Micro-mesoporous TiO2/SiO2 nanocomposites: Sol-gel synthesis, characterization, and enhanced photodegradation of quinoline

Abstract

Micro-mesoporous TiO2/SiO2 nanocomposite powders have been successfully synthesized by the sol-gel process with different TiO2/SiO2 molar ratios and were applied in the UV-photodegradation of quinoline (λ = 254 nm). The structural, morphological, and textural characterization of the powders showed a homogeneous distribution of TiO2 nanoparticles within a porous amorphous SiO2 matrix. Due to the micro-mesoporous character of the materials, their textural characteristics were evaluated by the N2 adsorption method, by comparing BET, DR, Langmuir, and DFT theories. Si60Ti40 powders (60%SiO2/40%TiO2) presented the highest specific surface area (SSA) obtained from BET (SSA = 363 m2g-1), DR (SSA = 482 m2g-1), and Langmuir (SSA = 492 m2g-1) due to the adequate particle size of TiO2 and its high dispersion in the porous matrix. A higher degradation of quinoline in the presence of H2O2 (66%) was achieved using Si80Ti20 powders (80%SiO2/20%TiO2), as compared to pure sol-gel TiO2 powders, (51%) under the same reaction conditions (1 UVC lamp - 250W, t = 180 min). The better performance of the Si80Ti20 nanocomposite could be attributed to the small TiO2 anatase crystallite size (<5.7 nm), high dispersion of these crystallites in the SiO2 matrix, great specific surface area (DR SSA = 342 m2 g−1), and the formation of Ti–O–Si bond, which is associated with new catalytic sites in TiO2/SiO2 composite.