Preparation of monolithic amorphous silica aerogel through promising valorization of silicomanganese slag

Abstract

Monolithic silica aerogels were successfully synthesized from silicomanganese slag by a highly efficient hydrometallurgical extraction process followed by solvent exchanges and ambient pressure drying. The silica content of the silicomanganese slag was first extracted by a facile and economical acid digestion-gelation process. The extracted silica hydrogel was then converted to silica aerogel through three-step solvent exchange, aging, and ambient pressure drying. No surface modifier was used. The characterization results revealed that the obtained silica aerogel had an amorphous structure having a low bulk density of ∼0.08 g/cm3, high specific surface area (∼509 m2/g), large pore volume (∼0.97 cm3/g), and an average pore diameter of ∼7.5 nm. Overall, the results showed that the proposed valorization process is a promising method to prepare monolithic silica aerogel from a cheap silica resource under ambient pressure drying without the use of any surface modification.