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Use of long-chain synthetic phenolic antioxidants to produce chromium-tanned leather without risk of hexavalent chromium formation / Irene Compte in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXVIII, N° 10 (10/2023)
[article]
Titre : Use of long-chain synthetic phenolic antioxidants to produce chromium-tanned leather without risk of hexavalent chromium formation Type de document : texte imprimé Auteurs : Irene Compte, Auteur ; Quim Torras, Auteur ; Francina Izquierdo, Auteur ; Rosa M. Cuadros, Auteur ; Anna Bacardit, Auteur Année de publication : 2023 Article en page(s) : p. 439-449 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Antioxydants
Auto-oxydation
Cuirs et peaux de moutons
Essais accélérés (technologie)
Lipides
Phénols
Tannage au chromeIndex. décimale : 675 Technologie du cuir et de la fourrure Résumé : Chromium tanned leather is the widest form of leather tanning across the world, but it might involve a risk of hexavalent chromium formation, which is restricted in leather products above 3 mg/ kg. Among other conditions, certain processes might lead to the oxidation of natural fats or fatliquoring agents with unsaturated carbon-carbon bonds, thus generating free radical molecules that can contribute to the Cr(III) oxidation to Cr(VI). The autooxidation of unsaturated lipids is promoted by exposure to high temperatures and light, specifically UV radiation. Among other relevant manufacturing practices, the addition of synthetic phenolic antioxidants (SPAs) during the synthesis of fatliquoring agents or during leather manufacturing can be a relevant tool for preventing lipid auto-oxidation.
The efficiency of the long-chain synthetic antioxidant 1135 (AO1135, CAS RN® 125643-61-0) has been assessed for Cr(VI) prevention. The performance of AO1135 has been tested in two different skin types (sheepskin, woolly sheepskin), with two different fatliquoring agents (unprotected and protected against oxidation). The protected fatliquoring agent was formulated with AO1135. Also, two commercial products that contain the AO1135 in its formulation have been applied to leathers. Upon completion of the post-tanning process, the leathers have undergone two different thermal ageing processes.
AO1135 has been verified an effective SPA for Cr(VI) prevention and its application during the post-tanning process does not alter the visual aspect of the leathers. Otherwise, if the post-tanning recipe does not contain well-sourced raw materials or Cr(VI) prevention tools, unsaturated fatliquoring agents or natural fats present in the skins can be a cause for Cr(VI) formation.Note de contenu : - INTRODUCTION : Origins of Cr(VI) in leather-hexavalent chromium containing substances - Influence of the pH value - Oxidation of fatliquoring agents - Natural extracts as a way for reducing formed Cr(VI) - Synthetic phenolic antioxidants as a tool for preventing lipid auto-oxidation - Forcing lipid auto-oxidation in leather - Determining the efficiency of antioxidant 1135 to prevent Cr(VI) formation - Commercial products with synthetic phenolic antioxidant
- EXPERIMENTAL : Design of the experiment - Samples - Chemicals and appartus - Methods - Determination of natural fat content in leather
- RESULTS : Cr(VI) content in the tanned leathers - Dispersion of the Cr(VI) content depending on the different parts of the leather
- DISCUSSION : Use of synthetic phenolic auxiliaries (AO1135) and its consequences on the Cr(VI) content - Zone of the leather and Cr(VI) distribution - Effect of different ageing treatments in Cr(VI)
- Table 1 : Structure of the study
- Table 2 : Conditions of sample exposure prior to Cr(VI) testing
- Table 3 : Cr(VI) content according to ISO 17075-2:2017 of sheep-skins produced
- Table 4 : Cr(VI) content according to ISO 17075-2:2017 of wooly sheep leathers produced
- Table 5 : Average and % RSD of leathers with Cr(VI) detectionDOI : https://doi.org/10.34314/jalca.v118i10.8232 En ligne : https://drive.google.com/file/d/1a3qDDoXd-GKDH-5gVHfu1cAh_Tje3ck8/view?usp=share [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=39942
in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXVIII, N° 10 (10/2023) . - p. 439-449[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 24241 - Périodique Bibliothèque principale Documentaires Disponible Valorization of pomegranate peel waste as retanning agent in leather industry and investigation of its effect on prevention of Cr(VI) formation / Cigdem Kilicarislan Ozkan in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXVIII, N° 2 (02/2023)
[article]
Titre : Valorization of pomegranate peel waste as retanning agent in leather industry and investigation of its effect on prevention of Cr(VI) formation Type de document : texte imprimé Auteurs : Cigdem Kilicarislan Ozkan, Auteur Année de publication : 2023 Article en page(s) : p. 51-58 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Agents de tannage
Antioxydants
Chrome trivalent -- Oxydation
Colorimétrie
Ecorces
Grenade (fruit) et constituants
Phénols
RetannageIndex. décimale : 675 Technologie du cuir et de la fourrure Résumé : Although Cr(VI) is not used in any step of the manufacturing process, the entity of Cr(VI) in leather and leather products has become a concern in the leather industry. Formation of free radicals may bring about conditions for the oxidation of free Cr(III) (if exists in leather) to Cr(VI) and these oxidations are usually catalyzed by heat and UV radiation. Antioxidants have an important role in order to inhibit oxidant compound activity by donating an electron to compounds. There are many studies on the prevention of Cr(VI) formation in leather production. The inhibiting properties of Cr(VI) formation were usually investigated by using commercial vegetable tannins (polyphenols) together with other retanning agents in retanning process. However, no study has been conducted on the possible use of pomegranate peel tannins as an alternative retanning agent, which is known as an important source of antioxidants, in leather making and their ability to prevent Cr(VI) formation. In the present study, pomegranate peels were extracted in different solvents and total phenolic content and antioxidant power of the extracts were determined by Folin-Ciocalteu, FRAP (The Ferric Reducing Ability of Plasma) and TEAC/ABTS (Trolox-Equivalent Antioxidant Capacity/2,2’-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)) methods. Furthermore, different amounts of pomegranate peel extracts were used in retanning processes and the leathers were investigated in terms of increases in thickness, color changes as well as effect on prevention of Cr(VI) formation. The results revealed that besides noticeable retanning performance, pomegranate peel extract has a spectacular effect on prevention of Cr(VI) formation as compatible with its antioxidant power. Note de contenu : - MATERIALS AND METHODS : Materials - Methods : Determination of moisture content of pomegranate peels - Preparation of extracts - Determination of maxiumm extractable materials (MEM) from pomegranate peels - Determination of extraction yields and tannin contents of extract solutions - Total phenols and antioxidant powers of pomegranate peels - Usage of extract solutions in retanning process - Post-retanning tests : Determination of filling coefficient - Determination of color changes - Artificial ageing of leather samples and Cr (VI) analysis
- RESULTS AND DISCUSSION : Moisture content, extraction yields and tannin contents of pomegranate peels - Total phenolic contents and antioxidant powers of pomegranate peels - Filling coefficient and color changes of retanned leathers - Cr(VI) contents of leather samples
- Table 1 : Retanning recipe
- Table 2 : The effect on extraction yields and tannin contents of different extractiontemperatures
- Table 3 : Total phenolic contents and antioxidant powers of pomegranate peels extracted in different solvents
- Table 4 : Filling coefficient values of retanned leathers
- Table 5 : Color measurement values of leathers retanned with pomegranate peel extracts at different ratios before and after ageingDOI : https://doi.org/10.34314/jalca.v118i2.6499 En ligne : https://drive.google.com/file/d/1XYA9ZHyQTB86dburXGWvLZtuqaKtswF0/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=38811
in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXVIII, N° 2 (02/2023) . - p. 51-58[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 23871 - Périodique Bibliothèque principale Documentaires Disponible