CONICET | Buscador de Institutos y Recursos Humanos

In this work, we report about cellulose acetate (CA) ultrafiltration (UF) and nanofiltration (NF) membrane preparation according to the phase inversion process and post-treatment (annealing). The effect of tempo of evaporation (0 and 90 seconds) and annealing temperature (75 to 88 ºC) on the morphology of the synthesized membranes were investigated. The morphology and structure of the resulting membranes were observed by scanning electron microscope (SEM). The permeation performances of the membranes were evaluated in terms of pure water flux (PWF),equilibrium water content (EWC), hydraulic permeability, and salts rejection rate (R) NaCl and Na2SO4.Using cross-sectional images obtained by SEM, we observed that the membranes have an asymmetric structure, a decrease in the size of the macro-pores in sub-cape and pore size with increasing evaporation time. In all cases, the increasing evaporation time produces a decrease in the thickness of the membrane, the equilibrium water content and porosity.The effect of annealing on the membrane performance was investigated by changing the annealing temperature in distillation water. The annealing had great influence on reducing pore size of membrane (Wang, 1994; Kim, 2002). In hydraulic permeability tests during the compaction stage there was a decrease in permeate flux with increasing temperature post-treatment. A linear correlation between the permeate flux and operating pressure was also observed. The salt rejection rate increased sharply in the membranes synthesized with longer evaporation times. On the other hand, the increase in annealing temperatures increases the percent rejection of salts and reduces the pure water and salts fluxes. This study showed that evaporation time and annealing temperature have significant effects on morphology and permeation flux.