School of Chemistry and Chemical Engineering, Northwestern Polytechnical University, Xi'an, 710072, Shaanxi, People's Republic of China.
Bull Environ Contam Toxicol. 2021 Jan;106(1):134-145. doi: 10.1007/s00128-020-03053-y. Epub 2021 Jan 4.
To explore the adsorption removal mechanism of Mg-Al layered double oxides (LDOs) for low-concentration (≤ 5 mg L) Cr(VI), the adsorption kinetics, adsorption isotherms and its influencing factors were studied by batch experiments. Cr(VI) adsorption reached equilibrium after 6, 11 and 15 h for initial Cr(VI) concentrations of 1, 3 and 5 mg L, respectively, and the final adsorption efficiency exceeded 99.0%. The residual concentration of Cr(VI) was within the allowable limit of Drinking Water Quality Standard of World Health Organization (0.05 mg L). The experimental data fitted the pseudo-second-order and Freundlich models well. Mg-Al LDOs showed effective adsorption efficiency in the range of pH 3-9, and the adsorption efficiency was influenced by anions competition (HPO > SO > CO > NO > Cl). The analyses of XRD, SEM and FT-IR spectra suggested adsorption Cr(VI) on Mg-Al LDOs was caused by capturing dichromate ions to reconstruct its structure. Therefore, Mg-Al LDOs is promising adsorbents for the low-concentration Cr(VI) treatment in polluted surface water and groundwater.
为了探究镁铝水滑石（LDO）对低浓度（≤5mg/L）Cr(VI)的吸附去除机制，通过批量实验研究了吸附动力学、吸附等温线及其影响因素。当 Cr(VI)初始浓度分别为 1、3 和 5mg/L 时，Cr(VI)的吸附在 6、11 和 15h 后达到平衡，最终吸附效率超过 99.0%。Cr(VI)的残留浓度均在世界卫生组织（WHO）《饮用水水质标准》（0.05mg/L）允许范围内。实验数据很好地符合拟二级动力学和 Freundlich 模型。Mg-Al LDO 在 pH 值 3-9 范围内表现出有效的吸附效率，且吸附效率受阴离子竞争（HPO > SO > CO > NO > Cl）影响。XRD、SEM 和 FT-IR 光谱分析表明，Cr(VI)在 Mg-Al LDO 上的吸附是通过捕获重铬酸根离子来重构其结构。因此，Mg-Al LDO 是一种很有前景的吸附剂，可用于处理受污染地表水和地下水中的低浓度 Cr(VI)。
