Visible Light Enhanced Degradation of Sulfamethoxazole by Beta Zeolite/TiO ₂ Photocatalyst

Abstract A visible light photoactive layered beta zeolite supported titanium dioxide (TiO 2 ) was successfully fabricated, whereby N,N ‐dimethylacetamide was used for the first time as a stacking agent, and tetramethylammonium hydroxide pentahydrate (TMAOH) as a template for beta structure via sol–gel assisted hydrothermal method. High‐resolution transmission electron microscopy (HRTEM) results confirmed homogenous dispersion of spherical TiO 2 nanoparticles onto the zeolite. The ultraviolet–visible (UV–vis) diffuse reflectance spectroscopy (UV–vis DRS), and Raman spectral shifts proved that nanocomposite had a visible light redshift bandgap of 2.88 eV for zeolite/TiO 2 (3.18 eV, TiO 2 ). Fourier‐transform infrared (FTIR) and energy‐dispersive X‐ray spectroscopy (EDS) analysis of zeolite/TiO 2 revealed the presence of a nitrogen atom from NH 4 OH, causing a redshift of the photocatalysts by substituting oxygen (O) atom from O─Ti─O to form O─Ti─N bond. This photocatalytic removal efficiency for sulfamethoxazole was 82% after 120 min of visible light irradiation at pH 5.5. This photocatalyst has superior visible light activity with k = 0.018 min −1 and 82% performance for SMX degradation compared to some recent zeolite/TiO 2 nanocomposite with UV light limitation. The recyclability and stability tests revealed efficient reuse for five cycles without major decline. A Type‐II heterojunction system observed suggest a cyclic charge pair transfer whereby an electron moves from a high CB of zeolite into low CB of TiO 2 , whereas holes (h + ) move from a lower VB of TiO 2 into higher VB of zeolite.