Effective removal of hexavalent chromium with magnetically reduced graphene oxide bentonite

IF 1.1 4区地球科学 Q4 CHEMISTRY, PHYSICAL

Clay Minerals Pub Date : 2023-02-16 DOI:10.1180/clm.2023.4

Shoufan Cao, Jingtao Guo, Jianchao Ma, Jin Pang, Siyu Zhang, Haidong Hao, Danlei Wu, Shaobin Wang

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引用次数: 2

Abstract

Abstract Water pollution by hexavalent chromium (Cr(VI)) is widespread and problematic. As a result, more research into economic Cr(VI) removal is needed. In this study, we created and employed an adsorption–reduction mechanism to remove Cr(VI). Magnetically reduced graphene oxide bentonite (MrGO-BT) is acid resistant and can undergo magnetic separation. The hydroxyl group of chitosan (CS) condensed with the functional groups on the surface of bentonite (BT), and the MrGO-BT sandwich has been fabricated and constructed from an Fe3O4 core layer sandwiched by reduced graphene oxide (rGO) and a BT shell, with CS acting as a crosslinker. Cr(VI) elimination by MrGO-BT was exothermic and spontaneous according to thermodynamic analyses. The adsorption kinetics and adsorption isotherms were characterized by the pseudo-second order kinetic theory and the Langmuir model, respectively. Regarding the elimination of Cr(VI), the greatest adsorption ability for Cr(VI) elimination achieved was 91.5 mg g–1. Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy suggested that Cr(VI) was reduced by C–O–H on MrGO-BT to produce Cr(III) and H–C=O, and that Cr(III) chelated with amino groups or exchanged with BT after intercalation. In addition, the introduction of Cu2+ increased the positive charge of MrGO-BT and amplified the electrostatic interaction between Cr2O72− and HCrO4–, which is what caused Cr(VI) to be eliminated. Cu2+ and reduced Cr(III) combined with -NH2 on the surface of MrGO-BT to form -NH-Cr(III) or -NH-Cu2+, and Cr(VI) elimination via chelation and ion exchange was confirmed. MrGO-BT is shown to be an adsorbent with high acid resistance and good magnetic responsiveness and stability.

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磁还原氧化石墨烯膨润土有效去除六价铬

摘要六价铬（Cr（VI））对水的污染是普遍存在的问题。因此，需要对经济去除Cr（VI）进行更多的研究。在本研究中，我们创建并采用了吸附-还原机制来去除Cr（VI）。磁性还原氧化石墨烯膨润土（MrGO BT）具有耐酸性，可以进行磁性分离。壳聚糖（CS）的羟基与膨润土（BT）表面的官能团缩合，由还原氧化石墨烯（rGO）夹在Fe3O4芯层和BT壳之间，CS作为交联剂，制备并构建了MrGO-BT三明治。根据热力学分析，MrGO BT对Cr（VI）的消除是放热和自发的。分别用拟二阶动力学理论和Langmuir模型对吸附动力学和吸附等温线进行了表征。关于Cr（VI）的去除，实现的Cr（Ⅵ）去除的最大吸附能力为91.5 mg g–1。傅立叶变换红外光谱和X射线光电子能谱表明，Cr（VI）在MrGO-BT上被C–O–H还原，产生Cr（III）和H–C=O，并且Cr（Ⅲ）在嵌入后与氨基螯合或与BT交换。此外，Cu2+的引入增加了MrGO BT的正电荷，并放大了Cr2O72−和HCrO4–之间的静电相互作用，这就是Cr（VI）被消除的原因。Cu2+和还原的Cr（III）在MrGO-BT表面与-NH2结合形成-NHCr（III）或-NH-Cu2+，并通过螯合和离子交换消除Cr（VI）。MrGO-BT被证明是一种具有高耐酸性和良好磁响应性和稳定性的吸附剂。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Clay Minerals 地学-矿物学

CiteScore

3.00

自引率

20.00%

发文量

审稿时长

6 months

期刊介绍： Clay Minerals is an international journal of mineral sciences, published four times a year, including research papers about clays, clay minerals and related materials, natural or synthetic. The journal includes papers on Earth processes soil science, geology/mineralogy, chemistry/material science, colloid/surface science, applied science and technology and health/ environment topics. The journal has an international editorial board with members from fifteen countries.