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Structural differences between commercial acacia mangium tannin and its effluent / Teng Bo in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXI, N° 3 (03/2016)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXI, N° 3 (03/2016) . - p. 92-100 Titre : Structural differences between commercial acacia mangium tannin and its effluent Type de document : texte imprimé Auteurs : Teng Bo, Auteur ; Xiaoyun Jian, Auteur ; Yanping Gao, Auteur ; Jinwei Zhang, Auteur ; Wuyong Chen, Auteur Année de publication : 2016 Article en page(s) : p. 92-100 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Acacia et constituants Eaux usées -- Analyse Tanins -- analyse Tanins végétaux Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : Recycling and reuse techniques provide an efficient way to overcome the environmental issues of the chrome tanning effluent. However, only few vegetable tanning related recycling techniques were developed due to the limited information about the effluent. In this study, a common vegetable tanning process was performed with a commercial Acacia Mangium tannin (CAMT) to produce Acacia Mangium tanning effluent (AMTE). The tannins in the AMTE and CAMT were characterized using Fourier transform infrared, nuclear magnetic resonance spectroscopy, matrix-assisted laser desorption/ ionization time of flight mass spectrometry, gel permeation chromatography and elemental analysis. The results showed that the stereochemistry and flavan-3-ol subunits of the tannins in the AMTE were the same with the CAMT. However the differences between the tannins in the AMTE and CAMT were presented in terms of the tannin category, molecular weight, and quantities of sulfo acid group. Tannins in the AMTE were mainly composed of procyanidin, while prodelphinidin and procyanidin content showed comparable in the CAMT. Average molecular weight of the AMTE was 1315Da, in contrast to an obviously higher value in the CAMT (2025Da). Meanwhile, higher sulfonic acid group content was also found in the AMTE. These differences were deduced in accordance with the collagen binding ability of the tannins. Results will be valuable for reuse and recycling of vegetable tanning effluent. Note de contenu : - EXPERIMENTAL : Sample preparation - FT-IR spectroscopy - MALDI-TOF MS spectroscopy - C NMR analysis - GPC analysis - Elemental analysis - RESULTS AND DISCUSSION : FT-IR spectroscopic characterization - MALDI-TOF MS analysis - C NRM spectra - GPC analysis - Element component of the tannins En ligne : https://drive.google.com/file/d/1h93Wgfoj7jQ915nRritx4c69BlUNfT03/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=25744 [article]

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A further investigation on collagen-Cr(III) interaction at molecular level / Weimo Han in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXI, N° 3 (03/2016)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXI, N° 3 (03/2016) . - p. 101-106 Titre : A further investigation on collagen-Cr(III) interaction at molecular level Type de document : texte imprimé Auteurs : Weimo Han, Auteur ; Yunhang Zeng, Auteur ; Wenhua Zhang, Auteur Année de publication : 2016 Article en page(s) : p. 101-106 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Chrome trivalent Collagène Dynamique moléculaire Groupement carboxyle Réactions chimiques Tannage au chrome Thermodynamique Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : As we know, the reaction of chrome tanning primarily occurs at carboxyl groups of collagen, tacitly assumed at aspartic and glutamic side chains. However, the differences of the reactivity and reaction extent at these sites, as well as the effect of environmental conditions on the reaction are still unclear at molecular level. This paper presents a theoretical analysis of the reactivity of collagen carboxyl groups and Cr(III) species based on electrophilicity index (?), and the driving force for tanning reaction by using density functional theory (DFT) with Lanl2dz for chrome atom and 6-31g(d) for non-metal atoms. Glutamatic acid (Glu) and aspartatic acid (Asp) were used as the models of collagen side chains containing carboxyl group. Based on visual minteq calculation, the main Cr(III) species in chrome tanning liquor were found to be Cr(SO4)(H2O)4+, Cr(H2O)63+, Cr2(OH)2(H2O)84+, and Cr3(OH)4(H2O)105+ under the pH range of tanning process, and the content of multi-nuclear Cr(III) species increases with the rise of pH. The reactivity of collagen carboxyl groups is in the sequence of ionized Asp (Asp-) > ionized Glu (Glu-) > unionized Glu > unionized Asp, while the reactivity of the main Cr(III) species is sequenced by Cr3(OH)4(H2O)105+ > Cr2(OH)2(H2O)84+ > Cr(H2O)63+ > Cr(SO4)(H2O)4+. The data of thermodynamic driving force for tanning reaction indicate that ionized carboxyl groups have stronger tendency to form more stable carboxyl-Cr(III) complexes compared with unionized carboxyl groups, and the order of the tendency is Glu- > Asp- > Asp > Glu. Obviously, for Glu- and Asp- or Glu and Asp, the thermodynamic driving force is exactly the opposite with reactivity. Therefore, as for collagen carboxyl groups, the predominant reaction bonding site is determined by both thermodynamic and kinetic conditions. As for Cr(III) species, the order of thermodynamic driving force is Cr3(OH)4(H2O)105+ > Cr2(OH)2(H2O)84+ > Cr(H2O)63+ > Cr(SO4)(H2O)4+ which is consistent with the order of reactivity. Note de contenu : - METHODS : The main Cr(III) species under the pH range of tanning - The models of colagen carboxyl groups - The theoretical parameters - RESULTS AND DISCUSSION : The states of Cr2(SO4)3 and collagen carboxyl groups under tanning condition - The reactivity of the reactants - The driving force of typical reaction of chrome tanning En ligne : https://drive.google.com/file/d/1Mte56ufxy5sTOAeowKKeQJgcarvCPx9-/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=25745 [article]

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Early detection of looseness in bovine hides using ultrasonic imaging / Hannah C. Wells in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXI, N° 3 (03/2016)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXI, N° 3 (03/2016) . - p. 107-112 Titre : Early detection of looseness in bovine hides using ultrasonic imaging Type de document : texte imprimé Auteurs : Hannah C. Wells, Auteur ; Geoff Holmes, Auteur ; Richard G. Haverkamp, Auteur Année de publication : 2016 Article en page(s) : p. 107-112 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Cuirs et peaux -- Analyse Cuirs et peaux -- Défauts Détection de défauts (Ingénierie) Imagerie ultrasonore Peaux creuses Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : The processing of bovine hides to leather results in a significant proportion of defective leather known as loose leather. It has not previously been possible to recognize hides that may produce loose leather. Hides were processed through to leather with samples retained at the pickle, wet blue and crust leather stages with material that resulted in loose leather compared with that resulting in tight leather, using ultrasonic imaging. The loose precursor is characterized by a lower density of material in the mid grain layer. The looseness is quantified by amplitude differences in ultrasound line scans or cross-sectional area scans between loose leather and tight leather with 2-4 times the amount of low intensity area in loose leather at all three process stages. This enables detection of hides that will result in loose leather and may enable unsuitable hides to be diverted to other process streams to save substantial processing costs. Note de contenu : - Sample selection - Leather preparation - Looseness evaluation - Ultrasonic imaging - Scanning electron microscopy - Sample detection - Ultrasonic images - Scanning electron microscopy En ligne : https://drive.google.com/file/d/1HxuzfKlZNnYq_HBFfMsAEn0o3ryD2U7J/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=25746 [article]

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Development of a new leather intermediate : wet-bright with a high dye affinity / Anna Bacardit in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXI, N° 3 (03/2016)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXI, N° 3 (03/2016) . - p. 113-122 Titre : Development of a new leather intermediate : wet-bright with a high dye affinity Type de document : texte imprimé Auteurs : Anna Bacardit, Auteur ; M. Gonzàlez, Auteur ; S. van der Burgh, Auteur ; J. Armengol, Auteur ; Lluis Ollé, Auteur Année de publication : 2016 Article en page(s) : p. 113-122 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Cuirs et peaux -- Teinture Cuirs et peaux de bovins Cuirs et peaux de moutons Eaux usées -- Analyse Formulation (Génie chimique) Tannage minéral Tannage dans lequel interviennent différents minéraux. Le plus répandu est le tannage aux sels de chrome, mais aussi à l’aluminium Wet-blue (tannage) Peau tannée au chrome (le chrome donne une couleur bleue) Wet-bright (tannage) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : In this work we develop a new tanning process (that we call wet-bright) that produces leather free of chromium, aldehydes, aldehyde precursors and organic solvents. Due to the mineral character of the new system, the leather offers a perfect dyeability and high dye affinity, allowing for very bright colors in all leather applications. The leathers offer a perfect dyeability due to the brilliant whiteness of the wet-bright intermediate. This new system consists of the application of Tanfor Tâ„¢ system (from Kemira) which is safe for both humans and environment and is not classified as hazardous. In addition, when compared to existing traditional processes, there are economic and environmental advantages resulting from the use of this new system. Note de contenu : - TABLES : 1. Wet-blue tanning formulation - 2. Wet-bright tanning formulation - 3. Wet-end formulation for automotive - 4. Wet-end formulation for upholstery - 5. Wet-end formulation for shoe uppers - 6. Wet-end formulation for bovine garment - 7. Wet-end formulation for ovine garment - 8. Comparison of physical tests - 9. Comparison ofpollution in wastewaters En ligne : https://drive.google.com/file/d/1HS5M6qbBKBXcgUrXlLTuomHLqsx7dfW4/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=25747 [article]

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