Exploration of theDiffusion, Binding and Crosslinking of Chromium Complex within Hides during Chrome Tanning

Abstract

Understanding the persuasive mechanisms of the accessibilityand interactions of chromium complex with collagen is animportant fundamental issue for maximizing the utilization ofchromium during the transformation of collagen to leather bychrome tanning technology. This study details thesemechanisms through process monitoring of the effects oftechnical conditions of chromium diffusion and its binding withthe collagen matrix. The results indicated that there was nodiscernible impact of carboxylic masking agents on bothdiffusion and binding behavior of chromium complexes at lowpH before basification, but it portentously declined the totalchromium absorption at the end of chrome tanning. The resultsmade known that in the course of chrome tanning, the higherpH conditions encouraged the diffusion and binding behavior ofchromium complexes with collagen matrix not only before butafter the basification as well. Chrome tanning at high pH did notcause excessive surface tanning effects of the leather, but theWAXD study indicated that there was much more crosslinking(both intra and inter triple helix) of collagen fibers in the innerlayers of leather matrix, which had a robust impact on thefullness, tightness and stiffness of the finished leather. Thesefindings could provide more theoretical foundations for thedevelopment of high exhaustion chrome tanning technology asa method for reduced chromium emission and improved thequality of leather during leather manufacture.