Ahmad Fausi Ismail, Abdul Rahman Hassan and Ng Be Cheer

pp. 879 - 889

Abstract

Asymmetric nanofiltration membranes were fabricated from a ternary dope composition consisting
of cellulose acetate (CA), formamide and acetone using a simple dry/wet phase inversion process. In order to
fabricate a high performance nanofiltration membrane, the effects of rheological factor of dope solutions,
that is shear rate on the performance of nanofiltration membranes for water desalination has been studied.
The membranes performances that are based on percentage of rejection of sodium chloride (NaCl) and fluxes
with different concentrations of sodium chloride are reported. Generally, the percentage of rejection and
fluxes were found to increase with increasing of shear rate until a critical level of shear rate is achieved.
The experimental results showed that the fluxes were increased and percentage of rejection is decreased
with sodium chloride concentrations. An optimum percentage of rejection and fluxes obtained were about
56.76% and 7.44 × 10^-4 m/s, respectively. The optimum shear rate was found to be at 304 s^-1. It was also found
that membranes with shear rate below 152s^-1 are not suitable to be used as a nanofiltration membrane due
to their low mechanical strength.

Keywords

• asymmetric membrane
• nanofiltration
• water desalination
• shear rate
• cellulose acetate
• fluxes and percentage of rejection