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Kinetics of alkaline hydrolysis of the insoluble protein fraction following enzymatic hydrolysis of chrome-tanned shavings / J. Hrncirik in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. C, N° 1 (01/2005)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. C, N° 1 (01/2005) . - p. 1-7 Titre : Kinetics of alkaline hydrolysis of the insoluble protein fraction following enzymatic hydrolysis of chrome-tanned shavings Type de document : texte imprimé Auteurs : J. Hrncirik, Auteur ; Karel Kolomaznik, Auteur ; J. Kupec, Auteur ; F. Hruska, Auteur ; M. Dvorackova, Auteur Année de publication : 2005 Article en page(s) : p. 1-7 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : The problem of using chrome-tanned wastes (namely shavings) has been the subject of a number of reports. One path is enzymatic hydrolysis with possible utilization of both the protein fraction as well as chromium. After hydrolysis and subsequent filtration, a so-called filter (or chrome) cake is formed, which is composed of hydrated Cr2O3 heavily contaminated with protein products of hydrolysis (removable, e.g. in washing) as well as with a non-hydrolysable fraction. The fraction requires breaking down, e.g. with strong alkali, as was performed in tests conducted to provide data for evaluating hydrolysis kinetics. Applying a number of simplifying assumptions, efforts were directed to expressing formal kinetics of this alkaline hydrolysis with a KOH solution. According to calculations, the reaction appears to agree well with a second-order reaction, with effective values of rate constant c = 3.9.10-3 l/(mol.s) and activation energy Ea = 130 kJ/mol at hydrolysis temperature of 116°C. En ligne : https://drive.google.com/file/d/1oU3ce67tRFLR-MZNtxcMLIOJrrgMn2wP/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=4084 [article]

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A drying study for glutaraldehyde-tanned leather / Cheng-Kung Liu in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. C, N° 1 (01/2005)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. C, N° 1 (01/2005) . - p. 8-15 Titre : A drying study for glutaraldehyde-tanned leather Type de document : texte imprimé Auteurs : Cheng-Kung Liu, Auteur ; Joseph Lee, Auteur ; Nicholas P. Latona, Auteur Année de publication : 2005 Article en page(s) : p. 8-15 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : The environmental and health concerns over the use and disposal of chrome-tanned leather have encouraged the use of non-chrome-tanned (chrome-free) leather. The drying operation is a critical leather-making step to attainthe required physical properties for leather products. We recently conducted a drying study on non-chrome-tanned leather made with a glutaraldehyde-tanning process. Results showed that the physical properties of leather, such as area retention and softness, were affected significantly by the drying method. Data revealed that leather with inferior fracture energy often resulted in poor grainbreak. In addition, observations showed that drying methods using toggling produced higher areayield; however, it resulted in stiffer leather. Our research showed that residual water content plays an important role in controlling the softness of leather. Vacuum drying without toggling yields better toughness and softness. A dimensionless quantity "toughness index" showed a strong correlation with the resultant area retention, which agrees with our previous findings for chrome-tanned leather. En ligne : https://drive.google.com/file/d/1ZEAeRJ2nsZu84oaN6E5UKRBy3U1mcj8v/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=4085 [article]

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Treatment of tannery effluent by an electrocoagulation process / Z. Zaroual in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. C, N° 1 (01/2005)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. C, N° 1 (01/2005) . - p. 16-21 Titre : Treatment of tannery effluent by an electrocoagulation process Type de document : texte imprimé Auteurs : Z. Zaroual, Auteur ; M. Zertoubi, Auteur ; Y. Karhat, Auteur ; N. Saib, Auteur ; M. Azzi, Auteur Année de publication : 2005 Article en page(s) : p. 16-21 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : An electrocoagulation process is applied to tannery wastewater treatment. The effects of electrocagulation time, current and potential on process performance is examined. An iron electrode is used as a sacrificial anode. The optimal conditions are (0.15 A/cm2, 30 min) and (0.70 V, 90 min) for composite and tannage effluents, respectively. The removal efficiency of chromium exceeded 99% for the both tested wastewaters. Further, the experimental results show that electrocoagulation can neutralize wastewater pH. Several mechanisms for the pH variation are suggested. En ligne : https://drive.google.com/file/d/17AaZISY1O9qZ7DO3Mdbmmk_CNjxAj3Ub/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=4086 [article]

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Characteristics of leather tanned with Nano-SIO2 / Haojun Fan in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. C, N° 1 (01/2005)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. C, N° 1 (01/2005) . - p. 22-28 Titre : Characteristics of leather tanned with Nano-SIO2 Type de document : texte imprimé Auteurs : Haojun Fan, Auteur ; Biyu Peng, Auteur ; Qiang He, Auteur ; Bi Shi, Auteur ; Ling Li, Auteur Année de publication : 2005 Article en page(s) : p. 22-28 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : A nano-precusor which can, in-situ, produce nano-SiO2 under particular triggering condition was introduced into leather to improve the hydrothermal stability. In order to elucidate the reaction of nano-SiO2 with proteinand how it influences the properties of the protein, collagen was used as a model in a detailed investigation. The results from FTIR (Infrared) indicated that two new chemical bonds arose during the formation of the organic-inorganic nano-hybrid. One appears to be the reaction between nano-SiO2 formed in-situ by the hydrolysis of tetraethoxy silane and the -C=N-groups of arginine, histidine, and tryptophane in the backbone of collagen. In a second bond, occurring at the same time as the condensation of silanol proceeds, the pendent hydroxyl groups of collagen may partly react with Si-OH and form a strong interaction between the organic and inorganic phases. These two chemical bonds seem to contribute to the leather's high hydrothermal stability. The size distribution of nano-SiO2 as determined by Atomic Force Microscopy is approximately 50-80 nm and there appeared to be no agglomeration. Organic-inorganic nano-hybrid can improve the hydrolysis stability of collagen efficiently in the presence of enzyme, acid, and alkali. When the bated pelt is treated with 0.3 wt % nano-SiO2 (based on bated pelt weight), the shrinkage temperature reached above 95°C. Although the mechanical properties of nano-SiO2 tanned leather are inferior to chromium tanned leather, other properties of nano-SiO2 tanned leather, such as yield, grain, fullness and softness together with washability are all superior to chromium tanned leather. En ligne : https://drive.google.com/file/d/1ohLq2CUJ-Oo_mR-8noT-ldL7pN59s7c6/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=4087 [article]

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