Functionalized chitosan electrospun nanofiber membranes for heavy-metal removal.

Abstract In order to improve the removal ability of chitosan (CS) to heavy metal ions, in this study, rich amino-functionalized CS electrospun membranes have been prepared. During the efficient synthesis, poly (glycidyl methacrylate) (PGMA) and polyethylenimine (PEI) were sequentially grafted on the surface of CS electrospun membrane. The success of introduction of amino-group on the CS were confirmed by X-ray diffractometer (XRD), attenuated total reflection-fourier transform infrared (ATR-FTIR), and X-ray photoelectron spectroscopy (XPS). The ability of remove heavy metal ions (Cr(VI), Cu(II) and Co(II)) of the as-prepared membrane (CS-PGMA-PEI) was investigated. The adsorption equilibrium of the heavy metal ion solutions was rapidly established in 60 min. Adsorption kinetics analysis reveals that the adsorption process of CS-PGMA-PEI electrospun membrane was dominated by a Pseudo-second-order model. Its adsorption isotherm can be described by the Langmuir model. The maximum adsorption capacities calculated by Langmuir model were 138.96, 69.27 and 68.31 mg g −1 for Cr(VI), Cu(II) and Co(II), respectively. The adsorption ability of CS-PGMA-PEI electrospun membrane toward metal ions was found in an order of Cr(VI) > Cu(II) > Co(II). CS-PGMA-PEI membrane also exhibited a good reproducibility and stability. Our study may provide a way to synthesize membranes for water purification. Graphical abstract The PEI-grafted CS (named as CS-PGMA-PEI) electrospun membrane was demonstrated by the following steps: (1). In order to expose the amino groups on the surface of the chitosan, the CS/PEO electrospun membrane was immersed in water to remove the PEO; (2). Poly (glycidyl methacrylate) (PGMA) and polyethylenimine (PEI) were sequentially grafted onto the CS electrospun membrane by a ring-opening reaction of epoxy groups with amino groups to obtain PEI-immobilized CS membrane; (3). A series of batch adsorption experiments were carried out to determine the adsorption performance. Image 1 Highlights • The PEI-grafted chitosan electrospun membrane has been prepared. • The adsorption ability of CS-PGMA-PEI electrospun membrane is in an order of Cr(VI) > Cu(II) > Co(II). • The CS-PGMA-PEI electrospun membrane exhibited good regenerability and stability for heavy-metal removal. [ABSTRACT FROM AUTHOR]