Analysis and characterization of chromium sludge treated by acid leaching / Li Wen-Xin in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 97, N° 1 (01-02/2013)  

[article]  inJOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 97, N° 1 (01-02/2013) . - p. 33-37 Titre : Analysis and characterization of chromium sludge treated by acid leaching Type de document : texte imprimé Auteurs : Li Wen-Xin, Auteur ; Ye Yu-Xuan, Auteur Année de publication : 2013 Article en page(s) : p. 33-37 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Analyse spectrale Boues résiduaires Caractérisation Chrome Extraction (chimie) Lixiviation Métaux Microscopie électronique à balayage Sulfurique, Acide Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Acid leaching has been developed for the extraction of chromium, iron, magnesium and other metals from industrial solid wastes. Leather industries which promote hide stabilization by chrome tanning are a major source of chromium sludge. In the method, sulphuric acid was used to extract chromium and the leach liquor was analyzed. Different influences, such as dosage, volume ratio, temperature, reaction time and mode of action were investigated. Under the optimum conditions, the maximum extraction rate was up to 70%. The samples (before and after acid leaching) were compared by scanning electron microscope (SEM) and the content of each element was determined and analyzed by energy disperse spectrometer (EDS). SEM results display large changes in the surface appearance. The surface area of the sludge is greatly increased. Compared with other methods, acid leaching is simpler and economical and has good potential. Note de contenu : - EXPERIMENTAL PROCEDURE : Materials - Methods - RESULTS AND DISCUSSION : Results for each component in chromium sludge - Influence of acid volume ratio and acid dosage - Influence of leaching methods - Influence of temperature - Influence of reaction time - Results measured by EDS - Surface appearance En ligne : https://drive.google.com/file/d/1MRSbJXbVtLGGqg5aoeAayh1DLRg5mWPY/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=17451 [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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Dispersion enhancement of multi-walled carbon nanotubes in nitrile rubber / A. Boonbumrung in INTERNATIONAL POLYMER PROCESSING, Vol. XXIX, N° 3 (07/2014)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXIX, N° 3 (07/2014) . - p. 317-324 Titre : Dispersion enhancement of multi-walled carbon nanotubes in nitrile rubber Type de document : texte imprimé Auteurs : A. Boonbumrung, Auteur ; P. Sae-oui, Auteur ; Chakrit Sirisinha, Auteur Année de publication : 2014 Article en page(s) : p. 317-324 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Caoutchouc nitrile-butadiène Composites à fibres de carbone -- Propriétés électriques Composites à fibres de carbone -- Propriétés mécaniques Mélange Nanotubes Nanotubes de carbone à parois multiples Un nanotube de carbone multifeuillet est constitué de plusieurs feuillets de graphènes enroulés les uns autour des autres. Il existe deux modèles pour décrire la structure des nanotubes multifeuillets : - le modèle poupée russe: les plans de graphène sont arrangés en cylindres concentriques ; - le modèle parchemin: un seul feuillet de graphène est enroulé sur lui-même, comme une feuille de papier. Nitrique, Acide Permanganate de potassium Sulfurique, Acide Traitement chimique Ultrasons Index. décimale : 668.4 Plastiques, vinyles Résumé : A study of reinforcement mechanism of multi-walled carbon nanotubes (MWCNT) in nitrile rubber (NBR) matrix was carried out. Attempts to enhance the dispersion degree of MWCNT and the NBR-MWCNT interaction were conducted using numerous approaches, namely, sonication and chemical treatments of MWCNT with nitric acid (HNO3), nitric-sulfuric acid mixture (HNO3/H2SO4) and potassium permanganate (KMnO4). Rheological behavior, dynamic properties and electrical properties of MWCNT/NBR vulcanizates were monitored. Results gained reveal the magnitude of Payne effect increases with MWCNT content and mixing time. The expanded MWCNT and continuous-network formation are observed with an increase in mixing time, yielding enhanced mechanical properties and electrical properties. With MWCNT modification, a significant reduction in the state-of-mix of MWCNT composites is exhibited. SEM results demonstrate the highest magnitude of MWCNT dispersion in the system with HNO3, but relatively poor interaction with NBR. The HNO3/H2SO4 or KMnO4 system demonstrates poor MWCNT dispersion after treatment which is probably due to the compaction of MWCNT during the drying stage after the chemical treatment process, giving the detrimental effect to mechanical and electrical properties of vulcanizates. Note de contenu : - EXPERIMENTAL : Materials - Composite preparation - RESULTS AND DISCUSSION : Effect of mixing time - Effect of MWCNT modification DOI : 10.3139/217.2928 En ligne : https://drive.google.com/file/d/1GlLhu_VldQPbLjN1_w1EYZ7HuzVDyUJv/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=21728 [article]

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Effects of alkali and acid on the solubility and molecular weight of collagen hydrolysates extracted from bovine hide in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXVII, N° 10 (10/2022)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXVII, N° 10 (10/2022) . - p. 412-421 Titre : Effects of alkali and acid on the solubility and molecular weight of collagen hydrolysates extracted from bovine hide Type de document : texte imprimé Année de publication : 2022 Article en page(s) : p. 412-421 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Collagène Cuirs et peaux de bovins Hydrolysats de protéines Hydroxyde de sodium L'hydroxyde de sodium, appelé également soude caustique7, est un corps chimique composé minéral de formule chimique NaOH, qui est à température ambiante un solide ionique. Fusible vers 318 °C, il se présente généralement sous forme de pastilles, de paillettes ou de billes blanches ou d'aspect translucide, corrosives et très hygroscopiques. Il est très soluble dans l'eau et légèrement soluble dans l'éthanol. La solution d'hydroxyde de sodium, souvent appelée soude, est une solution aqueuse transparente. Concentrée, elle est corrosive et souvent appelée lessive de soude. Les propriétés chimiques de l'hydroxyde de sodium sont surtout liées à l'ion hydroxyde HO- qui est une base forte. En outre, l'hydroxyde de sodium réagit avec le dioxyde de carbone (CO2) de l'air et se carbonate. La solubilité de la soude caustique dans l'eau augmente avec la température, à pression constante ou ambiante. Poids moléculaires Solubilité Sulfurique, Acide Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Preparation of collagen hydrolysates with high molecular weight to meet its industrial demand is a crucial step for resource utilization of solid waste of animal skins/hides. However, it is very difficult to achieve both higher molecular weight and solubility of collagen hydrolysates through the traditional methods. In this study, we attempted to prepare bovine hide collagen hydrolysates with high molecular weight and solubility through the application of NaOH or different types of acid. Influences of the concentration of alkali and acid, hydrolysis temperature and time on the molecular weight and solubility were studied, respectively. The results showed that NaOH has a strong hydrolysis effect on bovine collagen, making it a suitable candidate for the preparation of collagen hydrolysates with medium or low molecular weight. Under these optimized NaOH treatment conditions, i.e., NaOH concentration of 0.13 mol/L, hydrolysis temperature of 60 - 70°C and time of 5 h, we achieved 96% of solubility for hide pieces and the molecular weight of collagen hydrolysates were in the range of 25 - 30 kDa. By contrast, the molecular weight of the hydrolysates prepared through H2SO4 hydrolysis method was higher than that of NaOH hydrolysis method. Under the optimized H2SO4 treatment conditions, i.e. H2SO4 concentration of 0.5 mol/L, hydrolysis temperature of 50°C and time in the range of 5 - 7 h, the solubility of hide pieces reached up to 80 - 97%. Additionally, in the H2SO4 hydrolysates, the proportion of macromolecular components with molecular weight of about 100 kDa was 41 - 55% and that of medium molecular components with molecular weight of about 20 kDa was 45 - 59%. This study showed that high solubility and high molecular weight collagen products can be obtained by H2SO4 hydrolysis under specific conditions. Thus, this study provided a useful scientific method and process parameters to guide the controlling of molecular weight and the industrial application of collagen from waste on a bigger scale. Note de contenu : - MATERIALS AND METHODS : Materials - Preparation of bovine hide hydrolysates through NaOH hydrolysis method - Preparation of bovine hide hydrolysates through acid hydrolysis method - Determination of hypro by chloramine T method - Determination of molecular weight of bovine hide hydrolysates by GPC method - RESULTS AND DISCUSSION : Effect of NaOH hydrolysis conditions on the molecular weight of collagen hydrolysate - Effect of NaOH concentration - Effect of NaOH hydrolysis time - Effect of NaOH hydrolysis temperature - Effect of acid hydrolysis conditions on the molecular weight of collagen hydrolysates - Effect of acid type - Effect of H2SO4 concentration - Effect of H2SO4 hydrolysis temperature - Effect of HSO4 hydrolysis time - Table 1 : Conditions of hydrolysis by different acids - Table 2 : Molecular weight of different acid hydrolyzed collagen hydrolysates - Table 3 : Molecular weight and distribution of collagen hydrolystes with varying H2SO4 concentrations - Table 4 : Molecular weight and distribution of collagen hydrolysates by H2SO4 hydrolysis with different H2SO hydrolysis temperature (CH2SO4 = 0.5 mol/L, 5h) - Table 5 : Molecular weight and distribution of collagen hydrolysates by H2SO4 hydrolysis with varying time (CH2O4 = 0.5 mol.L, 50°C) DOI : https://doi.org/10.34314/jalca.v117i10.6181 En ligne : https://drive.google.com/file/d/1icwFY3afKUPxPe1ggPfep0XQmjiahBYR/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=38227 [article]

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Evaluation of the anticorrosive behavior of epoxy-Nb2O5 paint in high temperatures submitted to the environment with sulfuric acid / Maria Eduarda Dias Serenario in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 17, N° 5 (09/2020)  

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Exploration of the diffusion, binding and crosslinking of chromium complex within hides during chrome tanning / Chunxiao Zhang in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXIV, N° 5 (05/2019)  

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Influence du foulonnage sur la qualité du cuir et l'absorption des produits chimiques / Hans Herfeld in TECHNICUIR, N° 6 (06-07/1973)  

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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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A practical chrome recovery system using magnesium oxide / Anthony D. Covington in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 67 (Année 1983)  

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Short-term hide preservation with acid and salt / Jaume Soler in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 102, N° 3 (05-06/2018)

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Studies on use of fish oil methyl ester for chamois leather manufacture / N. Vedaraman in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CVII, N° 12 (12/2012)  

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The effect of different acids in the warm circulator system sole leather tannage / D. A. Williams-Wynn in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 54, N° 10 (10/1970)  

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The role of neutral salt for the hydrolysis and hierarchical structure of hide fiber in pickling / Cheng Haiming in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CIX, N° 4 (04/2014)  

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