We studied different face velocity and carbon dioxide (CO₂) initial concentration to examine the adsorption behavior of calcium oxide (CaO) impregnated activated carbon (AC) filter and also to discuss pseudo-first-order, pseudo-second-order and intra-particle diffusion three kinetic models. The experimental results show that saturation time and saturation capacity were decreased and increased with higher inlet concentration at the same face velocity, respectively. Simulation results show that pseudo-second-order correlation coefficient (r₂² = 0.921) is higher than pseudo-first-order (r₁² = 0.7815) and intra-particle diffusion (r_i² = 0.905). Therefore, the adsorption process of CO₂ onto CaO impregnated AC filter media is appropriate for the pseudo-second-order kinetic model.

The adsorption of toluene onto commercially available coconut-based granular activated carbon (GAC) loaded within a piece of nonwoven fabric was investigated in a filter media at face velocities 0.076 through 0.152 m/s. The results showed that the adsorption capacity increases with increasing toluene concentration but decreases as the face velocity was increased. In order to investigate the adsorption mechanisms, three simplified kinetic models, i.e., the pseudo-first-order, second-order kinetic models, and intraparticle diffusion model were used to describe the kinetic data and the rate constants were calculated. The rate parameter, k _i, of intraparticle diffusion, the rate parameter, k ₂, of the pseudo-second-order and k ₁, the rate parameter for the pseudo-first-order mechanism were compared. It was found that the pseudo-first-order adsorption mechanism is predominant and the overall rate of the GAC adsorption process appears to be controlled by more than one step, namely both the external mass transfer and intraparticle diffusion mechanisms.