A Novel Xylose-Derived Tanning Agent with Dual Tanning/Retanning Capabilities for Sustainable Leather Manufacturing

To address the severe environmental pollution caused by conventional chrome tanning, the development of efficient and eco-friendly chrome-free tanning agents is essential for the green transition of the leather industry. In this study, a biomass-based tanning agent (TX) was synthesized from 2,4,6-trichloro-1,3,5-triazine (TCT) and D-(+)-Xylose, and its tanning and retanning performances were systematically evaluated. Tanning experiments showed that TX-tanned leather exhibits excellent hydrothermal stability (T_s > 80 °C), a thickness increase of over 40%, and superior collagen fiber dispersion compared to TWS and F-90 tanning agents. In addition, TX-tanned leather demonstrated good dyeing uniformity and significantly better antiyellowing properties than aldehyde-tanned leather. TX also serves as an effective retanning agent, providing additional thickening, greater softness, and a high dye uptake rate of approximately 80% for anionic dyes. The tanning wastewater exhibited a BOD₅/COD_cr ratio of 0.46, indicating good biodegradability. Overall, TX derived from renewable xylose offers a sustainable and effective solution for chrome-free leather manufacturing, with promising potential for practical application in cleaner production.