Optimized preparation conditions of TiO2 deposited on SiO2 solid superacid nanotubes as filler materials

Abstract

The preparation conditions have an important impact on the structure and properties of TiO₂ deposited on SiO₂ solid superacid nanotubes (TSANs). In this paper, the preparation conditions of TSANs such as the molar ratio of Ti/Si, the concentration of the aqueous solution of sulphuric acid, the dipping time in the aqueous solution of sulphuric acid and the calcination temperature, etc., were investigated and optimized and the optimum preparation conditions were finally determined. TSANs were employed as novel filler materials to prepare TSANs/PSF composite membranes with micro reaction locations (MRLs) inside the channels and on the surface of the composite membranes. TSANs and TSANs/PSF composite membranes were characterized and studied by SEM, TEM, EDX, FT-IR, BET and the contact angle of water, etc. The results indicate that the thickness of the tube walls is 50 nm, the ratio of the length to the diameter of TSANs is approximately 23, and SO₄²⁻/TiO₂–SiO₂ solid superacid nanotubes were formed, as shown by the stretching vibration peak of SO double bonds at 1300 cm⁻¹ in the FT-IR spectra. The contact angle decreased from 76.5° to 36.5° and the oil retention ratio of TSANs/PSF composite membranes reached 94.2%, which confirms the attractive hydrophilic and antifouling properties of TSANs/PSF composite membranes. Therefore, TSANs are desirable as novel filler materials for PSF membranes to improve their integrated properties.