[article]
| Titre : |
The diffusion barrier within the unhairing process |
| Type de document : |
texte imprimé |
| Auteurs : |
Carlos S. Cantera, Auteur ; Maria Laura Garro, Auteur ; M. L. Goya, Auteur ; L. Barbeito, Auteur ; Betina Galarza, Auteur |
| Année de publication : |
2007 |
| Article en page(s) : |
p. 29-32 |
| Note générale : |
Bibliogr. |
| Langues : |
Anglais (eng) |
| Catégories : |
Epilage
Peaux brutes
|
| Index. décimale : |
675 Technologie du cuir et de la fourrure |
| Résumé : |
Hair-saving processes for bovine hides are being applied in tanneries in several countries to replace traditional hair burning systems. The factors that are taken into account when using this unhairing technique are :
- the need for a pelt that is suitable for the production of different types of leather
- a reduction in the effluent load arising from the beamhouse
- the recovery of the partially degraded hair as a solid waste with potential industrial applications
It is well known that the organic matter, the sulfide ion content and the presence of suspended solids in the liquid effluent is greatly dependant on the unhairing process employed. Within the sulfide unhairing system there are problems associated with toxicity, odour and effluent treatment.
Hydrogen sulfide is a highly toxic gas, and can be liberated from within the unhairing process and from effluent treatment. In extreme cases it has led to the death of workers, and in the wider environment creates an odour within the tannery surroundings which causes associated complaints. The acceptable maximum concentration in the work environment, in which a worker can remain for 8 hours/day and 5 days/a week, is 10 cm3 H2S/m3 (15 mg/m3) without suffering physical damage.
The enzymatic removal of intact hair offers a suitable alternative to destructive sulfide unhairing. However, interest in the enzyme unhairing process cornes and goes. This is because of difficulties in managing the process, mainly because the proteolysis cannot be accurately focused and controlled. Essentially, the enzyme activity is not restricted to the function of hair removal, but also affects the structure of the dermis. The grain layer is therefore partially digested hence there is a decrease in the quality of the grain structure in the final leather. Enzyme unhairing remains a fascinating concept, but is full of difficulties.
Nevertheless, the problems and costs of treating effluent to acceptable standards are considerable. If hair could be removed intact without using sulfide, then there would be a significant easing of techniques, capital equipment and power requirements to achieve discharge limits. In addition, the volume of sludge would be considerably reduced, with the hair remaining as a new clean raw material with many potential ourlets. |
| Note de contenu : |
- The epidermis as a diffusion barrier
- The role of lipids within the epidermis
- The diffusion of substances across the epidermis
- Enhancers for penetration, or promoters for reactions : Sodium sulfite - Surfactants - Proteolytic enzymes - Trypsin - Urea - Organic solvents
- Phases of the unhairing process |
| En ligne : |
https://drive.google.com/file/d/14I1LkOfYwz-xkhH5GSFeR0kmgJqXd9Yb/view?usp=drive [...] |
| Format de la ressource électronique : |
pdf |
| Permalink : |
https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=35688 |
in WORLD LEATHER > Vol. 18, N° 6 (10/2005) . - p. 29-32
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The diffusion barrier within the unhairing process in WORLD LEATHER, Vol. 18, N° 6 (10/2005)
