CARBOHYDRATE POLYMERS

Acesso restrito: Texto completo. p. 954-961Asymmetric membranes may be used in a broad range of applications such as reverse osmosis, hemodialysis and separation of organic mixtures. In this paper, asymmetric membranes were produced using cellulose acetate (CA) from biomass: newspaper and mango seed. The degree of substitution of CA was 2.65 ± 0.07. Different formulations were used to prepare the CA membranes: CA/dichloromethane/water with and without magnesium perchlorate. The asymmetry of the membranes was characterized by scanning electron microscopy (SEM). Membranes produced with magnesium perchlorate presented higher water vapor flux than those produced without this salt. This difference is due to pore formation in the membrane skin when using magnesium perchlorate. Membrane substructure showed to be a determining factor in ion diffusion experiments. The coefficient of ion diffusion for the membrane of cellulose acetate from mango seed was 1.82 10 8 cm2 s 1 while for the membrane of cellulose acetate from newspaper was 7.43 10 8 cm2 s 1 which similar to the value reported in the literature for commercial CA (8.46 10 8 cm2 s 1)