated soil as the research object,the relationship between lead concentration and pH value in leaching solution was measured by acid/alkali titration test and pH related dissolution test.Five fractions of chemical occurrence of lead were determined by sequential extraction procedures.The change of chemical dissolution characteristics of cement solidified heavy metal contaminated clay and the relationship between the dissolution of heavy metal pollutants and pH value under carbonization were studied.The results show that the acid/alkali buffering capacity of solidified contaminated soil decreases by 18.5%-72.4%under carbonation.The relationship between the solubility of lead and pH value shows the behavior characteristics of amphoteric substances.The solubility of lead is relatively small when the pH value is between 7 and 11,and it is larger when the pH value is less than 7 or more than 11.The chemical occurrence forms of lead in the solidified contaminated soil are mainly Fe-Mn oxides bound phase.Under the action of carbonation,the proportion of exchangeable phase and carbonate bound phase of cement stabilized soil increases by 4.3%and 3.5%respectively,while the proportion of Fe-Mn oxides bound phase,organic matter bound phase and residual phase decreases by 2.1%,0.9%and 4.8%respectively.Under the combined action of acid rain and carbonation,lead in cement stabilized soil is more easily dissolved.
作者
彭之晟
曹智国
章定文
PENG Zhisheng;CAO Zhiguo;ZHANG Dingwen(School of Transportation,National Demonstration Center for Experimental Road and Traffic Engineering Education,Southeast University,Nanjing 211189,P.R.China;Yellow River Engineering Consulting Institute Co.,Ltd.,Zhengzhou 450003,P.R.China)
出处
《土木与环境工程学报（中英文）》
CSCD
北大核心
2022年第3期195-202,共8页
Journal of Civil and Environmental Engineering
基金
国家自然科学基金(52078129)。
关键词
碳化
固化/稳定化
铅污染土
化学溶出
carbonation
solidification/stabilization
lead contaminated soil
chemical dissolution
