SORPTIVE SEPARATION OF ETHANOL-WATER MIXTURES WITH A BI-DISPERSED HYDROPHOBIC MOLECULAR-SIEVE, SILICALITE - MEASUREMENT AND THEORETICAL-ANALYSIS OF COLUMN DYNAMICS

Separation of dilute ethanol-water mixtures in a fixed bed of bi-dispe rsed hydrophobic adsorbent, silicalite, is considered. The column dyna mics are well described with a differential model accounting for axial dispersion, external him mass transfer and intraparticle diffusion. D iffusion within the solid is firmly controlled by transport through th e liquid filled non-selective macropores giving access to the selectiv e micropores of the embedded hydrophobic crystals. A sensitivity analy sis indicates that, given the adsorption isotherm, all the mass transf er parameters can be estimated or predicted a priori. The model is ver ified against a small scale adsorption column making due allowance for the entrance and exit effects; such effects are frequently ignored bu t are shown here to be significant with small columns.