Preparation of Hydroxylated Silica Gel Using Acetic Acid to Enhance CO2 Adsorption Performance
A hydroxylated silica gel adsorbent was prepared by acetic acid modification for CO2 static adsorption research to reveal the effects of acetic acid concentration and adsorption temperature on the ad-sorption performance of hydroxylated silica gel.By hy-droxylating silica gel with acetic acid,the pores of the silica gel can be cleaned and the surface hydroxyl groups can be exposed,improving the CO2 equilibrium adsorption capacity.Under the conditions of optimal acetic acid concentration of 6 mol/L,optimal adsorp-tion temperature of 20 ℃,and adsorption pressure of 0.62 MPa,the equilibrium adsorption capacity of ad-sorbent SG-C-6 can reach 35.88 mL/g,which is 14.3％higher than that of silica gel.The adsorbent SG-C-6 was selected for repeated use performance ex-periments.After 10 repeated uses,the equilibrium ad-sorption capacity still reached 34.44 mL/g,which was 4％lower than that of the first adsorption,indicating that it had good reusability.A molecular structure model of hydroxylated silica gel was constructed,revea-ling the hydroxylation mechanism of hydroxylated ad-sorbents at the atomic level.The results show that the adsorption energy of the hydroxylated adsorbent decrea-ses from-5.87 kJ/mol to-10.57 kJ/mol,and the lower adsorption energy indicates that the affinity of the hydroxylated adsorbent to CO2 is higher,which further proves the necessity of hydroxylation of silica gel with acetic acid.
CO2 adsorptionsilica gelhydrox-ylationpore structurereusability
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