Electrospun functionalized polyacrylonitrile–chitosan Bi-layer membranes for water filtration applications
Water scarcity has become a global systemic risk, prompting the development of more efficient filtration technologies. Recently, increasing attention has been given to low cost membrane materials such as polyacrylonitrile (PAN) nanofibers for water filtration. In this study, electrospun PAN nanofibrous membranes were functionalized with zinc oxide (ZnO) nanoparticles and coated with a layer of electrospun chitosan (Cs), in order to improve the mechanical properties, and anti-bacterial and water filtration performance of the membranes. Morphological analysis revealed that the PAN/ZnO–Cs membranes featured a structural hierarchy comprising a layer of highly porous nanofibrous PAN membranes and a less fibrous and thinner layer of a Cs coating. Addition of the Cs layer increases the tensile strength and elastic modulus of the membranes. Results acquired from a water permeability test indicated that the bi-layer membranes possessed adequate transport properties for typical membrane applications. Furthermore, the additional Cs layer and ZnO nanoparticles significantly improved the heavy metal ion adsorption performance of the PAN membranes. Moreover, the efficiency of the PAN/ZnO–Cs membrane for bacteria filtration has a log reduction value 2 orders of magnitude higher than PAN membranes, while the efficiency of these membranes for antibacterial action (i.e. in terms of log reduction value) is 6 orders of magnitude higher than PAN membranes. These results indicate the PAN/ZnO–Cs membranes are structurally more stable than PAN membranes, better at bacteria removal during the filtration process and better at self-cleaning (i.e. membrane biofouling resistance) than PAN membranes, signifying the potential of these membranes for water filtration applications.