Efficient production of lignin nanoparticle colloids and their feasibility for eco-friendly dyeing of natural and synthetic textile fabrics
Paulo Pereira, Silgia Aparecida da Costa, Sirlene Maria da Costa, Valdeir Arantes
Abstract
Lignin extracted from sugarcane bagasse on a pilot scale within a biorefinery framework was converted into colloidal dispersions of lignin nanoparticles (LNPs) through disc ultra-refining under varied operating conditions. The resulting spherical LNPs were analyzed using spectroscopic techniques, including TGA , FT-IR, 13 C NMR, UV, and zeta potential measurements, and employed as natural colorants for eco-friendly dyeing of natural (wool and cotton) and synthetic (acrylic, acetate, polyamide) textile fabrics, with and without mordants. The conversion process reduced lignin particle size from micrometers to the nanoscale, enhancing colloidal stability. TGA analysis revealed thermal degradation temperatures above 245 °C for LNPs and an enhanced char-forming ability. No significant differences were observed among the LNPs regarding morphology, zeta potential, or chemical structure . Qualitative and quantitative assessments demonstrated that LNP colloids efficiently and uniformly dyed fabrics in shades of light to dark brown, with wool and polyamide showing the highest color intensity. Only slight differences were observed in the dyeing performance of the LNPs of different sizes, with or without mordants. Proposed mechanisms the interactions between sugarcane LNPs and fabrics, focusing on their functional groups and structural features. Dyed wool, polyamide , and cotton fabrics were further characterized. FTIR analysis identified characteristic absorption bands, confirming the anchoring of LNPs to the fabrics. SEM revealed morphological changes on the fabric surfaces, while fluorescence microscopy and EDX analyses indicated the presence of LNPs on the surface of the fabrics. TGA analyses showed that fabrics dyed with LNPs exhibited significantly increased char-forming capacity, suggesting potential fire-retardant properties. In summary, this study successfully produced highly stable colloidal LNP dispersions that served as efficient and environmentally friendly natural colorants for sustainable dyeing of both synthetic and natural textile fabrics. Additionally, the dyed fabrics demonstrated fire-retardant properties, with color intensity varying based on fabric type.