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Influence of ultrasound on the adsorption, diffusion and kinetics of leather dyeing process : mechanistic insight / Venkatasubramanian Sivakumar in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXV, N° 7 (07/2020)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXV, N° 7 (07/2020) . - p. 239-247 Titre : Influence of ultrasound on the adsorption, diffusion and kinetics of leather dyeing process : mechanistic insight Type de document : texte imprimé Auteurs : Venkatasubramanian Sivakumar, Auteur Année de publication : 2020 Article en page(s) : p. 239-247 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Colorants -- Adsorption Colorants acides Cuirs et peaux -- Teinture Diffusion (physique) Rouge (couleur) Ultrasons Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Leather is a natural porous material, which is composed of a three-dimensional weave of tanned collagen fibre bundles. This paper studies the influence of power ultrasound on the adsorption and kinetics of leather dyeing process. Dyeing experiments have been carried out using ultrasound (150 W, 33 kHz) and compared with that of static control dyeing process. The data of dye uptake in leather have been analysed using Freundlich and Langmuir adsorption isotherms. Intra Particle diffusion model has been employed to calculate Intra particle diffusion rate constant and Boundary Layer effect. Diffusion coefficient (D) of dye through leather matrix has also been calculated. Kinetics of leather dyeing process has been studied through pseudo first and second order rate equation. The Freundlich constant (Kf), Langmuir parameter (Qm), Intra Particle diffusion rate constant (Kd) Apparent Diffusion coefficient (D) and Pseudo First order kinetic constant, K1 have been calculated to be 18.67 mg/g, 50 mg/g, 0.006 min-1, 1.89 * 10-6 cm2/s and 1.7 mg/g min0.5 respectively for ultrasound assisted leather dyeing as compared to that of 0.1 mg/g, 26.67 mg/g, 0.733 min-1, 0.19 * 10-6 cm2/s and 0.003 mg/g min0.5 respectively for control process. The results indicate that significant enhancement in adsorption capacity with more favorable dye adsorption as well as about 10- fold increase in Apparent Diffusion coefficient with significant reduction in boundary layer effect, improved kinetic parameters due to the use of ultrasound in leather dyeing as compared to control. Mechanisms for enhancement in Adsorption and Kinetic Parameters in leather dyeing due to the use of ultrasound have been presented and corroborate well with better dye penetration, color value and fastness properties. Therefore, the present study demonstrates that the use of ultrasound in leather dyeing helps both in adsorption of dyes as well as diffusion process through the leather matrix. Note de contenu : - INTRODUCTION : Novelty of the present work - EXPERIMENTAL : Ultrasonic experimental set-up - Materials and methods - Analysis of acid red dye - RESULTS AND DISCUSSIONS : Adoption isotherm - Intra particle diffusion model - Diffusion coefficient in leather dyeing - Kinetic constants in leather dyeing - Mechanisms for enhancement in adsorption and kinetic parameters in leather dyeing due to the use of ultrasound DOI : https://doi.org/10.34314/jalca.v115i7.3834 En ligne : https://drive.google.com/file/d/1OGWRbzN7QUB-aQY6ZXbm_whWvwnOXx3p/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=34325 [article]

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Visualization of penetration and reaction of aldehyde tanning agent in leather using fluorescence technique / Ying Song in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXV, N° 7 (07/2020)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXV, N° 7 (07/2020) . - p. 248-254 Titre : Visualization of penetration and reaction of aldehyde tanning agent in leather using fluorescence technique Type de document : texte imprimé Auteurs : Ying Song, Auteur ; Siqi Wu, Auteur ; Ya-Nan Wang, Auteur ; Yudan Yi, Auteur ; Yunhang Zeng, Auteur ; Bi Shi, Auteur Année de publication : 2020 Article en page(s) : p. 248-254 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Agents de tannage Cuirs et peaux -- Analyse Glutaraldéhyde Pénétration (physique) Réactions chimiques Spectroscopie de fluorescence Tannage organique Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : Penetration and reaction of tanning agents in leather greatly influence tanning performance and leather quality. Aldehyde tanning agents are widely used in leather manufacture, but their penetration and reaction in leather cannot be detected easily. Considering the fact that aldehyde can form a fluorescent Schiff base with amino groups of collagen, we visualized the distribution and reactivity of typical aldehyde tanning agents in leather during tanning process using a fluorescence microscope. The results showed that glutaraldehyde in leather was easily observed under the fluorescein isothiocyanate (FITC) filter system. The fluorescence intensity of pelt/leather gradually increased with penetrating of glutaraldehyde, basifying and heating, which was consistent with the formation of Schiff base and the increase in Ts of pelt/leather. Oxidized sodium alginate and dialdehyde sodium carboxymethyl cellulose in leathers were also detected using a fluorescence microscope because the aldehyde group of the two tanning agents formed a fluorescent Schiff base with amino groups of collagen. The oxazolidine tanned leather and the tetrakis hydroxymethyl phosphonium tanned leather emitted little fluorescence because they crosslinked collagen with hydroxymethyl group. These results indicate the fluorescent technique is useful to visualize the penetration and reaction of aldehyde tanning agents that crosslink collagen with aldehyde groups. Note de contenu : - EXPERIMENTAL : Materials - Effect of glutaraldehyde crosslinking on fluorescence intensity of collagen - Determinations of penetration and reaction of glutaraldehyde in leather - Analyses of fluorescence intensity and Tg of the leathers tanned by different tanning - RESULTS AND DISCUSSION : Fluorescence emission spectra of GC - Penetration and reaction of glutaraldehyde in leather - Change in Tg of pelts/leathers during glutaraldehyde tanning process - Detection of other aldehyde tanning agents in leather DOI : https://doi.org/10.34314/jalca.v115i7.3835 En ligne : https://drive.google.com/file/d/1PdIgVX4Jfy5KYDKoEKiVPiF2pF9Ldfv1/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=34326 [article]

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Nonionic short-chain fluorinated surfactants in the fatliquoring of chrome-tanned goat skin / Yichao Shen in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXV, N° 7 (07/2020)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXV, N° 7 (07/2020) . - p. 255-262 Titre : Nonionic short-chain fluorinated surfactants in the fatliquoring of chrome-tanned goat skin Type de document : texte imprimé Auteurs : Yichao Shen, Auteur ; Yong Jin, Auteur ; Shuangquan Lai, Auteur ; Liangjie Shi, Auteur ; Yutang Zhou, Auteur ; Rong Zhou, Auteur Année de publication : 2020 Article en page(s) : p. 255-262 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Angle de contact Caractérisation Chromatographie sur gel Cuirs et peaux -- Propriétés mécaniques Cuirs et peaux de chèvres Douceur (toucher) Fourier, Spectroscopie infrarouge à transformée de Liqueurs de tannage Microscopie électronique à balayage Surfactants fluorés Tannage au chrome Tension superficielle Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Surfactants as essential auxiliaries are used in almost all chemical processes in leather production. In this work, a series of nonionic short-chain fluorinated surfactants (Fn-Fn, where n = 2, 4, or 6) were successfully prepared and used as fatliquoring auxiliaries in the fatliquoring process of chrome-tanned goat skin. The chemical structure of these nonionic short-chain fluorinated surfactants was characterized by FTIR and the molecular weight was determined by GPC. The surface tension measurement results revealed that these three fluorinated surfactants showed excellent surface activities. The effect of type and dosage of Fn-Fn as well as fatliquoring temperature on fatliquoring properties of chrome-tanned goat skin were estimated by the softness and physical mechanical properties characteristic of resultant leather. The results revealed that the leather treated with 1 wt% F4-F4 at the fatliquoring temperature of 40oC showed the best overall performance, whose softness and physical mechanical properties were improved significantly. Moreover, the collagen fiber morphology and waterproof performance of leather treated with Fn-Fn were also investigated which showed that the addition of Fn-Fn in the fatliquoring process could promote the loosening of collagen fibers while effectively enhancing the water repellency of the leather surface. Therefore, such types of nonionic short-chain fluorinated surfactants are promising to be as desired fatliquoring auxiliaries in the leather industry. Note de contenu : - MATERIALS AND METHODS : Materials - Synthesis of nonionic short-chain fluorinated surfactants (Fn-Fn) - Fourier Transform Infrared Spectra (FTIR) - Gel permeation chromatography (GPC) - Surface tension measurement - Application of nonionic short-chain fluorinated surfactants - Analysis of leather properties - RESULTS AND DISCUSSION : Synthesis and characterization of nonionic short-chain fluorinated surfactants (Fn-Fn) - Surface properties - Effect of type of Fn-Fn on the softness and physical mechanical properties of leather - Effect of dosage of Fn-Fn on the softness and physical mechanical properties of leather - Effect of fatliquoring temperature on softness and physical mechanical properties - SEM analysis of leather - Contact angle DOI : https://doi.org/10.34314/jalca.v115i7.3833 En ligne : https://drive.google.com/file/d/1jWVv4Z3q7D9OPMovPW4gKqVpNEXR8J3d/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=34327 [article]

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A novel approach for quantitative characterization of hydrolytic action of glycosidases to glycoconjugates in leather manufacturing / Fengxiang Luo in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXV, N° 7 (07/2020)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXV, N° 7 (07/2020) . - p. 263-269 Titre : A novel approach for quantitative characterization of hydrolytic action of glycosidases to glycoconjugates in leather manufacturing Type de document : texte imprimé Auteurs : Fengxiang Luo, Auteur ; Zhong Xiang, Auteur ; Chunxiao Zhang, Auteur ; Biyu Peng, Auteur ; Zhongzhen Long, Auteur Année de publication : 2020 Article en page(s) : p. 263-269 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Caractérisation Epilage enzymatique Essais (technologie) Glycoprotéines Glycosidases Les Glycoside hydrolases (ou glycosidases) catalysent l'hydrolyse de liaisons glycosidiques et libèrent au moins un composé osidique. Ce sont des enzymes extrêmement communes, dont les rôles sont aussi divers que la dégradation des glucides complexes (cellulose et hémicellulose), les défenses anti-bactériennes (ex. le lysozyme), la pathogénicité (ex. les neuraminidases virales) ou le métabolisme cellulaire (amylases ou enzyme de débranchement du glycogène pour le métabolisme énergétique, mannosidases comme modulateur de glycosylation des protéines, ...). Les glycosyltransférases et les glycosides hydrolases sont les deux classes majeures d'enzymes impliquées dans la synthèse et la rupture des liaisons osidiques. Hydrolyse enzymatique Peaux brutes -- Trempe Poudre de peaux Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Glycoconjugates, herein glyco-protein conjugates, composed of protein and saccharide chains are the main components of the interfibrillar matrix in skin which need to be fully removed in the leather making process. The application of glycosidases can assist unhairing and skin fiber opening-up, resulting in the improvement of leather quality, by breaking the glycoconjugates safely and efficiently in mild conditions. The biotechnology assisted by glycosidases, a big family of over 200 kinds of enzymes, has a great potential but the related mechanisms and the efficiency of different glycosidases are still not clear, which interferes with its wide application. To screen the proper glycosidases, a novel method of evaluating the catalytic hydrolysis properties of glycosidases towards skin glycoconjugates based a special hide powder substrate, simulating the actual leather processing, was established through detecting the produced amount of the total sugar in the solution. The special substrate was prepared, the determination conditions were optimized, then the performances of several typical glycosidases were evaluated and their application effects in soaking process of leather making were also investigated. The results show that the optimum testing conditions are lower than 4 h of the reacting time, optimally 2 h, and lower than 40 U/mL of the enzyme concentration, optimally 0-25 U/mL based on 2 g of the substrate; the results to evaluate the properties of some glycosidases based on the established method are positively related to their applying effects in soaking. The new method with better repeatability can be used as an available tool to correctly select glycosidases and optimize process parameters for correct use. Note de contenu : - MATERIALS AND METHODS : Materials - Preparation of the hide powder substrate containing glycoconjugates - Assay of glycosidase activity based on the prepared substrate - Optimization of parameters of the testing method - Glycosidase soaking trial - RESULTS AND DISCUSSION : Parameters of the prepared hide powder substrate - Optimization of the testing conditions in detecting glycosidase activity - Evaluation of properties of typical glycosidases - Relationship between glycosidases activities to glycoconjugates and soaking effect DOI : https://doi.org/10.34314/jalca.v115i7.3836 En ligne : https://drive.google.com/file/d/1kbuXsp8wOESPhNaKvy8ct9TgkMOnJu9y/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=34328 [article]

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