The dual role of oxygen in redox-mediated removal of aqueous arsenic(III/V) by Fe-modified biochar. (November 2021)

• Record Type: Journal Article
• Authors: Feng, Yu; Xu, Yong; Xie, Xianjun; Gan, Yiqun; Su, Chunli; Pi, Kunfu; Finfrock, Y. Zou; Liu, Peng
• Is Part Of: Bioresource technology. Volume 340(2021)
• Publication Date: 2021-11
• Subjects: As(III/V) -- O2 -- Fe-modified biochars -- Redox transformation -- X-ray absorption spectroscopy; Biomass -- Periodicals; Biomass energy -- Periodicals; Bioremediation -- Periodicals; Agricultural wastes -- Periodicals; Factory and trade waste -- Periodicals; Organic wastes -- Periodicals; Bioénergie -- Périodiques; Déchets agricoles -- Périodiques; Déchets industriels -- Périodiques; Déchets organiques -- Périodiques; Déchets (Combustible) -- Périodiques; 662.88
• DOI: 10.1016/j.biortech.2021.125674
• Languages: English
• ISSNs: 0960-8524

Abstract

Graphical abstract: Highlights: As removal by FeBC was improved in the presence of O2. As(III) oxidation by FeBC was promoted when O2 was involved. As(III) oxidation continued in solid-phased FeBC. As(V) reduction was inhabited by FeBC in solutions when O2 was available. Both As(III) and As(V) were bidentate corner-sharing complexed to Fe oxides. Abstract: The Fe-modified biochar (FeBC) was used to remove aqueous As(III/V), and the role of oxygen (O2 ) in As removal was investigated by integrating aqueous and solid analyses. The removal efficiencies for As(III) and As(V) increased from 86.4% and 99.2% under anoxic conditions, respectively, to >99.9% when O2 was available. FeBC removed As(III) from As(III)-spiked systems by surface-oxidation following adsorption, where oxidation of As(III) was promoted by O2 . As(V) was first reduced, re-oxidized in solutions, and then adsorbed to FeBC in As(V)-spiked systems, where reduction of As(V) was inhibited at the presence of O2 . Both As(III) and As(V) were bidentate corner-sharing complexed to Fe oxides/hydroxides on FeBC, with As coordinated to Fe at ~3.4 Å according to As extended X-ray absorption fine structure (EXAFS) modeling. These findings identified the effect of ambient O2 in As(III/V) redox transformations and removal, guiding the further application of FeBC in environmental treatment.