High performance leathers finishing through zero waste and metal-free leather wastes valorization.

A contemporaneous functionalization of leathers and valorization of metal-free tannery waste was performed by reducing the waste into fine powders through mechanical grinding. The morphology of the milled wastes constited of fibers with diameters of a few microns (1-3 μm) and below. XRD analysis of leather powders confirms that even after the milling treatment, the leathers maintain retains its helical structure. The fibers were added to a finishing ink, and the resulting materials were characterized from different perspectives. The fibers containing finishing allows for better surface preservation, due to well-dispersed nanofibers filling the micropores of the coating, thus reducing the density of defects in the coating itself and improving the rubbing fastness. It should be noted that the presence of milled leather can impart color to the finished leather without requiring additional dyes. This approach results in cost-saving, and, more importantly, has positive environmental and ethical impacts.