A novel bio-facilitated synthesis of GO/ZnO/Ag nanocomposite via Citrulline Lanatus and OPEFB for enhanced photocatalytic degradation of imidacloprid: Kinetics, mechanism and byproduct analysis

In this study, a biomass derived photocatalyst GO/ZnO/Ag i.e., a graphene oxide (GO) interfaced zinc oxide (ZnO), doped with silver (Ag) for imidacloprid (IMD) degradation, under UV–Visible light irradiation , is reported. Oil Palm Empty Fruit Bunch Fibre (OPEFB) was used to prepare GO and Citrulline Lanatus extract was used for green synthesis of ZnO . The characterization studies confirmed the favorable weight ratio morphology, anisotropic polycrystalline lattice framework, enhanced fluorescence quenching , reduced bandgap values of 2.96 eV, roughened surface topology, maximized BET surface area of 71.43 m 2 g −1 , chemically favorable surface-functionalization and oxidation states. These specifications facilitated IMD degradation following pseudo first-order kinetics model with a rate constant (k app ) of 0.0382 min −1 for GO/ZnO/Ag nanocomposite which is 3.93, 3.50 and 2.24 times greater than commercial ZnO, synthesized ZnO, and GO/ZnO respectively. Furthermore, the reusability test of GO/ZnO/Ag nanocomposite is demonstrating its sustainability and reproducibility. The radicals, • O 2 − and • OH were found to be the predominant reactive oxygen species (ROS) in scavenging assay testing. The intermediate products which formed during photo-oxidation of IMD such as 2-chloro-5-methylpyridine (7; m / z = 127.6) and imidazolidin-2-one (8; m/z = 86.1) were identified in GC–MS analysis. • OPEFB and WRE biomass mediated GO/ZnO/Ag nanocomposite was prepared. • 100 % degradation IMD by GO/ZnO/Ag under 135 min of UV–visible light irradiation. • Photocatalytic parameters, photocatalyst stability, and reaction kinetics assessed. • • O 2 − and • OH radicals were the predominant reactive oxygen species. • Degradation pathway and by-products analysed by GC–MS.