Pages 397–411
Abstract
Research summary supplied by the authors
The leather industry has long faced the dual challenges of chromium pollution and solid waste management. This study proposes an innovative strategy that not only achieves chrome-free tanning by adopting a novel pH-responsive zirconium-based metal-organic framework (MOF) but also transforms waste leather into high-value functional catalysts. Firstly, by introducing a boronate ester pH-stimuli-responsive module into the ligand, a new pH-responsive MOF tanning agent is constructed. This agent maintains structural stability under neutral tanning conditions while undergoing controlled decomposition in acidic environments, thereby effectively addressing the long-standing issues of poor penetration and low utilization rate of zirconium ions in traditional zirconium tanning systems. Subsequently, by loading traditional zirconium tanning agents into the MOF framework, this study establishes a composite zirconium tanning agent with a controlled release mechanism, promoting the uniform distribution of zirconium ions within the collagen matrix. Test results show that the shrinkage temperature of the tanned leather exceeds 800C. Notably, the dispersed tanned leather can serve as an efficient heterogeneous catalyst for Knoevenagel condensation reactions. Thanks to the uniformly distributed zirconium active sites and the abundant amino groups derived from collagen, the catalyst demonstrates outstanding catalytic performance, maintaining a yield of over 87% through five consecutive Knoevenagel reaction cycles. This work not only provides an environmentally friendly alternative for tanning but also opens new pathways for the valorization of leather waste, achieving a complete paradigm shift from waste management to resource creation— turning waste into treasure.