模拟土样有机碳和矿物质对TCE吸附贡献的实验研究  

Laboratory study of the impact of model soil organic carbon content and mineral matter on TCE sorption behaviors

作　　者：韩璐[1] 何江涛[1] 张晶[1] 张坤峰[1] 

机构地区：[1]中国地质大学水资源与环境学院,北京市重点实验室,北京100083

出　　处：《岩石矿物学杂志》2011年第6期1118-1124,共7页Acta Petrologica et Mineralogica

基　　金：国家自然科学基金项目(40702060);国家高技术研究发展计划(863)项目(2006AA100205-3)

摘　　要：为研究均一介质条件下有机碳含量及矿物质对TCE吸附行为的影响,简化了土壤环境的复杂性和异质性,以固定矿物质（高岭土∶石英砂=3∶7）作为土壤基体,添加不同质量分数的腐殖质（foc=0.16%~2.29%）配制成模拟土样,进行矿物质和模拟土样对TCE的吸附批实验。实验结果显示,TCE的吸附等温线呈非线性。随有机碳含量增加,表现为线性吸附增强,矿物质对TCE的吸附贡献随有机碳含量增加而减小。foc〉0.82%时,矿物质对吸附作用的贡献率〈5%;foc〉1%时,可以基本忽略矿物质对吸附的影响。此外,TCE初始浓度也会影响有机碳和矿物质的吸附能力。用Freundlich模型分别拟合TCE吸附等温线的低浓度段和高浓度段（以Ce=500μg/L为浓度高低的分界）,Freundlich指数n值呈现由大到小的趋势;TCE初始浓度越高,有机碳的吸附贡献率相对上升,而矿物质的贡献率则下降。TCE初始浓度在50~500μg/L之间、foc由0.16%增大到1%时,矿物质的吸附贡献率范围由28%~16%缩小到3%~1%之间,此时TCE初始浓度对有机碳和矿物质的吸附贡献率基本没有影响。In this experiment,the authors simplified the complexities and heterogeneities of the soil environment in order to study the impact of soil organic matters and minerals on the TCE sorption behaviors in homogeneous soils.The given minerals,which were mixed kaolin clay and silica sand according to the proportion of 3∶7 and served as the soil matrix structure,were added to different amounts of humic substance（foc=0.16%~2.29%）to comprise the model soils.The parallel experiments of the TCE sorption were carried out both in minerals and model soils respectively by using the batch experimental method.It is concluded that the sorption of the TCE was characterized by nonlinear isotherm.The linear sorption reaction was enhanced and the contribution rate of the minerals to the sorption was reduced with the increasing amount of the organic matters.The sorption contribution rate of minerals was less than 5% when the organic carbon content was more than 0.82%,and even could be neglected when the organic carbon content was higher than 1%.Also the original concentration of the TCE could affect the capacity of the sorption and the sorption contribution of the organic carbon and minerals in some way.The Freundlich sorption model was used to simulate the TCE isotherm sorption patterns in two segments,with Ce=500 μg/L as the boundary.The fitting exponential of Freundlich（n） decreased with the increasing TCE concentration.Besides,the contribution rate of the organic carbon increased while that of the minerals went down with the increasingly higher TCE concentration.When the TCE concentration varied from 50 to 500 μg/L and foc was 0.16%,the sorption contribution rate of minerals fluctuated in the range of 28%~16% and decreased to 3%~1% at foc equal to 1%,whereas the TCE concentration almost had nothing to do with their contributions.

关 键 词：土壤有机碳 矿物质 三氯乙烯 吸附 贡献率 

分 类 号：P579[天文地球—矿物学] X703[天文地球—地质学]