Grafting dynamics, structures and properties of nano TiO₂-SA photocatalytic materials

Salicylic acid (SA) was successfully grafted onto nano-TiO₂ surfaces (TiO₂-SA) by post-treatment surface modification. The effects of ultrasound stiring, solvents, material ratio, pH value, and temperature on the grafting process and photocatalytic material properties were investigated, and the grafting reaction kinetics was determined. The structures of the materials were determined using Fourier transform infrared (FT- IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). A structural model was proposed. The properties of the photocatalytic material were examined using contact angle analysis, simultaneous thermogravimetry-differential scanning calorimetry (TG-DSC), ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), and scanning electron microscopy (SEM). Compared with bare TiO₂, the modified TiO₂ had good hydrophobicity and dispersion properties, a lower sedimentation velocity in solvents, better adsorption stability at oil-water interfaces, and extended visible light absorption. The TiO₂-SA gave excellent photocatalytic performances in nitrobenzene degradation under ultraviolet-light irradiation.