Incorporation of Al2O3 into cellulose triacetate membranes to enhance the performance of pervaporation for desalination of hypersaline solutions

Abstract

In this study, nanocomposite membranes were prepared by incorporating alumina (Al2O3) nanoparticles into cellulose triacetate (CTA) membranes in order to enhance the performance of pervaporative desalination. The resulting membranes were characterized by SEM, TGA, water contact angle, water uptake, tensile strength, and FTIR. The desalination performance was investigated as a function of Al2O3 loading, feed temperature (ranging from 40 to 70 °C) and feed concentration (varying from 0 g/L to 90 g/L NaCl). Pervaporation (PV) experiments showed that incorporating 2% Al2O3 into a CTA membrane increased the water flux by 204% compared to pristine CTA (from 2.2 kg m−2 h−1 to 6.7 kg m−2 h−1) for a 30 g/L NaCl feed solution at 70 °C, while the salt rejection remained above 99.8%. Moreover, when the CTA-2% Al2O3 nanocomposite membrane was tested with a 90 g/L feed solution, only 25% flux reduction without sacrificing the salt rejection. Furthermore, different feed concentration affected the activation energy of water molecules to diffuse through pristine CTA and CTA/Al2O3 nanocomposite membrane. However, the nanocomposite membrane has a lower apparent activation energy even at high NaCl concentrations, compared to the pristine CTA. This suggests that the developed CTA/Al2O3 nanocomposite membrane is suitable for desalting hypersaline water.