Memory effect based on layered double hydroxides for uniform modification of collagen by zirconium sulfate

Tanning agents are chemical substances that cause structural changes in collagen. Zirconium tanning agent is a promising alternative to chromium tanning agent, but the problem of uneven tanning due to its rapid binding to collagen limits its practical application in leather manufacturing. In this study, a combined tanning strategy based on layered double hydroxides (LDHs) and zirconium sulfate was proposed, aiming to promote the uniform distribution of conventional zirconium tanning agents in collagen fibers and to improve the physicochemical properties of tanned leather through the memory effect of LDHs. The nanostructure of LDHs was modulated by calcination treatment to increase their specific surface area, Al 3+ defects and oxygen vacancies. The results showed that by adding layered double oxides (LDO), the uptake of zirconium sulfate by collagen was increased and the uniform distribution of zirconium sulfate in collagen fibers was promoted, which improved the thermal stability and physico-mechanical properties of the leather. In addition, LDO binds to collagen via hydrogen, ionic and coordination bonds, whereas Zr(SO 4 ) 2 binds to collagen mainly via coordination bonds. This study provides a new strategy for the effective application of zirconium tanning agents in the clean production of leather.