Mesoporous structure TiO₂/SiO₂ composite for methylene blue adsorption and photodegradation

In this work, a mesoporous structure TiO ₂ /SiO ₂ (M-TS) composite with excellent adsorption and photocatalytic properties was fabricated by a sol–gel process combined with calcination. The structure of the samples was characterised by scanning electron microscopy and Brunauer–Emmett–Teller analysis. The factors influencing the adsorption behaviours of methylene blue (MB) onto M-TS, including ingredient, dosage, initial concentration and temperature were investigated. The M-TS was produced by removing poly(vinylpyrrolidone) from the precursor gel was vital to the excellent adsorption capacity. Furthermore, the isotherm and kinetic data were fitted by using Langmuir and Freundlich isotherm models, pseudo-first-order and pseudo-second-order equations, and the intra-particle diffusion model. The Langmuir isotherm model and the pseudo-second-order kinetics were the most suitable models for describing the adsorption of MB onto M-TS. It was also found that the adsorption capacity of cationic dyes on M-TS is better than that of anionic dyes. The experimental results of adsorption and photodegradation proved that improvement of adsorption capacity enhances the decolourisation efficiency. This work shows that the M-TS could be used as an effective adsorbent and photocatalyst to remove cationic dyes from wastewater.