Photocatalytic Performance of Ag 3 PO 4/ BiVO 4 P-N Type Heterojunction for Treatment of Landfill Leachate Tailwater

Yan Wang, Muxi Zhang, Yabo Wang, Zhi Hong, Zitong Wang, Xiaojie Sun (), Hongxia Zhang (), Yu Song, Yapan Li and Hongxiang Zhu
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Yan Wang: Guangxi Key Laboratory of Environmental Pollution Control Theory and Technology, Guilin University of Technology, Guilin 541006, China
Muxi Zhang: Guangxi Key Laboratory of Environmental Pollution Control Theory and Technology, Guilin University of Technology, Guilin 541006, China
Yabo Wang: Guangxi Key Laboratory of Environmental Pollution Control Theory and Technology, Guilin University of Technology, Guilin 541006, China
Zhi Hong: Guangxi Key Laboratory of Environmental Pollution Control Theory and Technology, Guilin University of Technology, Guilin 541006, China
Zitong Wang: Guangxi Key Laboratory of Environmental Pollution Control Theory and Technology, Guilin University of Technology, Guilin 541006, China
Xiaojie Sun: Guangxi Key Laboratory of Environmental Pollution Control Theory and Technology, Guilin University of Technology, Guilin 541006, China
Hongxia Zhang: Guangxi Key Laboratory of Environmental Pollution Control Theory and Technology, Guilin University of Technology, Guilin 541006, China
Yu Song: Lubin Environmental Technology (Shanghai) Co., Ltd., Shanghai 201315, China
Yapan Li: Lubin Environmental Technology (Shanghai) Co., Ltd., Shanghai 201315, China
Hongxiang Zhu: College of Light Industry and Food Engineering, Guangxi University, Nanning 530004, China

Sustainability, 2026, vol. 18, issue 4, 1-25

Abstract: A novel Ag 3 PO 4 /BiVO 4 heterojunction was synthesized via a combined hydrothermal–in situ precipitation method. With an optimal Bi:Ag molar ratio of 1:2 and after calcination at 200 °C for 22 h, 0.9 g of this composite reduced the chemical oxygen demand (COD) of landfill leachate tailwater from 232 mg·L −1 to 142 mg·L −1 and its UV 254 absorbance from 0.22 to 0.156 under visible light irradiation within 140 min. The material exhibited a bandgap of 2.56 eV, along with enhanced visible-light absorption and improved charge-carrier separation efficiency. In the Ag 3 PO 4 /BiVO 4 /peroxymonosulfate (PMS)/visible light system, using 0.5 g of catalyst and 2.0 g·L −1 of PMS at pH 11 reduced the COD from 242 mg·L −1 to 138 mg·L −1 . A subsequent two-stage treatment process, integrating the Ag 3 PO 4 /BiVO 4 /PMS/vis and P25/UV process, achieved a final tailwater COD of 90 mg·L −1 —meeting standard discharge limits—and a 69.5% removal of humic-like substances. The heterojunction catalyst retained its activity over four consecutive cycles. Radical quenching experiments and electron paramagnetic resonance (EPR) spectroscopy identified photogenerated holes (h + ), hydroxyl radicals(·OH), and sulfate radicals (SO 4 − ·) as the primary reactive species. Gas chromatography–mass spectrometry (GC–MS) analysis identified intermediate organic compounds and proposed plausible degradation pathways. These results support a reaction mechanism in which h + oxidizes H 2 O to generate ·OH, while PMS accepts electrons to produce SO 4 − · and further ·OH radicals, leading to effective pollutant mineralization. Collectively, this solar-driven, sulfate radical-based advanced oxidation process offers an energy-efficient strategy with reduced chemical consumption for the sustainable treatment of refractory wastewater.

Keywords: Ag 3 PO 4 /BiVO 4; landfill leachate; photocatalysis; Ag 3 PO 4 /BiVO 4 /PMS/vis (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2026
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