State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing, 100083, People's Republic of China.
School of Water Resources and Environment, China University of Geosciences, Beijing, 100083, People's Republic of China.
Environ Sci Pollut Res Int. 2014 Feb;21(3):1944-1953. doi: 10.1007/s11356-013-2097-8. Epub 2013 Sep 7.
Activated natural siderite (ANS) was used to investigate its characteristics and mechanisms of As(V) adsorption from aqueous solution. Batch tests were carried out to determine effects of contact time, initial As(V) concentration, temperature, pH, background electrolyte, and coexisting anions on As(V) adsorption. Arsenic(V) adsorption on ANS well-fitted pseudo-second-order kinetics. ANS showed a high-adsorption capacity of 2.19 mg/g estimated from Langmuir isotherm at 25 °C. Thermodynamic studies indicated that As(V) adsorption on ANS was spontaneous, favorable, and endothermic. ANS adsorbed As(V) efficiently in a relatively wide pH range between 2.0 and 10.0, although the removal efficiency was slightly higher in acidic conditions than that in basic conditions. Effects of background electrolyte and coexisting anions were not significant within the concentration ranges observed in high As groundwater. Results of XRD and Fe K-edge XANES analysis suggested ANS acted as an Fe(II)/(III) hybrid system, which was quite effective in adsorbing As from aqueous solution. There was no As redox transformation during adsorption, although Fe(II) oxidation occurred in the system. Two infrared bands at 787 and 872 cm(-1) after As(V) adsorption suggested that As(V) should be predominantly adsorbed on ANS via inner-sphere bidendate binuclear surface complexes.
采用天然活性菱铁矿（ANS）研究其从水溶液中吸附砷（V）的特性和机制。进行了批量试验，以确定接触时间、初始砷（V）浓度、温度、pH 值、背景电解质和共存阴离子对砷（V）吸附的影响。砷（V）在 ANS 上的吸附很好地符合伪二级动力学。ANS 在 25°C 时根据 Langmuir 等温线估计具有 2.19mg/g 的高吸附容量。热力学研究表明，ANS 上的砷（V）吸附是自发的、有利的和吸热的。ANS 在 2.0 和 10.0 之间的相对较宽 pH 范围内有效地吸附了砷（V），尽管在酸性条件下的去除效率略高于碱性条件下的去除效率。在高砷地下水观察到的浓度范围内，背景电解质和共存阴离子的影响并不显著。XRD 和 Fe K 边 XANES 分析的结果表明，ANS 作为 Fe(II)/(III)混合体系，在从水溶液中吸附砷方面非常有效。虽然系统中发生了 Fe(II)氧化，但在吸附过程中没有发生砷的氧化还原转化。砷（V）吸附后出现的 787 和 872cm(-1) 两个红外带表明，砷（V）主要通过内球双齿双核表面络合物吸附在 ANS 上。
