CO2 KINETIC SORPTION RATE STUDY DEPENDING ON PRESSURE AND CONCENTRATION STEP

In this work, the sorption kinetics were studied for two selected samples with different shapes of isotherms up to a pressure of 1 bar (0.015 p/ps), at a temperature of 25 degrees C using a gravimetric sorption analyser. The CO2 kinetic sorption data was fitted by the unipore and linear driving force (LDF) models, which contain only one characteristic coefficient. Concerning the dependence of sorption rate constants,'different trends have been reported in literature and they both increase and decrease with pressure. These differences could be related to several factors including the choice of model, experimental conditions or the adsorbent used. In our study, the sorption rate decreases for one sample and slightly increases for the other as the system pressure increases. The results show that the sorption rate is dependent upon the type of isotherm. However, the sorption rate is not dependent only on the pressure but it also depends on the additional sorption of the adsorbate by the adsorbent which is introduced during the pressure step.. Therefore, comparison of the results obtained at constant pressure steps and the results obtained by setting the pressure steps in a way that the sorbed amount is constant during each sorption step was done.