Ionic-liquid-processed keratin-based biocomposite films with cellulose and chitin for sustainable dye removal

Abstract

Poultry is a widely consumed meat worldwide; however, its industrial processing generates a significant amount of feather waste. Since the major component of chicken feathers is keratin (90 wt. %), this study focused on using acetate-based ionic liquids (ILs) to fully dissolve chicken feathers and recover keratin, using a sustainable and cost-effective approach, ultimately allowing waste valorisation. The recovered keratin was processed into films, either pure or blended with cellulose and α-chitin, aiming to develop a structural polymer biocomposite with improved mechanical properties. Experimental parameters were evaluated using different blend ratios, altering the pH, and adding glycerol as a plasticiser. Physico-chemical analysis revealed that all films exhibited hydrophilic behaviour and are stable up to 160 °C. Furthermore, the tensile strength of the keratin-based films significantly increased by adding chitin (achieving up to 66 ± 1 MPa). Considering the growing significance of biopolymer-based films in wastewater treatment applications, the keratin-based films were evaluated as adsorbents for dye removal. Reactive Blue 4 (RB4) was used as a model dye, and the adsorbent dosage and pH of the dye solution were carefully investigated. The investigated films exhibited high dye uptake efficiency, achieving up to 98 % RB4 removal (initial dye concentration of 300 ppm). Additionally, the maximum adsorption capacity obtained (209 mg·g-1) for the keratin-chitin film emphasises the potential of this biomaterial in wastewater treatment.