Preparation of SiO 2 /TiO 2 composite aerogel and its photocatalytic degradation of organic pollutants

Hydrophobic SiO₂/TiO₂ composite aerogels were prepared by the sol-gel method using methyltrimethoxysilane (MTMS) as silicon source, tetrabutyl titanate (TBT) as titanium source, ethanol as solvent, and trimethylchlorosilane as modification solution. The structure and morphology of the SiO₂/TiO₂ composite aerogel were characterized by FTIR, XRD, and SEM. Additionally, its hydrophobicity and photocatalytic performance were investigated. The results showed that the composite aerogel was a porous structure, which facilitated the formation of a high specific surface area, and TiO₂ nanoparticles were uniformly dispersed within the aerogel matrix. FTIR and XRD analyses confirmed that the Ti-O-Si bond was formed in SiO₂/TiO₂ composite aerogels, as well as the presence of the rutile and anatase crystal phase, which contributed to its enhanced photocatalytic oxidation performance. SEM analysis revealed that increasing the TiO₂ content enhanced the specific surface area of the aerogel. A larger surface area provides more contact interfaces, thereby improving the efficiency of organic pollutant degradation. Contact angle test confirmed that SiO₂/TiO₂ composite aerogels had excellent hydrophobicity, and the contact angle could reach 131.5° after aging modification. Photocatalytic degradation experiments under simulated UV irradiation demonstrated enhanced degradation efficiency of methyl orange, Congo red, methylene blue, and formaldehyde with increasing TiO₂ doping content in the aerogel, at 12.5% TiO₂ content, the composite aerogel achieved exceptional degradation rates of 93%, 98%, 95%, and 84% for methyl orange, Congo red, methylene blue, and formaldehyde, respectively, after 60 min of UV irradiation following dark adsorption, indicating outstanding photocatalytic performance, particularly for a range of organic pollutants.