Biochar-based microporous nanosheets-mediated nanoconfinement for high-efficiency reduction of Cr(VI)

Dongxu Yang; Ruoyu Deng; Mengli Chen; Tao Liu; Liang Luo; Qiang He; Yi Chen

doi:10.1016/j.jhazmat.2023.132283

Biochar-based microporous nanosheets-mediated nanoconfinement for high-efficiency reduction of Cr(VI)

J Hazard Mater. 2023 Oct 5:459:132283. doi: 10.1016/j.jhazmat.2023.132283. Epub 2023 Aug 12.

Authors

Dongxu Yang¹, Ruoyu Deng¹, Mengli Chen¹, Tao Liu¹, Liang Luo¹, Qiang He¹, Yi Chen²

Affiliations

¹ Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China; College of Environment and Ecology, Chongqing University, Chongqing 400045, China.
² Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China; College of Environment and Ecology, Chongqing University, Chongqing 400045, China. Electronic address: chenyi8574@cqu.edu.cn.

PMID: 37591172
DOI: 10.1016/j.jhazmat.2023.132283

Abstract

Biochar-based materials have been widely used to remove Cr(VI). However, current strategies mainly focus on slow adsorption through electrostatic and functional group properties, ignoring the confinement catalytic fast kinetics caused by inherent porous properties. Herein, we designed a confinement strategy to achieve high-efficiency Cr(VI) reduction by encapsulating the catalytic reaction of Cr(VI) and oxalic acid (OA) in the micropore of PCRN-3-10-2-800. The results showed that the removal rate constant of the PCRN-3-10-2-800/OA system was 14.3 and 146.8 times higher than that of the BC-800/OA system (low porosity) and PCRN-3-10-2-800 alone (adsorption), which was highest removal rate constant in the current reported materials under the same system. The structure-activity relationship indicated that the catalytic activity of Cr(VI) depended on the micropore characteristics of the catalyst. Density functional theory calculations confirmed that nanoscale space could enhance Cr(VI) adsorption and reduce the energy barrier of the rate-determining step. The electron paramagnetic resonance spectrum demonstrated the rapid conversion of Cr(VI) to Cr(III). Furthermore, the PCRN-3-10-2-800/OA system showed good applicability and high efficiency for Cr(VI) removal (nearly 100% in 5 min) in industrial electroplating wastewater treatment. This work first proposes a nanoconfinement-induced heavy metal reduction strategy and guides biochar's universality design in wastewater treatment.

Keywords: Biochar; Cr(VI) reduction; Nanoconfinement; Oxalic acid; Porous carbon material.