Enhancing methyl orange photodegradation over a reusable Ag-TiO2/SBA-15 nanocomposite

Currently, wastewater treatment is an industrial opportunity to rejuvenate freshwater resources. It is highly needed in water-stressed countries. This work presents a one-step microwave-assisted hydrothermal method for making Ag-TiO2/SBA-15 nanophotocatalysts. XRD, N2 adsorption-desorption isotherms-desorption isotherms, AFM, UV-Vis, and UV-DRS analyses were carried out to characterize the obtained photocatalyst sample. With high Ag loading on the surface of TiO2 nanoparticles, agglomeration of silver nanoparticles and also clogging occurring in the SBA-15 pores are confirmed by AFM analysis. The optical bandgap energies obtained by DRS analysis were significantly blue-shifted, which is the quantization effects improving photocatalytic activities under visible light illumination due to the presence of silver nanoparticles that act as photosensitizer and reduce the recombination of the formed charge carriers (e and hole). Photocatalytic performances of Ag-TiO2/SBA-15 nanophotocatalyst were evaluated by methyl orange (MO) dye photodegradation at different Ag/TiO2 ratios. In MO destruction experiments, the highest photocatalytic efficiency was obtained in the Ag/TiO2-SBA-15 (Ag: TiO2=1.0) photocatalyst at 76.0% and all efficiencies over the synthesized nano photocatalysts are higher than commercial bulk TiO2 nano photocatalyst activity due to the low UV part of the applied visible light halogen lamp and also Ag/TiO2 nano photocatalyst that maybe due to the poor dispersion of active phases. The Ag-TiO2/SBA-15 (1.0) had the highest photocatalytic efficiency at pH=4. The photocatalyst can be reused six times without losing its effectiveness. This shows that the photocatalyst is stable and can be used repeatedly.