Comparison of powdered and colloidal SiO2 nanofillers in nanocomposite pervaporation desalination membranes

Abstract

In this work, cellulose triacetate/SiO2 nanocomposite pervaporation (PV) membranes were successfully fabricated in order to enhance the membrane performance for desalination. Two sources of SiO2 nanoparticles; powdered SiO2 and the colloidal silica solution (LUDOX AS40) were investigated. The fabricated PV nanocomposite membranes were characterized to study the membrane morphology by Scanning electron microscopy (SEM), the chemical composition by Fourier transform infrared (FTIR), and the surface hydrophilicity by water contact angle. SiO2 colloidal nanoparticles disperse more better compared to the SiO2 powder in the dope solution. Therefore, the SiO2-colloidal nanoparticles were even distributed on the membrane surface. Furthermore, membrane performance was investigated to treat the feed solution at 30 g L−1 of sodium chloride (NaCl) at operating temperature of 70 °C. Pervaporation (PV) experiments showed that incorporating 1% SiO2-powder nanoparticles into a CTA membrane improved the water flux by 123% compared to pristine CTA (from 2.16 kg m−2 h−1 to 4.82 kg m−2 h−1), while added 1% SO2-collodial nanoparticles increased the water flux by 257% (from 2.16 kg m−2 h−1 to 7.72 kg m−2 h−1), both of CTA/SiO2 nanocomposite membranes kept the salt rejection above 99 %. Additionally, the CTA/SiO2 colloidal nanocomposite membrane has a positive stability of PV desalination performance for 12 hours separation. Hence, the results suggests that the developed CTA/SiO2-colloidal nanocomposite PV membrane is the best for desalination.