Preparation of Cellulose Acetate Membranes for Ultra- Nano- Filtrations

Abstract

Cellulose acetate (CA) membranes were prepared from CA powder, formamide and acetone by phase inversion. Production conditions used included evaporation times of 20, 30 and 60 seconds, gelation temperature of 1 – 2 °C and annealing temperature of 70 and 75°C. The product membranes were coded CA620-70, CA630-70 CA660-70, CA620-75, CA630-75 and CA660-75 and were tested to have Molecular weight cutoff (MWCO) between 1500 and 10000 Da. The pure water flux tests classified the membranes CA620-70, CA630-70 CA660-70, CA620-75 as ultra-filtration type and CA630-75 and CA660-75 as nano-filtration membranes. Tannin was easily filtered with the rejection of 78 - 100 % for different membrane types and pressures. Rejection of protein BSA was successful at nearly 100 % rejection for all the product membranes. SEM micrographs showed an average pore longest axis of 0.066 ± 0.029 micron and pore densities of 1.95 – 3.02 pores/micron2. The membrane strength was tested to have the ultimate tensile strength of 1.64 – 2.82 N, Young’s modulus of 54.74 – 175.36 MPa and the percent elongation at failure of 15.57 – 23.00