An antisolvent crystallization involved process for drying silica hydrogel

Abstract

Herein, we depicted the crystal salt formation within silica hydrogel pores via antisolvent crystallization of thermally decomposable salts followed with the crystal salt decomposition for drying the hydrogel to aerogel at relatively low temperature and ambient pressure. Results showed that the dried silica with relatively large pore volume (e.g., 3.2 cm³/g), large surface area (e.g., 667.7 m²/g), small D₅₀ (e.g., 6.9 μm) as well as narrow particle size distribution was obtained. The confined salt left mesopores when decomposed. In comparison with other salts and antisolvents, ammonium carbonate and isopropanol, respectively, showed remarkable improvement for the pore properties of the silica product. Furthermore, the as-dried silica as the coating flatting agent showed improved film transmittance and extinction indices when compared with a commercial sample.

Keywords:

• Silica
• antisolvent
• thermally decomposable salt
• grain drying
• flattening agent

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by National Natural Science Foundation of China, NSFC (No. 21476186).