Separation of cationic methylene blue dye from its aqueous solution by S-sulfonated wool keratin-based sustainable electrospun nanofibrous membrane biosorbent

The use of electrospun nanofibrous membranes for the treatment of dyehouse effluent is drawing attention because of their high surface area, and dye adsorption capability. In this work, nanofibrous membranes of S-sulfonated wool keratin protein/poly(vinyl alcohol) or PVA were prepared by electrospinning, and their effectiveness as an adsorbent for the removal of cationic methylene blue (MB) dye was studied. The electrospun nanofibers fabricated from keratin/PVA had a considerably finer average diameter (79.0 nm) compared to the average diameter (255.4 nm) exhibited by nanofibers produced from PVA alone. The optimal adsorption capacity was attained at a pH value close to neutral at ambient temperature (238.7 mg g-1), and the pseudo-second-order model was determined to be a reliable fit for the experimental data. Based on the fitted Langmuir model and MB adsorption data, the adsorption mechanism followed a monolayer pattern on the surface of the membrane. The MB dye adsorption capacity was slightly influenced by the presence of sodium chloride. The study demonstrated that the PVA/keratin nanofibrous membrane exhibited good reusability as only a small loss in absorption capacity was observed after three recycling and reuses. The developed biosorbent could be suitable for the high removal of dyes from textile dyehouse effluent.