One-pot synthesis of 3D ZnO@g-C3N4: A multifunctional composite for efficient photocatalysis and advanced membrane-assisted dye purification

The one-pot synthesis of ZnO@g-C 3 N 4 composites (band gap: 2.95 eV) offers a simple and efficient strategy to produce multifunctional materials with high potential for water purification. While ZnO@g-C 3 N 4 is known for its photocatalytic activity, its systematic evaluation in both degradation kinetics and membrane-assisted treatment remains limited. This study investigates the photocatalytic activity of ZnO@g-C 3 N 4 for methylene blue (MB) degradation under UV and daylight irradiation, followed by its application in polyvinylidene fluoride (PVDF) membranes. Photocatalytic tests achieved MB removal efficiencies of 94.33% (UV) and 95.33% (daylight), both fitting a second-order kinetic model. Incorporation into PVDF membranes further enhanced performance, with removal efficiencies of 97.72% (UV) and 97.44% (daylight), along with a substantial flux increase from 20.84 to 172.01 kg.m -1 .h -1 owing to improved hydrophilicity. These results demonstrate the potential of one-pot synthesized ZnO@g-C 3 N 4 as a promising photocatalyst and as an effective component for membrane-assisted wastewater treatment.