Characterization and the Effect of Different Parameters on Photocatalytic Activity of Montmorillonite/TiO2 Nanocomposite under UVC Irradiation

Abstract

This study aimed to modify montmorillonite (MMT) with titanium dioxide (TiO₂) by wet stirring method combined with ultrasonic to form MMT/TiO₂ nanocomposite and used as a photocatalyst in the removal of organic dye rhodamine B (RhB). The characteristics of the synthesized samples were analyzed by methods such as energy-dispersive X-ray spectroscopy (EDX), scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and UV-Vis diffuse reflectance spectra (UV-Vis DRS). The degradation of RhB was carried out for 210 min under UVC irradiation, and the decolorization efficiency of RhB was evaluated by UV-vis spectroscopy. The results show that the TiO₂ anatase nanoparticles are randomly distributed on the surface or the space between the MMT sheets to form a house-of-card structure. After 210 min of exposure under a UVC light source, the decolorization efficiency reached 91.5% for the solution with pH = 6.8, photocatalyst content 0.1 g/L, initial concentration RhB 10 mg/L, and UVC power 15 W. Liquid chromatography–mass spectrometry (LCMS) identified the degradation intermediates that MMT/TiO₂ successfully cleaved the chromophore structure and formed more minor broken-ring by-products. The influence of operating parameters on RhB removal efficiency, including solution pH, photocatalyst content, initial dye concentration, inorganic, and organic scavengers, was studied. In addition, the kinetic modeling study shows that the RhB photodegradation reaction is consistent with the Langmuir-Hinshelwood first-order kinetic model.