Alternative process for recovery of chrome(III)-effluents / Jaime Cot in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 92, N° 4 (07-08/2008)  

[article]  inJOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 92, N° 4 (07-08/2008) . - p. 139-149 Titre : Alternative process for recovery of chrome(III)-effluents Type de document : texte imprimé Auteurs : Jaime Cot, Auteur ; Agusti Marsal, Auteur ; Albert M. Manich, Auteur ; Pedro J. Celma, Auteur ; F. Fernandez, Auteur ; J. Cot-Gores, Auteur Année de publication : 2008 Article en page(s) : p. 139-149 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Bisulfite de sodium Eaux usées -- Epuration Eaux usées -- Teneur en chrome Fluidisation Glucose Gommes et résines Oxydoréduction Peroxyde d'hydrogène Le peroxyde d'hydrogène (H2O2), communément appelé eau oxygénée ou encore perhydrol (appellation industrielle), est un composé chimique liquide et visqueux, aux puissantes propriétés oxydantes (il est aussi réducteur). C'est donc un agent blanchissant efficace qui sert de désinfectant et (à haute concentration) d'oxydant ou monergol dans les fusées spatiales. Récupération (Déchets, etc.) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : This scheme aims to set up an alternative process to recover chrome(III) from tannery effluents. The use of the conventional technique of alkaline precipitation (magnesium oxide) of chromium(III) is well known from the literature and is in daily practice in tanneries worldwide. This technique may in fact represent the cheapest treatment nowadays; however, the latest economic studies have revealed the influence of parameters that could significantly alter investment costs and thus open a door to alternative processes. The main problems that the precipitation technique carries with it are : - a) the presence of highly masked chrome(III) complexes, difficult to precipitate even in alkaline medium. - b) the speed of precipitation and the density of the precipitate can be a major problem. Sometimes, the application of heat is required. - c) filtration of the precipitate and subsequent drying to remove possibly 30% of the water content of the chromecake (various techniques are used). - d) recovered chrome(III) obtained by re-dissolving the cake with sulphuric acid and final adjustment to 33°Sch basicity can occlude large amounts of highly masked chrome (III) complexes which, in turn, produce uneven dyed grain surfaces ; limiting dyeing to dark shades. Furthermore, basic factors such as energy consumption, the lengthy nature of the overall process, the simple but numerous stages, and limited coverage of fashion colours indicate that an alternative process is possible. This part of the work aims to recover the chromium1 of wastewater coming from the various chrome using processes and, at the same time, to get an effluent that can be used directly without complementary treatments. It is important to give a clearer and detailed idea of the developed process. Note de contenu : - INTRODUCTION : Resin selection - Wastewater oxidation process - Wastewater loading - Chromium reduction process - EXPERIMENTAL PROCEDURE : Equipment and reagents used - Resin Amberlite IRA-96 - Sample preparation - Wastewater load and reduction - Fluidisation system - Fluidisation mechanism (see appendix for symbols) - Calculation off luidisation for the pilot plant - Reduction in a batch system - Table 1 : Amberlite IRA-96 resin characteristics - Table 2 : Optimal operation conditions - Table 3 : Chromium recovered using acid hydrogen peroxide as reducer - Table 4 : Chromium recovered using sodium bisulphite as reducer - Table 5 : Chromium recovered using glucose as reducer En ligne : https://drive.google.com/file/d/1k7CnOQf4zEsbildKyaGXxsI_elC93m2i/view?usp=share [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=38963 [article]

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Transformation plant for converting chromium waste into chemical products for the leather industry / Jaime Cot in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CIII, N° 3 (03/2008)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CIII, N° 3 (03/2008) . - p. 103 - 113 Titre : Transformation plant for converting chromium waste into chemical products for the leather industry Type de document : texte imprimé Auteurs : Jaime Cot, Auteur ; J. Cot-Gores, Auteur ; F. Fernandez-Hervas, Auteur ; Pedro J. Celma, Auteur ; Albert M. Manich, Auteur ; Agusti Marsal, Auteur Année de publication : 2008 Article en page(s) : p. 103 - 113 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : The experience gained by our research team in recent years has led to the optimization of a quick and effective procedure for the complete dechromation of chromium waste. This procedure is based on the oxidation of chromium (III) to chromium (VI) through the action of hydrogen peroxide in an alkaline medium. The highly toxic chromium (VI) is stored in a stainless steel tank before being subsequently reduced to chromium (III), which can be reused in the tanning process. The oxidation reaction, at room temperature, leads to the formation of peroxochromates that have great oxidizing power and which significantly accelerate the pre-hydrolysis; corresponding to the maceration stage in the gelatine production process. In this way, gelatine or any other type of collagen biopolymer can be obtained in a single stage and with an excellent yield. We have designed an industrial transformation plant for chromium waste in chemical products used by the tanning industry. This plant consists of the following equipment: defibering machine, hydroextractive centrifuge, two reactors (dechromation and for obtaining biopolymers), tank for storage and reduction of chromium (VI), atomizer (optional), simple equipment for heating concentrated biopolymer solutions, transportation truck. Given that the overall investment has a payback back in five years, the cost of the plant can easily be borne by the tanner. This project has two objectives: firstly, to help solving an important environmental problem faced by the leather industry, which incurs significant costs in managing this type of waste; and secondly, to enable acceptable financial gains in terms of obtaining chemical products designed for the tanning industry. These products are: basic chromium (III) salts from the chromium waste, collagen biopolymers suitable for retanning, filling, basifying, deliming and glazing finishes that can partially and/or totally replace casein. Our proposed transformation plant for chromium waste was designed in such a way as to be adaptable to the individual circumstances of all interested leather industries, thus avoiding the need to build a communal plant, where the costs of transporting waste would have a negative effect on final savings. The plant is designed to process all types of chromium waste produced during the tanning process and in the subsequent stages of manufacture (fatliquoring, retanning, dyeing and finishing), and includes chromium waste with wool/hair (double-face). A financial study of the overall installation and the corresponding cost in obtaining the new chemical products was also been carried out and reveals significant savings for the tanner. En ligne : https://drive.google.com/file/d/1YMEn_JJMYoQ1bS88gsP7UcK8UX5vP8rl/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2578 [article]

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