Enhanced Photodegradation of Imidacloprid Using ZnO@Ca‐Alginate Composites: Optimization of pH and pHzcp for Effective Water Treatment

Abstract This research focused on the photodegradation of the insecticide imidacloprid (IM) via a ZnO@Ca‐Alginate composite catalyst to address water contamination issues, particularly in agricultural areas such as Palestine. The composite was synthesized and characterized by scanning electron microscopy (SEM), X‐ray diffraction (XRD), energy dispersive X‐ray (EDX), thermogravimetric analysis (TGA), and Fourier transform infrared (FT‐IR) spectroscopy, confirming the presence of ZnO. Photocatalytic experiments under simulated solar light revealed significant IM degradation, with a 50 % reduction in 40 minutes, an 80 % reduction in 2 hours, and up to 94 % in 3 hours. The degradation efficiency was influenced by the point of zero charge (pHzcp) and solution pH, with optimal performance under neutral to slightly basic conditions. UV‐visible spectrophotometry, high‐performance liquid chromatography (HPLC), and total organic carbon (TOC) analyses verified complete IM mineralization, yielding CO₂, Cl − , and NO₃ − after 3 hours. The ZnO@Ca‐Alginate composite demonstrated high reusability, highlighting its potential for treating pesticide‐contaminated water. This study emphasizes the need for efficient pollutant removal technologies in regions where agricultural pollutants are prevalent.