Closing the cycle: Enzymatic recovery of high purity glucose and polyester from textile blends

Abstract

Enzymatic recovery of glucose and polyester from cotton / polyester textile blends was investigated. Grinding to a fibre length of 0.5 mm increased cellulose recovery from 53.6 to 85.4%. Subsequent steam explosion combined with alkaline pre-treatment led to complete hydrolysis of cotton while sonication and solvent pre-treatments were less effective. Comparison of weight loss and HPLC analysis indicated the presence of cellu-oligomers besides glucose. Recovery of enzymes via ultrafiltration only caused less than 5% in activity loss when used in five subsequent hydrolysis cycles. Similar bioethanol yields were determined for the hydrolysate and commercial glucose as carbon source for S. cerevisiae. The absence of peaks at 3600 cm−1 and 3000 cm−1 in FT-IR analysis and differential scanning calorimetry (DSC) analysis indicated no cellulose present in the polyester fraction. Re-granulation led to an intrinsic viscosity of 0.6 dl g−1 suitable for fibre spinning and production of towels thereby closing the cycle.