A study on the kinetics of ethanol-activated carbon fiber: Theory and experiments

An experimental and theoretical study has been conducted on the adsorption kinetics of ethanol onto a pitch-based activated carbon fiber (ACF) of type (A-20). Experiments have been carried out across assorted adsorption temperatures that are useful to the operation of adsorption chillers. The kinetic curve for each isotherm is measured accurately using a thermal-gravimetric analyzer (TGA) from which the diffusion time constant and consequently, the overall mass transfer coefficient could be evaluated. A novel concentration profile, with an exponent parameter k, has been proposed in the theoretical model which accounts for the effect of meso- and micro-pore structures within the ACF. The proposed concentration profile removes the restrictions between the overall mass transfer coefficient and the diffusion time constant. Using the measured kinetics, the numerical value of k is evaluated, leading to a new form of the linear driving force (LDF) model for cylindrical adsorbent that could capture the higher ethanol uptake in ACF and this LDF model has been validated experimentally.