Characterization of cellobiohydrolase activities of selected commercial cellulase formulations for improved cotton/polyester separation in textile recycling

Textile recycling is essential in today's world. Currently, less than 1% of textile waste is being recycled into new clothing. Fiber-to-fiber recycling is the most sustainable way to create new value from textile waste. The ReSTex (Recovery Strategies for Textiles) project at Josef-Ressel-Zentrum is developing environmentally friendly technologies to recycle mixed cotton and polyester fabric by selectively separating the fractions using cellulases. The purified PET can be processed into high-quality granulate, and the glucose into bioethanol. In this project different cellulase-based enzyme formulations from various manufacturers are characterized for their suitability in this process by determining their cellobiohydrolase activity.
For degradation of cellulose, the β-1,4-glycosidic bonds of are hydrolysed by cellulase. This requires a synergistic action of three enzyme activities: endoglucanase, cellobiohydrolase and ß-glucosidase, which are all present in the characterized enzyme formulations. Cellobiohydrolases act as exoglucanases and release cellobiose from the reducing and non-reducing ends of the cellulose chains. In this work, the cellobiohydrolase activity is characterised by the release of reducing sugars using the substrate Avicel®PH-101, which has a microcrystalline cellulose structure. By comparison of the results of the reaction rate of the tested enzyme formulations, we will evaluate which one is the most efficient for degradation of cellulose and, therefore, the separation of polyester and cotton fibers in the treated textiles.