Sustainable Superheated Water Hydrolysis of Black Soldier Fly Exuviae for Chitin Extraction and Use of the Obtained Chitosan in the Textile Field

Interest in insects as waste biomass bioconverters and their use as valuable resources for fat, proteins, and chitin has increased considerably in the last few years. In this study, proteins were extracted from defatted black soldier fly (BSF) (Hermetia illucens) exuviae by green hydrolysis using superheated water at 150 °C for 20 h, and the remaining chitin was deacetylated into chitosan and used as a finishing agent for polyester fabrics. A total amount of 7% fat, 40% proteins, and 20% chitin was obtained from BSF exuviae. Different hydrolysis times ranging from 1 to 20 h were tried until the complete purification of chitin. The purity of chitin and the obtained chitosan after deacetylation was assessed by Fourier transform infrared spectroscopy and thermal analysis. A preliminary study was successfully carried out to use the obtained chitosan as a finishing agent for polyester pretreated fabrics using citric acid as a grafting agent. The presence of chitosan on the fabric was verified by scanning electron microscopy and by dyeing of the pretreated polyester fabric using a reactive dye with sulfonated groups that are able to be absorbed by electrostatic attraction because of the created cationic nature of the fiber surface treated by chitosan.