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Composition and structural analysis of organic acid masked aluminum tanning solutions using 27Al NMR / Keyi Ding in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CI, N° 11 (11/2006)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CI, N° 11 (11/2006) . - p. 381-387 Titre : Composition and structural analysis of organic acid masked aluminum tanning solutions using 27Al NMR Type de document : texte imprimé Auteurs : Keyi Ding, Auteur ; J. Liu, Auteur ; T. Zhang, Auteur Année de publication : 2006 Article en page(s) : p. 381-387 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : In this study, 27Al NMR was applied to gain information about the composition distributions and the structures of organic acid masked aluminum complexes in tanning solutions. The result indicated that in the pH range of aluminum tanning condition, three classes of organic acid masked aluminum complexes were found, i.e.: mononuclear complexes, linear polymeric complexes containing 2 - 4 Al3+ and "Al13 like" complexes. The predominated species was the "Al13 like" complexes, with more than 70% of the Al3+ in this state when the solution pH was ≥ 3.5. "Al13 like" complexes have a stiff spherically symmetrical structure (e-Keggin structure), consisting of one central [AlO4]5- tetrahedron, and surrounded with 9 - 30 octahedral aluminum complexes sharing edges. The diameter of a "Al13 like" complex is about 8 - 16 A. The understanding about the special structure of "Al13 like" complexes gives a rational explanation as to why in organic acid masked aluminum complex solutions, most of the added organic acid anions were in "free" state. The results of this study provide a basis for better understanding the mechanism of aluminum tannage or aluminum combination tannage with other tanning agents.. En ligne : https://drive.google.com/file/d/1a6f4XJs-9jvLyOe4sl_Si3DvJVUdShxF/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=3968 [article]

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Single step hair removal and fiber opening process : Simultaneous and successive addition of protease and a-amyiase / Palanisamy Thanikaivelan in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CI, N° 11 (11/2006)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CI, N° 11 (11/2006) . - p. 388-398 Titre : Single step hair removal and fiber opening process : Simultaneous and successive addition of protease and a-amyiase Type de document : texte imprimé Auteurs : Palanisamy Thanikaivelan, Auteur ; B. Chandrasekaran, Auteur ; C. K. Bharath, Auteur ; Subramani Saravanabhavan, Auteur ; C. Anandhi, Auteur ; Jonnalagadda Raghava Rao, Auteur ; Balachandran Unni Nair, Auteur Année de publication : 2006 Article en page(s) : p. 388-398 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : The use of enzyme based products for many areas in leather making has found its way into commercial practice. Proteolysis and a-amylase enzymes have found use in hair removal and fiber opening, producing comparable results to the conventional practice of lime and sulfide based dehairing and fiber opening. However, this process is a two step sequence in which dehairing is performed by the proteolysis enzyme followed by fiber opening through a-amylase. This study aims at transforming the two-step method into a single-step process, while maintaining environmental sustainability. Experiments were carried out using various percentages of dehairing enzyme and a-amylase following successive, simultaneous addition. The order of addition of the enzymes is also varied. Standardization experiments at bulk level were carried out to obtain best results. The leathers obtained from simultaneous addition of enzymes (1 % protease and 0.75 % a-amylase) were comparable to that of the conventionally produced leathers in terms of physical properties and appearance. The input-output analysis shows complete dehairing and fiber opening, which is also confirmed through scanning electron micrographs. There is reasonable reduction in water consumption, wastewater discharge, COD and TS loads when compared to the conventional leather processing. En ligne : https://drive.google.com/file/d/1jP8zEP1uDaan8sy04ImHihO5DjlTXhUI/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=3969 [article]

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Influence of retanning and fatliquoring processes on the characteristics of goatskins / Ramón Palop in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CI, N° 11 (11/2006)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CI, N° 11 (11/2006) . - p. 399-407 Titre : Influence of retanning and fatliquoring processes on the characteristics of goatskins Type de document : texte imprimé Auteurs : Ramón Palop, Auteur ; Agusti Marsal, Auteur ; Albert M. Manich, Auteur Année de publication : 2006 Article en page(s) : p. 399-407 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : The effect of three different offers of both vegetable retanning agent (0, 3 and 6 %) and fatliquoring agent (0, 5 and 10 %) on the physical properties of skins was assessed. A standard process was applied to the left halves of goatskins from Nigeria, whereas the right halves were subjected to the corresponding variables. The variation in the results of each studied property was evaluated. The statistical analysis of the results obtained in the experimental plan was carried out by means of the of the Analysis of Variance (ANOVA), through the Statgraphics Plus Program. The best results of softness and physical resistances were obtained with the highest fatliquoring agent offer (10 %). On the other hand, the effect of vegetable retanning agent offer depends on the physical property considered. En ligne : https://drive.google.com/file/d/1CNSzGQhlAB70c8dhxipMpGNMtJnaYXh2/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=3970 [article]

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The oxidative degradation of keratin (wool and bovine hair) / William N. Marmer in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CI, N° 11 (11/2006)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CI, N° 11 (11/2006) . - p. 408-416 Titre : The oxidative degradation of keratin (wool and bovine hair) Type de document : texte imprimé Auteurs : William N. Marmer, Auteur ; Robert L. Dudley, Auteur Année de publication : 2006 Article en page(s) : p. 408-416 Note générale : bibliogr. Langues : Américain (ame) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : In our development of multiple formulations for alkaline oxidative dehairing, using perborate, percarbonate, and hydrogen peroxide/cyanate systems, we wondered whether all the oxidative dehairing reactions could be described by a single reaction mechanism. The present study investigated the parameters of base concentration, oxidant, and reaction time, and sought evidence for hair immunization (the formation of protein species insoluble in alkaline sulfide) and cystine oxidation. The base likely played two roles, a catalyst for the hydrolysis of the polypeptide backbone and an aid in the swelling of the hair shaft. The disulfide linkages in cystine were oxidatively cleaved by the oxidizing agent and the reaction mechanism was the same for all of the oxidative systems. MALDI TOF/TOF spectrometry indicated that at least some of the cysteine in solubilized keratin liberated from treatment of alkaline peroxide/cyanate remained intact (unoxidized), but proton NMR spectroscopy showed the oxidation of cystine to cysteic acid for all oxidizing systems studied. Base was effective in hydrolyzing the keratin, but the addition of an oxidizing reagent (perborate) increased the amount of hair (wool) solubilized and decreased the amount of solubilized keratin with a MW > 3.5 KDa. The increased rate of alkaline solubilization of wool by incorporation of oxidizing agents suggested that the cleavage of the disulfide linkage further allowed the hair to swell and take up water (and base). En ligne : https://drive.google.com/file/d/1b9_UCItRY-s_f5j_9M6w-k_tABqjm7fe/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=3971 [article]

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