Managing chrome in leather manufacture / Jürgen Christner in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CVII, N° 12 (12/2012)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CVII, N° 12 (12/2012) . - p. 409-415 Titre : Managing chrome in leather manufacture Type de document : texte imprimé Auteurs : Jürgen Christner, Auteur ; Florian Doeppert, Auteur ; Jens Fennen, Auteur ; Jan-Tiest Pelckmans, Auteur Année de publication : 2012 Article en page(s) : p. 409-415 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Additifs Antioxydants Chrome hexavalent Formaldéhyde -- Elimination Polysulfonique, Acide Retannage Tannage -- Aspect de l'environnement Tannage au chrome Wet-blue (tannage) Peau tannée au chrome (le chrome donne une couleur bleue) Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : Chrome Tanning, being still the most used tanning method, has been challenged more and more in the recent past. The main reasons were questions of sustainability and the fact that chromium VI can be formed in leathers tanned with chromium III compounds. From a technical point of view, many solutions exist for using the chrome tanning agent in a most economical and ecological way. In this paper another way is shown for maximizing the distribution of chromium in the cross section of the hide as well as the exhaustion of chromium from tanning float, thus reducing the total chromium emission into the environment. Also the leaching of chrome from wet blue during retanning operations will be considered. The type of chemicals used and the process conditions play an important role in this regard, as well as the type of chrome tannage used to manufacture the wet blue. Various measures and solutions will be discussed in this presentation. The role of chromium VI in tanning is looked at with special attention to the real risks associated with it. Finally the formation of chromium VI will be discussed as well as methods to prevent its formation. A new additive (anti oxidant), which is able to eliminate existing chromium VI and reduce the likelihood of reformation, will be introduced. Note de contenu : - Emission of chromium into the environment - Pickling and tanning with polysulphonic acids (PA) - Chromium exhaustion and fixation in the wet-end processes - Strategies for treating chrome containing waste floats - Chromium toxicity, prevention of chromium (VI) in the wet end En ligne : https://drive.google.com/file/d/1ewCz1iVwEd6ahu0z6oJxE-8ks3AUo9Ur/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=16746 [article]

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Methods for managing chrome in leather making / Florian Doeppert in LEATHER INTERNATIONAL, Vol. 213, N° 4816 (11-12/2011)  

[article]  inLEATHER INTERNATIONAL > Vol. 213, N° 4816 (11-12/2011) . - p. 40-42 Titre : Methods for managing chrome in leather making Type de document : texte imprimé Auteurs : Florian Doeppert, Auteur ; Jan-Tiest Pelckmans, Auteur ; Markus Hess, Auteur ; Jürgen Christner, Auteur Année de publication : 2011 Article en page(s) : p. 40-42 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Chrome hexavalent 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. Polysulfones Sulfoniques, Acides Tannage Tannage au chrome Wet-blue (tannage) Peau tannée au chrome (le chrome donne une couleur bleue) Index. décimale : 675.2 Préparation du cuir naturel. Tannage Note de contenu : - Fixation of chromium in wet-blue - Pickling and tanning with polysulphonic acids - Chromium exhaustion and fixation - Prevention of chromium (VI) En ligne : https://drive.google.com/file/d/16lh3Sh30l9Pa6lNfnQhywFM0YGxMaMSK/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=12757 [article]

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The sulphide challenge / Jens Fennen in LEATHER INTERNATIONAL, Vol. 215, N° 4836 (11-12/2013)  

[article]  inLEATHER INTERNATIONAL > Vol. 215, N° 4836 (11-12/2013) . - p. 25-27 Titre : The sulphide challenge Type de document : texte imprimé Auteurs : Jens Fennen, Auteur ; Daniel Herta, Auteur ; Jan-Tiest Pelckmans, Auteur ; Jürgen Christner, Auteur Année de publication : 2013 Article en page(s) : p. 25-27 Langues : Anglais (eng) Catégories : Atmosphère -- Pollution Cuirs et peaux -- Industrie -- Aspect de l'environnement Industrie -- Pollution -- Lutte contre Odeurs -- Lutte contre Sulfure d'hydrogène Sulfures Travail de rivière (cuir) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Tanneries are often associated with the characteristic and obnoxious "sulfide smell", which is in fact caused by low concentrations of sulfhydric gas, also known as hydrogen sulfide. Levels as low as 0.2 ppm of H2S are already unpleasant for humans and a concentration of 20 ppm is unbearable. As a result, tanneries might be forced to close down beamhouse operations or are forced to re-locate away from populated areas. As beamhouse and tanning are often done in the same facility, smell is actually the lesser problem. Through human errors, this always holds the danger of mixing acidic floats with the sulfide containing beamhouse float and releasing higher amounts of H2S. At a level of 500 ppm all olfactory receptors are blocked and the gas, therefore, becomes unnoticeable and an exposure for 30 min results in a life threatening intoxication. At a concentration of 5,000 ppm (0.5%), the toxicity is so pronounced that a single breath is enough to cause immediate death within seconds. Despite all these problems and risks, sulphide has been the preferred chemical for unhairing for more than a century. This can be attributed to unavailable workable alternatives: the use of organic sulphides has shown to be practicable but not really accepted due to the extra costs involved. Unhairing solely by proteolytic and keratolytic enzymes has been tried over and over again but for the lack of selectiveness was difficult in practice to control. A lot of work has also been invested in oxidative unhairing, but until today it is very limited in its use as it is hard to get consistent results. Note de contenu : - The unhairing process - Soaking is a key factor for efficient unhairing - Low sulphide enzymatic assisted unhairing - A low sulphide, low time hair safe process En ligne : https://drive.google.com/file/d/1LagW96JfoonNNG_1joIQYOLE8LsGPvj2/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=20450 [article]

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The use of lipases in the beamhouse processes / Jürgen Christner in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), LXXXVII, N° 4 (04/1992)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > LXXXVII, N° 4 (04/1992) . - p. 128-139 Titre : The use of lipases in the beamhouse processes Type de document : texte imprimé Auteurs : Jürgen Christner, Auteur Année de publication : 1992 Article en page(s) : p. 128-139 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : The use of lipases to degrase hides and pelts has been discussed in the literature for many years. However, there were several problems associated with their use which hindered the broad introduction of lipases in practice. First of all these products were relatively high in cost and not available in the quantities needed. The available lipases, extracted from pancreas glands or various strains of fungi, had an optimal pH activity range of pH 5 to 8. Their degreasing effect in soak and particularly in the lime was not sufficient to justify the cost of the lipase New lipase derived from bacterial sources are now available which are active in a pH range from pH 8 to 12. This enables us to use them effectively in soaking and liming. A highly synergistic effect in degreasing is achieved when special proteases and emulsifying systems are used at the same time. Proteases break down the cell membranes of fat cells in the hide and the new lipase reduces the amount of emulsifier needed. In addition to improved degreasing a better soaking and liming effect is obtained. The grain of limed hides is very clean and hides are much less drawn. En ligne : https://drive.google.com/file/d/1_sFbowphqQVmpYITQtXMDUbbPz7inn0O/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=8313 [article]

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