Polymer Composite CNT/Chitosan Nanofiltration Membranes for Water Desalination

Abstract

Rapid population growth and industrialization throughout the world are creating a serious problem of access to clean drinking water. This makes the search for water treatment solutions effective and efficient. Removal of salt from contaminated water remains a significant challenge. In consideration of above, present study aims to develop nanofiltration polyethersulfone membranes using the phase inversion technique by incorporating novel combination of chitosan and carbon nanotubes to enhance salt rejection. The various membranes were fabricated including pristine PES membrane, PES membrane with chitosan (0.75 wt. %), with carbon nanotubes (0.1 wt. %) and CNT/chitosan composite in (0.1 wt. %) concentration composition. The membranes were further analyzed using attenuated total reflection–fourier-transform infrared spectroscopy (ATR-FTIR) for functional group analyses, scanning electron microscopy (SEM) for morphology and cross-sectional view of membranes, atomic-force microscopy (AFM) for surface roughness studies, water retention for water uptake analysis, mechanical testing for strength of membranes, and contact angle for water wettability. For membranes with the chitosan/carbon nanotubes composite, Scanning Electron Microscopy micrographs showed higher level of porous channels to render a better permeability potential, repeated by the flux rate results. Response surface methodology model was used to investigate the effect of feed temperature, feed concentration and feed pressure on flux and salt rejection. The salt rejection rates for the polymer CNT/chitosan were remarkable for Na2SO4 salt removal. The flux rate and salt rejection were also assessed for Na2SO4, and the results showed an increase from ±103 L/m2h to ±436 L/m2h for water flux and the salt rejection up to 95%. The increase in values of water uptake from ±54.39% to ±91.2% and decrease in contact angle from ±77.74° to ±61.26° showed an increase in the hydrophilic character of the membrane. The observed results are promising and provide an opportunity to treat water to remove contamination to improve the quality of drinking water.