A mechanistic approach of chromium (VI) adsorption onto manganese oxides and boehmite
A mechanistic approach of chromium (VI) adsorption onto manganese oxides and boehmite
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DOI：
10.1016/j.jece.2019.103515
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发表时间：
2020-04-01
影响因子：
7.7
通讯作者：
Awual, Md. Rabiul
中科院分区：
文献类型：
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作者：
Islam, Md. Aminul;Angove, Michael J.;Awual, Md. Rabiul
由于其流动性和急性毒性，土壤中六价铬的浓度是一个重要的环境问题。由于其毒性，清除该物种非常重要。 Cr(VI) 的迁移率很大程度上取决于其在矿物表面上的吸附。锰氧化物是天然存在的清除剂，对铬酸盐物质的分布和传输具有重大影响。因此，为了了解铬酸盐物质的命运及其去除过程，研究六价铬的吸附非常重要。在本研究中，水钠锰矿（δ-MnO2）、软锰矿（β-MnO2）、黑锰矿（Mn3O4）、亚锰矿（γ-MnOOH）、勃姆石（γ-AlOOH）和Mn-Al二元氧化物被用作吸附剂，在一定范围的溶液pH值和初始Cr（VI）浓度下吸附Cr（VI）。使用 Langmuir 和 Freundlich 模型、质子化学计量和表面络合模型 (SCM) 的组合方法已用于描述可能的 Cr(VI) 吸附过程。水钠锰矿是低 pH 条件下最有效的吸附剂。 Langmuir 模型可以很好地描述平衡等温线数据，表明均匀的表面性质。质子化学计量表明 Cr(VI) 吸附涉及不止一种类型的反应。研究结果证实，Cr(VI) 物质通过内球和外球铬酸盐配合物与官能团结合，结合程度取决于溶液 pH 值。本文提出的研究可应用于具有各种表面特性、pH 值和 Cr (VI) 浓度的土壤。这项研究进一步加深了我们对固水界面 Cr(VI) 和矿物质之间相互作用的理解。
The concentration of chromium (VI) in the soil is an important environmental concern due to its mobility and acute toxicity. Due to its toxicity, removal of this species is very important. The mobility of Cr(VI) is highly governed by its adsorption onto the mineral surfaces. Manganese oxides are naturally-occurring scavengers and have a significant influence on the distribution, and transport of chromate species. Thus, to understand the fate of chromate species and its removal process, it is important to study chromium (VI) adsorption. In this study, birnessite (delta-MnO2), pyrolusite (beta-MnO2), hausmannite (Mn3O4), manganite (gamma-MnOOH), boehmite (gamma-AlOOH), and Mn-Al binary oxide was used as adsorbents to adsorb Cr(VI) over a range of solution pH and initial Cr(VI) concentrations. A combined approach using the Langmuir and Freundlich models, proton stoichiometry and surface complexation model (SCM) have been used to describe the probable Cr(VI) adsorption process. Birnessite was the most potent adsorbent at low pH. The Langmuir model could describe the equilibrium isotherm data well, suggesting a uniform surface nature. Proton stoichiometry indicated that Cr(VI) adsorption involved more than one type of reaction. The findings confirm that Cr(VI) species bind to functional groups by the inner- and outer-sphere chromate complexes, with the extent of binding dependent on solution pH. The study presented herein can be applied to soils with a variety of surface properties, pH, and Cr (VI) concentrations. The study further advances our understanding of the interaction between Cr(VI) and minerals at the solid-water interface.