Preparation of ultrafiltration membranes of HCEC and CTA blend, and studies of resistance to microbiological degradation and other properties

Blends of high cyanoethylated cellulose (HCEC) (D s = 2.5) and cellulose triacetate (CTA) (D s = 2.8) were prepared for evaluation as ultrafiltration membranes. The rejection R a and water permeability ( P w) of these membranes with respect to bovine serum albumin (BSA), were measured with the variations in composition and conditions of preparation. It was possible to define the reaction conditions and compositions that offered optimum performance with respect to R a and J w, and resistance to microbial degradation as well as acid and alkali hydrolysis. The morphology of membrane thereby obtained was characterized by scanning electron microscopy (SEM). The UF membrane cast from a solution of 1,4-dioxane: 12.5 g, acetone: 12.5 g, HCEC: 1.5 g, CTA: 3 g and PEG (MW = 1000): 10.5 g showed the optimum performance of P w = 10 × 10 −10 m 3/(m 2 s Pa), BSA Rejection ( R a) = 99%, ( J w = 17.3 m 3/(m 2 day) at ΔP = 0.2 MPa) and a molecular weight cut off at 4.9 × 10 4 Da. After immersion in mud for 170 days, reduction of R a was only 8% for UF membrane containing 10 wt% HCEC blend, and was not observed to be obviously different from the membrane containing more than 30 wt% HCEC blend. The higher permeability and rejection of blend membrane may be attributable to the network structure formed via CTA and HCEC penetration.