| 水铁矿及其胶体对砷的吸附与吸附形态 |
| 摘要点击 4215 全文点击 1346 投稿时间：2017-06-26 修订日期：2017-07-14 |
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| 中文关键词 砷 水铁矿胶体 吸附 结合形态 化学形态 |
| 英文关键词 arsenic ferrihydrite colloid adsorption fraction speciation |
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| 中文摘要 |
| 采用吸附实验，通过吸附动力学和吸附等温模型，研究了水铁矿及其胶体对As（Ⅲ）和As（Ⅴ）的吸附能力.在此基础上，使用连续提取和As化学形态提取技术分别对水铁矿及其胶体固相上吸附As的结合形态和化学形态进行提取分析.吸附动力学研究以及Langmuir和Freundlich两种吸附等温模型拟合结果表明，水铁矿及其胶体对As的吸附为多层吸附，且易于进行.水铁矿胶体对As（Ⅲ）和As（Ⅴ）的吸附量分别为194.8 g·kg-1和107.3 g·kg-1，而水铁矿对As（Ⅲ）和As（Ⅴ）的吸附能力分别为155.2 g·kg-1和104.4 g·kg-1，均低于水铁矿胶体.水铁矿及其胶体吸附的As以专性吸附As、无定形铁氧化物结合As和晶型铁氧化物结合As形式存在，胶体上未形成残渣态As.因此，水铁矿胶体吸附As的牢固程度低于吸附As后形成残渣态As的水铁矿，且所吸附的As容易重新释放到环境中，增加环境风险.水铁矿单独存在时不具有将As（Ⅴ）还原为As（Ⅲ）的能力. |
| 英文摘要 |
| Batch experiments were conducted to investigate the adsorption kinetics and adsorption isotherms of As(Ⅲ) and As(Ⅴ) on ferrihydrite and its colloid. A sequential extraction technique and As speciation extraction were used to assess the chemically bound fractions of As and As species in solids, respectively. The kinetic and isotherm data showed that the adsorption was multilevel and readily occurred. The adsorption of As(Ⅲ) and As(Ⅴ) on the ferrihydrite colloid was 194.8 g·kg-1 and 107.3 g·kg-1, respectively, which was higher than that on ferrihydrite (155.2 g·kg-1 and 104.4 g·kg-1). The specifically adsorbed As, amorphous oxide bound As, and crystalline oxide bound As were the major fractions of adsorbed As on ferrihydrite and its colloid. The residual As was absorbed on the ferrihydrite surface instead of on the ferrihydrite colloid. Therefore, As adsorption on ferrihydrite was much stronger than that on ferrihydrite colloid. The ferrihydrite and ferrihydrite colloid could not reduce As(Ⅴ) to As(Ⅲ). |
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