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Transposition of chrome tanning in leather making / Chao Wu in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CIX, N° 6 (06/2014)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CIX, N° 6 (06/2014) . - p. 176-183 Titre : Transposition of chrome tanning in leather making Type de document : texte imprimé Auteurs : Chao Wu, Auteur ; Wenhua Zhang, Auteur ; Xuepin Liao, Auteur ; Yunhang Zeng, Auteur ; Bi Shi, Auteur Année de publication : 2014 Article en page(s) : p. 176-183 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Absorption Cuirs et peaux -- Propriétés mécaniques Eau -- Consommation -- Réduction Eaux usées -- Analyse Morphologie (matériaux) Oxydes de chrome Post-tannage Procédés de fabrication Récupération (Déchets, etc.) Stabilité hydrothermale Tannage au chrome Tannage organique Wet-white (tannage) Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : To avoid the release of chrome from leather into post tanning effluents and the generation of chrome shavings, an inverse chrome tanning technology based on wet white was investigated. Conventional bated pelt was firstly tanned using an amphoteric organic tanning agent (Tingjiang white tanning agent, TWT) without pickling. Then, the TWT tanned wet white was directly processed with conventional post tanning processes. Chrome tanning was transposed to the end of the post tanning. The wet white had a shrinkage temperature (Ts) around 85°C that met the needs of shaving operation, and did not generate chrome shavings. The Ts and Cr2O3 content of the leather, by using this inverse chrome tanning technology, were higher than those of the conventional chrome tanned leather. With this inverse technology, the chrome output was reduced by 48%, mainly because no chrome was released from leather in post tanning processes. Meanwhile, the volume of chromium-containing wastewater discharged from the inverse processes was barely 31% of that from the conventional processes, which makes it much easier to collect and recover chromium from the effluents. Additionally, the tensile strength, tear strength and general appearances of the leather produced by the inverse technology were comparable to those of the conventional chrome tanned leather. Note de contenu : - EXPERIMENTAL : Materials - Leather making processes - Analyses of leather properties (Hydrothermal stability - Distribution of chrome in leather - Morphology of leather - Physical properties) - Analyses of effluents (Total organic carbon concentration (TOC) - Concentration of chrome in effluents - RESULTS AND DISCUSSION : pH change in leather making processes - Content and distribution of Cr2O3 in leather - Discharge of chrome from leather making processes - Absorption capacity of leathers of retanning and fatliquoring chemicals - Morphology in leathers -Physical properties of leathers En ligne : https://drive.google.com/file/d/1uviZiCwz4VgYvS-NNEWcomxG72XyP5nM/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=21515 [article]

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Green synthesis of monodispersed iron oxide nanoparticles for leather finishing / M. Nidhin in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CIX, N° 6 (06/2014)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CIX, N° 6 (06/2014) . - p. 184-188 Titre : Green synthesis of monodispersed iron oxide nanoparticles for leather finishing Type de document : texte imprimé Auteurs : M. Nidhin, Auteur ; Rathinam Aravindhan, Auteur ; Kalarical Janardhanan Sreeram, Auteur Année de publication : 2014 Article en page(s) : p. 184-188 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Caractérisation Cuirs et peaux -- Finition Cuirs et peaux -- Propriétés physiques Nanoparticules Oxyde de fer Pigments métalliques Polysaccharides Les polysaccharides (parfois appelés glycanes, polyosides, polyholosides ou glucides complexes) sont des polymères constitués de plusieurs oses liés entre eux par des liaisons osidiques. Les polyosides les plus répandus du règne végétal sont la cellulose et l’amidon, tous deux polymères du glucose. De nombreux exopolysaccharides (métabolites excrétés par des microbes, champignons, vers (mucus) du ver de terre) jouent un rôle majeur - à échelle moléculaire - dans la formation, qualité et conservation des sols, de l'humus, des agrégats formant les sols et de divers composés "argile-exopolysaccharide" et composites "organo-minéraux"(ex : xanthane, dextrane, le rhamsane, succinoglycanes...). De nombreux polyosides sont utilisés comme des additifs alimentaires sous forme de fibre (inuline) ou de gomme naturelle. Ce sont des polymères formés d'un certain nombre d'oses (ou monosaccharides) ayant pour formule générale : -[Cx(H2O)y)]n- (où y est généralement x - 1). On distingue deux catégories de polysaccharides : Les homopolysaccharides (ou homoglycanes) constitués du même monosaccharide : fructanes, glucanes, galactanes, mannanes ; les hétéropolysaccharides (ou hétéroglycanes) formés de différents monosaccharides : hémicelluloses. Les constituants participant à la construction des polysaccharides peuvent être très divers : hexoses, pentoses, anhydrohexoses, éthers d'oses et esters sulfuriques. Selon l'architecture de leur chaîne, les polysaccharides peuvent être : linéaires : cellulose ; ramifiés : gomme arabique, amylopectine, dextrane, hémicellulose et mixtes : amidon. Résistance au vieillissement Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Industries worldwide, including leather, have had to phase out pigments based on lead, chromium(VI), cadmium etc. due to the toxicity associated with these transition metal ions. Coupled to this phase out is also a need to enhance the functional properties of the otherwise safe pigments, with low use, so as to avoid wastage. In this direction, the use of nano-pigments is slowly coming into vogue. This paper explores the advantages of replacing an otherwise popular brown pigment — the hematite (?-Fe2O3) with nanosized oxides in leather finishing. Any synthesis methodology for nanoparticles is sustainable only when green methods are employed for their synthesis. This work takes adequate care in employing an environmentally friendly methodology based on biocompatible polysaccharide — starch as a template. The advantages of this method, such as the monodisperse character of the oxide, low particle size, ability of the carbon residue from the template to aid easy homogenization of the pigment to the finish formulation have resulted in excellent covering of surface, improved levelness, no overloading of grain, excellent physical properties and ageing resistance. Note de contenu : - Materials and methods - Synthesis of ?-Fe20 nanoparticles - Characterization of the synthesized nanoparticles - Application trials En ligne : https://drive.google.com/file/d/15U_-C1t3S1SPye9dZ20uqubPQ54w-4kA/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=21516 [article]

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1-butyl-3-methylimidazolium acetate as an alternative solvent for type I collagen / Jie Liu in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CIX, N° 6 (06/2014)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CIX, N° 6 (06/2014) . - p. 189-196 Titre : 1-butyl-3-methylimidazolium acetate as an alternative solvent for type I collagen Type de document : texte imprimé Auteurs : Jie Liu, Auteur ; Zhou Xu, Auteur ; Chen Yi, Auteur ; Haojun Fan, Auteur ; Bi Shi, Auteur Année de publication : 2014 Article en page(s) : p. 189-196 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Chimie analytique Collagène -- Solubilité Solvants -- Suppression ou remplacement Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Low solubility and undesirable denaturation in conventional solvents continue to represent a significant challenge for efficient extraction, accurate characterization and versatile processing of collagen. In the present study, a room temperature ionic liquid (IL), 1-butyl-3-methylimidazolium acetate ([BMIM]Ac), was synthesized, and then evaluated as an alternative solvent for type I collagen. Real-time polarizing optical microscope observation indicated complete disintegration of hierarchical structure of collagen aggregates as solubilized in [BMIM]Ac at 25°C. The solubility reached up to approximately 8.0 wt.% at 25°C, more than ten times higher than that in conventional dilute acetic acid. In comparison with dilute acetic acid and recently reported chloridion ILs, high solubility of collagen in [BMIM]Ac at room temperature was ascribed to loose binding between [BMIM]+ and acetate, as well as stronger proton-accepting ability of [BMIM]Ac, which enabled rupture of those intermolecular hydrogen bonds and ionic bonds that stabilized collagen aggregates. However, such bond-rupturing effect was found selective at room temperature. As demonstrated by Fourier transform infrared, circular dichroism, atomic force microscope, and ultrasensitive differential scanning calorimetry analysis, [BMIM]Ac did not destroy the special triple-helical structure of tropocollagen molecules that had been identified as being of importance for the functional and bioactive properties of collagen. According to these results, the discovery of [BMIM]Ac as an ideal solvent for collagen may open up new possibilities for the chemistry and engineering of collagen, which has long been established as a readily accessible and renewable resource with many unique properties. Note de contenu : - EXPERIMENTAL : Materials - Synthesis of [BMIM]Ac - Dissolution of collagen in [BMIM]Ac - Polarizing optical microscope (POM) observation - FTIR analysis - CD measurement - AFM observation - DSC measurement - RESULTS AND DISCUSSION : Dissolution mechanism of collagen in [BMIM]Ac - Triple-helical structure of collagen regenerated from [BMIM]Ac En ligne : https://drive.google.com/file/d/1sm3cYDSvhjqbYBv8WJIDxo4nbF5k-kaO/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=21517 [article]

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Covalent immobilization of organophosphorus hydrolase onto insoluble bovine collagen fibers / Yanhong Li in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CIX, N° 6 (06/2014)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CIX, N° 6 (06/2014) . - p. 197-206 Titre : Covalent immobilization of organophosphorus hydrolase onto insoluble bovine collagen fibers Type de document : texte imprimé Auteurs : Yanhong Li, Auteur ; Xinju Jia, Auteur ; Biyu Peng, Auteur Année de publication : 2014 Article en page(s) : p. 197-206 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Caractérisation Cinétique chimique Glutaraldéhyde Hydrolase pH Poudre de peaux Température Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : An organophosphorous hydrolase (OPH) was prepared and partially purified from Flavobacterium sp. The crude enzyme, with an activity of 1030U/g, was immobilized onto insoluble bovine collagen fibers (hide powder), instead of collagen membrane, through glutaraldehyde coupling. Optimal conditions of enzyme immobilization and properties of the immobilized enzyme preparation were investigated. Compared to glutaraldehyde tanned and chrome tanned hide powders, non-tanned hide powder showed higher immobilized enzyme activity. The optimal enzyme immobilization conditions are as follows: 10mg of enzyme was immobilized onto 500mg of hide powder in a 50mM phosphate buffer of pH 7.5 at 20°C, and 20% glutaraldehyde offer (based on the hide powder weight) was used to couple the enzyme and collagen fibers. The enzyme activity yield was about 35% and the hide powder immobilized OPH has an enzyme activity of about 7U/g. The immobilized enzyme showed the same temperature and pH profiles as the free enzyme, and it performed at much higher pH and with better thermal stability. The Km value of the immobilized enzyme was a somewhat higher (0.388mM) than that of the free enzyme (0.215mM). The reusability test showed that about 85% activity was retained after 10 use cycles. After storing for eight months at 20°C, the residual activity of the immobilized enzyme preparation was 98%. Note de contenu : - MATERIALS AND METHODS : Materials - Methods (Preparation and partial purification of organophosphorus hydrolase (OPH) from flavobacterium sp. - Preparation of tanned hide powder - OPH activity assay - OPH activity stability against glutaraldehyde - Immobilization of OPH on hide powders - Activity assay and characterization of immobilized OPH) - RESULTS AND DISCUSSION : The influence of glutaraldehyde on OPH activity - Factors affecting immobilization of OPH on hide powder (OPH immobilized on different hide powders - Effect of pH - Effect of glutaraldehyde dosage - Effect and temperature - Effect of added enzyme amount) - Characterization of immobilized OPH (pH and temperature-activity profiles - pH and thermal stability of immobilized enzyme - Kinetics parameters - Operational and storage stability) En ligne : https://drive.google.com/file/d/1-aAAxLzbsyLkcO9tzzpc_gUMX5hFAqhP/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=21518 [article]

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