Self-assembled sandwich-like SA–GO/PAN membranes with high-performance for pervaporative desalination of salt solutions

In this work, we proposed a self-assembly method to fabricate a novel pervaporative membrane for desalination. The graphene oxide (GO) layer was deposited on polyacrylonitrile (PAN) ultrafiltration membrane support by vacuum assistance, and then a thin cross-linked sodium alginate (SA) layer was coated on the GO/PAN membrane surface to form a sandwich-like SA–GO/PAN composite membrane. The morphology and physicochemical structure of the composite membrane were characterized using attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), scanning electronic microscopy (SEM), and atomic force microscopy (AFM) techniques and contact angle measurement. The thin SA layer would stabilize and protect the structure of GO layer of SA–GO/PAN membrane, thus GO layer was not easy to fall off or crack during pervaporation desalination. The effects of SA coating concentration, feed temperature, salt concentration, and multicomponent salt solutions on the desalination performance of the prepared membrane were investigated. SA–GO/PAN membrane showed a good desalination performance for high salt concentration solutions and multicomponent salt solutions. When the feed temperature raised from 30 to 80 °C, the flux of the SA–GO/PAN composite membrane increased from 5.61 to 18.35 kg m⁻² h⁻¹, while the rejection still remained above 99.8%. The experimental results showed that SA–GO/PAN composite membrane performed well in pervaporative desalination of salt solution with excellent long-term stability.