Abstract
<jats:p>The Josef Ressel Center “ReSTex – Recovery Strategies for Textiles” addresses one of the central issues on the way to more sustainable societies and bioeconomies: the recycling of textiles. The focus lies on the utilization and recycling of cellulosic textiles as well as on the separation of cellulosic blends, such as cotton/ polyester, the so-called “polycotton”. The Ressel Centre is funded by the Christian Doppler Research Association (CDG) and is located at the University of Applied Sciences Wiener Neustadt, Biotech Campus Tulln. It tackles the scientific challenges of the topic together with its scientific partners, two institutes at the University of Natural Resources (BOKU University) and one at TU Wien, Vienna, and three partner companies: Salesianer Miettex GmbH, a textile rental company, provides clean and sorted starting material of known composition. Starlinger & Co Gesellschaft m.b.H. and EREMA GmbH provide PET recycling machines and seek to optimize their processes for fibrous material and expand their portfolio to textile recycling machinery. Two general recycling routes will be explored: first, biotechnological cellulose hydrolysis by biotechnological methods converts cellulose to fermentable carbohydrates while purifying the PET fraction from polycotton blends. Second, the selective dissolution of cellulosic blended textiles aims at separating the cotton and PET fractions in polymeric form without extensive degradation. Initial work phases address the screening and characterization of starting textile blends, as well as evaluation of requirements for recycling. A database of spectral analysis data is established and processed by AI and machine learning tools. Several pre-treatment methods and special solvents for separation of cotton-rich articles are tested. The enzymatic hydrolysis of cotton involves mechanical pre-treatment of cotton/PET blends, chemical activation procedures, and evaluation of conditions for enzymatic action, as well as the screening of commercially available enzyme formulations. Follow-up work optimizes the solvents/solvent systems towards improved selectivity, suitable conditions for minimal impact on polymer integrity in case of high cotton fractions. Cellulose residues remaining in the PET fraction, which negatively influence the extrusion process are addressed by two different methods: elimination by selective dissolution and by stabilization of cellulose for the extrusion process. In later phases, process engineering will allow scale-up of the processes to pilot scale. All developments will be accompanied by economic and ecological considerations, including life cycle analysis. This contribution provides an overview of the structure and objectives of the initial work phases on enzymatic hydrolysis, including mechanical pre-treatment of cotton/ PET blends, chemical activation, and optimization of enzymatic conditions.</jats:p>