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Fluorescent tracing of dialdehyde sodium alginate tanning agent in leather matrix / Min Zhu in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXVIII, N° 9 (09/2023)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXVIII, N° 9 (09/2023) Titre : Fluorescent tracing of dialdehyde sodium alginate tanning agent in leather matrix Type de document : texte imprimé Auteurs : Min Zhu, Auteur ; Yudan Yi, Auteur ; Jia Fu, Auteur ; Yunhang Zeng, Auteur ; Ya-Nan Wang, Auteur Année de publication : 2023 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Agents de tannage Alginate de sodium dialdéhyde Cuirs et peaux -- Analyse Traçage fluorescent Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : Dialdehyde polysaccharides possess a sustainable nature and good tanning performance. However, the lack of specific detectable groups in their molecular structure results in the difficulty in the determination of the location of dialdehyde polysaccharides in leather fiber networks. In this study, dialdehyde sodium alginate (DSA) tanning agent was fluorescent labeled by 5-(4,6-dichlorotriazinyl) aminofluorescein (DTAF). The purified DTAF–DSA showed high and stable fluorescent intensity at emission wavelength of 515.2 nm when the pH was over 6.0, and the temperature was in the range of 20°C to 50°C. DTAF–DSA was used in tanning and tracked using fluorescence microscopy. Its penetration in the fiber network could be clearly visualized, and its distribution in leather differed with the molecular weight of DSA. As a result, this fluorescence tracing technique could display the mass transfer behavior of dialdehyde polysaccharide tanning agents in leather matrix, which will provide underlying data for tanning mechanism exploration. Note de contenu : - EXPERIMENTAL : Materials - Preparation of DSA - Fourier Transform Infrared (FT-IR) spectroscopy analysis - Determination of aldehyde group content of DSA - Preparation of DTAF labeled DSA (DTAF-DSA) - Analysis of fluorescence emission spectra - Thermal and pH stability of DTAF-DSA - Determination of molecular weight - Observatio of DTAF-DSA during tanning - RESULTS AND DISCUSSION : Characteristics of DSA - Characteristics of DTAF-DSA - Fluorescent tracing of DTAF-DSA in leather - Table 1 : Molecular weight of DSA and DTAF-DSA DOI : https://doi.org/10.34314/jalca.v118i9.8189 En ligne : https://drive.google.com/file/d/102ZOVOqbg3NIxrQXuw1XmjwRI5mq8gYX/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=39826 [article]

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Resource utilization of bovine hair recycling from enzymatic unhairing during leather manufacturing : Alkali-protease synergistic preparation of keratin and its in vitro antioxidant activity / Ting Liu in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXVIII, N° 9 (09/2023)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXVIII, N° 9 (09/2023) . - p. 367-378 Titre : Resource utilization of bovine hair recycling from enzymatic unhairing during leather manufacturing : Alkali-protease synergistic preparation of keratin and its in vitro antioxidant activity Type de document : texte imprimé Auteurs : Ting Liu, Auteur ; Chunxiao Zhang, Auteur ; Xu Zhang, Auteur ; Biyu Peng, Auteur ; Mengchun Gao, Auteur Année de publication : 2023 Article en page(s) : p. 367-378 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Bases (chimie) Cuirs et peaux de bovins Epilage enzymatique Extraction (chimie) Hydrolyse enzymatique kératines La kératine est une protéine, synthétisée et utilisée par de nombreux êtres vivants comme élément de structure, et également l'exemple-type de protéine fibreuse. La kératine est insoluble, et peut être retrouvée sur l'épiderme de certains animaux, notamment les mammifères, ce qui leur garantit une peau imperméable. Parfois, lors d'une friction trop importante, la kératine se développe à la surface de la peau formant une callosité. Les cellules qui produisent la kératine meurent et sont remplacées continuellement. Les morceaux de kératine qui restent emprisonnés dans les cheveux sont couramment appelés des pellicules. La molécule de kératine est hélicoïdale et fibreuse, elle s'enroule autour d'autres molécules de kératine pour former des filaments intermédiaires. Ces protéines contiennent un haut taux d'acides aminés à base de soufre, principalement la cystéine, qui forment un pont disulfure entre les molécules, conférant sa rigidité à l'ensemble. La chevelure humaine est constituée à 14 % de cystéine. Il y a deux principales formes de kératines : l'alpha-kératine, ou α-keratin, présente chez les mammifères notamment, dont l'humain, et la bêta-kératine, ou β-keratin, que l'on retrouve chez les reptiles et les oiseaux. Ces deux types de kératines ne présentent clairement pas d'homologie de séquence. Chez l'être humain, la kératine est fabriquée par les kératinocytes, cellules se trouvant dans la couche profonde de l'épiderme. Les kératinocytes absorbent la mélanine (pigment fabriqué par les mélanocytes), se colorent et ainsi cette pigmentation de l'épiderme permet de protéger les kératinocytes des rayons ultraviolets du Soleil. (Wikipedia) Peptidases Poils -- Recyclage Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : With the development of enzymatic unhairing technology in the leather industry, enhancing the recycling of bovine hair is a new issue emerging in leather-making. In this work, the effects of alkali concentration, time, and temperature in the pretreatment, as well as enzyme dosage, time, temperature, and pH in the following treatment on the dissolution performance and keratin yield of bovine hair were investigated. Hence, the extraction process of keratin from bovine hair by the alkali-enzyme method was optimized. The results sho that the optimal conditions for the keratin extraction are as follows: for the pretreatment with alkali, the alkali concentration is 0.4 M, the pretreatment time is 1.0 h, the pretreatment temperature is 65°C, and for the following enzymatic treatment, the enzyme dosage is 3324 U/g bovine hair, the action time is 4.0 h, action temperature is 45°C, and the pH is controlled between 8.5-11.5. Compared with the alkali method, the alkali-enzyme method increases the keratin yield from 24.4% to 58.1%, and the alkali dosage is reduced by 50%. The prepared keratin had high in vitro antioxidant activity, which provided a new idea for the resource utilization of bovine hair waste. Note de contenu : - MATERIALS AND METHODS : Pretreating the bovine hair with differing concentration of NaOH before enzymatic hydrolysis - Effect of alkaline pretreating time on enzymatic hydrolysis of bovine hair - Effect of alkaline pretreating temperature on enzymatic hydrolysis of bovine hair - Effect of protease dosage on enzymatic hydrolysis of bovine hair - effect of pH on enzymatic hydrolysis of bovine hair - Effect of time on enzymatic hydrolysis of bovine hair - Effect of temperature on enzymatic hydrolysis of bovine hair - orthogonoal experiments for hydrolysis of bovine hair by alkali-enzyme synergy - Determination of bovine hair solubility and keratin extraction rate - Determination of molecular weight - Analysis of amino acid composition of bovine hair keratin - Determination of DPPH scavenging activity - Determination of ABTS scavenging activity - RESULTS AND DISCUSSION : Optimization of alkali pretreatment parameters - Optimization of enzymatic hydrolysis parameters - Optimization of orthogonal experiment - Analysis and evaluation of the keratin extracted from bovine hair - Amino acid composition of bovine hair keratin - DPPH free radical scavenging ability - ABTS free radical scavenging ability - Table 1 : Horizontal table of orthogonal experimental factors - Table 2 : Molecular weight distribution of keratin with differing NaOH concentration - Table 3 : Results of orthogonal experiment of keratin preparation obtained from bovine hair by alkaly-enzyme method - Table 4 : Comparison of keratin extraction of alkali-enzyme and alkaline hydrolysis method - Table 5 : Molecular weight distribution of keratin - Table 6 : Analysis of amino acid compositio of bovine hair and keratin (mg/100 mg - Table 7 : DPPH free radical scavenging abilities of keratin under different concentrations - Table 8 : ABTS free radical scavenging abilities of keratin under different concentrations DOI : https://doi.org/10.34314/jalca.v118i9.8190 En ligne : https://drive.google.com/file/d/1_PY7W_CJUD1RdJJrotAmABi-_4Cq_QnI/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=39827 [article]

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Graphene oxide modified dye : Preparation and its application in the gyeing of biomass-derived aldehyde-tanned chrome-free leather / Song Guo in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXVIII, N° 9 (09/2023)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXVIII, N° 9 (09/2023) . - p. 379-385 Titre : Graphene oxide modified dye : Preparation and its application in the gyeing of biomass-derived aldehyde-tanned chrome-free leather Type de document : texte imprimé Auteurs : Song Guo, Auteur ; Wei Ding, Auteur ; Xiaoyan Pang, Auteur ; Zhiwen Ding, Auteur Année de publication : 2023 Article en page(s) : p. 379-385 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Aldéhydes Un aldéhyde est un composé organique, faisant partie de la famille des composés carbonylés, dont l'un des atomes de carbone primaire (relié au plus à 1 atome de carbone) de la chaîne carbonée porte un groupement carbonyle. L'aldéhyde le plus simple est le formaldéhyde (ou méthanal), aussi appelé formol lorsqu'il est en solution aqueuse. Un aldéhyde dérive formellement d'un alcool primaire (oxydation) dont le groupement hydroxyde -OH est en bout de chaîne et se forme suite à l'enlèvement de deux atomes H d'où le nom "alcool déshydrogéné" ou aldéhyde. Caractérisation Colorants -- Absorption Colorants réactifs Cuirs et peaux -- Teinture Oxyde de graphène Photostabilité Statistique Tannage chrome free Tannage synthétique Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : In this work, a graphene oxide (GO) modified small molecule reactive dye was prepared and further applied in the dyeing of the biomass-derived aldehyde tanning agent (BAT) tanned chromefree leather for clarifying its application properties. The modified dye (GORD) was prepared by introducing Reactive Red180 (RRD180) onto the surface of GO using the dehydration condensation method. GORD was characterized using FTIR spectroscopy, UVVis spectroscopy, and thermogravimetric analysis. The uptake ratios and the color fastness to sunlight of the GORDs were tested. FTIR and amino group consumption tests showed that RRD-180 was successfully grafted onto the GO lamellar structure, and the color rendering feature of the GORD was similar to that of RRD-180. The introduction of GO reduced the initial degradation temperature of GORD in the second stage (from 170ºC to 150ºC), but this did not affect the shrinkage temperature of the dyed leather. The uptake ratios of RRD-180 and GORDs were both higher than 90%, indicating that GO modification did not affect the reactive dye’s uptake by leather. Importantly, the coloring fastness to sunlight of the grain and flesh sides of the dyed leather was improved, indicating that the GORD endowed the dyed leather with a certain UV-shielding performance. This work provides new ideas for promoting the industrial applications of GO and GO-based functional materials in chrome-free leather manufacturing. Note de contenu : - EXPERIMENTAL : Materials - Preparation of GORD - Dyeing of leather using GORD - Characterizations - Statistical analysis - RESULTS AND DISCUSSION : Structure characterizations - Application performance of GORD in leather dyeing - Table 1 : The content of amino groups in RRD-180 and GORD - Table 2 : The Ts of the dyed leather samples DOI : https://doi.org/10.34314/jalca.v118i9.8191 En ligne : https://drive.google.com/file/d/1xZ22nk1Yfo4NdPYMZgNxBiew8IiSTWAl/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=39828 [article]

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Investigation of high penetration and dispersion of functional nanoparticles in leather / Zhou Ji-Bo in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXVIII, N° 9 (09/2023)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXVIII, N° 9 (09/2023) . - p. 386-395 Titre : Investigation of high penetration and dispersion of functional nanoparticles in leather Type de document : texte imprimé Auteurs : Zhou Ji-Bo, Auteur ; Nan Sun, Auteur ; Xue-pin Liao, Auteur ; Bi Shi, Auteur Année de publication : 2023 Article en page(s) : p. 386-395 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Charges (matériaux) Cuirs et peaux -- Propriétés mécaniques Matériaux -- Propriétés fonctionnelles Nanoparticules Pénétration (physique) Polyacryliques Retannage Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : The use of nanoparticle-based functional leather products has stimulated sustainable growth of the conventional leather industry. However, functional nanoparticles (FNPs) face challenges to be well penetrated and dispersed in leather because of their aggregation and mismatch charges with leather. In this study, the acrylic resin (AR) retanning agent, which was originally utilized in leather processing, was applied for the modification of FNPs. It has been demonstrated that AR can improve the electrostatic and steric repulsion among nanoparticles, inhibiting their aggregation and ensuring their penetration and dispersion in leather. Because of the limitation of leather porosity, the maximum loading amount for FNPs was about 40wt% (based on leather weight). The leather got higher results in fullness, thickening ratio, and tensile strength when the loading amount of FNPs was 11.25%. Moreover, the proposed approach in this study can be used well for other types of FNPs loaded in leather, suggesting its broad applicability. Note de contenu : - MATERIALS AND METHODS : Materials - Modification of FNPs - Physicochemical properties of modified FNPs - Penetration of modified FNPs in leather - Effect of different factors on the penetration of FNPs in leather - Influence of FNPs on the mechanical performance of leather - RESULTS AND DISCUSSION : Basic properties of modified FNPs - Analysis of the dispersibility of modified Gd2O3FNPs in water - Penetration of pristing/modified FNPs in leather - Effect of different factors on the penetration and dispersion of modified FNPs in leather - Influence of modified FNPs on the orgnaoleptic and physical performance of leather - Table 1 : Retanning processes DOI : https://doi.org/10.34314/jalca.v118i9.8192 En ligne : https://drive.google.com/file/d/10908iVZoLJzZjsvx-zHjmXixuJudFNla/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=39829 [article]

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