Growth regulation mechanism of nano-silica based on new ammonia-based CO₂ capture under external fields

Conventional CO₂ capture technologies often focus on the simple capture process, while the absorption and high-value utilization of carbon capture products have profound significance, especially when combined with the utilization of biomass energy. Novel ammonia-based CO₂ capture coupled with selective silicon dissolution was proposed with process regulation of external fields (i.e. magnetic field, microwave field, ultrasound field) used to prepare nano silica. The results show that the magnetic field plays a dual role of “vibration stirring” and adding energy (11.2 J/mol) on the formation and dispersion of nano silica. The specific surface area of nano-silica is increased from 140.24 m²/g to 280 m²/g by microwave field (250 W), and its “internal heating” promotes the formation of crystal nuclei. The ultrasonic field reduces the primary particle size of nano-silica by 3.17 nm, and inhibits the particle growth through cavitation and mechanical vibration. It would provide parameter support and optimization guidance for the low-cost high-quality nano silica for high-value utilization of ammonia-based CO₂ capture products.