Preparation of Porous Composite Materials through Silicon Component Foaming and Special Heat Treatment

This study proposes a foaming method along with calcination to produce silica-based porous materials. The high-silicon-content waste residue reacts with sodium hydroxide for hydrogen evolution foaming reactions. Then, the foaming green bodies are embedded and calcined in the calcination powder consisting of silicon, silicon carbide, graphite, and activated carbon at 1200 °C. The calcination powder creates a reducing atmosphere and prevents adhesion of the foaming green bodies to the crucible during calcination. Furthermore, the addition of activated carbon and calcination improve the macroporosity issue of the prepared sample through a gas-liquid-solid transformation. The BET surface area measurement is 64.197 m²/g, and the mercury intrusion porosimetry measurement indicates a porosity of 56.48%, with an average pore diameter of 396.48 nm. The porous composite materials exhibit the capability to adsorb methylene blue in solution. The porous materials possessing functional groups suggest promising potential for future development and application prospects.