Pervaporation Separation of Water/2-Propanol Mixtures by Use of the Blend Membranes of Sodium Alginate and (Hydroxyethyl)cellulose: Roles of Permeate−Membrane Interactions, Zeolite Filling, and Membrane Swelling

In an effort to improve membrane performance of pristine sodium alginate (NaAlg) for 2-propanol dehydration, blend membranes of NaAlg with (hydroxyethyl)cellulose (HEC) (5, 10, and 20 mass %) were prepared. Membranes were prepared by solution casting and cross-linked by a two-stage process as confirmed by Fourier transform infrared spectroscopy. The blend membrane of NaAlg with 10 mass % HEC gave the highest selectivity of 63 000 for 5 mass % water in feed mixture (highest selectivity achieved so far in the literature) by removing 99.97% of water, giving a flux of 0.04 kg/m2·h. Incorporation of ZSM-5(40) zeolite in the blend membrane increased flux without affecting selectivity. Swelling results are used to study the membrane−solvent interactions. Sorption and diffusion selectivity values were computed from experimental data, which were comparable with the theoretically calculated values obtained from thermodynamic treatment based on Flory−Huggins theory.