Improved chrome utilisation in chrome tanning / William C. Prentiss in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 66 (Année 1982)  

[article]  inJOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 66 (Année 1982) . - p. 32-34 Titre : Improved chrome utilisation in chrome tanning Type de document : texte imprimé Auteurs : William C. Prentiss, Auteur ; I. V. Prasad, Auteur Année de publication : 1982 Article en page(s) : p. 32-34 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Déchets -- Réduction Masquage Mesure pH Produits chimiques -- Consommation -- Réduction Tannage au chrome Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : In a recent article Smith notes that emphasis on environment, health, and energy conservation has led to new studies to increase the efficiency of chromium usage in a tannery. He cites four basic concepts for increasing efficiency, these being improved uptake, recycling chrome liquors, precipitation and recovery of chrome for reuse and alkaline incineration. Utilising various techniques, all of the first three are practical commercially, while the fourth is being studied seriously from both chrome recovery and solid waste disposal perspectives. Since the first disclosure of a practical chrome tanning process in 1858 there have been literally hundreds of publications about the chemistry and technology of chrome tanning. It is estimated that about half relate to improved chrome uptake, but they can be classified into four main categories. These are control of pH, selection of masking agents, control of time and temperature, and control of float (or concentration). pH control does not necessarily mean increasing the pH at the end of chrome tanning by adding more neutralising agent. It does include employing more modern techniques such as adding magnesium oxide, a sparingly soluble basifying agent, for control of neutralisation ; or a combination of conventional and self-basifying chrome ; or even a chelated chrome added immediately following the bate. Selection of masking agents can be very critical. The more conventional formate and acetate masking can lead to more rapid arome penetration, while the more complex, polybasic acids which affect the size of the chrome complex can decrease penetration but improve fixation. Time, temperature and control of float are all rational and interrelated. Since chrome tanning is both a physical (diffusion) and a chemical (reaction) process which ultimately leads to an equilibrium situation, any condition which achieves equilibrium more rapidly or at equilibrium increases the quantity of total fixed chrome relative to the total unfixed chrome will improve uptake. The conditions are, of course, low float, higher temperature and longer running times. It is now possible to add a fifth category to the techniques for improved chrome uptake. Although currently there is insufficient evidence to establish the mechanism of action, it is apparent that a class of chemicals has been discovered, broadly defined as amine salts, which shifts the equilibrium of chrome between stock and float such that more chrome is exhausted in the stock and less remains in the exhaust liquor. This paper describes the results of our laboratory programme to determine the effect of process variations and define an optimum process for tannery trials. The results of confirmatory tannery trials are also reported. Note de contenu : - EXPERIMENTAL : Tanning process - Measurements - RESULTS AND DISCUSSION : Effect of reduced chrome - Effect of chrome exhaust aid level - Effect of pickle pH - Effect of masking - Effect of stock pH after neutralisation - Addition of exhaust aid with the chrome compared with addition before the chrome - Proposed optimised process En ligne : https://drive.google.com/file/d/1Xq6Amudrel-rlxTG9vUNEZYcPehDW-wa/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=34208 [article]

Réservation

Réserver ce document

Exemplaires (1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
007129	-	Périodique	Bibliothèque principale	Documentaires	Disponible

Improved chrome utilization in chrome tanning / William C. Prentiss in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. LXXVI (Année 1981)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. LXXVI (Année 1981) . - p. 395-403 Titre : Improved chrome utilization in chrome tanning Type de document : texte imprimé Auteurs : William C. Prentiss, Auteur ; I. V. Prasad, Auteur Année de publication : 1981 Article en page(s) : p. 395-403 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : Since the discovery of chromium as a tanning agent, there have been hundreds of publications discussing mechanisms of chrome tanning. Because of the emphasis on effluent control and the rising cost of chrome as a primary material, current work has centered on improving the efficiency of chrome tanning and on recycling (or reuse) of chrome. We have discovered a chemical which, when used in the primary chrome tanning step, apparently improves the penetration and distribution of chrome whithin the leather. This paper describes process variables and results which show that a significant reduction in chrome charged can be realized while maintaining chrome content in the leather and reducing the chrome content of exhaust liquors. Other benefits of the new process based on tannery trials are described. Note de contenu : - EXPERIMENTAL : Tanning process - Measurements - RESULTS AND DISCUSSION : Effect of reduced chrome - Effect of pickle pH - Effect of masking - Effect of stock pH after neutralization - Effect of adding exhaust aid with chrome - Proposed optimized process En ligne : https://drive.google.com/file/d/1p3H7PjDINZpJ-o7tOKIRrqiR1DZfLCVc/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=17678 [article]

Exemplaires (1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
008514	-	Périodique	Archives	Documentaires	Exclu du prêt

Practical leather processes using the novel pretan concept / William C. Prentiss in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. XXVII (Année 1982)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. XXVII (Année 1982) . - p. 84-92 Titre : Practical leather processes using the novel pretan concept Type de document : texte imprimé Auteurs : William C. Prentiss, Auteur ; I. V. Prasad, Auteur ; Marcel Siegler, Auteur Année de publication : 1982 Article en page(s) : p. 84-92 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : The work reported here was undertaken to demonstrate a workable pretan process and provide information to support larger scale tannery trails. These trials have shown that the process is workable, can be of advantage to tanners, can produce a variety of leathers of superior quality, and perhaps most important, can be of significant assistance in control of waste and effluent. En ligne : https://drive.google.com/file/d/1CudqbFlckeIzMHm55jgjOQWdWkfNzfB7/view?usp=share [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=17417 [article]

Exemplaires (1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
008515	-	Périodique	Archives	Documentaires	Exclu du prêt

---

1 (1 - 3 / 3)