Northampton Electronic Collection of Theses and Research

Fundamental aspects of the chrome tanning reaction

Menderes, Ö. (2002) Fundamental aspects of the chrome tanning reaction. Doctoral thesis. University of Leicester.

Item Type: Thesis (Doctoral)
Abstract: Fundamental elements of chrome-collagen interactions and the crosslinking mechanism at the molecular level have been investigated to gain detailed understanding that can be translated into improvements in the commercial process. Amide group hydrolysis during conventional liming proceeds by two mechanisms: direct hydrolysis with hydroxyl catalysis or intramolecular catalysed hydrolysis that can be measured by the degree of racemisation at Lasparagine Gas chromatography mass spectrometry analysis of limed collagen demonstrated that there was no initial rise in the amount of D-aspartic acid during the first 24 hours of liming, indicating that, within the conventional period of liming, collagen remained intact. Circular dichroism has demonstrated that beamhouse processing has dispersive and relaxing effects on the collagen triple helices, but without disruption. Attenuated total reflection Fourier transform infrared spectroscopy analysis provided information regarding changes in the secondary structure of collagen during tanning. Complete breakdown of chrome tanned collagen was achieved by the use of a cocktail of proteolytic enzymes: this allowed an analysis of the isolated crosslinks, which indicated preferred reaction at aspartate sidechain carboxyls. This is supported by chrome tanning studies following treatment of collagen by amidase enzymes. Geometric details of chromium(lll) species involved in the tanning reaction were elucidated by extended X-ray absorption fine structure analysis. Linear tetrameric chromium species were found to be predominant in the tanning process. Direct measurements of the mechanism were made using electron spin resonance spectroscopy. A two-stage reaction mechanism is postulated: physical interaction and chemical complexation, affected by reaction conditions such as pH, temperature and the presence of neutral salts. Nuclear magnetic relaxation dispersion measurements confirmed changes in the speciation of chromium(lll) under tanning conditions
Additional Information: This University of Northampton thesis was validated by the University of Leicester
Subjects: T Technology > TS Manufactures > TS967 Chemistry and science of leather
T Technology > TS Manufactures > TS940 Leather industries. Tanning
Creators: Menderes, Özlem
Department: School of Applied Sciences (to 2009) > Leather Technology (to 2009)
Faculties, Divisions and Institutes: University Faculties, Divisions and Research Centres - OLD > Faculty of Arts, Science & Technology > Theses (Arts, Science & Technology)
University Faculties, Divisions and Research Centres - OLD > School of Applied Sciences (to 2009) > Theses (to 2009)
Date: 2002
Date Type: Completion
Number of Pages: 227
Language: English
Status: Unpublished
Institution: University of Leicester

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