Received: 4 October 2021 Accepted: 17 December 2021
In this study, the solubilization of waste coarse wool as a precursory step for the large-scale valorization of keratin was investigated using a green deep eutectic solvent (DES) based on L-cysteine and lactic acid. The investigation was undertaken via the response surface methodology and based on the Box–Behnken design for four process variables of temperature (70–110 °C), dissolution time (2–10 h), the mass of L-cysteine (0.5–2.5 g) in 20 mL of lactic acid, and wool load in the DES (0.2–0.6 g). Temperature was the most significant process variable influencing keratin yield from the waste coarse wool. The optimum keratin yield (93.77 wt.%) was obtained at the temperature of 105 °C, 8 h dissolution time, with 1.6 g L-cysteine in 20 mL of lactic acid using 0.5 g of wool. This study suggests L-cysteine and lactic acid as a green solvent with the potential to scale up keratin recovery from waste wool without significant destruction in the structure of the recovered keratin.
Keywords: Deep eutectic solvent; Green keratin extraction; Optimization; Surface response methods; Waste valorization