Cellulose Acetate Membrane with Improved Perm-selectivity through Modification Dope Composition and Solvent Evaporation for Water Softening

Abstract

Membrane technology has been developed because applicated on several fields. Hence, in this study carried the production of cellulose acetate nano-filtration membranes for water softening. The main objective of this study was determined the effect of solvent evaporation time and the effect of adding PEG to the morphology and perm-selectivity of asymmetry membrane for water treatment. Membranes prepared by dry/wet phase inversion method with variation of solvent evaporation time of 10-15 sec and addition of 2.5-5 wt% PEG in the dope solution. Membrane characterization consists of calculation of membrane flux and rejection with brackish water as a feed, SEM and FTIR analysis. The research concluded that asymmetric cellulose acetate membrane can be made by dry/wet phase inversion method. The results of FTIR analysis showed the larger absorption peaks indicates that the increasing concentrations of PEG addition make the PEG molecular weight and the unit re-CH2-CH2O-greater. The results of SEM analysis exhibited that all the membranes are formed has an asymmetric structure consisting of a thin fine porous structure selective barrier and sub-structure of the porous layer is thicker. Moreover, the addition of PEG, the larger pore of membrane will be formed. Performance optimum membrane was obtained on the composition of 23 wt% cellulose acetate, polyethylene-glycol 5 wt%, 72 wt% acetone and 1 wt% of distilled water in the solvent evaporation time of 25 sec and temperature coagulant at room temperature. Characterization of the optimum membrane were flux 22.33 L/m2/h/bar, 92% rejection for turbidity, rejection for dissolved solids 85 and 81% rejection for ions Ca2+, with modulus young around 12433 N/cm2, respectively.