Oxidant-assisted catalytic degradation of Congo red by Pd/NiO nanoparticles under visible light

Abstract

This study investigates the catalytic performance of synthesized Pd/NiO nanoparticles (NPs) and the influence of oxidant-assisted advanced oxidation processes (AOPs) on the degradation of Congo red (CR), a model azo dye and a hazardous organic contaminant in water. Pd/NiO NPs are successfully synthesized via chemical coprecipitation and characterized using X-ray diffraction, transmission electron microscopy, scanning electron microscopy with energy-dispersive X-ray analysis, ultraviolet–visible (UV–Vis) spectroscopy, and the Brunauer–Emmett–Teller technique. These characterization techniques confirm the successful synthesis of Pd/NiO NPs. The photocatalytic degradation of CR dye under visible light irradiation is assessed using Pd/NiO NPs. The influence of various reaction conditions, including pH, irradiation time, catalyst dosage, and initial dye concentration, on the degradation process is studied. Pd/NiO NPs demonstrate exceptional performance in degrading CR dye, with degradation kinetics following a pseudo-first-order model. Additionally, the combined effects of hydrogen peroxide (H2O2) and persulfate (S2O82−) on photocatalytic efficiency are explored. The addition of these oxidants significantly enhances degradation, achieving 89.7% and 94.1% removal, respectively.