A sustainable chrome-free tanning approach based on Zr-MOFs functionalized with different metals through post-synthetic modification

•Two kinds of novel bimetallic MOFs were obtained via post-synthesis modification.•An effective method to solve the difficulty of zirconium penetration.•An innovative scientific and engineering solution for the leather industry. The development of chrome-free tanning agents is of great significance for the green and sustainable improvement of the leather industry. Metal organic framework (MOFs) is a kind of nanomaterial with steady framework formed by the coordination of metal clusters with organic ligands, which gives it a natural self-masking structure. Herein, two kinds of bimetallic MOFs were obtained via post-synthesis modification and used in the tanning to produce leather with good hydrothermal stability. Mn+- replacing Zr-MOFs is denoted as Zr/M−MOFs (Mn+ = Ti4+, Al3+). Zr/M−MOFs were characterized by XRD, SEM, FT-IR, TG, XPS, and N2 adsorption/desorption. The results indicate that Mn+- replacing provides more active site that can be combined with collagen fibers. Compared to the Zr-MOFs tanned leather (75.3 °C), the shrinkage temperature of Zr/M−MOFs tanned leather (79.9 °C) has been further improved. In addition, Zr/M−MOFs can also avoid the problems caused by traditional metal tanning, such as the worse washability of aluminum tanning. A new strategy to improve the tanning performance of MOFs-based tanning agents was provided. It gives a new approach to the development of chrome-free tanning agents.