State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China; Research Center for Environmental Nanotechnology (ReCENT), Nanjing University, Nanjing 210023, China.
State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China.
Water Res. 2018 Apr 15;133:173-181. doi: 10.1016/j.watres.2018.01.038. Epub 2018 Jan 19.
Although the removal of Se(VI) from water by using zero-valent iron (ZVI) is a promising method, passivation of ZVI severely inhibits its performance. To overcome such issue, we proposed an efficient technique to enhance Se(VI) removal via pre-corrosion of ZVI with HO/HCl in a short time (15 min). The resultant pcZVI suspension was weakly acidic (pH 4.56) and contained abundant aqueous Fe. Fe Mössbauer spectroscopy showed that pcZVI mainly consisted of Fe (66.2%), hydrated ferric oxide (26.3%), and FeO (7.5%). Efficient removal of Se(VI) from sulfate-rich solution was achieved by pcZVI compared with ZVI (in the absence and presence of HO) and acid-pretreated ZVI. Moreover, the efficient removal of Se(VI) by pcZVI sustained over a broad pH range (3-9) due to its strong buffering power. The presence of chloride, carbonate, nitrate, and common cations (Na, K, Ca, and Mg) posed negligible influence on the removal of Se(VI) by pcZVI, while the inhibitory effect induced by sulfate, silicate, and phosphate indicated the significance of Se(VI) adsorption as a prerequisite step for its removal. The consumption of aqueous Fe was associated with Se(VI) removal, and X-ray absorption near edge structure revealed that the main pathway for Se(VI) removal by pcZVI was a stepwise reduction of Se(VI) to Se(IV) and then Se as the dominant final state (78.2%). Moreover, higher electron selectivity of pcZVI was attributed to the enhanced enrichment of Se oxyanions prior to their reduction.
虽然使用零价铁 (ZVI) 去除水中的硒 (VI) 是一种很有前途的方法，但 ZVI 的钝化严重抑制了其性能。为了克服这个问题，我们提出了一种有效的技术，通过在短时间内 (15 分钟) 用 HO/HCl 对 ZVI 进行预腐蚀来增强 Se(VI)的去除。所得的 pcZVI 悬浮液呈弱酸性 (pH 4.56)，并含有丰富的水合铁。Fe Mössbauer 光谱表明，pcZVI 主要由 Fe（66.2%）、水合氧化铁（26.3%）和 FeO（7.5%）组成。与 ZVI（在不存在和存在 HO 的情况下）和酸预处理 ZVI 相比，pcZVI 可有效去除富硫酸盐溶液中的 Se(VI)。此外，pcZVI 在较宽的 pH 范围内（3-9）有效去除 Se(VI)，这是由于其具有较强的缓冲能力。Cl-、CO32-、NO3-和常见阳离子（Na、K、Ca 和 Mg）的存在对 pcZVI 去除 Se(VI)的影响可忽略不计，而硫酸盐、硅酸盐和磷酸盐引起的抑制作用表明 Se(VI)吸附作为其去除的先决条件的重要性。水合铁的消耗与 Se(VI)的去除有关，X 射线吸收近边结构表明 pcZVI 去除 Se(VI)的主要途径是 Se(VI)逐步还原为 Se(IV)和 Se，作为主要的最终状态 (78.2%)。此外，pcZVI 具有更高的电子选择性，这归因于在还原之前对 Se 含氧阴离子的富集增强。
