Enhancing tetracycline antibiotic photocatalytic degradation using TiO2–slag nanocomposite: optimization using response surface model

Abstract

ABSTRACT Economically disadvantaged regions lacking centralized wastewater treatment systems require cost-effective solutions for antibiotic remediation. This study optimizes tetracycline degradation using a TiO2–slag catalyst under simulated solar irradiation. The catalyst was synthesized and characterized via scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffraction, and Fourier Transform Infrared (FTIR) spectroscopy. Box–Behnken design was used to evaluate the degradation efficiency using three operational variables, and the resulting quadratic regression model demonstrated strong predictive capability (R2 = 0.99–0.98, p < 0.05). Catalyst dosage was the most influential parameter, resulting in 99.64% degradation efficiency of tetracycline antibiotics under optimal operating parameters, which were identified as a solution pH of 11, a TiO2–slag catalyst dosage of 50 mg/L, and an initial tetracycline concentration of 25 mg/L at a fixed irradiation period of 60 minutes. This predicted efficiency (99.64%) was subsequently validated through confirmatory experiments, which achieved an experimental degradation efficiency of 99.16% under the same optimal conditions. Moreover, the catalyst exhibited excellent stability and reusability, maintaining degradation efficiencies of 98.96, 95.19, 93.12, 92.34, and 89.95% across five successive cycles. These findings demonstrate that the TiO2–slag nanocomposite is a promising and cost-effective photocatalyst with potential applicability for antibiotic removal in industrial wastewater treatment systems.