In a paper just published in Nature Communications, researchers at the Industrial Sustainable Chemistry group of the University of Amsterdam (UvA) present a solution to the challenging problem of recycling polycotton textile waste. The process, developed in cooperation with the company Avantium, starts with fully removing all cotton from the fabric using superconcentrated hydrochloric acid at room temperature. The cotton is converted into glucose, which can be used as a feedstock for biobased products such as renewable plastics. The remaining polyester fibres can be reprocessed using available polyester recycling methods.

The research was led by Prof. Gert-Jan Gruter, who heads the Industrial Sustainable Chemistry group at the UvA’s Van ‘t Hoff Institute for Molecular Sciences (HIMS) as a parttime professor. Gruter is Chief Technology Officer at Avantium where he leads the development of renewable and circular polymer materials and technologies that are key to transforming our fossil-based economy into a renewable, bio-based economy. “Being able to recover glucose from the cotton in textile waste is a crucial contribution to this, as glucose is a key bio-based feedstock. Currently, it is produced from starch from corn and wheat. If and when we will be producing plastics from biomass on a large scale, the world will need a lot of non-food glucose.”

Equally important, the process now presented in the Nature Communications paper provides a solution to the mammoth problem of recycling textile waste. According to Gruter, it is the first effective method for recycling both cotton and polyester components of polycotton with high efficiency. Gruter’s PhD student Nienke Leenders, first author of the paper, performed many tests under the four-year MiWaTex project that has been funded by the Dutch Research Council NWO and is now about halfway. The project entails cooperation with textile sorting and recycling company Wieland, workwear producer Groenendijk Bedrijfskleding, Modint, the trade association for the Dutch clothing and textile industry, and CuRe, developer of advanced technology for chemical recycling of polyester.

Scalability and cost-effectiveness
The Nature Communications paper describes how Leenders performed experiments using Avantium’s pilot plant for its proprietary Dawn Technology which was originally developed to convert non-food plant-based feedstock (e.g wood) into glucose and lignin. Its key feature is using highly concentrated hydrochloric acid (43% by weight) at room temperature. Leenders tested batches of actual post-consumer polycotton waste textiles in Avantium’s Dawn pilot plant. It turned out the cotton cellulose could be fully hydrolyzed into glucose under industrially relevant conditions. The polyester part of the fabric remained intact and could be easily separated. The trials demonstrated high glucose yields, indicating scalability and cost-effectiveness.

The cotton-derived glucose from the process can be used in a wide range of industrial applications, including polymers, resins and solvents. It can for example be used by Avantium to produce its lead product 2,5-furandicarboxylic acid (FDCA), a crucial component in the production of the biobased PEF polyester (polyethylene furanoate) that offers a renewable alternative to PET bottles.

The process also enables the complete recycling of polyester from polycotton. It can be chemically recycled to form new virgin polyester, as was established by tests performed by CuRe.

Favorable techno-economic analysis
According to Gruter, the research lays the foundation for actual industrial-scale recycling of polycotton textiles and the first commercial availability of non-food glucose. “Many parties are trying to get either of these things done but no one has succeeded yet. Our techno-economic analysis looks rather favourable and Avantium has already invested substantially in this development. Our ambition is to advance this technology to the next phase of commercialization, together with partners. So we might very well be the first to market non-food glucose obtained through a bio-refinery approach.”