Ultrafast extraction of uranium from seawater using photosensitized biohybrid system with bioinspired cascaded strategy

Enhancing Commercially Iron Powder Electron Transport by Surface Biosulfuration to Achieve Uranium Extraction from Uranium Ore Wastewater

The zero-valent iron (ZVI) has attracted increasing attention due to the enhanced reactivity of ZVI to uranium wastewater. However, ZVI practical application is hampered due to its susceptibility to oxidation and the formation of passivation layers during storage and in situ restoration. To address these issues, we used a biosulfuration approach to modify ZVI for application in uranium ore wastewater treatment. A series of physicochemical characterization tools and photoelectronic analyses showed that BS-ZVI considerably increased carrier separation efficiency and visible light absorption capacity, resulting in a significant photoassisted enhancement effect on uranium extraction. Accordingly, the uranium removal efficiency of BS-ZVI reached 91% within 60 min, and its maximum adsorption capacity was 336.3 mg/g. By analyzing the mechanism, the improved U(VI) removal performance was mostly responsible on the dissolution of the passivation layer on the surface of ZVI, the generation of Fe(II) and FeS, and the important role of Shewanella putrefaciens extracellular polymers (EPS). Overall, the BS-ZVI biohybrid merges with the high activity of ZVI, bio-FeS, and self-regeneration ability of bacteria, expanding a promising new approach for sustainable treatment of uranium mine wastewater.

Enhanced azo dye reduction at semiconductor-microbe interface: The key role of semiconductor band structure

Low-energy environmental remediation could be achieved by biocatalysis with assistance of light-excited semiconductor, in which the energy band structure of semiconductor has a significant influence on the metabolic process and electron transfer of microbes. In this study, direct Z-scheme and type II heterojunction semiconductor with different energy band structure were successfully synthesized for constructing semiconductor-microbe interface with Shewanella oneidensis MR-1 to achieve acid orange7 (AO7) biodegradation. UV-vis diffuse reflection spectroscopy, photoluminescence spectra and photoelectrochemical analysis revealed that the direct Z-scheme heterojunction semiconductor had stronger reduction power and faster separation of photoelectron-hole, which was beneficial for the AO7 biodegradation at semiconductor-microbe interface. Riboflavin was also involved in electron transfer between the semiconductor and microbes during AO7 reduction. Transcriptome results illustrated that functional gene expression of Shewanella oneidensis MR-1 was upregulated significantly with photo-stimulation of direct Z-scheme semiconductor, and Mtr pathway and conductive pili played the important roles in the photoelectron utilization by Shewanella oneidensis MR-1. This work is expected to provide alternative ideas for designing semiconductor-microbial interface with efficient electron transfer and broadening their applications in bioremediation.