Revolutionizing Dye Degradation: Enhanced Photocatalytic Performance of CQDs-Mg-ZnO Nanocomposites via RSM Optimization

The global environmental crisis, particularly concerning aquatic pollution, necessitates the development of efficient and sustainable wastewater treatment technologies. Photocatalytic technology is one of the effective approaches to eliminate and degrade these aqueous pollutants. This study investigates the potential of novel carbon quantum dot (CQD)-based photocatalysts for the degradation of acid orange 7 (AO7), a persistent organic dye pollutant. In this regard, two novel photocatalysts CQDs-magnesium (Mg) and CQDs-Mg-zinc oxide (ZnO) were synthesized and characterized. The average nanoparticle size of CQDs-Mg (55.4 nm) and CQDs-Mg-ZnO (123.8 nm) were determined. BET analysis revealed a higher surface area for CQDs-Mg-ZnO (135.296 m²g⁻¹) compared to CQDs-Mg (65.437 m². g⁻¹), suggesting improved catalytic performance. Also, the influence of key operating parameters (pH, photocatalyst concentration, and initial AO7 concentration) on the photocatalytic degradation of AO7 was studied and optimized using response surface methodology (RSM). The RSM model exhibited a high determination coefficient (R² = 0.984), accounting for 98% of the response variability. Optimal degradation conditions were achieved with a photocatalyst content of 0.6 g l⁻¹, pH 4, and an initial AO7 concentration of 30 ppm. Under these conditions, complete degradation of AO7 was observed. These synthesized photocatalysts exhibit excellent photocatalytic activity, high reusability, and the potential for scalability, offering a viable solution for addressing water pollution.