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

Abstract

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.

Keywords

nuclear wastewater / S-scheme heterostructure / uranium recovery

References

[1] Xie Y, Chen C, Ren X, et al. Emerging natural and tailored materials for uranium-contaminated water treatment and environmental remediation. Prog Mater Sci. 2019;103:180-234.

[2] Zhang H, Li A, Li K, et al. Ultrafiltration separation of Am(VI)-polyoxometalate from lanthanides. Nature. 2023;616(7957):482-487.

[3] Cui W-R, Zhang C-R, Xu R-H, et al. Low band gap benzoxazole-linked covalent organic frameworks for photo-enhanced targeted uranium recovery. Small. 2021;17(6):2006882.

[4] Zhang HL, Liu W, Li A, et al. Three mechanisms in one material: uranium capture by a polyoxo-metalate-organic framework through combined complexation, chemical reduction, and photocatalytic reduction. Angew Chem Int Ed. 2019;58(45):16110-16114.

[5] Liang P-l, Yuan L-y, Deng H, et al. Photocatalytic reduction of uranium(VI) by magnetic ZnFe₂O₄ under visible light. Appl Catal B Environ. 2020;267:118688.

[6] Cui W-R, Zhang C-R, Xu R-H, et al. Rational design of covalent organic frameworks as a groundbreaking uranium capture platform through three synergistic mechanisms. Appl Catal B Environ. 2021;294:120250.

[7] Li H, Zhai F, Gui D, et al. Powerful uranium extraction strategy with combined ligand complexation and photocatalytic reduction by postsynthetically modified photoactive metal-organic frameworks. Appl Catal B Environ. 2019;254:47-54.

[8] Chen T, Yu K, Dong C, et al. Advanced photocatalysts for uranium extraction: elaborate design and future perspectives. Coord Chem Rev. 2022;467:214615.

[9] Zhang S, Liu Y, Ma R, et al. Molybdenum (VI)-oxo clusters incorporation activates g-C₃N₄ with simultaneously regulating charge transfer and reaction centers for boosting photocatalytic performance. Adv Funct Mater. 2022;32(38):2204175.

[10] Li S, Yang X, Cui Z, et al. Efficient photoreduction strategy for uranium immobilization based on graphite carbon nitride/perovskite oxide heterojunction nanocomposites. Appl Catal B Environ. 2021;298:120625.

[11] Liu T, Gu A, Wei T, et al. Ligand-assistant iced photocatalytic reduction to synthesize atomically dispersed Cu implanted metal-organic frameworks for photo-enhanced uranium extraction from seawater. Small. 2023;19(26):2208002.

[12] Wang W, Luo Q, Li J, et al. Photothermal-amplified single atom nanozyme for biofouling control in seawater. Adv Funct Mater. 2022;32(36):2205461.

[13] Yuan Y, Niu B, Yu Q, et al. Photoinduced multiple effects to enhance uranium extraction from natural seawater by black phosphorus nanosheets. Angew Chem Int Ed. 2020;59(3):1220-1227.

[14] Ong WJ, Tan LL, Ng YH, et al. Graphitic carbon nitride (g-C₃N₄)-based photocatalysts for artificial photosynthesis and environmental remediation: Are we a step closer to achieving sustainability? Chem Rev. 2016;116(12):7159-7329.

[15] Yang L, Peng YT, Luo XD, et al. Beyond C₃N₄ pi-conjugated metal-free polymeric semiconductors for photocatalytic chemical transformations. Chem Soc Rev. 2021;50(3):2147-2172.

[16] Zhou Q, Guo Y, Ye Z, et al. Carbon nitride photocatalyst with internal electric field induced photogenerated carriers spatial enrichment for enhanced photocatalytic water splitting. Mater Today. 2022;58:100-109.

[17] Jiang XH, Xing QJ, Luo XB, et al. Simultaneous photoreduction of uranium(VI) and photooxidation of arsenic (III) in aqueous solution over g-C₃N₄/TiO₂ heterostructured catalysts under simulated sunlight irradiation. Appl Catal B Environ. 2018;228:29-38.

[18] Fu J, Yu J, Jiang C, et al. g-C₃N₄-Based heterostructured photocatalysts. Adv Energy Mater. 2018;8(3):1701503.

[19] Mane GP, Talapaneni SN, Lakhi KS, et al. Highly ordered nitrogen-rich mesoporous carbon nitrides and their superior performance for sensing and photocatalytic hydrogen generation. Angew Chem Int Ed. 2017;56(29):8481-8485.

[20] Wang YL, Liu ZY, Li YX, et al. Umbellate distortions of the uranyl coordination environment result in a stable and porous polycatenated framework that can effectively remove cesium from aqueous solutions. J Am Chem Soc. 2015;137(19):6144-6147.

[21] Shen N, Yang Z, Liu S, et al. 99TcO4-removal from legacy defense nuclear waste by an alkaline-stable 2D cationic metal organic framework. Nat Commun. 2020;11(1):5571.

[22] Li ZJ, Huang ZW, Guo WL, et al. Enhanced photocatalytic removal of uranium(VI) from aqueous solution by magnetic TiO₂/Fe₃O₄ and its graphene composite. Environ Sci Technol. 2017;51(10):5666-5674.

[23] Chen M, Liu T, Zhang X, et al. Photoinduced enhancement of uranium extraction from seawater by MOF/black phosphorus quantum dots heterojunction anchored on cellulose nanofiber aerogel. Adv Funct Mater. 2021;31(22):2100106.

[24] Yang H, Liu X, Hao M, et al. Functionalized iron–nitrogen–carbon electrocatalyst provides a reversible electron transfer platform for efficient uranium extraction from seawater. Adv Mater. 2021;33(51):2106621.

[25] Meng Q, Yang X, Wu L, et al. Metal-free 2D/2D C₃N₅/GO nanosheets with customized energy-level structure for radioactive nuclear wastewater treatment. J Hazard Mater. 2022;422:126912.

[26] Wu L, Yang X, Chen T, et al. Three-dimensional C₃N₅/RGO aerogels with enhanced visible-light response and electron-hole separation efficiency for photocatalytic uranium reduction. Chem Eng J. 2022;427:131773.

[27] Wu L, Zhang L, Liu R, et al. 2D/2D g-C₃N₄/1T-MoS2 nanohybrids as Schottky heterojunction photocatalysts for nuclear wastewater pretreatment. ACS ES&T Water. 2021;1(10):2197-2205.

[28] Xu QL, Zhang LY, Cheng B, et al. S-Scheme heterojunction photocatalyst. Chem. 2020;6(7):1543-1559.

[29] Zhang LY, Zhang JJ, Yu HG, et al. Emerging S-scheme photocatalyst. Adv Mater. 2022;34(11):2107668.

[30] Zhang Y, Sun H, Gao F, et al. Insights into photothermally enhanced photocatalytic U(VI) extraction by a step-scheme heterojunction. Research. 2022;2022:9790320.

[31] She X, Wu J, Xu H, et al. High efficiency photocatalytic water splitting using 2D α-Fe₂O₃/g-C₃N₄ Z-scheme catalysts. Adv Energy Mater. 2017;7(17):1700025.

[32] Geng Y, Chen D, Li N, et al. Z-Scheme 2D/2D α-Fe₂O₃/g-C₃N₄ heterojunction for photocatalytic oxidation of nitric oxide. Appl Catal B Environ. 2021;280:119409.

[33] Li X, Yu J, Jaroniec M, et al. Cocatalysts for selective photoreduction of CO₂ into solar fuels. Chem Rev. 2019;119(6):3962-4179.

[34] Low J, Yu J, Jaroniec M, et al. Heterojunction photocatalysts. Adv Mater. 2017;29(20):1601694.

[35] Zhang J, Li Z, Liu B, et al. Insights into the role of C–S–C bond in C₃N₅ for photocatalytic NO deep oxidation: Experimental and DFT exploration. Appl Catal B Environ. 2023;328:122522.

[36] Kumar P, Vahidzadeh E, Thakur WK, et al. C₃N₅: A low bandgap semiconductor containing an Azo-Linked carbon nitride framework for photocatalytic, photovoltaic and adsorbent applications. J Am Chem Soc. 2019;141(13):5415-5436.

[37] Xia P, Cao S, Zhu B, et al. Designing a 0D/2D S-scheme heterojunction over polymeric carbon nitride for visible-light photocatalytic inactivation of bacteria. Angew Chem Int Ed. 2020;59(13):5218-5225.

[38] Li P, Wang J, Wang Y, et al. An overview and recent progress in the heterogeneous photocatalytic reduction of U(VI). J Photochem Photobio C Photochem Rev. 2019;41:100320.

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2024 The Authors. SusMat published by Sichuan University and John Wiley & Sons Australia, Ltd.