Sustainable Production of ZnO Nanoparticles: Low‐Temperature Synthesis and Enhanced Photocatalytic Performance for Dyes Removal

Abstract Photocatalysis has gained significant attention as an efficient and sustainable approach for degrading organic pollutants in wastewater. In the present study, zinc oxide (ZnO) nanoparticles were synthesized via a simple, solvent‐free, and low‐temperature (75 °C) co‐precipitation method using only zinc sulfate and sodium hydroxide without the need for surfactants, calcination, or hazardous solvents. The prepared ZnO was thoroughly characterized by SEM, EDX, XRD, FTIR, UV–vis, zeta potential, TGA–DTA, and BET analyses, confirming its high purity, wurtzite crystalline structure, thermal stability, and mesoporous features. The photocatalytic performance of ZnO was evaluated under UV light for the degradation of Safranin (cationic) and Reactive Red 180 (RR180, anionic) dyes. Complete degradation of RR180 was achieved in 30 min and Safranin in 90 min under optimized conditions (pH 8, ZnO dose 0.75 g/L, dye concentration 10 mg/L), following pseudo‐first‐order kinetics. The higher degradation rate of the anionic dye is attributed to favorable surface charge interactions with ZnO. Scavenger experiments confirmed that valence band holes (h⁺) and hydroxyl radicals (•OH) were the primary reactive species driving the photocatalytic process. The ZnO photocatalyst retained high activity over five reuse cycles, indicating good stability.