Development of multifunctional nano/ultrafiltration membrane based on a chitosan thin film on alginate electrospun nanofibres

The aim of this study was to develop a high flux three-tier composite membrane composed of a coating layer based on chitosan and chitosan with silver nanoparticles, electrospun alginate nanofibres as a midlayer and nonwoven as a mechanical support substrate. The nanofibres were prepared by electrospinning of alginate with the aid of synthetic electrospinnable polyethylene oxide (PEO), and ionically crosslinked with calcium chloride followed by chemical crosslinking using glutaraldehyde. The silver nanoparticles were synthesized using a chitosan solution and thermal treatment. The silver nanoparticles were found to be well dispersed on the coating layer, which improved the antibacterial activity of the membrane against both Gram negative and Gram positive bacteria. The chitosan and silver nanoparticles containing chitosan coated membrane displayed similar flux and a high rejection of nanoparticles (>98%) and oil (>93%). Both membranes showed a higher flux rate and oil rejection than the commercial membrane. The presence of silver nanoparticles improved the dye rejection, reaching more than 95% rejection throughout the five filtration cycles test. These observations show that the incorporation of silver nanoparticles can enhance the antibacterial activity of the membrane with a promising potential in the field of dye removal and oil separation.