Kinetics modeling of adsorption and desorption of benzaldehyde and benzyl alcohol on polymeric resin in supercritical CO2

In this work, a kinetics model was developed for the adsorption and desorption processes of benzaldehyde and benzyl alcohol on the polymeric resin adsorbent in supercritical carbon dioxide (scCO(2)). This kinetics model takes into account adsorption equilibrium, internal diffusion in porous medium, mass transfer between fluid-sold interfaces, and axial dispersion in supercritical fluid. The breakthrough curves measured in a fixed-bed have been fitted by this model under various operational conditions. This model uses the intraparticle diffusion coefficient as the fitting parameter and other transfer parameters can be calculated through current correlation equations. A satisfactory agreement between the modeling results and the experimental data has been obtained with just one fitting parameter. The effect of temperature, pressure, and concentration on the intraparticle diffusion coefficient has been investigated and the molecular pore diffusion within the solid adsorbent is found to be the rate-controlling step for the overall adsorption process. Moreover, the theoretical model has also been demonstrated to reasonably predict the desorption behavior for the two solutes in scCO(2). Our work presents an effective and concise theoretical framework for adsorption/desorption kinetics in scCO(2) fluid.