[article]
| Titre : |
Cyclic dechroming process for chrome shavings by coordination substitution reaction and photocatalysis |
| Type de document : |
texte imprimé |
| Auteurs : |
Yuling Tang, Auteur ; Hu Zaiyin, Auteur ; Huitun Liu, Auteur ; Hu Wei, Auteur ; Wang Ru, Auteur |
| Année de publication : |
2014 |
| Article en page(s) : |
p. 380-388 |
| Note générale : |
Bibliogr. |
| Langues : |
Américain (ame) |
| Catégories : |
Chrome
Déchets industriels -- Elimination
Déchromage
Ethylène diamine tétra acétiqueL'EDTA (Ethylène Diamine Tétra Acétique), ou acide éthylène diamine tétraacétique, est un acide diaminotétracarboxylique de formule C10H16N2O8.
L'EDTA comporte six sites basiques, quatre correspondant aux bases conjuguées (carboxylates) des fonctions carboxyliques et deux correspondant aux fonctions amines. Ces sites basiques sont également des centres ligands, faisant de l'EDTA un ligand hexadentate (ou parfois tétradentate, lorsque seuls les sites carboxyliques sont utilisés). C'est d'ailleurs sa principale caractéristique, son fort pouvoir chélatant (ou complexant) par lequel il forme des complexes métalliques très stables, ce qui en fait un traitement en cas d'intoxication aux métaux lourds comme le plomb, avec une concentration adaptée (Voir Applications et chélation). Dans les complexes, l'EDTA est lié aux cations métalliques sous la forme d'une de ses bases conjuguées9.
Extraction (chimie)
Photocatalyse
Sulfurique, Acide
Tannage -- Déchets
|
| Index. décimale : |
675 Technologie du cuir et de la fourrure |
| Résumé : |
The cyclic dechroming process for chrome shaving by method of coordination substitution reaction and photocatalysis was investigated. Using EDTA (ethylene diamine tetraacetic acid) as dechroming agent and NaOH as recovery agent, the process conditions were optimized through the orthogonal tests. The removal efficiency of chrome from chrome saving was 98,88% when dechroming was undertaken in 0.03mol/L EDTA solution at 50°C and pH 6.0 for 14 days with stirrung and then treated in the same solution under ultraviolet (145 W, 254 nm) for 8 days, and the loss of collagen was 5.31%. The chrome was separated from the dechroming solution as Cr(OH)? precipitate by adding NaOH into the dechroming solution (conc. og NaOH=1.00mol/L) and stirring at 70°C for 1d. The solution containing EDTA was reused for dechroming again after filtering and adjusting pH to 6.0 by sulfuric acid and the removal efficiencies of chrome were all more than 97% in triplicate trials. The structure of collagen after chrome extraction was characterized by SEM and FT-IR. The results indicated that the triple helix structure of collagen was well preserved. The thermal stability of collagen after chrome extraction was characterized by DSC; the results indicating that it was in conformity with rawhide. The dechroming process without strong acid and alkali can prevent collagen from hydrolisis. A certain amount of Cr(VI) appeared by adding alkali in precipitating Cr and recovering EDTA. However, Cr(VI) was reduced to Cr(III) when pH of recovered EDTA solution was ajusted to 6.0 by adding sulfuric acid. This kind of closed recycling dechroming technology can reuse dechroming process. |
| Note de contenu : |
- EXPERIMENTAL : Materials and chemicals - Equipment - Experimental procedure. Dechroming through coordination substitution reaction and photocatalysis - Observation of structural change of collagen - Optimization of dechroming process by orthogonal test - Recovery of EDTA in dechroming Solution - Cyclic dechroming experiment - Analysis method
- RESULTS AND DISCUSSION : EDTA dechroming through coordination substitution reaction and photocathalysis - Physico-chemical characteristics of collagen before and after dechroming - Observation of structural change of collagen - The thermostability change of collagen thermal stability
- Mechanism of EDTA Dechroming through coordination substitution reaction and photocatalysis - Optimization of dechroming process by orthogonal test - Recovery of EDTA in dechroming solution - Cyclic dechroming experiment |
| En ligne : |
https://drive.google.com/file/d/1B6mJIpCCQa2dDv83UJ9qOnrAijAY3qKI/view?usp=drive [...] |
| Format de la ressource électronique : |
Pdf |
| Permalink : |
https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=22279 |
in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CIX, N° 11 (11/2014) . - p. 380-388
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