Pervaporation Membranes from Natural Rubber Latex Grafted with Poly(2-hydroxyethyl methacrylate) (NR-g-PHEMA) for the Separation of Water-Acetone Mixtures

NR-graft-PHEMA latexes were synthesized by the use of graft emulsion polymerization. By increasing the HEMA monomer concentration, We found that the grafting percentage (GP) also increased. In addition, GP increased significantly at low initiator concentrations before it leveled off at moderate concentrations, and a slight decrease was observed at high initiator concentrations. NR-g-PHEMA latexes were prepared as pervaporation membranes for the separation of water-acetone mixtures. From the equilibrium swelling, the nonideal behavior of membrane swelling in water-acetone mixtures was found such that there appeared the maximum swelling degree at a certain concentration of liquid mixtures. Moreover, the water concentration at maximum Swelling shifted to high water concentration with increasing amount Of graft-PHEMA. The sorption study suggested the preferential sorption of water on the membranes. Also, the sorption isotherms implied that there was a coupling between water and acetone molecules. Pervaporation separation of water-acetone mixtures was Studied with NR-g-PHEMA membranes. As the feed water concentration increased, the partial water fluxes increased in contrast to the Partial fluxes of acetone. From the permeation ratio, theta(w), the strong coupling of acetone on the water transport was observed, Particularly for the membrane with high graft-PHEMA Under acetone-rich conditions. As the feed temperature increased, the total permeation across the membranes was enhanced. The partial fluxes of water and acetone as a function Of temperature followed the Arrhenius relationship by which the activation energies for permeation were estimated as 3.53 kJ/mol for water and 21.95 kJ/mol for acetone. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 113: 3313-3321, 2009