Material Separation from Polyester/Cotton Blended Fabrics Using Hydrothermal Treatment

Abstract

The production of textile products is increasing annually, and most of them are disposed of after use without recycling. One of the reasons for the low recycling percentage of discarded textile products is the difficulty of recycling as a single material as these products are produced from a combination of two or more materials. Therefore, a technology to separate materials is necessary to improve the recycling percentage of textile products and to build a sustainable recycling industry. The aim of this study was to separate the most common combination of materials, such as cotton/polyester, in an environmentally friendly technique using hydrothermal treatment with only water. Herein, the optimal treatment conditions for blended fabrics in a high-pressure reactor were studied. Moreover, cotton could be separated by treating the fabrics at 220 to 230 °C for 10 min while maintaining the shape of the fabrics. Additionally, polyester showed a melting point, confirming that polyester could be separated without decomposition into monomers, unlike common chemical recycling. The strength of the separated cotton and the molecular weight of the polyester were evaluated, and a kinetic analysis of the changes due to the treatment was conducted. The activation energy obtained from the Arrhenius plot was 111.8 kJ/ mol for PET, which was smaller than 142.6 kJ/mol for cotton. This indicates that the decrease in the molecular weight of PET is more likely to occur than the change in the strength of cotton, suggesting the possibility of separating the materials from the kinetic analysis.

Physicochemical Properties of Cellulose Nanocrystals Extracted from Postconsumer Polyester/Cotton-Blended Fabrics and Their Effects on PVA Composite Films

“…Consequently, there has been a growing research focus on the recycling and reutilisation of blended polyester–cotton fabric in recent times. Generally, there exist two primary approaches for achieving the recycling of polyester–cotton fabric: one involves direct recovery without separating polyester and cotton, as proposed by Zou et al [ 4 ], while the other method involves recovering polyester or cotton individually based on their distinct chemical properties, including dissolution [ 5 , 6 , 7 ], hydrothermal separation [ 8 , 9 , 10 ], hydrolysis [ 11 , 12 ], and enzymolysis [ 13 , 14 ]. The former yields textiles of lesser quality, including items like carpeting, padding, and nonwoven goods [ 15 ], as the mechanical treatment easily damages the strength of the fibres.…”