Electrospun Bilayer PAN/Chitosan Nanofiber Membranes Incorporated with Metal Oxide Nanoparticles for Heavy Metal Ion Adsorption

Bilayer nanofiber membranes with enhanced adsorption and mechanical properties were produced by combining a layer of polyacrylonitrile (PAN) functionalized with metal oxides (MO) of ZnO or TiO2 with a layer of chitosan (CS) via consecutive electrospinning. The adsorption properties of the bilayer PAN/MO–CS nanofiber membranes against lead (Pb(II)) and cadmium (Cd(II)) ions were investigated, including the effects of the solution pH, initial ion concentrations, and interaction time. The integration of a CS layer into PAN/MO nanofibers increased the adsorption capacity of lead by 102% and cadmium by 405%, compared to PAN/MO single layer. The nonlinear optimization method showed that the pseudo-second-order kinetic model and Langmuir isotherm equation better described the adsorption results. More importantly, the incorporation of a supportive CS nanofiber layer enhanced the tensile strength of PAN/MO–CS bilayer by approximately 68% compared to the PAN/MO single layer, owing to the strong interaction between the fibers at the interface of the two layers.