Metal induced degradation of leather
type: CreativeWork
description: Large quantities of leather waste are generated from manufacturing processes and disposal of leather goods. Environmental directives encourage diversion of solid waste from landfills through viable recycling methods. Since leather is resistant to microbial degradation, direct recycling of leather waste through biodegradation methods are impractical. In this research, the mechanism and potential application of metal induced oxidative degradation of leather were studied. Experimental work on the effects of retanning vegetable tanned samples with salts of the first row transition metals indicated the presence of unstable tannin-metal interactions in samples containing V(IV), Fe(II) and Cu(II) salts. Denaturation of collagen at ambient conditions was observed in leather samples treated with V(IV) and Fe(II) salts. Autodegradation of leather samples containing Fe(II) and V(IV) ions occurred during at ambient conditions of storage. The process of degradation in the leathers was characterised in terms of the decline in hydrothermal stability, progressive lowering of tensile strength, loss of metal-tannin binding interactions, changes in the fibre structure and the occurrence of gelatinisation. Direct evidence on the reduction of V(V) by tannins was obtained using electron paramagnetic resonance spectroscopy. Results of spectrophotometric studies of polyphenol-metal ion interaction in acidic media indicated that Fe(II) and V(IV) ions act as catalysts in the oxidation of tannins. To explain the phenomena of metal induced degradation, a mechanism involving redox cycling of the iron ions (Fe2+/Fe3+) and vanadium ions (V02+/V02+) was proposed. In the semi-metal tanned leathers, Fe(II) and V(IV) species are oxidised by air, producing superoxide anion. Subsequently Fe(III) and V(V) are reduced back to the lower oxidation states by the o- diphenol moieties of tannins. In this way, the metal ions act as catalysts for the oxidation of tannins. Autoxidation of Fe(II) and V(IV) specie…
abstract: Large quantities of leather waste are generated from manufacturing processes and disposal of leather goods. Environmental directives encourage diversion of solid waste from landfills through viable recycling methods. Since leather is resistant to microbial degradation, direct recycling of leather waste through biodegradation methods are impractical. In this research, the mechanism and potential application of metal induced oxidative degradation of leather were studied. Experimental work on the effects of retanning vegetable tanned samples with salts of the first row transition metals indicated the presence of unstable tannin-metal interactions in samples containing V(IV), Fe(II) and Cu(II) salts. Denaturation of collagen at ambient conditions was observed in leather samples treated with V(IV) and Fe(II) salts. Autodegradation of leather samples containing Fe(II) and V(IV) ions occurred during at ambient conditions of storage. The process of degradation in the leathers was characterised in terms of the decline in hydrothermal stability, progressive lowering of tensile strength, loss of metal-tannin binding interactions, changes in the fibre structure and the occurrence of gelatinisation. Direct evidence on the reduction of V(V) by tannins was obtained using electron paramagnetic resonance spectroscopy. Results of spectrophotometric studies of polyphenol-metal ion interaction in acidic media indicated that Fe(II) and V(IV) ions act as catalysts in the oxidation of tannins. To explain the phenomena of metal induced degradation, a mechanism involving redox cycling of the iron ions (Fe2+/Fe3+) and vanadium ions (V02+/V02+) was proposed. In the semi-metal tanned leathers, Fe(II) and V(IV) species are oxidised by air, producing superoxide anion. Subsequently Fe(III) and V(V) are reduced back to the lower oxidation states by the o- diphenol moieties of tannins. In this way, the metal ions act as catalysts for the oxidation of tannins. Autoxidation of Fe(II) and V(IV) specie…
author: Feyisa, Addis Duki
language: eng
date published: 2014
date modified: 2026-07-24T03:26:46Z
provider: University of Northampton
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Northampton