Electrospun Chitosan Nanofiber Membrane for Adsorption of Cu(II) from Aqueous Solution: Fabrication, Characterization...

The preparation, characterization and application of chitosan (CS) based electrospun nanofiber membrane for the adsorptive removal of Cu(II) from water were systematically investigated. Homogeneous, porous polyvinyl alcohol (PVA)/CS nanofiber membrane with amorphous structure, and average fiber diameter of 49 nm was successfully fabricated. The adsorption of Cu(II) onto the positively charged PVA/CS nanofiber membrane (pH < 6) was due to chemisorption rather than electrostatic adherence, and was highly pH-dependent. The adsorption equilibrium of Cu(II) by the PVA/CS nanofiber was established within 120 min, which was much faster than that by CS beads, and the adsorption kinetics followed pseudo-second-order model well (r 2 > 0.995). The adsorption isotherm data were well fitted with Langmuir model, and the maximum Cu(II) adsorption capacity of PVA/CS nanofiber membrane was 90.3 mg·g-1, which was much higher than that of CS beads. The adsorbed Cu(II) formed strong inner-sphere complex with the adsorbent. Coexisting cations of iron, lead, cadmium, nickel, calcium, and magnesium have insignificant effect on the Cu(II) adsorption, indicating the adsorbent has good selectivity for Cu(II) adsorption. FTIR and XPS analysis reveal amine, hydroxyl and ether groups are responsible for the Cu(II) adsorption. This work demonstrates the electrospun PVA/CS nanofiber membrane is a promising adsorbent for heavy metal removals.