Evaluation of thermally crosslinkable chitosan-based nanofibrous mats for the removal of metal ions

• The thermally crosslinkable and thermally sensitive copolymer was synthesized.
• The chitosan-based composite nanofibrous mats were fabricated via electrospinning.
• The incorporation of a thermo-responsive polymer improved the desorption of Cu(II).

Environmentally sensitive composite nanofibrous mats capable of metal ion adsorption were successfully prepared via electrospinning. The composite nanofibers were fabricated with different ratios of chitosan to thermo-responsive polymer, poly(N-isopropylacrylamide-co-N-methylolacrylamide) (poly(NIPAAm-co-NMA), PNN). NMA provided the function of thermal crosslinking of the nanofibrous mats to form water-stable nanofibers in aqueous solution. Subsequently, glutaraldehyde was used as a secondary crosslinking agent to increase the gel fraction of the nanofibrous mats. The morphology changes of the nanofibers in different environments were studied. Comparing the nanofibrous mats and films of the same material, the fibrous mats showed significantly increased adsorption of Cu(II). The adsorption amount of Cu(II) on the chitosan/PNN (50/50) nanofibrous mats could reach 79 ± 2 mg/g-mats, and its desorption was relatively effective. The incorporation of poly(NIPAAm-co-NMA) significantly improved the desorption of Cu(II) from the nanofibrous mats. The chitosan/PNN fibrous mats maintained the capacity of Cu(II) adsorption for 4-time regeneration.