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De-chroming of chromium shavings without oxidation to hazardous Cr6+ / Ján Matyasovsky in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CVI, N° 1 (01/2011)
[article]
Titre : De-chroming of chromium shavings without oxidation to hazardous Cr6+ Type de document : texte imprimé Auteurs : Ján Matyasovsky, Auteur ; Ján Sedliacik, Auteur ; Peter Jurkovic, Auteur ; J. Kopny, Auteur ; Peter Duchovic, Auteur Année de publication : 2011 Article en page(s) : p. 8-17 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Cuirs et peaux
DéchromageIndex. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : After the process of hide tanning to leather, almost 25% weight of input raw material proceeds to chromium tanned waste. The occurrence of such a large amount of waste presents economic and mainly ecologic problem for this industry ; thus substantial global effort is given to development of improved technologies for the disposal of chromium tanned waste. The results of this effort are different technologies whereit is possible to separate chromium from collagen. Application of these procedures in industry and also the proportion of valuation of chromium waste depend on effective application of the separated materials. The aim of our work was development of ecological de-chroming technology of chromium shavings without oxidation of Cr3+ to Cr6+ with retaining acceptable fibril structure. The pH value, temperature and number of dechroming bath have an influence on amount of removed extracted chromium. The influence of these parameters on losses of collagen after hydrolysis was determined. The degree of hydrolytic collagen decay was evaluated by determination of iso-electric point and determination of collagen increased solubility in dependence on de-chroming temperature. The results include optimization of technology; determination of the influence of temperature, pH, quantification of de-chroming released Cr3+ and determined qualitative collagen parameters. En ligne : https://drive.google.com/file/d/1yNe0kdPtkg3tzPtvxqxXahgqACiYiJot/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=10519
in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CVI, N° 1 (01/2011) . - p. 8-17[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 012733 - Périodique Bibliothèque principale Documentaires Disponible Cyclic dechroming process for chrome shavings by coordination substitution reaction and photocatalysis / Yuling Tang in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CIX, N° 11 (11/2014)
[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 -- DéchetsIndex. 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 experimentEn ligne : https://drive.google.com/file/d/1B6mJIpCCQa2dDv83UJ9qOnrAijAY3qKI/view?usp=drive [...] Format de la ressource électronique : 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[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 16623 - Périodique Bibliothèque principale Documentaires Disponible Dechroming of chromium-containing leather waste with low hydrolysis degree of collagen / Wei Ding in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 99, N° 3 (05-06/2015)
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Titre : Dechroming of chromium-containing leather waste with low hydrolysis degree of collagen Type de document : texte imprimé Auteurs : Wei Ding, Auteur ; Xuepin Liao, Auteur ; Wenhua Zhang, Auteur ; Bi Shi, Auteur Année de publication : 2015 Article en page(s) : p. 129-133 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Chaux
Collagène -- Détérioration
Cuirs et peaux -- Déchets -- Recyclage
Déchromage
Hydrolyse
Séparation (technologie)
Sulfurique, AcideIndex. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : Dechroming is essential for utilization of chromium-containing leather wastes. Strong hydrolysis conditions favour breaking of the Cr and collagen linkage, but lead to a high degree of hydrolysis of the collagen se that the separation of chromium from the gelatinous hydrolysates becomes difficult. In this research, a mild acid-alkali alternate treatment of the waste with hydrolysis assistants was investigated, so as to develop a technology that has high dechroming level and low hydrolysis degree of collagen. A satisfactory dechroming method with four steps was finally obtained and the reaction conditions for each step were optimized as follows. Step 1 — waste in the solution with 2g1L NaOH and 40g/L urea {hydrolysis assistant) was stirred for 0.5 hours at 40°C. Step 2 — waste in 50g/L sulfuric acid solution was stirred for 1 heur at 40°C. Step 3 — waste in 40 g/L Cap% suspension was stirred for 2 hour at 30°C. Step 4 — waste in 50g/L suffuric acid solution was stirred for 1 hour at 30°C. With this method, total extent of the dechroming of the waste was higher Chan 97% while the hydrolysis degree of collagen was lower than 10%. Note de contenu : - MATERIALS AND METHODS : Materials - Dechroming procedure of the leather waste - Estimation of the degree of hydrolysis of collagen
- RESULTS AND DISCUSSION : Effect of hydrolysis assistant on extent of dechroming - Effect of reaction temperature on dechroming extent - Effect of sulfuric acid concentration on dechroming extent - Effect of calcium hydroxide concentration on extent of dechroming - Hydrolysis degree of collagenEn ligne : https://drive.google.com/file/d/190QFQUqFJeTolMygTcMeLAUQr_rYV12n/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=24257
in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 99, N° 3 (05-06/2015) . - p. 129-133[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 17271 - Périodique Bibliothèque principale Documentaires Disponible Dechroming spent tanning liquor using filtration cake from enzymatic hydrolysis of chromium shavings / P. Kocurek in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 99, N° 6 (11-12/2015)
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Titre : Dechroming spent tanning liquor using filtration cake from enzymatic hydrolysis of chromium shavings Type de document : texte imprimé Auteurs : P. Kocurek, Auteur ; Karel Kolomaznik, Auteur ; Michaela Barinova, Auteur ; J. Hendrych, Auteur Année de publication : 2015 Article en page(s) : p. 288-292 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Déchromage
Filtration
Hydrolyse enzymatique
Liqueurs de tannageIndex. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : The work presented deals with the treatment of spent tanning liquor using the chromium cake from alkall enzymatic hydrolysis of leather shavings, the scheme is seen as a part of complete recycling of chromium in the leather industry.
There is a long-term worldwide effort to keep all chromium under control, ideally in a closed loop, since chromium, especially in its hexavalent form, has a negative impact on the environment and human health. The filtration cake obtained by hydrolysis contains a significant amount of chromium and, due to its alkaline character it could be used for the treatment of spent tanning liquor. The work demonstrates that total dechroming of spent tanning liquor is possible. The efficiency of the process depends on the weight ratio between chromium cake and spent tanning liquor and on the retention time. Using a ratio of 0.3 and a retention time of 1 hour, the dechroming level achieved was 81.6%; for a ratio of 1, the dechroming reached up to 98.3%. Using the tonner ratio, the dechroming level increased to 94.1% atter 6 hours. The treatment process has some limitations —the feed composition plays an important role in the process setup to achieve the high dechroming level.Note de contenu : - EXPERIMENTAL PROCEDURES : Materials - Analyses - Alkaline enzymatic hydrolyis - Spent tanning liquor treatment
- RESULTS AND DISCUSSION : Alkaline enzymatic hydrolysis - Spent liquor treatment - Kinetic of precipitationEn ligne : https://drive.google.com/file/d/1orHl-HxISp4Sv4ssT0FR21CgztymF-IT/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=25101
in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 99, N° 6 (11-12/2015) . - p. 288-292[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 17683 - Périodique Bibliothèque principale Documentaires Disponible Leather powder as an agent for removing environmentally hazardous organic compounds / Anita Przepiórkowska in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 87, N° 6 (11-12/2003)
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Titre : Leather powder as an agent for removing environmentally hazardous organic compounds Type de document : texte imprimé Auteurs : Anita Przepiórkowska, Auteur ; G. Janowska, Auteur ; L. Slusarski, Auteur ; S. Wolniak, Auteur Année de publication : 2003 Article en page(s) : p. 223-226 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Absorption
Analyse thermique
Cuirs et peaux -- Déchets
Déchets industriels -- Elimination
Déchromage
Poudre de cuir
Substances dangereuses -- Elimination
Tannage -- DéchetsIndex. décimale : 675 Technologie du cuir et de la fourrure Résumé : In the processes of leather tanning, about 30-40% of the leather substance processed in manufacture is rejected, mainly as shavings, in the form of protein wastes containing 3-5% of chromium (III) compounds. Such wastes may be described as hazardous to the environment. They must not be disposed of in common landfills
because of the possibility of chromium (III) leaching into the soil and subsurface water, the alternative specially protected landfills are very expensive. These wastes should also not be incinerated since such a process results in the formation of volatile carcinogenic chromyl
compounds.Note de contenu : - METHOD FOR MAKING DECHROMED LEATHER POWDER : Analytical methods
- THE CAPACITY OF HIDE POWDER TO ABSORB SUBSTANCES HAZARDOUS TO THE ENVIRONMENT : Selection of the agent composition for absorbing hazardous substances
- THERMAL ANALYSIS
- Table 1 : Leather powder composition before and after dechroming
- Table 2 : The absorptivity of dechromed hide powder
- Table 3 : The results of thermal analysisEn ligne : https://drive.google.com/file/d/1iCSrOCI3QKd4q_4ch_XEFinGBhH8IldW/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=39705
in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 87, N° 6 (11-12/2003) . - p. 223-226[article]Oxidative dechroming of leather shavings under ultrasound / Danhong Sun in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 87, N° 3 (05-06/2003)
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