Evaluation of Zn-Al-SO4 layered double hydroxide for the removal of arsenite and arsenate from a simulated soil solution: Isotherms and kinetics
Evaluation of Zn-Al-SO4 layered double hydroxide for the removal of arsenite and arsenate from a simulated soil solution: Isotherms and kinetics
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DOI：
10.1016/j.clay.2014.02.028
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发表时间：
2014-06-01
影响因子：
5.6
通讯作者：
Wang, Yujue
中科院分区：
文献类型：
--
作者：
Bagherifam, Saeed;Komarneni, Sridhar;Wang, Yujue
本研究的主要目的是评估合成的Zn-Al-SO 4层状双氢氧化物（LDH）去除模拟土壤溶液中的砷和砷酸盐的有效性。采用水热法合成了Zn-Al-SO 4，并采用Langmuir和Freundlich吸附模型研究了其对砷的吸附性能。此外，吸附动力学进行了测试，使用伪第一，伪第二，颗粒内扩散和Elovich模型。实验结果表明，Zn-Al-SO 4 LDHs对As（Ⅲ）和As（Ⅳ）的吸附等温线符合Langmuir吸附等温式，最大吸附容量分别为34.24和47.39 mg g（-1）。砷的吸附动力学符合准二级动力学，而砷的吸附符合颗粒内扩散模型。此外，还研究了两种主要的共存竞争二价阴离子SO 42-和CO 32-对Zn-Al-SO 4吸附As（Ⅲ）和As（Ⅳ）的影响，结果表明，CO 32-对Zn-Al-SO 4吸附As（Ⅲ）和As（Ⅳ）的影响大于SO 42-。X射线衍射分析结果表明，Zn-Al-SO 4 LDHs对As（Ⅲ）和As（Ⅳ）的吸附机理可能主要是外表面和边缘的交换，但也可能是层间交换。(C)2014爱思唯尔有限公司版权所有。
The main objective of the present study was to evaluate the effectiveness of synthetic Zn-Al-SO4 layered double hydroxide (LDH) for the removal of arsenite and arsenate from a simulated soil solution. The Zn-Al-SO4 was synthesized using a hydrothermal method and the adsorption of arsenic was studied using Langmuir and Freundlich models. Moreover, the kinetics of adsorption was tested using pseudo-first, pseudo-second, intraparticle diffusion and Elovich models. The results of the experiments revealed that the adsorption isotherms of arsenite and arsenate on the Zn-Al-SO4 LDHs can be described well with Langmuir isotherm and maximum adsorption capacities were calculated to be 34.24 and 47.39 mg g(-1) for arsenite and arsenate, respectively. The adsorption kinetics of arsenate followed pseudo-second order while arsenite uptake showed better correlation with intraparticle diffusion model. Furthermore, the effects of two major coexisting and competing divalent anions such as SO42- and CO32- on the uptakes of arsenite and arsenate were studied and the results showed that CO32- had greater adverse effect on the uptakes of arsenite and arsenate by Zn-Al-SO4 than SO42-. Based on X-ray diffraction results, the main underplaying adsorption mechanism of arsenite and arsenate might be the exchange on the external surfaces and edges of Zn-Al-SO4 LDHs, but possibly some topotactic exchange may occur through the substitution of arsenic anions with sulfate in the interlayer region. (C) 2014 Elsevier B.V. All rights reserved.