Pervaporation Separation of Ethyl Butyrate/Wate Mixture: Experimental and Mass Transfer Investigation

In this study pervaporation (PV) of ethyl butyrate (ETB)/water mixtures using synthesized poly (ether-block-amide) (PEBA) membranes was investigated. The membranes were made via solution casting on water surface (as non solvent). After studying the effects of different parameters on the membranes morphology, it was found that the mixture of (1 n-butanol/ 3 iso-propyl alcohol), temperature range from 70-800C and polymer concentration range from 4-7 wt could be used to obtain uniform membranes. PV separation of ETB/water mixtures was carried out using these membranes. The results showed that with increasing ETB concentration, both total permeation flux and ETB separation factor increase. Increasing temperature, in the studied limited range, resulted in decreasing separation factor and increasing permeation flux. With decreasing permeate pressure, permeation flux increased and separation factor decreased. Overall mass transfer coefficient was evaluated using steady state ETB permeation flux equation. Membrane mass transfer coefficient, boundary layer thickness and liquid boundary layer mass transfer coefficient were calculated using the modified concentration polarization equation and the resistance in series model. Concentration polarization index (using membrane and liquid boundary layer mass transfer coefficients) was defined and used to present extent of the concentration polarization phenomenon. The modified Arrhenius model was used to correlate ETB permeation flux and the operating temperature. Good agreement was observed between the experimental results and the model predictions. Results showed that the effect of temperature on sorption is greater than that on diffusion.