ABSTRACT

To efficiently treat hexavalent chromium (Cr(VI)) wastewater, K₂FeO₄ was used to remove and reduce Cr(VI) in presence of Mn(II) in this paper. Batch removal experiments were carried out to study the effect of Fe/Mn molar ratios, initial pH, in-situ and ex-situ and co-existing ions on Cr(VI) removal. The results showed the removal efficiency of Cr(VI) was 97.7% for the initial Cr(VI) concentration of 10.0 mg/L at Fe/Mn molar ratio of 2:3 and initial pH 8.0. Meanwhile, the high removal efficiency of Cr(VI) had been maintained throughout the pH range of 3.0–8.0 in the experimental study. Moreover, the removal process was relatively stable regardless of in-situ and ex-situ, and co-existing ions such as Ca²⁺ and low concentration of ${\mathrm{HCO}}_3^{-}$ had no intense effect on Cr(VI) removal, while ${\mathrm{SO}}_4^{2-}$ inhibited Cr(VI) removal in the reaction system. To investigate the removal mechanism of Cr(VI) by K₂FeO₄ in presence of Mn(II), the reaction products were characterized by the Fourier transformed infrared spectrometer, X-ray powder diffraction, Transmission electron microscopy and the high-resolution X-ray photoelectron spectroscopy. The results indicated the ferrate decomposition products of γ-FeOOH/γ-Fe₂O₃ had the ability to adsorb Cr(VI) and react with Mn(II) to form γ-Fe₂O₃-Mn(II) complex to adsorb and reduce Cr(VI).

摘要

为有效处理六价铬(Cr(VI))废水，本文采用K ₂ FeO ₄在Mn(II)存在下去除和还原Cr(VI)。进行批量去除实验以研究 Fe/Mn 摩尔比、初始 pH 值、原位和非原位以及共存离子对 Cr(VI) 去除的影响。结果表明，在 Fe/Mn 摩尔比为 2:3 和初始 pH 值为 8.0 时，初始 Cr(VI) 浓度为 10.0 mg/L，Cr(VI) 的去除效率为 97.7%。同时，在实验研究中，在 3.0-8.0 的 pH 范围内，Cr(VI) 的高去除效率一直保持不变。此外，无论原位还是异位，去除过程相对稳定，同时存在Ca ²⁺等离子和低浓度的${\mathrm{碳酸氢钠}}_3^{-}$对 Cr(VI) 的去除没有显着影响，而${\mathrm{所以}}_4^{2-}$抑制反应体系中 Cr(VI) 的去除。_{为了研究 K 2} FeO ₄在 Mn(II) 存在下去除 Cr(VI) 的机理，采用傅里叶变换红外光谱仪、X 射线粉末衍射仪、透射电子显微镜和高分辨率 X射线光电子能谱。结果表明，γ-FeOOH/γ-Fe ₂ O ₃的高铁酸盐分解产物具有吸附Cr(VI)并与Mn(II)反应形成γ-Fe ₂ O ₃ -Mn(II)络合物吸附的能力。并减少 Cr(VI)。