ETHANOL WATER TRANSPORT THROUGH SILICALITE MEMBRANES/

Transport mechanism of ethanol/water mixtures by pervaporation and vap or permeation through silicalite membrane was investigated. The activi ties of both ethanol and water in feed were controlled independently b y vapor permeation to study the feed composition effects quantitativel y. Also, adsorption experiments of single component and binary mixture s were carried out to measure the adsorbed mixture composition in the silicalite membrane. Ethanol permeance was independent of water concen tration in feed. Water permeance, however, seriously decreased by the presence of ethanol in feed, and water permeation was restricted by et hanol The adsorption-diffusion model was considered for the transport mechanism through the silicalite membrane. Ethanol selectively adsorbe d to silicalite membrane from ethanol/water vapor. The diffusion coeff icients of water and ethanol were calculated based on the adsorption-d iffusion model, and the results showed almost the same diffusivity bet ween the single component and mixture feed case. Thus, high ethanol se lective permeation through the silicalite membrane was explained by th e ethanol selective adsorption to the silicalite membrane. (C) 1998 El sevier Science B.V.