Hydrophobic TiO2‐SiO2 Aerogel Composites for Fast Removal of Organic Pollutants

Abstract

AbstractSiO2‐TiO2 aerogel composites were synthesized by co‐gelation of a titanium tetrachloride in an aqueous silicic acid solution. As‐prepared hydrogels were hydrophobized by trimethylchlorosilane and then dried at 150 °C and ambient pressure condition. The resulting gel composites are typical ‘pearl‐necklace’ aggregate silica structure which is intertwined at the nanometer level with titania, yielding a three‐dimensional hydrophobic SiO2‐TiO2 interpenetrating network with an improved pore structure, BET surface area, and photocatalytic performance when compared to their calcined hydrophilic gels. A hydrophobic aerogel composite which is optimized in an L9(34) orthogonal array features a fast removal (<30 mins) of organic compounds (> 89% removal of methyl orange and humic acid) in a 10 mg/L solution under UV light exposure, in which ethanol‐water was used as co‐solvent. In comparison, the calcined hydrophilic xerogel shows 10‐fold longer degradation time (∼ 300 mins) to remove the same concentration waste from the water streams.