Determination of free formaldehyde in leather chemicals / Yudan Yi in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXIV, N° 10 (10/2019)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXIV, N° 10 (10/2019) . - p. 382-390 Titre : Determination of free formaldehyde in leather chemicals Type de document : texte imprimé Auteurs : Yudan Yi, Auteur ; Wei Ding, Auteur ; Ya-Nan Wang, Auteur ; Bi Shi, Auteur Année de publication : 2019 Article en page(s) : p. 382-390 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Agents de tannage Chimie analytique Cuir -- Teneur en formaldéhyde Polyamines Produits chimiques -- Teneur en formaldéhyde Retannage Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Formaldehyde is widely used in the synthesis of various leather chemicals due to its high reactivity and low cost. It is probably introduced into leather when applying the chemicals to processing, and then released during storage and use of leather, which may pose a potential risk to human health. Existing method for determining formaldehyde in leather is helpless to deal with the complicated chemicals. In this study, a method was optimized for determination of free formaldehyde in leather chemicals based on ISO 27587. A 0.5-2.0 g sample of leather chemical (formaldehyde could range from 1.25 to 1250 mg/kg) was heated at 90°C in nitrogen atmosphere. The released formaldehyde was purged at a flow rate of 300 mL/min for 30 min, captured and derivatized using a bubble absorption tube containing 2,4-dinitrophenylhydrazine absorption solution, and then detected by HPLC-diode array detector. The recovery rate of formaldehyde standard solution was 91.0% with relative standard deviation (RSD) of 4.87% in seven times repeated trials. The repeated determinations of aldehyde tanning agents showed the formaldehyde recoveries higher than 90% and RSD lower than 7%, indicating the accuracy and precision of the method. Powdery amino resins were determined to contain a tiny amount of free formaldehyde using this method. However, it should be noted that hydrolyzed formaldehyde will be formed when the amino resins were dissolved in water and used in retanning, leading to the potential for bringing leather with high content of formaldehyde. Note de contenu : - EXPERIMENTAL : Materials - Determination of formaldehyde in leather chemicals - Effects of extraction conditions on the determination of formaldehyde - Effect of derivative devices on the determination of formaldehyde - Determination of formaldehyde in amino resin and leather - RESULTS AND DISCUSSION : Effect of extraction conditions on the determination of formaldehyde - Validation parameters of the proposed method - Effect of derivative devices on the determination of formaldehyde - Determination of formaldehyde content in amino resins and retanned leather En ligne : https://drive.google.com/file/d/1ovkzKqph88a5PaXbxWN0an2EWrZffTZZ/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=33034 [article]

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Effect of cationic monomer structure on the aggregation behavior of amphoteric acrylic polymer around isoelectric point / Qijun Li in JOURNAL OF LEATHER SCIENCE AND ENGINEERING, Vol. 4 (Année 2022)  

[article]  inJOURNAL OF LEATHER SCIENCE AND ENGINEERING > Vol. 4 (Année 2022) . - 9 p. Titre : Effect of cationic monomer structure on the aggregation behavior of amphoteric acrylic polymer around isoelectric point Type de document : texte imprimé Auteurs : Qijun Li, Auteur ; Yudan Yi, Auteur ; Ya-Nan Wang, Auteur ; Jing Li, Auteur ; Bi Shi, Auteur Année de publication : 2022 Article en page(s) : 9 p. Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Caractérisation Composés amphotériques Monomères cationiques Point isoélectrique En biochimie, le point isoélectrique (pI) ou potentiel hydrogène isoélectrique (pHI) est le pH auquel une molécule est sous forme d'ion mixte ou, en physico-chimie, le pH d'une solution aqueuse dans laquelle un solide existe sous un potentiel électrique neutre. En physico-chimie : Selon Bolger, le caractère acide ou basique d'une surface s'exprime par son point isoélectrique " Is ou IEPS (Iso Electric point for the surface) " ou point de charge nulle " PCN ou PZC (Point of Zero Charge) ", défini comme étant le pH de la solution aqueuse dans laquelle le solide existe sous un potentiel électrique neutre. Si le pH de la solution est basique, la surface est acide, et inversement. La différence entre le PZC et l'IEPS est basée sur le phénomène d'adsorption spécifique. On peut considérer que si la grandeur mesurée ne dépend pas de la solution utilisée pour la mesurer (pH, concentration, nature des ions), alors on a affaire à un PZC. Dans le cas contraire, c'est un IEPS que l'on mesure. Par exemple, quand la mesure de goutte sessile à deux liquides est utilisée, on considère en général qu'il n'y a pas adsorption des ions de cette goutte et que la goutte déplace complètement l'alcane qui sert de deuxième liquide: on est alors en présence d’un PZC. Au contraire, dans les mesures de potentiel d'écoulement (streaming potential), la solution joue un rôle important et c'est un IEPS que l'on mesure. Enfin, la charge nette se définit grâce au pH de la solution aqueuse dans laquelle la surface métallique existe, dans un état électriquement neutre (c’est-à-dire [M-OH2+ surf]=[M-O- surf]) et au PZC. - Si pH < PZC alors la charge nette est positive - Si pH > PZC alors la charge nette est négative. Il existe plusieurs méthodes expérimentales permettant de décrire l’état acido-basique de la surface : la mesure du potentiel d’écoulement, la photoélectrochimie, la mesure de l’angle de contact, et la spectroscopie XPS. Polyacryliques Précipitation (chimie) Retannage Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : Amphoteric polymer can be used as retanning agent in leather manufacture. It is particularly useful in chrome-free tanning systems since it can regulate the charge properties of chrome-free leather and enhance the fixation of anionic post-tanning chemicals in leather. However, the aggregation and precipitation of amphoteric polymer retanning agents around the isoelectric point (pI) hinder their wide application. Herein, we synthesized five amphoteric acrylic polymers (AAPs) by free radical copolymerization with acrylic acid and five different cationic acrylic monomers. The effect of cationic monomer structure on the aggregation behavior of AAPs was investigated. The aggregation of AAPs in aqueous solution showed pH and concentration dependence. Light scattering analysis showed that Poly (AA-co-MAPTAC) and Poly (AA-co-DMAPMA) were in the shape of coiled linear flexible chains with small particle size (Rg 7.6 nm and 14.8 nm, respectively) near the pI. However, Poly (AA-co-DAC), Poly (AA-co-DMC) and Poly (AA-co-DMAEMA) were in the shape of hollow spheres and exhibited serious aggregation. Quantum chemical calculations suggested that the amide groups in the cationic monomers MAPTAC and DMAPMA enhanced the nucleophilicity of AAPs. Thus the corresponding AAPs could carry a large number of cationic charges to slow their aggregation when the pH just climbed over the pI. The results are expected to provide theoretical reference for the synthesis and widespread application of AAPs. Note de contenu : - EXPERIMENTAL : Materials - Preparation of AAPs - FT-IR analysis - 13C NMR analysis - SEC analysis - Isoelectric point (pI) and particle size determination - Turbidity measurement - DLS/SLS analysis - DWS analysis - Cationic degree determination - Quantum chemical calculations - RESULTS AND DISCUSSION : Structural characterization of AAPs - Molecular weight and pI of AAPs - Effect of pH on the aggregation behavior of AAPs - Effect of concentration on the aggregation behavior of AAPs - DLS/SLS analysis - DWS analysis - Analysis on the charge-carrying ability of AAPs - Table 1 : Molecular weight and pI of AAPs - Table 2 : Light Scattering Parameters of AAPs - Table 3 : Zeta potentials of AAPs near the pI - Table 4 : Quantum chemical calculations of molecular models of AAPs DOI : https://doi.org/10.1186/s42825-022-00078-3 En ligne : https://link.springer.com/content/pdf/10.1186/s42825-022-00078-3.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=37572 [article]

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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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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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