Synthesis of rGO/g-C3N4 for methyl orange degradation in activating peroxydisulfate under simulated solar light irradiation

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• Metal-free rGO/g-C 3 N 4 composite was synthesized successfully by a simple polymerization-hydrothermal method. • rGO/g-C 3 N 4 /PDS system exhibited superior degradation efficiency of MO under stimulated solar light irradiation. • SO 4 ¯ · , h + , O 2 ¯ · and non-radical reaction pathway were involved in the removal of MO. In this study, reduced graphene oxide-based graphitic carbon nitride (rGO/g-C 3 N 4 ) composite was fabricated via thermal polymerization-hydrothermal method and were utilized to activate peroxydisulfate (PDS) under simulated solar light irradiation. The as-synthesized rGO/g-C 3 N 4 was demonstrated to effectively remove methyl orange (MO) in wastewater. Notably, 92.3% of MO (15 mg/L) was removed within 120 min in the presence of 0.2 g/L rGO/g-C 3 N 4 and 0.225 g/L PDS. The influence of activator dosage, PDS concentration and co-existing solution matrix on the removal efficiency was investigated. Free radical capture experiments confirmed that SO 4 ¯ · , photogenerated holes (h + ), O 2 ¯ · and non-radical reaction initiated by rGO played a major role in MO removal. Furthermore, PDS and rGO acted as the electron acceptor and transfer carrier of the photogenerated charges, respectively, resulting in the efficient activation of PDS. The promoting visible light absorption might be ascribed to the defect sites on the surface of rGO/g-C 3 N 4 , which generated from the rGO loading. This study revealed that the as-synthesized rGO/g-C 3 N 4 composite exhibits wide promising application prospects as a photocatalytic activator of PDS for the degradation of azo dyes in textile wastewater.