Adsorption Equilibria of Propyl Acetate on Activated Carbon Under Supercritical CO₂ Conditions

The regeneration of spent activated carbon used to adsorb alkyl acetates, which are the main volatile organic compounds (VOCs) used in the printing industry, is important because of numerous economic and environmental factors. Regeneration by supercritical CO2 (scCO2) avoids the high temperatures associated with the commonly used thermal regeneration method, which may damage the activated carbon. However, previous studies cover only a limited range of operating conditions, and more extensive research is required for better understanding the scCO2 process. In this study, the adsorption equilibria of propyl acetate on activated carbon in scCO2 were investigated using the fixed-bed adsorption method at 313 K–353 K and 10 MPa–20 MPa. Our results agree with previous reports of other VOCs on the effect of temperature and pressure on adsorption equilibria. Furthermore, the Dubinin–Astakhov (DA) equation is used to correlate the measured data with an average relative deviation of 5.6%. Evidently, the adsorbed amounts of propyl acetate are higher than those of ethyl acetate but lower than those of butyl acetate, which can be attributed to their different volatilities in scCO2 and different affinities for the used adsorbent.