Nanostructured Membrane of Sodium Montmorillonite Reinforced Cellulose Acetate for Adsorption of Ca(II) and Mg(II) Ions in Hard Water

Abstract

Permanent hard water softening was conducted with the use of cellulose acetate (CA)/sodium montmorillonite (Na+-MMT) nanostructured membranes. Fabrication of the nanostructured membranes with various Na+-MMT loading (0%, 5%, 10%, 15%) was made possible by electrospinning technique, which was carried out at 25°C, 30 kV applied voltage, needle size of 25G and a tip to collector distance of 18 cm. The effect of Na+-MMT content on the morphology of the fiber was examined with the use of Scanning Electron Microscope (SEM). It was determined that increasing the Na+-MMT loading decreases the average fiber diameter. The molecular structure of the blend nanostructured membranes were investigated using Fourier Transform Infrared (FTIR) Spectroscopy and the existence of CA and Na+-MMT in the electrospun nanostructured membrane was confirmed. Better adsorption performance was observed for the blend with 15% Na+-MMT as compared to pure CA and maximum uptake rate was attained at 7 hours for pure CA and only 5 hours for CA/Na+-MMT (85%/15%) blend. Increasing the initial hard water concentration increases the driving force for diffusion and in turn increases adsorption capacity of both pure CA and the CA/Na+-MMT (85%/15%) blend. More so, the results of the experiment best fitted the pseudo-second order kinetic model and the Freundlich isotherm model. Integration of Na+-MMT in CA increases the surface area for adsorption of the nanostructured membrane, and thus, could be used as an effective adsorbent for hard water softening.