Mathematical modeling of chloroform adsorption onto fixed-bed columns of highly siliceous granular zeolites



Adsorption of chloroform to granular ZSM-5 zeolite in fixed-bed columns was measured and the breakthrough curves predicted with a film-pore and surface diffusion (FPSD) model. Parameters for the FPSD model were estimated from published correlations and from data taken from batch adsorption rate studies. It was found that the adsorption rate was enhanced with decrease in particle size, however, the total adsorption capacity using granular ZSM-5 with different particle sizes remained constant. The FPSD model accounted for the effects of axial dispersion, external film transfer resistance, and intraparticle mass transfer resistances. Generally, good agreement between the simulated results and the experimental data was obtained. Furthermore, a sensitivity analysis was carried out to investigate the relative impact of kinetic parameters on the FPSD model predicted breakthrough profiles and showed that the model calculations were insensitive to either the effective pore diffusivity coefficient (Dp,e) or the axial dispersion coefficient (Ez), but were sensitive to the external mass transfer coefficient (kf). The large impact of kf on the results and the relatively low Biot numbers determined by the FPSD model indicated that under the experimental conditions employed in the study, film diffusion was the primary controlling mass transfer mechanism. © 2011 American Institute of Chemical Engineers Environ Prog, 2011