Diving into commercial cellulase formulations for circular polyester/cotton separation through targeted...

Area of Science:

• Biotechnology
• Materials Science
• Environmental Science

Background:

• The textile industry's rapid growth and fast fashion result in substantial polyester (PET)/cotton blend waste.
• Effective fiber separation is critical for recycling blended textiles, but current methods have limitations.

Purpose of the Study:

• To investigate commercial cellulase formulations for enzymatic cotton depolymerization.
• To identify optimal enzyme activity patterns for recycling PET/cotton blends.
• To introduce and evaluate 'protein efficiency' as a metric for enzyme efficacy.

Main Methods:

• Biochemical characterization of 35 cellulase formulations (protein quantification, activity assays).
• Categorization of formulations by physical state, optimal conditions, and use case.
• Practical evaluation of 10 formulations in a reactor system for cotton removal efficiency (weight loss).

Main Results:

• Conventional enzyme activity assays did not reliably predict reactor performance.
• Protein efficiency (separation efficiency per protein content) emerged as a critical metric.
• High-performing formulations featured high endoglucanase activity, with moderate cellobiohydrolase and minor beta-glucosidase.

Conclusions:

• Enzyme activity assays alone are insufficient for predicting real-world textile recycling efficiency.
• Protein efficiency offers a more accurate assessment of enzyme performance and economic viability.
• Optimized cellulase cocktails, particularly those rich in endoglucanase, are promising for PET/cotton blend recycling.