Cu(Ⅱ)、Pb(Ⅱ)和Cd(Ⅱ)在红壤胶体和非胶体颗粒上吸附的比较  

Adsorption of Cu(Ⅱ),Pb(Ⅱ) and Cd(Ⅱ) on Colloidal and Non-colloidal Particles in Two Red Soils

作　　者：周琴 姜军[1] 徐仁扣[1] 

机构地区：[1]土壤与农业可持续发展国家重点实验室(中国科学院南京土壤研究所),南京210008 [2]中国科学院大学,北京100049

出　　处：《土壤学报》2018年第1期131-138,共8页Acta Pedologica Sinica

基　　金：国家自然科学基金项目(41230855)资助~~

摘　　要：研究了湖南长沙和海南昆仑的2种红壤胶体和非胶体的矿物组成、阳离子交换量(CEC)及Cu(Ⅱ)、Pb(Ⅱ)和Cd(Ⅱ)在土壤胶体和非胶体颗粒表面的吸附行为,以明确红壤胶体对土壤表面化学性质的贡献。X射线衍射分析结果表明,两种红壤胶体的矿物组成均以次生矿物为主,次生矿物又以1∶1型高岭石所占比例最高。土壤非胶体颗粒中石英等原生矿物含量较高。土壤铁铝氧化物主要富集在土壤胶体部分,土壤胶体颗粒中游离氧化铁和游离氧化铝含量明显高于非胶体颗粒,如湖南长沙红壤胶体颗粒游离氧化铁的含量为78.03 g kg^(-1),而非胶体颗粒中仅为9.93 g kg^(-1)。土壤胶体颗粒的CEC显著高于非胶体颗粒部分,2种红壤胶体的CEC约为非胶体的12倍。等温吸附实验结果表明,土壤胶体颗粒对Cu(Ⅱ)、Pb(Ⅱ)与Cd(Ⅱ)的最大吸附量和吸附亲和力均显著大于非胶体颗粒,湖南红壤胶体对3种重金属的吸附量大于海南红壤胶体,与土壤胶体的矿物组成和CEC大小一致。Cd(Ⅱ)在红壤胶体和非胶体颗粒表面主要发生静电吸附,而静电吸附和非静电吸附两种机制均对Cu(Ⅱ)和Pb(Ⅱ)的吸附有重要贡献。【Objective】The purpose of this article is to study mineral composition and cation exchange capacity（CEC）of the colloids and non-colloids in the two red soils collected from Hunan and Hainan provinces,separately,and adsorption behavior of Cu（Ⅱ）,Cd（Ⅱ）and Pb（Ⅱ）on the colloids and non-colloids,too.【Method】Soil colloidal and non-colloidal fractions were separated from bulk soils using sedimentation method,where particles in the upper portion of the suspension are collected as colloids at fixed time intervals after stirring.X-ray diffraction analysis was performed to determine mineral compositions of the colloids and non-colloids in the red soils.Free Fe and Al oxides were extracted with the DCB method and determined using ICP-AES.The batch method was used to investigate adsorption and desorption of Cu（Ⅱ）,Cd（Ⅱ）and Pb（Ⅱ）on and from soil colloids and non-colloids.Un-buffered salt of 1.0 mol L^-1 Na NO3 was used to desorb pre-adsorbed heavy metals from soil colloids and non-colloids.【Result】X-ray diffraction analysis shows that the colloids in the two red soils were composed mainly of secondary minerals with 1∶1-typed kaolinite in dominancy and little of primary minerals.The contents of 2∶1 typed minerals,such as vermiculite and hydro-mica in the soil colloids decreased with increasing soil development degree,while the content of kaolinite changed oppositely.The non-colloids in the two red soils contained mainly quartz and some other primary minerals.Soil Fe and Al oxides accumulated mainly in the soil colloids.The contents of free Fe and Al oxides were much higher in the soil colloids than in the soil non-colloids.For example,the content of free Fe oxide was as high as 78.03 g kg^-1 in the colloids and only 9.93 g kg^-1 in the non-colloids of the red soil from Hunan.The colloids in the two red soils were also much higher than,or 12 times as high as the noncolloids of the soils in CEC.The isothermal adsorption experiment indicates that the colloids were significantly

关 键 词：红壤 土壤胶体 矿物组成 表面电荷 重金属 吸附-解吸 

分 类 号：S153.2[农业科学—土壤学]