Modeling of liquid/liquid separation by pervaporation: Toluene from water

The resistances-in-series model, the modified solution-diffusion model, the Flory-Rehner theory, and the film theory were used to calculate the diffus ion coefficients of two components of a liquid-feed mixture that are separa ted by pervaporation. The toluene and water fluxes through EPDM membranes o f various thicknesses were modeled for different mass-transfer coefficients in the feed boundary layer (k(L)). Ir is shown that the toluene flux depen ds strongly on the k(L) and the membrane resistance affects significantly t he toluene flux only for very high values of k(L) ( > 10(-4) m/s). The wate r flux increases linearly with the reciprocal value of the membrane thickne ss and is not affected by the boundary-layer resistance. The small increase in the water flux, due to the toluene concentration increase in the feed c an adequately be described by this model.