A highly efficient Ag@ZnCr2O4 nanocomposite for rapid photocatalytic degradation of selected pesticides

Abstract

One of the most urgent global challenges today is environmental pollution resulting from pesticide use and the release of reactive chemicals into natural ecosystems. In this study, a green approach was employed to synthesize a Ag@ZnCr₂O₄ nanocomposite using an extract from A. indica leaves. The nanocomposite was thoroughly characterized using XRD, SEM, TEM, FTIR, XPS, BET surface area analysis, UV-vis spectroscopy for band gap determination, and TOC analysis for mineralization. Ag@ZnCr₂O₄ exhibited a distorted sphere structure with Ag nanoparticles uniformly dispersed on the surface, enhancing the surface area and active sites. The material demonstrated higher photocatalytic activity under visible light than bare ZnO and ZnCr₂O₄, achieving over 90% degradation of endosulfan (ES) and metribuzin (MB) pesticides, following first-order reaction kinetics and Langmuir adsorption isotherm behavior. LC–MS analysis allowed the identification of intermediates and the construction of the degradation pathway. The nanocomposite showed excellent stability and reusability over 8 cycles, negligible Ag leaching, and remarkable reusability, highlighting its potential for industrial-scale applications.