• 关键词：Mg/Al双金属氧化物  砷酸根  等温吸附  动力学

• 基金项目：国家自然科学基金(No.40871102)

• 孙媛媛
• 中国农业科学院农业环境与可持续发展研究所/农业部农业环境与气候变化重点开放实验室, 北京 100081

• 曾希柏
• 中国农业科学院农业环境与可持续发展研究所/农业部农业环境与气候变化重点开放实验室, 北京 100081

• 白玲玉
• 中国农业科学院农业环境与可持续发展研究所/农业部农业环境与气候变化重点开放实验室, 北京 100081

• 摘要：研究了以镁铝水滑石为原料制备的Mg/Al双金属氧化物对溶液中As(V)的吸附作用及其影响因素. 结果表明: Mg/Al双金属氧化物对As(V)具有较强的吸附能力, 吸附规律符合Langmuir等温吸附方程, 根据计算所得的理论最大吸附量为51.02 mg · g^-1, 与实验得出的最大吸附量50.53 mg · g^-1基本一致; 运用3种动力学方程对实验数据进行拟合, 发现其吸附过程用准二级动力学方程表示时相关性最好; 溶液的pH值显著影响吸附剂对As(V)的吸附, 在pH=2时As(V)去除率最大; X射线衍射与扫描电镜结果显示,水滑石经过焙烧后丧失了原有的结构形成Mg/Al双金属氧化物, 并在吸附砷酸根离子后重新恢复水滑石的部分层状结构, 吸附机制主要为从溶液中获取阴离子以重建水滑石的晶体结构以及镁铝氧化物的共沉淀作用.

• Abstract：The adsorption characteristics of arsenate from aqueous solution by the Mg/Al layered double oxide (Mg/Al-LDO) and its influencing factors, such as the pH of aqueous solution, dosage of Mg/Al-LDO, equilibrium isotherm and adsorption kinetic, were studied. The results showed that the adsorption of arsenate by Mg/Al-LDO was consistent with the Langmuir isotherm. The maximum adsorption capacity of Mg/Al-LDO for arsenate was 50.53 mg · g^-1, close to the stoichiometric adsorption (51.02 mg · g^-1). Three kinetic models were used to fit the experimental data, indicating that the pseudo-second-order kinetics model could better describe the adsorption process. The pH of arsenate solutions has an significant effect on the adsorption if As(V) with the maximum removal rate found at pH=2.0, The results by X-ray diffraction (XRD) and scanning electronic microscopy (SEM) showed that the Mg/Al-LDO lost a typical structure of layered double hydroxides after calcining, and then the partial layered structure of layered double hydroxides was recovered after adsorbing arsenate. The removal arsenate mechanism of Mg/Al-LDO is mainly attributed to the reconstruction of its original layered structure in the presence of appropriate anions and co-precipitation with Mg/Al oxides.

• Key words：Mg/Al-LDO  arsenate  equilibrium isotherm  kinetics

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