A Review on Preparation Processes of SiO2 Aerogel Insulation Materials: Green Pathways for Silicon Source Extraction, Drying, and Modification

Abstract

Silica (SiO₂) aerogels, as highly promising high-performance thermal insulation materials, are of great significance in advancing sustainable material development through green synthesis routes. This review systematically summarizes recent progress in green synthesis techniques for SiO₂ aerogels, with a focus on three core aspects: silica source extraction, drying methods, and modification strategies. Regarding silica sources, chemical, microbial, and physical methods have been developed to efficiently and sustainably extract silica from agricultural waste such as rice husks and sugarcane bagasse, significantly reducing reliance on conventional toxic precursors. In terms of drying technologies, supercritical CO₂ drying offers excellent structural integrity and environmental friendliness, while ambient pressure drying and freeze-drying have made considerable progress in energy efficiency and safety. Emerging techniques such as combustion drying demonstrate potential for rapid and low-energy consumption processing. For modification strategies, the use of natural polymers—including cellulose, sodium alginate, and chitosan—along with green solvents, has significantly enhanced the mechanical and thermal insulation properties of aerogels through synergistic effects. These approaches also considerably improve biodegradability and environmental compatibility. These green strategies effectively reduce the environmental impact of the preparation process and provide strong support for industrial applications in fields such as energy-efficient buildings.