Content:
Synchrotron small-angle X-ray scattering (SAXS) technique was applied to leather research to understand the changes in molecular-level collagen structure during tanning and denaturation (shrinkage), which can help reduce the environmental impact from the extensive chrome usage. Based on SAXS results from realtime denaturation experiments on leather samples, we established a mechanistic model of chrome tanning indicated by the structural changes of collagen. It suggests that only a low level of chromium species is effectively involved in the cross-linking with collagen, which highlights the overuse of chrome during conventional tanning processes. Any extra amount of chrome added, however, can support the stabilisation of collagen possibly via a non-covalent mechanism. Such mechanism points towards a more environment-friendly tanning method by using suitable supplementary reagents to benefit tanning effect non-covalently instead of chrome.
By pre-treating with complexing agents such as sodium formate and disodium phthalate, as well as nanoclay (sodium montmorillonite), the uniformity through bovine hide collagen matrix were improved
significantly. These pre-treatments effectively reduce the reactivity of chromium during its cross-linking reaction with collagen while retaining its bound water. However, collagen pre-treated with a covalent
cross-linker (glutaraldehyde) results in a decrease in both chromium-collagen cross-linking and bound water while improving uniformity. These molecular-level insights can be developed into metrics to guide us towards a more sustainable future for the leather industry.
The coating on collagen fibrils can provide a pseudo-stabilisation effect of increasing the heat resistance of collagen. A group of tanning experiments were also conducted in situ on the SAXS beamline to observe the different mechanisms of free-of-chrome alternative tannages as potential replacements. Overall, synchrotron SAXS provides valuable information about collagen structure changes that could lead to more efficient use of chrome (or other tanning agents) in the global leather tanning industry.
Take-Away:
1. Kinetics of hydrothermal denaturation and collagen crosslinking mechanism proceed through different pathways
2. Alternative chemistries to enhance chrome uptake at low offers.
3. The role of collagen structure studies in understanding tanning mechanims
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:34139 |
| Date | 28 June 2019 |
| Creators | Zhang, Yi, Buchanan, Jenna K., Holmes, Geoff, Prabakar, Sujay |
| Contributors | International Union of Leather Technologists and Chemists Societies |
| Publisher | Verein für Gerberei-Chemie und -Technik e. V., Forschungsinstitut für Leder und Kunststoffbahnen (FILK) gGmbH |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, doc-type:conferenceObject, info:eu-repo/semantics/conferenceObject, doc-type:Text |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | urn:nbn:de:bsz:14-qucosa2-340872, qucosa:34087 |
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