A bi-layer nanofiltration membrane was created by applying a chitosan nanocomposite layer containing graphene oxide/polyaniline nanoplates onto a polyethersulfone (PES) base substrate. The solution casting method produced the PES-based membranes through the phase inversion technique. The chitosan nanocomposite layer containing different amounts of graphene oxide/polyaniline nanoplates was then introduced onto the PES membrane through a dip-coating method crosslinked by ethylene glycol. An investigation was conducted to examine the impact of the nanocomposite layer that was created on the physico-chemical properties and separation performance of the membranes. The membranes were characterized using scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray energy-dispersive spectroscopy, three-dimensional surface imaging, contact angle measurements, porosity and water content analysis, water permeability, sodium sulfate salt rejection, and methylene blue rejection. The water flux was increased from 4.6 L/m2.h for PES based membrane to 8.29 L/m2.h for the bi-layer modified membrane. The bi-layer membranes also exhibited a significant improvement in surface wettability. Surface morphology also changed from a rough surface to a smoother surface due to the surface modification. The sodium sulfate salt and methylene blue rejection were increased from 46.5% and 19.3% in the base PES membrane up to 67% and 61.3% for the double-layer nanofiltration membranes, respectively.
