Titanium dioxide nanoparticles modified by salicylic acid and arginine: Structure, surface properties and photocatalytic decomposition of p-nitrophenol

Abstract

In this study, titanium dioxide (TiO2) nanoparticles were surface-modified with salicylic acid (SA) and arginine (Arg) using an environmentally friendly and convenient method, and the bonding structure, surface properties and degradation efficiency of p-nitrophenol (PNP) were investigated. X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FT-IR), water contact angle (WCA) measurements, ζ-potentiometric analysis, UV/visible diffuse reflectance spectroscopy (UV–vis DRS), and thermogravimetric analysis (TGA) were performed to evaluate the modification effect. The degradation rates were determined by high-performance liquid chromatography (HPLC). The results show that bidentate or bridging bonds are most likely formed between SA/Arg and TiO2 surface. Surface modification with SA, Arg, or both can improve the lipophilic properties and decrease the zeta potential, and also result in a red shift of the absorption wavelength. TiO2 nanoparticles modified by Arg or both SA and Arg show a large specific surface area and pore volume. Further, degradation experiments under visible light show that Arg modification is most efficient. This simple and versatile synthetic method to produce TiO2 nanoparticles surface-modified with various organic capping agents can be used for novel multifunctional photocatalysts as required for various applications in energy saving and environmental protection.