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.