Nanostructure adsorbents namely nanofibers have been demonstrated to have a high adsorption rate and are efficient to treat wastewater. Herein, chitosan/poly(vinyl alcohol) (PVA) blend nanofiber membranes prepared by electrospinning method were crosslinked using glutaraldehyde and functionalized with 1-allyl-3-methylimidazolium chloride to be used as a potential bio-sorbent for heavy metal ions removal. The chitosan was first hydrolyzed before electrospinning with PVA, followed by crosslinking and further functionalized by ionic liquid to overcome the limitation of chitosan which has low adsorption capacity and unsuitable physical properties for the adsorption process. The morphology and the chemical bond formed were investigated by using field emission scanning electron microscopy with energy dispersive x-ray spectroscopy (FESEM-EDX) and Fourier transform infrared (FTIR) showing that the hydrolyzed chitosan/PVA nanofiber membranes were successfully crosslinked and functionalized. The synthesized adsorbent was evaluated in pure heavy metal ions solutions namely Pb(II), Mn(II), and Cu(II) and shown best performance for Pb(II) ions. The highest adsorption capacity recorded for Pb(II) ions was 166.34 mg/g and are well fitted to the Freundlich isotherm model and pseudo-second-order kinetic model to describe the adsorption equilibrium and kinetic rate of the Pb(II) uptake, respectively. The synthesized adsorbent clearly shows a great capability to remove Pb(II) ions. © 2021 Elsevier B.V.