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Regeneration of raw hide water balance by electrochemically activated water / A. H. Danylkovych in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXV, N° 10 (10/2020)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXV, N° 10 (10/2020) . - p. 355-364 Titre : Regeneration of raw hide water balance by electrochemically activated water Type de document : texte imprimé Auteurs : A. H. Danylkovych, Auteur ; O. I. Korotych, Auteur ; O. Romaniuk, Auteur Année de publication : 2020 Article en page(s) : p. 355-364 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Caractérisation Cuir et peau de cheval Cuirs et peaux -- Analyse Cuirs et peaux -- Propriétés mécaniques Electrochimie Humidité -- Absorption:Eau -- Absorption Peaux brutes -- Trempe Solutions aqueuses (chimie) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Improving the collagen structure, which was impacted by the curing process, increases the efficiency of all subsequent structural transformations during leather production and results in the formation of a high-quality leather material. Herein, we studied the process of soaking green-salted horsehides in electrochemically activated aqueous solutions and the properties of resulting chrome-tanned leather. It was found that the process of soaking horsehides can be effectively carried out using an electrochemically activated solution (ECAS) – a mixture of catholyte and anolyte at a volume ratio of 5 : 1. Using this soaking solution, sodium sulfide (an environmentally harmful reagent), sodium carbonate, and detergent can be completely excluded from the technological solution. The use of ECAS at the soaking stage effectively regenerates the water balance of horsehides while maintaining a stable pH during the soaking process and increases the efficacy of liming and all subsequent processes. Considering the prominent structural differences (density and thickness) between the front and shell of horsehide, the developed method, which utilize ECAS for soaking, allows the entire process to be carried out on uncut horse hides instead of processing two parts separately, which is normally required. The chrome-tanned leather produced by the developed method in semi-industrial conditions has elastic-plastic properties which are superior compared to the leather produced by current technology. The developed method also results in increasing the area yield by 2.5%. The resulting elastic leather can be used for manufacturing a variety of articles, including clothing, accessories, and footwear. Note de contenu : - MATERIALS AND METHODS : Laboratory testing - Semi-industrial testing - Physicochemical characterization - RESULTS AND DISCUSSION : Structure and composition of raw hides - Water absorption by horsehide - Properties of the horse leather produced in semi-industrial conditions DOI : https://doi.org/10.34314/jalca.v115i10.4173 En ligne : https://drive.google.com/file/d/1bLcuV1I1rbEzlX_BGYBxTNFiJbEz5PRL/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=34610 [article]

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Antibacterial and anti–biofilm activities of acetone extracts of Usnea sp. against mixed cultures of bacteria from soak liquor samples and tank surfaces / Didem Berber in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXV, N° 10 (10/2020)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXV, N° 10 (10/2020) . - p. 365-372 Titre : Antibacterial and anti–biofilm activities of acetone extracts of Usnea sp. against mixed cultures of bacteria from soak liquor samples and tank surfaces Type de document : texte imprimé Auteurs : Didem Berber, Auteur ; Ipek Türkmenoglu, Auteur ; Nüzhet Cenk Sesal, Auteur Année de publication : 2020 Article en page(s) : p. 365-372 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Acétone L'acétone en chimie, (nom officiel IUPAC propanone, aussi connue sous les noms de diméthylcétone, 2-propanone, propan-2-one et béta-cétopropane), de formule chimique CH3COCH3 est le composé le plus simple de la famille des cétones. C'est un isomère du propanal.L’acétone est un liquide transparent, inflammable, d'odeur caractéristique (plutôt fruitée). Sa température de fusion est de -95,4 °C et celle d'ébullition de 56,53 °C. Elle a une densité relative de 0,819 (à 0 °C). C'est un composé très soluble dans l'eau (c'est une molécule polaire à chaîne carbonée courte), dans l'éthanol et dans l'éther. L'acétone est le dérivé le plus simple de la série des cétones aliphatiques et la présence de la double liaison carbone-oxygène lui confère l'essentiel de sa réactivité. Antibactériens Biofilms Cuirs et peaux -- Conservation Lichens et constituants Peaux brutes -- Trempe Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Long-term or improper use of antibacterial agents utilized in the soaking process has led to the resistance of some bacteria in the leather industry. New agents may be the solution to combat these antibacterial resistant bacteria in the soaking process. As a natural resource, lichens are known to have many biological activities. In previous studies, we demonstrated that the acetone extracts of several lichen species including Usnea sp. may have potential antibacterial and anti–biofilm properties against some Bacillus species, which were isolated from different soak liquor samples. In the present study, it was questioned whether the same bioactivities of acetone extracts of Usnea sp. can be seen in the mixed cultures of tank surface samples and pre-and main soak liquor samples, which were obtained from different tanneries. Although the extracts did not show noteworthy antibacterial effect against one of the tank surface samples (inhibition ratios; 6.5–16.22 %), inhibition percentages were detected as 69.32 and 46.33 at the concentrations of 240 and 120 µg/mL for the other tank surface sample. The anti-biofilm potential of the extracts was tested on the sample where the antibacterial activity of the extracts was not observed. One of the mixed culture of samples from the tank surface could not be inhibited by the extracts in terms of bacterial growth. However, the extracts were tested on this biofilm-forming sample and detected more than 50% inhibition. Furthermore, the extracts inhibited the growth of the mixed culture of bacteria from pre-soak liquor by the percentages of 78.96, 61.5, 51.3, 45.1, and 33.4 at the concentrations of 240, 120, 60, 30 and 15 µg/mL, respectively. On the other hand, the same antibacterial efficacy could not be observed in the other mixed culture from pre-soak liquor sample obtained from a different tannery whereas this sample formed a biofilm structure. The mixed culture of samples from the main soaking process was inhibited by the extracts at the inhibition percentages of 62.13–78.17 at the concentrations of 240- 30 µg/mL. Similar results were also obtained for the other sample (64.6–76.5%) from main soak liquor sample obtained from a different tannery. In conclusion, lichen extracts may have potential antibacterial and anti-biofilm properties against the mixed culture of bacteria from tank surface, pre-and main soak liquor samples and maybe alternatively utilized in the leather industry. Note de contenu : - Lichen samples - Extraction of lichen samples - Samples - Antibacterial assays - Anti-biofilm assays DOI : https://doi.org/10.34314/jalca.v115i10.4174 En ligne : https://drive.google.com/file/d/1bymqwwbC7z2LVax6C5nzF0dCA1ucYOYl/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=34611 [article]

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Studies on collagen structure using X-ray scattering on a closed-loop leather process / Yi Zhang in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXV, N° 10 (10/2020)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXV, N° 10 (10/2020) . - p. 373-379 Titre : Studies on collagen structure using X-ray scattering on a closed-loop leather process Type de document : texte imprimé Auteurs : Yi Zhang, Auteur ; Jenna Buchanan, Auteur ; Jiasheng Su, Auteur ; Zhuangdou Zhang, Auteur ; Geoff Holmes, Auteur ; Sujay Prabakar, Auteur Année de publication : 2020 Article en page(s) : p. 373-379 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Collagène -- Analyse Cuirs et peaux -- Déchets -- Recyclage Diffractométrie de rayons X Diffusion aux petits angles Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Waste management in leather processing is crucial in limiting the excess use of hazardous materials that lead to environmental pollution and health concerns. A closed-loop approach was developed to recycle the spent solutions from leather processing to reduce waste in the effluent. The structural changes of collagen that accompany such processing are yet to be studied and is crucial in understanding the closed-loop process and its subsequent leather properties. In this study, we analysed the collagen structure at different processing stages across the closed-loop approach using synchrotron small-angle X-ray scattering. An increased filling effect in the collagen matrix was observed and attributed to the residual organic component and chromium species in recycled spent solutions. A high uptake of chromium was also observed from the increased scattering intensity from leathers treated with recycled chrome solution, indicating its efficient use. Additionally, the changes in scattering intensity from keratin and lipids indicated an effective unhairing process. Such findings on collagen structure changes will support the development of more environmentally and economically sustainable processing methods to benefit the leather industry. Note de contenu : - Sample preparation - Small-angle X-ray scattering (SAXS) DOI : https://doi.org/10.34314/jalca.v115i10.4175 En ligne : https://drive.google.com/file/d/1B-AuPs8xRaBRWnOHDBZ7bKgDVRzJMpeE/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=34612 [article]

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Mechanism of collagen processed with urea determined by thermal degradation analysis / Keyong Tang in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXV, N° 10 (10/2020)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXV, N° 10 (10/2020) . - p. 380-389 Titre : Mechanism of collagen processed with urea determined by thermal degradation analysis Type de document : texte imprimé Auteurs : Keyong Tang, Auteur ; Weilin Li, Auteur ; Jie Liu, Auteur ; Cheng-Kung Liu, Auteur ; Hongbo Pan, Auteur Année de publication : 2020 Article en page(s) : p. 380-389 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Collagène Collagène -- Détérioration Cuir nappa Pyrolyse La pyrolyse est la décomposition ou thermolyse d'un composé organique par la chaleur pour obtenir d'autres produits (gaz et matière) qu'il ne contenait pas. L'opération est réalisée en l'absence d'oxygène ou en atmosphère pauvre en oxygène pour éviter l'oxydation et la combustion (L’opération ne produit donc pas de flamme). Il s'agit du premier stade de transformation thermique après la déshydratation. Elle permet généralement d'obtenir un solide carboné, une huile et un gaz. Elle débute à un niveau de température relativement bas (à partir de 200 °C) et se poursuit jusqu'à 1 000 °C environ. Selon la température, la proportion des trois composés résultants est différente. Urée Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : During the beamhouse process for nappa leather, pelts are usually limed with amino compounds such as urea, ethylenediamine, and triethanolamine. However, the interaction between amino compounds and collagen is not well known. In this work, collagen fibers were soaked in various concentrations of urea and the thermal degradation of collagen fibers were studied by the methods Horowitz-Metzger and Coats-Redfern. The mechanism of the reaction between urea and collagen fibers is discussed, wherein the thermal degradation activation energy first decreases and then increases. The lowest thermal degradation activation energy of urea processed collagen appears at 2-3 mol/L urea, suggesting that the stability of collagen is the poorest when the pelt is processed in the urea solution. At the urea concentration above 6 mol/L, the thermal degradation activation energy of the sample is similar to samples without urea processing and the higher concentrations does not have the same effect as lower concentrations of urea. The collagen fibers with a urea processing history were washed to remove the urea in them, and the samples were studied again for their thermal degradation behavior. The results indicated that the thermal degradation activation energy of the collagen fibers might recover to the unprocessed level. Therefore, it was suggested that the reaction between urea molecules and collagen fibers is reversible. Urea molecules might help to destroy some of the hydrogen bonds between collagen peptides in the urea solution. After the urea is washed out, the structure of the collagen will return to its original state, because the hydrogen bonds might be reconstructed. Note de contenu : - EXPERIMENTAL : Materials and apparatus - Preparation of urea solutions - Preparation of different CCFs - TG/DTG analysis and data processing - RESULTS AND DISCUSSION : Thermal degradation behaviors of urea processed collagen fibers - Influence of water washing on the urea-processed CCFs DOI : https://doi.org/10.34314/jalca.v115i10.4172 En ligne : https://drive.google.com/file/d/1nmmnQ02Lho0CulCfzsKaRlV-3YIetnwB/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=34613 [article]

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