Identificação e separação de resíduos têxteis de algodão/poliéster com emprego de líquido iônico: uma abordagem para a sua reciclagem

Abstract

IDENTIFICATION AND SEPARATION OF COTTON/POLYESTER TEXTILE WASTE USING IONIC LIQUIDS: AN RECYCLING TO APPROACH. The accumulation of textile waste in the environment is an emerging concern that directly impacts environmental sustainability. The textile industry utilizes various types of fibers to produce fabrics, which can be natural, synthetic, or artificial. Among these, the blend of natural and synthetic fibers, such as cotton and polyester, constitutes one of the primary sources of textile waste. These materials are selected for their combined properties, such as comfort and durability. However, their recycling poses a significant challenge due to the difficulty in separating the fibers after production. This issue arises from the interweaving of natural and synthetic fibers, which makes it impossible to recycle mixed fabrics directly through conventional mechanical methods due to their differing properties (such as melting and degradation temperatures). Additionally, there is a lack of comprehensive information regarding the exact composition of these fabrics, including details on the types of fibers, plasticizers, and additives used. Consequently, there is a clear need to understand the true composition of blended fabrics and to develop methods for effectively separating cotton and polyester fibers for subsequent reuse. This study aims to address this need by conducting a quantitative and qualitative analysis of cotton/polyester blended fabrics, employing various morphological, chemical, and thermal techniques such as scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), solid-state nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Furthermore, the cotton/polyester fabric was separated by dissolving the cotton fibers in 1-butyl-3-methylimidazolium chloride (BMimCl). The reaction time and temperature conditions for this process were investigated using FTIR and TGA to ensure effective separation. The optimal conditions for fabric separation were validated through SEM and molecular orbital length profile (MOLP) analysis. The interactions between the ionic liquid and the cellulose and polyester polymer chains were also studied using molecular dynamics field theories and Hansen's solubility sphere. The cellulose separated from the mixed fabric was regenerated and subjected to enzymatic hydrolysis to convert it into glucose. Based on the obtained results, it was concluded that the chosen method for qualitative and quantitative characterization of the fabrics significantly influenced the observed outcomes, highlighting the importance of using multiple techniques for a comprehensive understanding. Separating the mixed fabric by dissolving cotton fibers in the ionic liquid proved effective, and the regenerated cellulose, when subjected to enzymatic hydrolysis, exhibited reducing sugar activity, indicating successful cellulose hydrolysis. Thus, combining ionic liquids and enzymatic hydrolysis presents a viable and sustainable route for recovering and reusing textile materials.