Efficient and stable immobilization of TiO2-based composite photocatalytic system for separation and purification of organic pollutants in wastewater under solar light

Abstract

Photocatalytic removal of organic pollutants emerging from untreated industrial and aquaculture wastewater are still limited by catalytic efficiency and stability in practical application. In this study, we report the development of a silicone-immobilized, PEG-assisted Ag-doped TiO2 composite for efficient and sustainable removal of organic pollutants under solar irradiation. Firstly, a silicone-immobilized pristine TiO2 (S-TiO2) photocatalytic system was developed, demonstrating superior and stable removal of the organic pollutant Rhodamine B (Rh B) compared to PVA-TiO2 and dip-coated TiO2. Subsequently, pristine TiO2 was modified with the surfactant PEG, Ag species (Ag2O, Ag3PO4), and synthesized using the hydrothermal method, immobilized on silicone (S-H-PEG/PAgT). The S-H-PEG/PAgT, characterized by SEM, XRD, UV–Vis, and WCA revealed surface roughness, crystalline phase, excellent light absorption in the visible region, a narrow band gap, and hydrophobicity. The S-H-PEG/PAgT showed enhanced catalytic performance than S-TiO2 (Control) in the removal of tetracycline, a representative emerging organic contaminant. Furthermore, it displayed remarkable stability over 10 cycles and practicability in environmental conditions. Mechanism analysis revealed •O2– and h+ as the dominant active species involved in the catalytic reaction. Notably, a synergistic effect of surface hydrophobicity, roughness, and photocatalytic activity contributed to the reduction of pollutants. Therefore, the developed novel solar light driven S-H-PEG/PAgT photocatalytic system shows great promise for practical purification of organics pollutants in wastewater.