Separation of higher molecular weight organic compounds by pervaporation

Two-liquid phase bioconversions can be used to produce medium and long-chain 1-alkanols from the corresponding n-alkanes. A pervaporation process has been investigated for the separation of the product accumulated in the apolar phase of such a two-liquid fermentation system. The separation characteristics of various dense membranes towards organic mixtures (octane/1-octanol) were determined. The performance of eighteen membranes in separating 1-octanol from a large excess of octane has been tested. The different membranes showed either reasonably high selectivity (alpha) and low permeation rates or low selectivities and high fluxes. Minimal requirements of the pervaporation process for a desired selectivity with one and multistage pervaporations are presented. The results indicate that it should be possible to separate economically interesting organic products from higher molecular weight organic mixtures, by tailoring suitable membranes with a reasonably good selectivity and high flux for single or for multistage pervaporation systems. (C) 1997 Elsevier Science S.A.