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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
摘要点击 119  全文点击 61  投稿时间:2018-01-31  修订日期:2018-03-23
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中文关键词  凹凸棒石  土壤  钝化修复  络合吸附  硅羟基  羧基
英文关键词  attapulgite  soil  passivation remediation  complexation adsorption  silanol group  carboxyl group
作者单位E-mail
陈展祥 中南林业科技大学环境科学与工程学院, 长沙 410004
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 
chenzhanxiang@163.com 
陈传胜 中南林业科技大学环境科学与工程学院, 长沙 410004  
陈卫平 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  
焦文涛 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 wtjiao@rcees.ac.cn 
中文摘要
      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CaCl2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Cd2+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Cd2+发生配位反应形成络合物,从而降低Cd2+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.
英文摘要
      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 Cd2+ 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 Cd2+ complexation reaction, while the modified attapulgite formed a complex mainly through the complexation of Cd2+ with carboxyl groups which existed in addition to the complexation with surface hydroxyl, thus reducing the mobility of Cd2+ 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.

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