A New Sunlight Active Photocatalyst Based on CuO-TiO₂-Clay Composite for Wastewater Remediation: Mechanistic Insights and Degradation Optimization

In this wok, a new CuO-TiO2-clay composite was synthesized by the sol-gel method and explored as a photocatalyst for wastewater remediation. The synthesized material was characterized by X-ray diffraction (XRD), Raman spectroscopy (RS), diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), X-ray fluorescence (XRF), and Fourier Transformer InfraRed (FTIR). The photocatalytic activity of the composite was tested on tartrazine dye (TARTZ) removal. Particular emphasis was focused on the effect of the key operating parameters such as photocatalyst dose, pH, light intensity, and initial concentration of dye. The optimization of three simultaneous parameters, namely methylene blue concentration (MB; pollutant in competition with TARTZ), NaCl concentration, and irradiation time, was examined via the response surface methodology (RSM). The CuO-TiO2-clay composite showed the best photocatalytic performance with 62.50% of photodegradation yield of TARTZ in visible light irradiation compared to 19.38% and 43.78% for pure TiO2 and TiO2-clay, respectively. This performance reached to 100% in sunlight source during the same time. The optimal conditions provided by the response surface methodology (RSM) were 180 min for irradiation time and 3.6 mg/L for MB concentration. After 120 min, 11.35% of TARTZ mineralization was obtained. The scavenger study revealed the involvement of OH and h(+) species, but especially O-2(-). as the main responsible for the photodegradation of the TARTZ. The current study highlights the potential of CuO-TiO2-clay composite as efficient photocatalytic systems for degrading hazardous organic pollutants in water.