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

• Published in: Bioelectrochemistry (Amsterdam, Netherlands) Netherlands), 2024-08, Vol.158, p.108699-108699, Article 108699
• Main Authors: Lin, Chi-Wen, Chen, Fung-Yu, Liu, Shu-Hui, Ma, Chih-Yu
• Format: Article
• Language: English
• Subjects: Biochar; Bioelectric Energy Sources - microbiology; Charcoal - chemistry; Copper - chemistry; Copper removal; Electrodes; Geologic Sediments - chemistry; Geologic Sediments - microbiology; Iron - chemistry; Nano zero-valent iron; Oxygen - chemistry; Oxygen-releasing beads; Response surface methodology; Sediment microbial fuel cell
• ISSN: 1567-5394; 1878-562X
• DOI: 10.1016/j.bioelechem.2024.108699

[Display omitted] •nZVI was used in sediment microbial fuel cell (SMFC) to improve Cu2+ removal.•Cu precipitation was found on the surface of nZVI-based O2-releasing bead (ORB).•nZVI-based ORBs were added to the SMFC cathode to improve power generation.•The obvious change of Fe-O group improves participation of nZVI in the reaction. 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 (ORBm) 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 ORBm) 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 ORBm 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 ORBm. This shows that the ORBm can improve the migration of Cu2+ in the sediment, providing a promising remediation method for Cu-contaminated sediments.