An effective and harmless recycling technology for hazardous chrome-tanned leather wastes / Minghui Li in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 108, N° 2 (03-04/2024)  

[article]  inJOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 108, N° 2 (03-04/2024) . - p. 67-77 Titre : An effective and harmless recycling technology for hazardous chrome-tanned leather wastes Type de document : texte imprimé Auteurs : Minghui Li, Auteur ; Xu Zhang, Auteur ; Honghong Chen, Auteur ; Sadaqat Ali Chattha, Auteur ; Xin Yan, Auteur ; Biyu Peng, Auteur Année de publication : 2024 Article en page(s) : p. 67-77 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Agents de tannage Chimie analytique Chrome -- Recyclage Croûte (cuir) On entend par "cuir en croûte" des cuirs ayant subi les opérations jusqu'au tannage, à l'exclusion de toute opération de corroyage ou de finissage, mais qui, par opposition aux wet-blue ont été séchés. Cuirs et peaux -- Déchets -- Recyclage Cuirs et peaux -- Propriétés mécaniques Cuirs et peaux -- Propriétés physiques Déchromage Hydrolysat de collagène Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : Utilizing leather production waste to create raw materials for leather chemicals, and reintroducing it into the leather making processing, represents an ideal approach to achieving an “internal circular economy” within the leather industry. This study focuses on the reutilization of dechromed collagen fibres, obtained from chromium shavings, to generate a retanning filling. The effects of hydrolysis conditions on the viscosity, and gel strength of the dechromed collagen hydrolysates were investigated. The application effectiveness of the collagen hydrolysates with different particle sizes in the leather retanning filling process was also compared. The findings indicate that alkali hydrolysis is more conducive to producing collagen hydrolysates with a relatively higher proportion of medium and low molecular weight components, while acid hydrolysis favours the production of collagen hydrolysates rich in high molecular weight components. Additionally, collagen hydrolysates with an average particle size of 162.8 nm exhibit the best filling efficacy, imparting favorable organoleptic and physical properties to the leather. Herein, a method for preparing protein fillers, using chrome shavings as raw materials, was established, i.e., the dechromed collagen fibres (with a chromium content of approximately 33.6 mg/kg) were mixed with 2000% of water and adjusted to pH 3.0 with a small amount of sulfuric acid, and heated at 60°C with continuous stirring for 11 hours. After hydrolysis, the pH was adjusted appropriately to reuse it in the wet blue retanning filling process. The research outcomes have significant guiding implications for promoting the "internal circular economy" and sustainable development within the leather industry. Note de contenu : - EXPERIMENTS AND METHODS : Experimental materials - Dechroming of chrome shavings - Hydrolysis of dechromed collagen fibres - Performance of collagen hydrolysate as a retanning agent - Analysis and testing - RESULTS AND DISCUSSION : Preparation and performance analysis of dechromed collagen fibres materials - Influence of hydrolysis conditions on the fundamental characteristics of collagen hydrolysates - Correlation between the particle size of collagen hydrolysates and filling efficiency - Table 1 : Properties of the collagen hydrolysates - Table 2 : Physical and mechanical properties of the crust leather En ligne : https://drive.google.com/file/d/1hD0IMUh9EOcTIH7DeQDo-eDaYvoQEeci/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=40933 [article]

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An effective way to prepare high performance biomass-based fatliquoring agent - Bromination modification of rapeseed oil and its fatliquoring and flame-retardant properties / Tao Luo in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXVIII, N° 8 (08/2023)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXVIII, N° 8 (08/2023) . - p. 346-353 Titre : An effective way to prepare high performance biomass-based fatliquoring agent - Bromination modification of rapeseed oil and its fatliquoring and flame-retardant properties Type de document : texte imprimé Auteurs : Tao Luo, Auteur ; Xu Zhang, Auteur ; Biyu Peng, Auteur ; Chunxiao Zhang, Auteur ; Sadaqat Ali Chattha, Auteur Année de publication : 2023 Article en page(s) : p. 346-353 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Absorption Analyse sensorielle Biomasse Bromation Substitution dans une molécule d'un atome d'hydrogène par un atome de brome. Combustion Croûte (cuir) On entend par "cuir en croûte" des cuirs ayant subi les opérations jusqu'au tannage, à l'exclusion de toute opération de corroyage ou de finissage, mais qui, par opposition aux wet-blue ont été séchés. Cuirs et peaux -- Analyse Douceur (toucher) Essais accélérés (technologie) Essais de résilience Fourier, Spectroscopie infrarouge à transformée de Huile de colza Ignifugeants Composé chimique utilisé pour réduire l'inflammabilité. Il peut être incorporé au produit durant sa fabrication ou appliqué ultérieurement à sa surface. Produits de nourriture du cuir Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : With the implementation of Carbon Neutralization strategy, it is urgently needed to develop low-carbon leather chemicals through replacing petrochemicals with biomass-based raw materials in leather industry. To solve the problems existing in the leather fatliquored by the biomass-based fatliquoring agents made from vegetable oils with high unsaturation, such as poor storability, unpleasant odor, yellowing and possible formation of hexavalent chromium, the strategy was put forward, improving the oil saturation through the double bonds addition reaction with halogen to solve the abovementioned problems resulting from the poor oxidation resistance of oil, and increase the binding ability of the oil with leather fibers and endow the leather with flame-retardant simultaneously. In this paper, the methods of modified rapeseed oil by bromine addition and its fatliquoring and flame-retardant properties were studied. The results showed that the bromine addition reaction of rapeseed oil was easy to proceed and the iodine value of the modified oil decreased almost linearly with the added amount of bromine. The binding and antioxidant properties of the oil and the physical properties of the fatliquored leather were significantly improved with the increase degree of bromination modification. Furthermore, above mentioned unpleasant odor, yellowing and hexavalent chromium formation problems were effectively solved when the iodine value of modified fatliquors was reduced to 31 g I2/100 g. Additionally, brominemodified rapeseed oil could endow leather with good flame-retardant properties and the fatliquored leather was changed from combustible to flame-retardant material with the increasing amount of bromine in the oil. The limit oxygen index (LOI) increased from 24% to 31%, the flame combustion time decreased from 127.0 s to 4.3 s, and the flameless combustion time decreased from 28.5 s to 0.0 s. This study provided an effective way to develop biomass-based and low-carbon fatliquors based on natural unsaturated oils. Note de contenu : - MATERIALS AND METHODS : Materials - Bromination modification of rapessed oil - Preparation of leather fatliquoring agent - Application of fatliquors in the fatliquoring process - Determination of the iodine value of oils - Fourier Transform Infrared Spectroscopy (FT-IR) of oils - Absorption rate of fatliquors - Distribution of Br element and collagen fibers - Binding ability of modified oils with leather fibers - Limiting oxygen index (LOI) test of crust leather - Vertical combustion test of crust leather - Ageing test of crust leather - Odor level evaluation of crust leather - Yellowing resistance property of crust leather - Softness and physical properties of crust leather - RESULTS AND DISCUSSION : Preparation and characterization of bromine-modified rapessed oil - Absorption rate of oil and its distribution in leather - Effect of rapessed oil modification degree on the properties of fatliquored leather - Table 1 : Absorption rate of fatliquors - Table 2 : Oil extraction test results - Table 3 : Leather vertical combustion test results - Table 4 : Leather softness test results DOI : https://doi.org/10.34314/jalca.v118i8.8092 En ligne : https://drive.google.com/file/d/12reqFQXSFwDRWiNVXr_pFHQVWb2biTpR/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=39674 [article]

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Application of acidic protease in the pickling to simplify the pelt bating process / Xu Zhang in JOURNAL OF LEATHER SCIENCE AND ENGINEERING, Vol. 3 (Année 2021)  

[article]  inJOURNAL OF LEATHER SCIENCE AND ENGINEERING > Vol. 3 (Année 2021) . - 14 p. Titre : Application of acidic protease in the pickling to simplify the pelt bating process Type de document : texte imprimé Auteurs : Xu Zhang, Auteur ; Mengchu Gao, Auteur ; Sadaqat Ali Chattha, Auteur ; Yiwen Zhu, Auteur ; Biyu Peng, Auteur ; Yongbin Ye, Auteur Année de publication : 2021 Article en page(s) : 14 p. Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Confitage Le confitage est une action biochimique effectuée au moyen de produits enzymatiques, qui a pour but de dégrader les fibres élastiques, contribuant ainsi à augmenter la souplesse du cuir. En outre, les enzymes complètent la dégradation des résidus épidermiques, donnant ainsi une fleur plus propre et plus lisse. Croûte (cuir) On entend par "cuir en croûte" des cuirs ayant subi les opérations jusqu'au tannage, à l'exclusion de toute opération de corroyage ou de finissage, mais qui, par opposition aux wet-blue ont été séchés. Cuirs et peaux Peptidases Picklage Le picklage consiste à faire absorber à la peau en tripe une quantité importante d'acide, en présence de sel neutre (NaCl) pour réprimer le gonflement que provoquerait l'acidité du milieu. Trypsine La trypsine (EC 3.4.21.4) est une enzyme digestive du suc pancréatique qui a pour rôle de digérer les protéines. Elle est synthétisée par le pancréas sous forme de trypsinogène (proenzyme inactive), puis stockée dans les vésicules enzymatiques des cellules acineuses d'où elle est excrétée au moment de la digestion. L'activation du trypsinogène en trypsine est le résultat de l'hydrolyse d'un propeptide sous l'action de l'entérokinase ou par un effet d'autoactivation de la trypsine par elle-même. La cholecystokinine-pancréozymine active la sécrétion des enzymes (donc de la trypsine) dans le suc pancréatique. La trypsine est une endoprotéase qui hydrolyse les liaisons peptidiques dans lesquelles un acide aminé basique (Lys-|-Xaa ou Arg-|-Xaa) engage sa fonction acide (sauf dans le cas où l'acide aminé suivant (schématisé ici par "Xaa") est une Proline). Elle coupe en C-terminal de ces acides aminés. En d'autres mots, elle transforme les chaînes polypeptides en chaînes protéiques plus courtes pour permettre la digestion. Efficace à pH 7,5 - 8,5, elle est inactivée et digérée en quelques heures à pH neutre (=7) dans l'intestin. La trypsine participe à l'activation d'autres enzymes comme l'alpha-chymotrypsine par coupure hydrolytique de la chaîne polypeptidique du chymotrypsinogène. Cette enzyme sert également lors de la 2e semaine du développement embryonnaire humain. Elle est sécrétée par le trophoblaste afin de digérer la zone pellucide entourant le blastocyste. Ce phénomène s'appelle l'éclosion. Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Traditionally, universally used pelt bating technologies rely on the application of trypsin, neutral and alkaline microbial proteases but suffer from complicated operation, limited bating efficiency and unsatisfactory leather performance. Therefore, devising a new pelt bating approach to achieve high bating efficiency and excellent leather performance has always been wished for by the leather industry. To pursue this goal, years of persistent research work enabled us to develop a novel approach for pelt bating by means of acidic proteases in pickling process. Initially, basic enzymatic characteristics and bating effectiveness of several typical acidic proteases in pelt pickling medium were investigated; then, the bating effectiveness through the quantitative characterization of protease activity of the optimal acidic protease was compared with that of the conventional bating enzyme. The results indicated that all of the selected acidic proteases had good salt-tolerance and exhibited optimum activity at pH 3.0–4.0. The novel pickling-bating method based on microbial origin acidic protease L80A led to an outstanding performance on pelt bating at the dosage of 150 U/mL of collagenolytic activity. The bating effectiveness of acidic protease L80A was comparable to and even better than that of trypsin BEM due to its moderate proteolytic ability. Moreover, the deep and even penetration of acidic protease in the pelt permitted it to produce soft, organoleptically stable and overall better quality crust leather than that of the conventional trypsin bating method. Additionally, pelt bating was performed along with the pickling process without extra inactivation and washing operation, making the bating operation more efficient, economical, and environment friendly. Results had made us to conclude that this cutting-edge acidic proteases based pickling-bating method could be the first step/ way forward to replace the decades-old traditional pelt bating technology. Note de contenu : - MATERIALS AND METHODS : Materials - Assay of proteolytic activity on casein substrate - Assay of proteolytic activity on collagen fiber substrate - Effect of salt concentration on the collagenolytic activity of acidic proteases - Bating pickling pelt with typical proteases - Comparison of the bating effectiveness of acidic protease L80A and trypsin BEM - Determination of soluble protein (SP) concentration in bating liquor - Determination of hydroxyproline concentration in bating liquor - Determination of chromium content in spent tanning liquors and wet blue - Histological analysis of collagen and elastin fiber - Scanning electron microscopy (SEM) analysis - Test of softness and physical properties of crust leather - RESULTS : Proteolytic characteristics of typical acidic proteases - Comparison bating effectiveness of different acidic proteases in pickling process - Relationship between collagenolytic activity and bating effect of pickling pelts - Comparison of bating effectiveness of the novel pickling-bating and conventional trypsin bating method - Table 1 The selected proteases - Table 2 Enzymatic characteristics of acidic proteases (25 ℃, pH 3.5) - Table 3 Amounts of proteases, soluble protein, hydroxyproline in the bating liquor and the softness of crust leather treated by the same dosage of caseinolytic activity (25℃, pH 3.5) - Table 4 Amounts of proteases, soluble protein, hydroxyproline in the bating liquor and the softness of crust leather treated by the same dosage of collagenolytic activity (25℃, pH 3.5) - Table 5 Relation of the softness and physical properties of the crust leathers to the collagenolytic activity of protease L80A (25℃, pH 3.5) - Table 6 Amounts of protease and testing results of the effluents and crust leathers DOI : https://doi.org/10.1186/s42825-021-00068-x En ligne : https://link.springer.com/content/pdf/10.1186/s42825-021-00068-x.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=37552 [article]

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Exploration of the diffusion, binding and crosslinking of chromium complex within hides during chrome tanning / Chunxiao Zhang in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXIV, N° 5 (05/2019)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXIV, N° 5 (05/2019) . - p. 180-188 Titre : Exploration of the diffusion, binding and crosslinking of chromium complex within hides during chrome tanning Type de document : texte imprimé Auteurs : Chunxiao Zhang, Auteur ; Jieming Hu, Auteur ; Desheng Yu, Auteur ; Cong Xia, Auteur ; Sadaqat Ali Chattha, Auteur ; Biyu Peng, Auteur Année de publication : 2019 Article en page(s) : p. 180-188 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Acides carboxyliques Cuirs et peaux -- Analyse Diffusion (physique) Eaux usées -- Analyse Formiate de sodium Formique, Acide Liaisons chimiques pH Picklage Le picklage consiste à faire absorber à la peau en tripe une quantité importante d'acide, en présence de sel neutre (NaCl) pour réprimer le gonflement que provoquerait l'acidité du milieu. Sulfurique, Acide Tannage au chrome Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : Understanding the persuasive mechanisms of the accessibility and interactions of chromium complex with collagen is an important fundamental issue for maximizing the utilization of chromium during the transformation of collagen to leather by chrome tanning technology. This study details these mechanisms through process monitoring of the effects of technical conditions of chromium diffusion and its binding with the collagen matrix. The results indicated that there was no discernible impact of carboxylic masking agents on both diffusion and binding behavior of chromium complexes at low pH before basification, but it portentously declined the total chromium absorption at the end of chrome tanning. The results made known that in the course of chrome tanning, the higher pH conditions encouraged the diffusion and binding behavior of chromium complexes with collagen matrix not only before but after the basification as well. Chrome tanning at high pH did not cause excessive surface tanning effects of the leather, but the WAXD study indicated that there was much more crosslinking (both intra and inter triple helix) of collagen fibers in the inner layers of leather matrix, which had a robust impact on the fullness, tightness and stiffness of the finished leather. These findings could provide more theoretical foundations for the development of high exhaustion chrome tanning technology as a method for reduced chromium emission and improved the quality of leather during leather manufacture. Note de contenu : - EXPERIMENTAL : Materials and instruments - Pickling and chrome tanning with carboxylic acid and sulfuric acid - Pickling and chrome tanning with different formic acid dosages - Chrome tanning with different sodium formate dosages - Chrome tanning at varying initial pH with sulfuric acid pickling - Determination of chromium concentration in spent tanning liquors - Determination of chromium content in leather - Scanning Electron Microscopy (SEM) analysis - Scanning Electron Microscope-X-ray energy dispersive spectroscopy (SEM-EDS) analysis - Wide-angle X-ray diffraction (WAXD) studies - RESULTS AND DISCUSSIONS : Influence of the molecular structure of carboxyl acid on chrome tanning - Effects of the dosages of carboxyl groupe on chrome tanning - Influence of pickling pH on chrome tanning En ligne : https://drive.google.com/file/d/1ZX8MWYG68fy_UO8IzDkwdpnHPv1SQBjW/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=32478 [article]

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Identification of gaps in knowledge and practices affecting the quality of skins/hides on the eve of Eid-ul-Adha in Pakistan / Sadaqat Ali Chattha in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXVIII, N° 11 (11/2023)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXVIII, N° 11 (11/2023) . - p. 474-477 Titre : Identification of gaps in knowledge and practices affecting the quality of skins/hides on the eve of Eid-ul-Adha in Pakistan Type de document : texte imprimé Auteurs : Sadaqat Ali Chattha, Auteur ; Abdul Rehman, Auteur ; Agha Saiddain, Auteur ; Biyu Peng, Auteur Année de publication : 2023 Article en page(s) : p. 474-477 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Cuirs et peaux -- Conservation Cuirs et peaux -- Industrie -- Pakistan Cuirs et peaux -- Qualité Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : The 2nd largest export-oriented leather industry of Pakistan fulfills its 40% annual raw material demand during the eve of Eid-ul-Adha on which 6.0-8.0 million best-quality animals are being slaughtered within three days. However, a major portion of raw skins and hides (RSH) gets putrefied due to delayed preservation. The aim of this study was to explore the knowledge, attitude, and practices about RSH quality and its preservation in the general public from Punjab, Pakistan. A cross-sectional survey was conducted from February to May 2022 in which 948 individuals from 12 districts participated. Out of six, the overall mean knowledge score of the respondents about RSH preservation was 3.69±1.6 (61.5%). More than half (52.3%) of the respondents answered that salt could be an appropriate option to preserve RSH. However, contrary to their knowledge, only 4.2% (40/948) of respondents applied it correctly. About 56.6% of respondents donated RSH to religious institutes. The mean knowledge and practice scores of the respondents from rural areas were significantly higher (p<0.001) than those from urban areas (knowledge: 4.03 vs. 3.13; practice: 4.9 vs. 3.9). The knowledge and practice of preserving RSH using common salt application significantly increased (p<0.001) with the level of education (ORs: never attended school=0.08; schoollevel education=0.22 & College/University education=1.0). In conclusion, almost half of the respondents had knowledge about RSH preservation; however, only a few (4%) practiced it correctly. These findings will be helpful to design effective and targeted interventions to improve the knowledge and practices of the public for better RSH preservation. Note de contenu : - METHODOLOGY : Study area and data collection - Data analysis - RESULTS : Demographic characteristics of the respondents - Respondents' knowledge - Respondent's attitudes and practices - Association of demographic factors with knowledge and preservation practices - Association of demographic characteristics with identified practices - DISCUSSION : Knowledge related to RSH preservation - Attitude and preactices related to RSH preservation - Table 1 : Description of questions included in KAP survey along with correct and incorrect answers - Table 2 : Demographic characteristics of respondents, general questions, and resopnses to questions related to knowledge, attitude, and practices about raw skins/hides preservation - Table 3 : Linear regression model to find out the association of education and locality with knowledge and practice about RSH preservation - Table 4 : Summary of multivariable logistic regression model to find out the association of education and locality with identified practices - Table 5 : Per annum loss (million PKR) due to RSH wastage on the eve of Eid-ul-Adha - Table 6 : Per annum estimated expense (million PKR) to save RSH on the eve of Eid-ul-Adha DOI : https://doi.org/10.34314/jalca.v118i11.8241 En ligne : https://drive.google.com/file/d/1IR6brwNaC56oATm2OKlUhvR6h5iC3XbB/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=40046 [article]

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Key mechanism of enzymatic dehairing technology for leather-making : permeation behaviors of protease into animal hide and the mechanism of charge regulation / Mengchu Gao in COLLAGEN AND LEATHER, Vol. 5 (2023)  

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A novel recycling technology for chrome shavings : Application of non-swelling acids during dechroming process / Sadaqat Ali Chattha in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXIX, N° 8 (08/2024)  

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A rapid method for measuring elastin degradation and its application in leather manufacturing / Xu Zhang in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXV, N° 8 (08/2020)  

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