Novel vapor-phase assisted hydrothermal decomposition of cellulose waste for future recycling of textiles

Abstract

A novel and practical approach has been employed to decompose and carbonize cotton waste using vapor-phase assisted hydrothermal treatment at low temperatures. This method represents an innovative solution for processing cotton waste while effectively minimizing environmental impact. The reaction involves hydrochloric acid (HCl) with varying doses, reaction times, and temperatures. During the process, the fabric’s color changes from white to dark brown and ultimately to black after depolymerization and carbonization. Compared to the untreated samples, the treated samples exhibited area shrinkage of approximately 4–13%. The mass yield was around 81%, indicating a weight loss of 19%, which reflects the effective conversion of cotton into a carbon-rich product. The CS9 and CS10 samples, treated at 100°C for 2 h with 1 mL and 2 mL of HCl, respectively, demonstrated the best carbonization results. Scanning electron microscopy (SEM) images revealed significant changes in the surface morphology and texture of the fibers, accompanied by a reduction in fiber diameter. Additionally, fourier transform infrared (FTIR) spectra confirmed the presence of C = C bonds, supporting the formation of carbonized structures and the occurrence of cross-linking reactions. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) measurements illustrated enhanced thermal stability, attributed to the formation of pre-graphitic structures with aromatic compounds at higher temperatures, producing carbonaceous materials.