Heterogeneous photocatalytic degradation of selected pharmaceutical and personal care products (PPCPs) under visible light using SiO ₂ –TiO ₂ /SnO ₂ : effect of tin precursors and SiO ₂

In this study, SiO₂-TiO₂/SnO₂ composites were synthesized using a facile sol-gel method to facilitate the heterogeneous photocatalytic degradation of selected pharmaceuticals and personal care products (PPCPs), namely tetracycline hydrochloride (TC) and ciprofloxacin (CIP), under visible light. The effects of different tin precursors (SnCl₄·5H₂O, SnCl₂ and Na₂SnO₃·3H₂O) along with the addition of SiO₂ on photocatalytic performance were systematically evaluated. The photocatalyst prepared by SnCl₄·5H₂O as the tin precursor showed the highest photodegradation performance for ciprofloxacin (CIP) and tetracycline (TC), and the photodegradation performance for tetracycline (TC) was 1.8, 4.33 and 43.33 times that of SnCl₂ and Na₂SnO₃·3H₂O as the tin precursor and pristine TiO₂, respectively. Furthermore, the incorporation of SiO₂ significantly improved the photocatalytic performance under visible light. The SiO₂-TiO₂/SnO₂ (SnCl₄) composites exhibited a 2.65-fold increase in tetracycline (TC) degradation compared to the SiO₂-free TiO₂-SnO₂ (SnCl₄) materials. The significant improvement of photocatalytic activity is attributed to the effects of tin precursors and SiO₂ on the physicochemical properties, charge carrier dynamics and surface reactivity of the composites. This study presents a novel method for developing composite photocatalysts with exceptional activity by employing various tin precursors and incorporating SiO₂ to enhance the removal of pharmaceutical and personal care products (PPCPs) under visible light. The findings have substantial implications for future research in the photocatalytic degradation of PPCPs, fostering environmentally friendly approaches in this field.