Spectroscopic investigation of magnetite surface for the reduction of hexavalent chromium.
Spectroscopic investigation of magnetite surface for the reduction of hexavalent chromium.
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DOI：
10.1016/j.chemosphere.2007.02.028
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发表时间：
2007-08
期刊：
影响因子：
8.8
通讯作者：
Yoo-jin Jung;Jeongyun Choi;Woojin Lee
中科院分区：
文献类型：
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作者：
Yoo-jin Jung;Jeongyun Choi;Woojin Lee
本研究通过批量动力学实验对添加 Fe(II) 的情况下磁铁矿将 Cr(VI) 还原为 Cr(III) 进行了表征，并研究了添加 Fe(II) 和 pH 值的影响。在磁铁矿悬浮液中添加Fe(II)提高了磁铁矿的还原能力。 80% 的 Cr(VI) 在 1 小时内被磁铁矿 (6.5gl−1) 和 Fe(II) (80mgl−1) 还原，而 60% 的 Cr(VI) 仅被磁铁矿去除。然而，Fe(II)对磁铁矿还原能力的提高程度小于磁铁矿和Fe(II)各自还原能力之和所预测的结果。在0-2.3范围内，Fe(II)磁铁矿悬浮液中Cr(VI)的还原随着Fe(II)与Cr(VI)摩尔比(0.6、1、1.5、2.3)的增加而增加，在pH 8.0-5.5范围内随着pH值的降低而增加。采用X射线光电子能谱研究了磁铁矿表面铬、铁和氧的形态。 Cr 2p3/2、Fe 2p3/2 和 O 1s 峰分别主要在 576.7 和 577.8eV、711.2eV 以及 530.2 和 531.4eV 处观察到。结果表明，反应后磁铁矿表面的优势物质为Cr(III)和Fe(III)，且优势物质覆盖磁铁矿表面并形成金属(羟基)氢氧化物。
The reduction of Cr(VI) to Cr(III) by magnetite in the presence of added Fe(II) was characterized through batch kinetic experiments and the effect of Fe(II) addition and pH were investigated in this study. The addition of Fe(II) into magnetite suspension improved the reductive capacity of magnetite. Eighty percent of Cr(VI) was reduced by magnetite (6.5gl−1) with Fe(II) (80mgl−1) within 1h, while 60% of Cr(VI) was removed by magnetite only. However, the extent of improved reductive capacity of magnetite with Fe(II) was less than that predicted by the summation of each reduction capacity of magnetite and Fe(II). The reduction of Cr(VI) in the magnetite suspension with Fe(II) increased with the increase of molar ratio of Fe(II) to Cr(VI) (0.6, 1, 1.5, 2.3) in the range of 0–2.3 and with the decrease of pH in the range of pH 8.0–5.5. The speciation of chromium, iron, and oxygen on the surface of magnetite was investigated by X-ray photoelectron spectroscopy. Cr 2p3/2, Fe 2p3/2, and O 1s peaks were mainly observed at 576.7 and 577.8eV, at 711.2eV, and at 530.2 and 531.4eV, respectively. The results indicates that Cr(III) and Fe(III) were the dominant species on the surface of magnetite after reaction and that the dominant species covered the magnetite surface and formed metal (oxy)hydroxide.