Magnetically Recoverable BiVO4/Fe3O4/g-C3N4 Photocatalyst via One-Pot Hydrothermal Synthesis for Visible-Light Methylene Blue Degradation

Abstract

The development of efficient and recyclable photocatalysts offers promising alternatives for wastewater treatment. However, significant challenges remain, including inefficient light utilization for photodegradation and rapid charge-carrier recombination. This study aims to synthesize a distinctive reusable BiVO4/Fe3O4/g-C3N4 (BNFC) photocatalyst with magnetic recovery via a one-pot hydrothermal method for visible-light methylene blue (MB) degradation. The optimal composite, BNFC-0.5, exhibited superior photocatalytic performance, achieving a degradation efficiency of 93.04% under optimal conditions of catalyst composition, pH 9, and 160 minutes of irradiation, with a TOC mineralization efficiency of 42.48%. The high degradation efficiency of the BNFC-0.5 composite is ascribed to its enhanced ability to harvest visible light, facilitate electron excitation with lower energy input, and promote effective electron–hole migration via the proposed Z-scheme configuration. Evaluation of the reactive oxygen species revealed that hydroxyl radicals (•OH) made the greatest contribution to the oxidation of MB. Kinetic assessment of the photocatalytic process revealed that the experimental behavior was adequately described by the Langmuir–Hinshelwood model, indicating a pseudo-first-order degradation pathway. In addition, the photocatalyst maintained a degradation efficiency of 79.32% over four cycles, demonstrating good stability and reusability, which is supported by the composite’s good structural stability. Overall, the findings demonstrate that constructing a ternary heterojunction is an effective strategy for enhancing the composite’s photocatalytic capability. Owing to its high degradation efficiency and reusability, the composite represents a promising candidate for wastewater purification under visible-light conditions.