Characterization of enzyme formulations for efficient recycling of cotton-polyester textiles

Abstract

Fast fashion and excessive consumption have made textile recycling an important topic today. Currently, less than one percent of textile waste is recycled into new clothing. The Josef Ressel Centre for Recovery Strategies for Textiles (ReSTex) at the the Biotech Campus Tulln aims to develop
new technologies for recycling mixed poly-cotton textiles. The goal is to selectively separate the cotton and PET fractions in their polymer forms without significant degradation, using enzymatic hydrolysis of cellulose.
The aim of this master thesis was to characterize different enzyme formulations from various manufacturers. For this purpose, the protein content, the reducing sugar concentration, and the activities of cellobiohydrolase (CBH) and β-glucosidase in these enzyme formulations were determined to identify the most suitable formulation for the ReSTex project. Additionally, an HPLC method for determining the soluble reducing sugar concentration in the bioreactor samples should be implemented as an alternative to the utilized neocuproine method.
The results from the enzyme activity assays showed that the total crude enzyme formulations achieve the highest enzyme activity for CBH and β-glucosidase. The disadvantage of total crude extracts is their elevated cellobiohydrolase activity, which results in the excessive release of glucose molecules, even though complete degradation of cellulose is not the intended goal in this project.
The endo-enriched cellulases are more suitable for recycling mixed polyester-cotton textiles due to their relatively high endoglucanase activity combined with low β-glucosidase activity.
The HPLC method can not be recommended due to a lack of correlation with the neocuproine method in this master thesis. Future studies should include additional soluble reducing sugars, like larger cellodextrins, into the HPLC analysis to enable a more accurate comparison between the
methods.
In this master thesis, 34 enzyme formulations could be characterized and tested in detail for their applicability in enzymatic textile recycling of polycotton.

Date of Award	2024
Original language	English
Supervisor	Christian B. Schimper (Supervisor) & Agnes Grünfelder (Supervisor)