凹凸棒石及其改性材料对土壤镉生物有效性的影响与机制  

Effect and Mechanism of Attapulgite and Its Modified Materials on Bioavailability of Cadmium in Soil

作　　者：陈展祥 陈传胜 陈卫平[2] 焦文涛[2] CHEN Zhan-xiang;CHEN Chuan-sheng;CHEN Wei-ping;JIAO Wen-tao(College of Environmental Science and Engineering,Central South University of Forestry and Technology,Changsha 410004,China;State Key Laboratory of Urban and Regional Ecology,Research Center for Eco-Environmental Sciences,Chinese Academy of Sciences,Beijing 100085,China)

机构地区：[1]中南林业科技大学环境科学与工程学院,长沙410004 [2]中国科学院生态环境研究中心城市与区域生态国家重点实验室,北京100085

出　　处：《环境科学》2018年第10期4744-4751,共8页Environmental Science

基　　金：中国科学院盱眙凹土中心项目(201506);中国科学院知识创新工程重点部署项目(ZDRW-2016-5-5)

摘　　要：采用室内盆栽实验和吸附平衡实验,研究了凹凸棒石及其改性材料对土壤镉移动性和生菜吸收镉的影响,并通过X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)以及X射线光电子能谱(XPS)探讨了其机制.结果表明,凹凸棒石及其改性材料均可显著降低生菜体内的Cd含量,改性材料作用优于未改性材料,分别使生菜地上部分Cd含量最大降低41.0%和56.5%.凹凸棒石及其改性材料在投加量为1%时均可显著降低土壤CaCl_2提取态Cd含量,最大降低幅度分别为34.2%和34.3%.凹凸棒石改性后对镉的饱和吸附容量明显提高.凹凸棒石主要是通过表面的硅羟基与Cd^(2+)发生配位反应形成络合物来固定土壤镉,而改性凹凸棒石材料能够通过其表面的硅羟基和羧基与Cd^(2+)发生配位反应形成络合物,从而降低Cd^(2+)在土壤中的移动性,进而达到钝化修复Cd污染土壤的效果.因此凹凸棒石及其改性材料均可被用于镉污染农田土壤修复,但机制不同.The effect of attapulgite（ magnesium aluminium phyllosilicate） and its modified materials on the extractability of soil Cd and the accumulation of Cd in lettuce（ Lactuca sativa） were investigated using a pot-culture experiment,and the immobilization mechanism of attapulgite and its modified materials was explored through X-ray diffraction（ XRD）,Fourier transform infrared spectroscopy（ FTIR） and X-ray photoelectron spectroscopy（ XPS）. The results showed that attapulgite and its modified materials could significantly reduce the Cd concentration in Lactuca sativa,with maximum reductions of 41. 0% and 56. 5%,respectively,and attapulgite modified materials treatments appeared more efficient than attapulgite treatments in reducing Cd uptake of Lactuca sativa. The saturated adsorption capacity for the adsorption of Cd^2＋on attapulgite rose distinctly after being modified. Attapulgite and its modified materials could significantly reduce Cd content in soil CaCl2 extract at the dosage of 1%,with the maximum reduction rates of 34. 2% and 34. 3%,respectively. The attapulgite formed a complex to immobilize Cd mainly through the surface silanol and Cd^2＋complexation reaction,while the modified attapulgite formed a complex mainly through the complexation of Cd^2＋with carboxyl groups which existed in addition to the complexation with surface hydroxyl,thus reducing the mobility of Cd^2＋and achieving remediation of Cd-contaminated soil. In summary,attapulgite and its modified materials can both be used for remediation of Cd-contaminated soil,and the mechanisms for this function were found to be different.

关 键 词：凹凸棒石 土壤 钝化修复 络合吸附 硅羟基 羧基 

分 类 号：X53[环境科学与工程—环境工程]