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Mechanistic insights into the simultaneous removal of As(V) and Cr(VI) oxyanions by a novel hierarchical corolla-like MnO2-decorated porous magnetic biochar composite: A combined experimental and density functional theory study

Author(s)
Choi, KeunsuLee, Seon YongKim, HeegonLee, Ki BongChoi, Jae-WooJung, Kyung-Won
Issued Date
2022-03
DOI
10.1016/j.apsusc.2021.151991
URI
https://scholarworks.unist.ac.kr/handle/201301/55102
Fulltext
https://www.sciencedirect.com/science/article/pii/S0169433221030270?via%3Dihub
Citation
APPLIED SURFACE SCIENCE, v.578, pp.151991
Abstract
A novel hierarchical corolla-like MnO2-decorated porous magnetic biochar composite (c-PMB/MnO2) was synthesized and used for the removal of As(V) and Cr(VI) from aqueous solutions. The experimental results indicated that the adsorption affinity order of c-PMB/MnO2 in the single-component system was As(V) (0.414 mmol/g) < Cr(VI) (0.421 mmol/g), whereas it was reversed in the binary-component system as As(V) (0.446 mmol/g) >> Cr (VI) (0.185 mmol/g), which were more pronounced in sequential adsorption systems. XPS results revealed that all components of c-PMB/MnO2 (i.e., Fe3O4, MnO2, and biochar) contributed to As(V) and Cr(VI) adsorption, while the selective reduction of adsorbed Cr(VI) to Cr(III) occurred via the redox reaction between Fe3O4 and Cr (VI). Density functional theory calculations further indicated that As(V) and Cr(VI) compete for the available binding sites in binary-component system, although the presence of reduced Cr(III) as a majority species serves as a strong binding site for As(V) via the formation of covalent bonding between Cr(III) and the O atom in As(V) with binding energies of - 123.1 and - 125.6 kcal/mol, thereby enhancing competitive As(V) adsorption in binary-component and sequential adsorption systems. These results may provide important information to better understand the competitive adsorption mechanisms for the simultaneous removal of As(V) and Cr(VI) in water.
Publisher
ELSEVIER
ISSN
0169-4332
Keyword (Author)
Hierarchical corolla-like MnO2Magnetic biochar compositeHeavy metal oxyanionsCompetitive adsorptionDensity functional theory
Keyword
HEAVY-METAL IONSTOTAL-ENERGY CALCULATIONSZERO-VALENT IRONACID ORANGE 7AQUEOUS-SOLUTIONWASTE-WATEREFFICIENT ADSORPTIONBISPHENOL-AOXIDEPERFORMANCE

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