Removal of aromatics from multicomponent organic mixtures by pervaporation using polyurethane membranes: experimental and modeling

Polyurethane (PU) dense membranes were used in the separation of binary and multicomponent aromatic/aliphatic mixtures by pervaporation. The PU membranes found to be selective towards aromatics in all systems studied. Both, swelling of polymer matrix and the permeate flux increase with aromatic weight fraction in the feed. The highest selectivity was achieved with benzene/n-hexane mixture in the whole feed composition range. The permeation of the organics through the PU membrane was modeled based on the sorption–diffusion mechanism. The sorption equilibrium was calculated using Flory–Huggins (FH) or UNIQUAC equations and Stefan–Maxwell (SM) equations were used to describe the transport inside the membrane matrix. A correction was introduced in the diffusion coefficients of the permeating species to take into account the polymer matrix plasticization. The experimental and predict data showed a good agreement, indicating that the PU membrane are useful to reduce the aromatic content of industrial solvent by pervaporation process.