Optimized combination of zero-valent iron and oxygen-releasing biochar as cathodes of microbial fuel cells to enhance copper migration in sediment

Chi-Wen Lin; Fung-Yu Chen; Shu-Hui Liu; Chih-Yu Ma

doi:10.1016/j.bioelechem.2024.108699

Optimized combination of zero-valent iron and oxygen-releasing biochar as cathodes of microbial fuel cells to enhance copper migration in sediment

Bioelectrochemistry. 2024 Mar 30:158:108699. doi: 10.1016/j.bioelechem.2024.108699. Online ahead of print.

Authors

Chi-Wen Lin¹, Fung-Yu Chen², Shu-Hui Liu³, Chih-Yu Ma⁴

Affiliations

¹ Department of Safety, Health and Environmental Engineering, National Yunlin University of Science and Technology, Yunlin 64002, Taiwan, ROC; Graduate School of Engineering Science and Technology, National Yunlin University of Science and Technology, Yunlin 64002, Taiwan, ROC.
² Department of Safety, Health and Environmental Engineering, National Yunlin University of Science and Technology, Yunlin 64002, Taiwan, ROC.
³ Department of Safety, Health and Environmental Engineering, National Yunlin University of Science and Technology, Yunlin 64002, Taiwan, ROC. Electronic address: shliu@yuntech.edu.tw.
⁴ Center for Low-temperature Plasma Sciences, Nagoya University, Nagoya, Japan.

PMID: 38574450
DOI: 10.1016/j.bioelechem.2024.108699

Abstract

Membrane-less single-medium sediment microbial fuel cells (single-SMFC) can remove Cu²⁺ from sediment through electromigration. However, the high mass transfer resistance of the sediment and amount of oxygen at the cathode of the SMFC limit its Cu²⁺ removal ability. Therefore, this study used an oxygen-releasing bead (ORB) for slow oxygen release to increase oxygen at the SMFC cathode and improve the mass transfer property of the sediment. Resultantly, the copper removal efficiency of SMFC increased significantly. Response surface methodology was used to optimize the nano zero-valent iron (nZVI)-modified biochar as the catalyst to enhance the ability of the modified ORB (ORB_m) to remove Cu²⁺ and slow release of O₂. The maximum Cu²⁺ removal (95 %) and the slowest O₂ release rate (0.41 mg O₂/d·g ORB_m) were obtained when the CaO₂ content and ratio of nZVI-modified biochar to unmodified biochar were 0.99 g and 4.95, respectively. When the optimized ORB_m was placed at the single-SMFC cathode, the voltage output and copper removal increased by 4.6 and 2.1 times, respectively, compared with the system without ORB_m. This shows that the ORB_m can improve the migration of Cu²⁺ in the sediment, providing a promising remediation method for Cu-contaminated sediments.

Keywords: Biochar; Copper removal; Nano zero-valent iron; Oxygen-releasing beads; Response surface methodology; Sediment microbial fuel cell.