School of Chemical Engineering and Technology, Tianjin University, Tianjin, PR China.
J Hazard Mater. 2012 May 30;217-218:301-6. doi: 10.1016/j.jhazmat.2012.03.032. Epub 2012 Mar 19.
In this study, the effects of Mn(II) on the sorption and mobilization of As(V) by synthetic hematite were investigated. Our results showed that As(V) removal by hematite was evidently dependent on pH, and simultaneous addition of Mn(II) and As(V) into hematite suspension resulted in more removal of As(V) via electrostatic attraction at pH 4.0, 7.0 and 8.3. However, in Mn(II) pre-loaded system, the removal percentages of As(V) at pH 8.3 decreased by 17.0%, 20.7% and 26.7% after 24h at the aging time of 2, 12 and 36 h, respectively. The concentrations of the released As(V) after the addition of 1mM Mn(II) were 23.6, 12.9 and 7.0 μM at pH 8.5 in 2, 3 and 4 g L(-1) hematite suspension, respectively. But Ca(2+) did not show such an effect under similar experimental conditions. Abiotic oxidation of Mn(II) on hematite played an important role in As(V) mobilization. The growing thin layer of Mn(III, IV) (hydr)oxides (MnO(x)) formed on hematite would take up the sorption sites pre-occupied by As(V) and resulted in the release of the adsorbed As(V) back into solution. This study enriched our understanding on As(V) fate in the coexistence of iron oxides and Mn(II).
在这项研究中，研究了 Mn(II) 对合成赤铁矿吸附和迁移 As(V) 的影响。结果表明，赤铁矿对 As(V) 的去除明显依赖于 pH 值，并且同时将 Mn(II) 和 As(V) 添加到赤铁矿悬浮液中，在 pH 值为 4.0、7.0 和 8.3 时通过静电吸引导致更多的 As(V) 去除。然而，在 Mn(II) 预加载系统中，在老化时间为 2、12 和 36 h 时，pH 值为 8.3 下 24 h 后，As(V)的去除百分比分别降低了 17.0%、20.7%和 26.7%。在 pH 值为 8.5 时，在 1mM Mn(II) 的添加下，在 2、3 和 4 g L(-1) 的赤铁矿悬浮液中，释放的 As(V)浓度分别为 23.6、12.9 和 7.0 μM。但是，在类似的实验条件下，Ca(2+) 没有显示出这种效果。赤铁矿上 Mn(II) 的非生物氧化在 As(V) 的迁移中起着重要作用。在赤铁矿上形成的越来越薄的 Mn(III,IV)（水合）氧化物（MnO(x)）层会占据 As(V) 先前占据的吸附位点，并导致吸附的 As(V) 重新释放到溶液中。这项研究丰富了我们对铁氧化物和 Mn(II)共存时 As(V)命运的理解。
