Keratin functionalized electrospun PEI/PAN microfiltration system as a simple and sustainable approach for anionic dye removal

Keratin an underutilised biopolymer, with its composite structure, amino acid composition and amphoteric nature is a potential material for sorption/desorption of toxic pollutants. We hypothesized that post-fabrication functionalization of keratin over electrospun mats could solve the problem of incompatibility existing between membrane polymers and keratin, which is due to the limited dissolution capacity of keratin in solvent used for membrane preparation. Accordingly, the PEI (Polyethyleneimine)/PAN (Polyacrylonitrile) based system was fabricated in a simple and sustainable manner over which keratin was functionalized via electrostatic interaction (with PEI). The functionalized membranes were then studied for their capacity to reject a recalcitrant anionic dye, Alizarin Red S in a dead end filtration setup. The keratin functionalized over the surface significantly altered the functionality and permeability of membranes, thus resulting in an enhanced rejection capacity of 93.25% as compared to 70.18% of the unfunctionalized membrane. The synergistic effect of decreased surface roughness (physical characteristic) and electrostatic repulsion mechanism (chemical characteristic) of the system was responsible for the enhanced rejections. This study has become the first of its kind in utilizing an electrospun microfiltration membrane for dye removal via a filtration mechanism, where so far only adsorption based experiments were effective.