Harnessing the reversible reaction principle: A novel Zr-based halide Perovskite tanning system for effective Zr4+ penetration in the leather collagen

The development of green chromium-free tanning agents continues to be actively researched as a prominent topic in the leather industry. Zirconium tanning agents have good tanning performance, but their permeability is poor. Halide perovskites, composed of metal ions and organic ligands, are metal-tunable nanomaterials. In order to improve the permeability of zirconium. In this study, Cs 2 ZrCl 6 was synthesized using zirconium ions and combined with Zr(SO 4 ) 2 for collagen modification application. Based on the principle of reversible reactions, the introduction of Zr(SO 4 ) 2 effectively alleviated the rapid hydrolysis of Cs 2 ZrCl 6 , ensuring the preservation of its nanostructure and enabling continuous penetration during the tanning process. The EDS analysis confirmed the uniform distribution of zirconium in leather collagen tanned with Cs 2 ZrCl 6 /Zr(SO 4 ) 2 . Compared with Zr(SO 4 ) 2 tanned leather (73.1 °C), the shrinkage temperatures of Cs 2 ZrCl 6 /Zr(SO 4 ) 2 tanned leather collagen (83.7 °C) is better. Additionally, the BOD 5 /COD cr ratio of the tannery wastewater in this system is 0.65, indicating excellent biodegradability. The development of the Cs 2 ZrCl 6 /Zr(SO 4 ) 2 tanning system provides a new approach for creating chromium-free tanning agents.