Sustainable fabrication of In 2 S 3 @ZnO heterojunction photocatalyst via plant-extract-assisted route for photocatalytic degradation of polyacrylamide in aqueous systems

In the petroleum extraction industry, produced water often contains high concentrations of organic polymers, particularly polyacrylamide (PAM). This polymer can gradually degrade, releasing significant amounts of acrylamide monomers, which pose severe neurotoxic risks to both humans and animals by damaging the peripheral nervous system. To enhance the removal efficiency of PAM, a photocatalytic nanocomposite material, In2S3@ZnO, was designed and synthesized via a one-step green synthesis method employing lotus leaf extract. In this composite, In2S3 nanosheets were decorated with ZnO nanoparticles ranging from 40 to 50 nm in size, forming a stable heterojunction structure. The photocatalytic activity and durability of the composite were assessed through the degradation of PAM under simulated solar light. Under optimal conditions—namely a catalyst loading of 1.0 g L−1, pH 8, and an initial PAM concentration of 10 mg L−1—the material achieved a maximum degradation efficiency of up to 98%. After four consecutive cycles, the material retained over 90% of its photocatalytic efficiency. The experimental results further demonstrated that the reactive species ·O2− and ·OH play dominant roles in the photocatalytic degradation of PAM, promoting its transformation into intermediate species and ultimately leading to complete mineralization. These degradation products were identified and confirmed by LC–MS analysis.