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Preparation of MnOx-Modified Biochar and Its Removal Mechanism for Cr(VI) in Aqueous Solution
Water ( IF 3.4 ) Pub Date : 2022-08-14 , DOI: 10.3390/w14162507
Jianxin Fan, Liang Qin, Ting Duan, Zenglin Qi, Lan Zou

Biochar (BC) is considered to be a great potential adsorbent to remove various contaminants, but the sorption capacity for chromium (Cr) is predominantly limited for the net negative charge. In this study, BC from rice husk was impregnated with Mn(NO3)2 solution to synthesize MnOx-modified BC (MnOBCs) for enhancing Cr(VI) removal in an aqueous solution. MnOBCs were characterized, and MnOx (manganese ore) was found to be the dominant crystal in MnOBCs. Batch sorption and kinetic experiments combined with spectral analysis were carried out to elucidate the sorption capacity and mechanisms of Cr(VI) sorption onto BC and MnOBCs. Results showed that the sorption kinetic process fitted to the Elovich model, and the modification enhanced the sorption capacity of Cr(VI) on BC. Compared to ion strength, pH is the main control factor for Cr(VI) fixed on BC and MnOBCs, and the sorption amount decreased with the pH value increasing. Moreover, X-ray photoelectron spectroscopy results showed that the proportion of Mn(II) decreased from 33.59% to 8.33%, and that of Mn(VI) increased from 30.58% to 52.72% after Cr(VI) sorption on MnOBCs. Meanwhile, the reduction reaction of Cr(VI) occurred during the sorption process on the BC and MnOBCs surface, and the reduction reaction was more obvious on the MnOBCs surface. MnOx loaded in BC can enhance the electrostatic attraction and redox capacity, which can improve the removal of Cr(VI) in an aqueous solution. This study provides information on the sorption and redox of Cr(VI) on BC, and allows us to better understand the mechanism of Cr(VI) removal in solutions by MnOBCs.

中文翻译:

MnOx改性生物炭的制备及其对水溶液中Cr(VI)的去除机理

生物炭 (BC) 被认为是去除各种污染物的巨大潜力吸附剂,但对铬 (Cr) 的吸附能力主要受限于净负电荷。在这项研究中,来自稻壳的 BC 被 Mn(NO 3 ) 2浸渍用于合成 MnOx 改性的 BC (MnOBCs) 的溶液以增强水溶液中 Cr(VI) 的去除。对 MnOBCs 进行了表征,发现 MnOx(锰矿)是 MnOBCs 中的主要晶体。进行了批量吸附和动力学实验,结合光谱分析,阐明了 Cr(VI) 在 BC 和 MnOBCs 上的吸附能力和吸附机制。结果表明,吸附动力学过程符合Elovich模型,改性提高了Cr(VI)对BC的吸附能力。与离子强度相比,pH 是 Cr(VI) 固定在 BC 和 MnOBCs 上的主要控制因素,吸附量随着 pH 值的增加而减少。此外,X射线光电子能谱结果显示,Mn(II)的比例从33.59%下降到8.33%,Mn(VI)的比例从30.58%上升到52%。在 MnOBCs 上吸附 Cr(VI) 后为 72%。同时,Cr(VI)在BC和MnOBCs表面吸附过程中发生还原反应,其中MnOBCs表面还原反应更为明显。负载在 BC 中的 MnOx 可以增强静电吸引力和氧化还原能力,从而提高水溶液中 Cr(VI) 的去除率。本研究提供了有关 Cr(VI) 在 BC 上的吸附和氧化还原的信息,并使我们能够更好地了解 MnOBCs 在溶液中去除 Cr(VI) 的机理。可提高水溶液中 Cr(VI) 的去除率。本研究提供了有关 Cr(VI) 在 BC 上的吸附和氧化还原的信息,并使我们能够更好地了解 MnOBCs 在溶液中去除 Cr(VI) 的机理。可提高水溶液中 Cr(VI) 的去除率。本研究提供了有关 Cr(VI) 在 BC 上的吸附和氧化还原的信息,并使我们能够更好地了解 MnOBCs 在溶液中去除 Cr(VI) 的机理。
更新日期:2022-08-14
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