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Novel carbohydrate polymeric blend membranes in pervaporation dehydration of acetic acid

Krishna Rao, K.S.V., Naidu, B.V.K., Subha, M.C.S., Sairam, M., Mallikarjuna, N.N., Aminabahvi, T.M.
Carbohydrate polymers 2006 v.66 no.3 pp. 345-351
composite polymers, polymerization, new products, cellulosic materials, cellulose, acrylamides, alginates, acetic acid, swelling (materials), artificial membranes, differential scanning calorimetry, synthesis, wastewater treatment, separation, drying, Fourier transform infrared spectroscopy, pervaporation
Due to the widespread usage of carbohydrate polymers in a variety of areas, the present study is undertaken to develop novel graft copolymers of hydroxyethylcellulose and acrylamide (HEC-g-AAm). Grafting reaction was confirmed by Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). The graft copolymers were blended in different ratios with a natural polymer, sodium alginate (NaAlg). Using these polymers, membranes were prepared by solution casting and were crosslinked with glutaraldehyde for testing in pervaporation (PV) dehydration of acetic acid. Swelling experiments have been performed on the blend membranes at 30 °C to test their stability in water-acetic acid mixtures. The present membranes, being hydrophilic, were able to successfully recover 89% of water from acetic acid solutions when tested for feed mixtures ranging from 10% to 50% (w/w) of water. Membrane flux and selectivity to water was increased at increasing amount of HEC-g-AAm grafted copolymer in the mixed blend of NaAlg. The membranes of this study showed selectivity of 27.9 with a flux of 0.058 kg/m² h to dehydrate 10% (w/w) water from aqueous acetic acid feed mixture through the blend membrane. Flux values increased with increasing concentration of water in the feed, while selectivity decreased considerably. To the best of our knowledge, this is indeed the first example of the use of this type of combination carbohydrate polymers for pervaporation dehydration of acetic acid, which is a well-known industrial solvent.