Removal of arsenate by ferrihydrite via surface complexation and surface precipitation
Removal of arsenate by ferrihydrite via surface complexation and surface precipitation
复制标题
水铁矿通过表面络合和表面沉淀去除砷酸盐
DOI：
10.1016/j.apsusc.2015.06.190
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发表时间：
2015-10-30
影响因子：
6.7
通讯作者：
Wang, Yuanpeng
中科院分区：
文献类型：
--
作者：
Jiang, Xiuli;Peng, Changjun;Wang, Yuanpeng
在这项研究中，宏观和光谱实验方法准确地模拟了砷酸盐在水铁矿上的吸附过程。EXAFS、X射线衍射和红外光谱表明，在酸性pH（3.0-6.0）条件下，As（V）在水铁矿上的吸附主要以表面络合和表面沉淀为主，而在较长时间间隔和较高Fe 3+浓度下，As（V）在水铁矿上的吸附以表面沉淀为主。砷酸盐与磷酸盐的宏观竞争吸附实验表明，在水铁矿表面存在两种类型的吸附位，不可交换的位点，其负责快速的表面复合物形成;和可交换的位点，用于表面沉淀物的缓慢积累。在缓慢生成的沉淀中，As（V）的表面覆盖率（mmol/g）与Fe ~（3+）的溶解量呈良好的线性关系（R ~（-2）= 0.952）。在表面沉淀过程中涉及三个步骤，即，(1)As（V）通过表面络合的初始吸收;（2）从水铁矿中浸出的Fe 3+在表面络合物上的再吸附;（3）As（V）通过表面络合的再次吸附并最终形成表面沉淀。(C)2015 Elsevier B. V.版权所有。
In this study, macroscopic and spectroscopic experimental methods accurately modeled the sorption process of arsenate on ferrihydrite. EXAFS, X-ray diffraction and infrared (IR) spectroscopy indicated that the behavior of As(V) adsorption onto ferrihydrite took place mainly via surface complexation and surface precipitation at acidic pH (3.0-6.0), while the surface precipitation was dominated at longer time intervals and higher Fe3+ concentration. The macroscopic competitive adsorption experiment between arsenate with phosphate indicated two types of adsorption sites existing on the surface of ferrihydrite, i.e., non-exchangeable sites, which are responsible for a rapid surface complex formation; and exchangeable sites for a slow build-up of surface precipitates. In the slow build-up precipitates, the As(V) surface coverage (mmol/g) exhibited a good linear relationship (R-2 = 0.952) with the amount of dissolved Fe3+. Three steps are involved during the process of surface precipitation, i.e., (1) an initial uptake of As(V) via surface complexation; (2) re-adsorption of Fe3+ leaching from ferrihydrite on the surface complex; and (3) As(V) adsorption via surface complexation again and finally forming the surface precipitate. (C) 2015 Elsevier B.V. All rights reserved.