Pervaporation of methyl–ethyl ketone and water mixture: Determination of concentration profile

Experimental studies were conducted to separate methyl–ethyl ketone (MEK) from water through pervaporation using poly di-methyl siloxane (PDMS) and poly (ether) block amide (PEBA) membranes. Experiments were carried out at different feed MEK concentrations (10, 15, and 20 wt.%), temperatures (40–60 °C), and downstream pressures (3–7.5 mm Hg), and their influences on flux and selectivity were observed. The selectivity of MEK–PDMS was found to be around 100 for 10 wt.% MEK–water solution at 40 °C with 3 mm Hg downstream pressure, whereas it was 13.5 for MEK-PEBA under the same conditions. However, PEBA membranes offered much higher fluxes. For the PEBA membrane, a flux of around 0.12 kg m− 2 h− 1 was typically observed under the same conditions, whereas this value was 0.06 kg m− 2 h− 1 for the PDMS membrane. The selectivity of MEK–PDMS was 7.4 times higher than that of MEK-PEBA, but in terms of flux, the PEBA membrane offered almost double the flux of the PDMS membrane.Concentration profiles across the PDMS membrane were determined based on an earlier published work (Mulder and Smolders, 1984). Concentration profiles were developed under the following two conditions: (i) apparent diffusion coefficients independent of concentration and (ii) doubling the apparent diffusion coefficients. Analysis of transport across membranes for an MEK-water mixture by pervaporation required efforts beyond the usual consideration of concentration-independent diffusion coefficients. Accordingly, concentration profiles across the membrane were obtained using the determined values of polymer–liquid and liquid–liquid interaction parameters.

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► Pervaporative separation of methyl-ethyl-ketone from water using PDMS/PEBA membranes.
► Selectivity of MEK-PDMS was 100 as compared to 13.5 for MEK-PEBA, under similar conditions.
► Higher sorption of MEK in the membrane phase indicate higher affinity for PDMS than for PEBA.
► Developed correlations predict flux and selectivity as functions of system variables.
► Even for concentration dependent diffusion coefficients, concentration profiles are linear.