An effective and harmless recycling technology for hazardous chrome-tanned leather wastes / Minghui Li in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 108, N° 2 (03-04/2024)  

[article]  inJOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 108, N° 2 (03-04/2024) . - p. 67-77 Titre : An effective and harmless recycling technology for hazardous chrome-tanned leather wastes Type de document : texte imprimé Auteurs : Minghui Li, Auteur ; Xu Zhang, Auteur ; Honghong Chen, Auteur ; Sadaqat Ali Chattha, Auteur ; Xin Yan, Auteur ; Biyu Peng, Auteur Année de publication : 2024 Article en page(s) : p. 67-77 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Agents de tannage Chimie analytique Chrome -- Recyclage Croûte (cuir) On entend par "cuir en croûte" des cuirs ayant subi les opérations jusqu'au tannage, à l'exclusion de toute opération de corroyage ou de finissage, mais qui, par opposition aux wet-blue ont été séchés. Cuirs et peaux -- Déchets -- Recyclage Cuirs et peaux -- Propriétés mécaniques Cuirs et peaux -- Propriétés physiques Déchromage Hydrolysat de collagène Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : Utilizing leather production waste to create raw materials for leather chemicals, and reintroducing it into the leather making processing, represents an ideal approach to achieving an “internal circular economy” within the leather industry. This study focuses on the reutilization of dechromed collagen fibres, obtained from chromium shavings, to generate a retanning filling. The effects of hydrolysis conditions on the viscosity, and gel strength of the dechromed collagen hydrolysates were investigated. The application effectiveness of the collagen hydrolysates with different particle sizes in the leather retanning filling process was also compared. The findings indicate that alkali hydrolysis is more conducive to producing collagen hydrolysates with a relatively higher proportion of medium and low molecular weight components, while acid hydrolysis favours the production of collagen hydrolysates rich in high molecular weight components. Additionally, collagen hydrolysates with an average particle size of 162.8 nm exhibit the best filling efficacy, imparting favorable organoleptic and physical properties to the leather. Herein, a method for preparing protein fillers, using chrome shavings as raw materials, was established, i.e., the dechromed collagen fibres (with a chromium content of approximately 33.6 mg/kg) were mixed with 2000% of water and adjusted to pH 3.0 with a small amount of sulfuric acid, and heated at 60°C with continuous stirring for 11 hours. After hydrolysis, the pH was adjusted appropriately to reuse it in the wet blue retanning filling process. The research outcomes have significant guiding implications for promoting the "internal circular economy" and sustainable development within the leather industry. Note de contenu : - EXPERIMENTS AND METHODS : Experimental materials - Dechroming of chrome shavings - Hydrolysis of dechromed collagen fibres - Performance of collagen hydrolysate as a retanning agent - Analysis and testing - RESULTS AND DISCUSSION : Preparation and performance analysis of dechromed collagen fibres materials - Influence of hydrolysis conditions on the fundamental characteristics of collagen hydrolysates - Correlation between the particle size of collagen hydrolysates and filling efficiency - Table 1 : Properties of the collagen hydrolysates - Table 2 : Physical and mechanical properties of the crust leather En ligne : https://drive.google.com/file/d/1hD0IMUh9EOcTIH7DeQDo-eDaYvoQEeci/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=40933 [article]

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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]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CVI, N° 1 (01/2011) . - p. 8-17 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 Déchromage Index. 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 : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=10519 [article]

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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]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CIX, N° 11 (11/2014) . - p. 380-388 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 acétique L'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 [article]

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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)  

[article]  inJOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 99, N° 3 (05-06/2015) . - p. 129-133 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, Acide Index. 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 collagen En ligne : https://drive.google.com/file/d/190QFQUqFJeTolMygTcMeLAUQr_rYV12n/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=24257 [article]

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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)  

[article]  inJOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 99, N° 6 (11-12/2015) . - p. 288-292 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 tannage Index. 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 precipitation En ligne : https://drive.google.com/file/d/1orHl-HxISp4Sv4ssT0FR21CgztymF-IT/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=25101 [article]

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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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A novel recycling technology for chrome shavings : Application of non-swelling acids during dechroming process / Sadaqat Ali Chattha in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXIX, N° 8 (08/2024)  

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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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