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

Keunsu Choi, Seon Yong Lee, Heegon Kim, Ki Bong Lee, Jae Woo Choi, Kyung Won Jung

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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.

Original languageEnglish
Article number151991
JournalApplied Surface Science
Volume578
DOIs
Publication statusPublished - 2022 Mar 15

Keywords

  • Competitive adsorption
  • Density functional theory
  • Heavy metal oxyanions
  • Hierarchical corolla-like MnO
  • Magnetic biochar composite

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics
  • Physics and Astronomy(all)
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

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