Effect of solvent and calcination process on physicochemical features of silica nanocapsule for CO2 capture

Abstract

Silica nanocapsules (SiNC) have gained considerable interest in their application as adsorbents due to its excellent physical structure and surface chemistry. The SiNC were synthesised via emulsion technique, whereby the effect of different solvents and calcination process were investigated. Diethyl ether as a solvent produced SiNC with the biggest surface area, 644 m2/g, followed by toluene and ethanol, 575 and 533 m2/g, respectively. The calcined SiNC had bigger surface area and pore volume, but smaller pore size as compared to their non-calcined counterparts. Diethyl ether and toluene as solvents produced SiNC with capsules or hollowed-core morphological structure, whereas by using ethanol, the SiNC was of solid core. The spectral analysis showed that the SiNC were of similar characteristics, whereby the ethanol-based SiNC had more intense hydroxyl (-OH) peaks and diethyl ether and toluene had an extra -CH3 peak. The carbon dioxide (CO2) adsorption measurement study showed that toluene-based SiNC performed the highest CO2 adsorption capacity (Q = 2.59 mmol/g), followed by diethyl ether-based (1.45 mmol/g) and ethanol-based, (1.28 mmol/g). The sufficiently competent CO2 adsorption capacity of the SiNC combined with their excellent physicochemical characteristics indicated their promising prospects for application as an adsorbent in CO2 adsorption.