Green and efficient depolymerization and recycling of polyester/cotton blended fabrics by ethanolamine

Abstract

The improper treatment of waste polyester/cotton blended fabrics results in significant environmental pollution and resource wastage, and there is an urgent necessity to address the efficient treatment of waste polyester/cotton blended fabrics. The present study employs a more environmentally friendly, gentle, and energy-efficient approach to effectively separate and recycle waste polyester/cotton blended fabrics. Firstly, the waste polyester/cotton blended fabrics are swollen using acetic acid to increase the gaps of the polyester molecular chain to facilitate contact between the polyester and the depolymerization solvent. Then, the polyester of the polyester/cotton blended fabrics was efficient degraded by ethanolamine and the regenerated cotton fibers were separated after simple filtration. The effects of pretreatment condition, depolymerization temperature and time on the depolymerization efficiency of polyester under atmospheric pressure and catalyst-free conditions were investigated, and the regenerated cotton were characterized and compared with virgin cotton. Considering the comprehensive energy consumption and other factors, the optimal swelling conditions were 40 °C for 50 min. The optimal depolymerization conditions were 80 °C for 3 h, and the depolymerization rate of polyester reached 96.00 %. The chemical structure and crystal structure of regenerated cotton is comparable to that of virgin cotton, and the tensile properties are weakened by about 0.67 N. Polyester depolymerization product bis(2-hydroxyethyl)terephthalamide (BHETA) can be used as a precursor for foams and adhesives. The “polyester dissolution for cotton retention” technology enables high-added-value utilization of waste polyester/cotton blended fabrics. The wide application of this technology is of great significance to the economy, ecological and environmental protection.