Influence of downstream pressure on pervaporation properties of PDMS and POMS based membranes

Properties of one POMS and two PDMS based (Pervatech, Pervap 4060) membranes in recovery of various organic components (acetone, butanol, ethanol, ethyl acetate) from aqueous binary mixtures (4 wt.% of organics) were determined during pervaporation at various permeate pressures (1–25 mbar). Performances of membranes were compared, finding that Pervap 4060 is the most effective membrane in all systems tested, whereas Pervatech is the least effective. Permeances of organics and water increased with an increase of pressure on the permeate side in the most of the tested binary aqueous mixtures. Selectivity of the tested membranes towards organics was improved by increase of permeate pressure. Comparing the effectiveness of membranes, it was found that it is related to the hydrophobicity of membranes expressed by surface free energy (SFE) parameter. SFE changes in the following order: Pervap 4060 > POMS > Pervatech. Membrane performances also follow this order during pervaporation.