Characterization and comparison of uniform hydrophilic/hydrophobic transparent silica aerogel beads: skeleton strength and surface modification

Abstract

Silica aerogel is a good adsorbent due to the large surface area and chemical stability. However, its inherent poor mechanical properties and hydrophobicity limit applications in water treatment. To improve the adsorption performance of silica aerogel, uniform transparent hydrophilic mesoporous silica aerogel beads with highly degree of sphericity were synthesized through a facile aging immersion and ambient pressure drying route. The designed hydrophilic silica aerogel beads possessed the mesopores, mean diameter of approximately with the average pore size of 12.51 nm, the specific surface area of 582.52 m² g⁻¹, and the pore volume of 1.46 cm³ g⁻¹. For comparison, hydrophilic silica aerogel beads without skeleton improvement and hydrophobic silica aerogel beads were also obtained, respectively. The synthesized novel hydrophilic silica aerogel beads displayed a significantly improved adsorption performance with a favorable dye absorption capacity, superior to that of previously synthesised silica-based aerogel beads materials. This study demonstrates a facile and low-cost route toward transparent silica aerogel beads with macroscopic beads structures, which can be used as adsorbents, catalytic supports or the template to synthesize novel functional materials requiring high transmittance, high surface area and effective mass transport.