Ultrasonic impregnation synthesis of GO/TiO2/SiO2 nanocomposite for photocatalytic and sonophotocatalytic degradation of atrazine

This experimental study explores the photocatalytic and sonophotocatalytic degradation of atrazine (ATZ) using a graphene oxide/titanium dioxide/silicon dioxide (GO/TiO 2 /SiO 2 ) composite synthesized via an ultrasonic-assisted impregnation method. Characterization confirmed the successful formation of the ternary composite and revealed structural and surface properties favorable for photocatalytic activity. RSM-CCD together with kinetic and isotherm analyses, were employed to optimize and interpret the experimental data. Under optimal conditions, the sonophotocatalytic system achieved 91.95% degradation at a GO/TiO 2 /SiO 2 concentration of 1.4 mg/mL, an ATZ concentration of 110 mg/L, pH 4.6, and an irradiation time of 117 min, whereas the photocatalytic process achieved 85.82% under similar parameters (pH 4.7, 134 min). Kinetic analysis indicated that the pseudo–first-order (PFO) model best described the reaction, with the sonophotocatalytic pathway showing a 33% rate enhancement (RE = 1.33) due to ultrasound-induced cavitation that enhanced radical generation and mass transfer. These findings demonstrate that coupling visible-light photocatalysis with ultrasound markedly improves ATZ degradation efficiency and reaction kinetics.