Synergistic Effects of Hybrid Zinc Oxide/Graphene Oxide Nanocatalyst on Photocatalytic Degradation of Acetamiprid Insecticide

Abstract

The persistence of pesticide residues in aquatic environments necessitates the development of efficient and sustainable remediation technologies. This study investigated the synergistic effects of a ZnO/GO nanohybrid on the photocatalytic degradation of acetamiprid in aqueous medium. The photocatalyst was synthesized via a co-precipitation method and characterized using XRD, SEM/EDX, FTIR, and BET analyses. XRD confirmed the formation of crystalline hexagonal wurtzite ZnO with an average crystallite size of 10.7 nm, while the characteristic diffraction peak of GO at 2θ = 11.1⁰ verified successful oxidation of graphite. SEM revealed layered GO sheets decorated with well-dispersed ZnO nanoparticles, whereas EDX analysis confirmed the elemental composition of the nanohybrid through the presence of Zn and O. FTIR spectra showed characteristic oxygen-containing functional groups and Zn-O vibrations. BET analysis revealed mesoporous structures with surface areas of 216.3 and 197.7 m²/g for GO and ZnO/GO, respectively, indicating suitability for adsorption and photocatalytic applications. Photocatalytic investigations at pH 9, a catalyst dose of 70 mg, and an irradiation period of 120 minutes resulted in maximum degradation efficiencies of 68%, 74%, and 96%. Kinetic analysis showed that acetamiprid degradation followed a pseudo-first-order model with a rate constant of 0.0246 min^-1 and a half-life of 28.17 min. Thermodynamic studies indicated a photon-driven process with low energy of activation and positive Gibbs free energy values. Photolysis resulted in only 9.6% degradation, while recyclability studies demonstrated good catalyst stability over five successive cycles. The enhanced photocatalytic performance was due to the interaction between ZnO and GO, demonstrating its potential for pesticide-contaminated wastewater treatment.