Controlled synthesis of hexagonal mesostructure silica and macroporous ordered siliceous foams for VOCs adsorption

Abstract

In this study, ordered hexagonal mesostructure siliceous materials and macroporous ordered siliceous foams were synthesized in pH = 5 buffer solution by simply adjusting the reaction temperature with P123 (EO₂₀PO₇₀EO₂₀) as a structure-directing agent and tetramethoxysilane (TMOS) as the silica source. Increasing the reaction temperature from 15 to 35 °C led to a structural evolution from ordered hexagonal mesostructure siliceous material with a pore size of 10 nm to macroporous ordered siliceous foam with a pore size of ∼100 nm. The adsorption and desorption performance of hexagonal mesostructure and macroporous ordered siliceous samples (HMS and MOSF) were investigated under static (water vapor, n-hexane and 93# gasoline) and dynamic (n-hexane) conditions. Compared with commercial silica gel (SG), activated carbon (AC) and HMS, MOSF show higher static adsorption capacity of n-hexane and 93# gasoline, higher dynamic n-hexane adsorption capacity, and more stable breakthrough time under dynamic adsorption conditions. The designed MOSF with highest volatile organic compounds (VOCs) removal capacity and recyclability show great potential for VOCs controlling.