Sustainable photocatalyst fabrication from Silau River-derived SiO2: PVA/TiO2/SiO2 for water purification

Silau River, Indonesia, is a river with areas along its banks used for fishing, factories, and transportation to the sea. The sand from the Silau River is a valuable resource that can be extracted to produce SiO₂, with substantial availability. This study aims to extract SiO₂ from Silau River sand and modify it using PVA and TiO₂ materials as a photocatalyst for water purification. The extraction of SiO₂ from the sand was carried out using the coprecipitation method. The PVA/TiO₂/SiO₂ composite membrane was synthesized by combining a simple mixing technique for filler preparation with mixing and solidification processes to form the composite membrane. Instruments used in this study include a Scanning Electron Microscope-Energy Dispersive X-Ray Spectroscopy (SEM-EDS), Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffractometer (XRD), Differential Scanning Calorimetry (DSC), and UV–Vis Spectroscopy. All characterization results indicate that PVA/TiO₂/SiO₂ has been successfully synthesized in every composition variation. The PVA/80 % TiO₂/20 % SiO₂ composite demonstrated the most effective performance, achieving 65.1 % color degradation in river water within 10 hours. Furthermore, the river water parameters, including TDS, turbidity, pH, Cr, Fe, and Mg, which initially failed to meet quality standards, improved after treatment with this composite, enabling the water to meet the quality standards outlined in Government Regulation No. 22 of 2021 of the Republic of Indonesia concerning the Implementation of Environmental Protection and Management.