Novel sodium alginate composite membranes incorporated with SBA-15 molecular sieves for the pervaporation dehydration of aqueous mixtures of isopropanol and 1,4-dioxane at 30°C

Composite membranes of sodium alginate (NaAlg) prepared by solution casting method after incorporating with SBA-15 and FeSBA-15 molecular sieves have been crosslinked with glutaraldehyde. These membranes have been tested for the pervaporation (PV) dehydration of isopropanol and 1,4-dioxane from their aqueous solutions at ambient temperature (30 degrees C) to judge their performance capabilities over that of the pristine NaAlg membrane. Infinite selectivity values with moderate fluxes have been observed for the composite membranes in the investigated feed compositions of 10-20 wt.% of water. A complete removal (100 wt.%) of water has been possible on the permeate side with a slight compromise in flux values. For the range of feed water compositions investigated, fluxes of the composite membranes have been slightly lower than the pristine NaAlg membrane. Pristine NaAlg could remove up to a maximum of 97 wt.% of water at higher feed water concentrations with considerably much lower values of selectivity. Dual pore system of SBA-15, having both hydrophilic micropores and hydrophobic mesopores, in addition to its molecular sieving effect as well as its interaction with the NaAlg matrix might have been responsible for an increased performance of the composite membranes. The results of this study would serve as a useful guideline to recommend the possible applications of these membranes for large-scale commercial exploitation. (c) 2005 Elsevier Inc. All rights reserved.