Thermodynamic analysis of the effect of rotation on gas adsorption

Abstract

Abstract This study examines the effect of a short term rotation on a system of constant volume. Adsorption of CO2 is performed on Activated Carbon (AC) at 281, 293 and 298 K with a special designed device that allows rotation. The adsorption isotherms were conducted up to 10 bar for both No Rotational (NoROT) and Rotational (ROT) cases. The ROT case refers to 60 s of rotation at 5000 rpm. The experimental results were fitted to Langmuir as well as to Dubinin–Astakhov (D–A) models with the latter presenting the best fit. A detailed thermodynamic analysis is performed in order to quantify the overall contribution of the rotation on gas adsorption compared to static case. For the ROT case, the maximum amount adsorbed (q max) is by 12 % higher than the NoROT counterpart, while a decrease in chemical potential as surface loading is increased, indicates that the process after rotation is entropy driven. The outcome of this work suggests that rotation enables gas molecules to access previously inaccessible sites, thus gaining more vacancies due to better rearrangement of the adsorbed CO2 molecules.