Photo-enhanced uranium recovery from spent fuel reprocessing wastewater via S-scheme 2D/0D C₃N₅/Fe₂O₃ heterojunctions

Re-extracting environmentally transportable hexavalent uranium from wastewater produced by spent fuel reprocessing using the photocatalytic technology is a crucial strategy to avoid uranium pollution and recover nuclear fuel strategic resources. Here, we have designed S-scheme 2D/0D C3N5/Fe2O3 heterojunction photocatalysts based on the built-in electric field and the energy band bending theory, and have further revealed the immobilization process of hexavalent uranium conversion into relatively insoluble tetravalent uranium in terms of thermodynamics and kinetics. According to the results, the hexavalent uranium removal and recovery ratios in wastewater are as high as 93.38% and 83.58%, respectively. Besides, C3N5/Fe2O3 heterojunctions also exhibit satisfactory catalytic activity and selectivity even in the presence of excessive impurity cations (including Na+, K+, Ca2+, Mg2+, Sr2+, and Eu3+) or various organics (such as xylene, tributylphosphate, pyridine, tannic acid, citric acid, and oxalic acid). It is believed that this work can provide a potential opportunity for S-scheme heterojunction photocatalysts to re-enrich uranium from spent fuel wastewater.