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A New Process for Extracting Alginates from Laminaria digitata: Reactive Extrusion ArchiMer
Vauchel, Peggy; Kaas, Raymond; Arhaliass, Abdellah; Baron, Regis; Legrand, Julien.
Alginates are natural polysaccharides that are extracted from brown seaweeds and widely used for their rheological properties. The main step in the extraction protocol used in the alginate industry is that of alkaline extraction. A batch process is used for this step, which is time-, water-, and reactant-consuming. The possibility of extracting by reactive extrusion was investigated. The reactive extrusion process appeared to be more efficient than the batch process for the alkaline extraction of alginates from Laminaria digitata in several key ways: Time demand is reduced from about an hour to only few minutes, water and reactant requirements are divided by more than a factor 2, extraction yield is 15% higher (relative enhancement), and the rheological...
Tipo: Text Palavras-chave: Intrinsic viscosity; Reactive extrusion; Laminaria digitata; Alkaline extraction; Alginate.
Ano: 2008 URL: http://archimer.ifremer.fr/doc/2008/publication-6255.pdf
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Decrease in dynamic viscosity and average molecular weight of alginate from Laminaria digitata during alkaline extraction ArchiMer
Vauchel, Peggy; Arhaliass, Abdellah; Legrand, Jack; Kaas, Raymond; Baron, Regis.
Alginates are natural polysaccharides that are extracted from brown seaweeds and widely used for their rheological properties. The central step in the extraction protocol used in the alginate industry is the alkaline extraction, which requires several hours. In this study, a significant decrease in alginate dynamic viscosity was observed after 2 h of alkaline treatment. Intrinsic viscosity and average molecular weight of alginates from alkaline extractions 1-4 h in duration were determined, indicating depolymerization of alginates: average molecular weight decreased significantly during the extraction, falling by a factor of 5 between 1 and 4 h of extraction. These results suggested that reducing extraction time could enable preserving the rheological...
Tipo: Text Palavras-chave: Laminaria digitata; Intrinsic viscosity; Depolymerization; Average molecular weight; Alkaline extraction; Alginate.
Ano: 2008 URL: http://archimer.ifremer.fr/doc/2008/publication-4060.pdf
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Dynamical modelling of a reactive extrusion process: Focus on residence time distribution in a fully intermeshing co-rotating twin-screw extruder and application to an alginate extraction process ArchiMer
Baron, Regis; Vauchel, Peggy; Kaas, Raymond; Arhaliass, Abdellah; Legrand, Jack.
The context of this study is the modelling of reactive extrusion process based on an alginate extraction protocol. Residence Time Distribution (RTD) is one important part to predict the kinetics of reactive compounds. A simple model is proposed to predict RTD in fully intermeshing co-rotating twin-screw extruders without reaction. This model, which can be easily extended to reactive case in a future work, is based on the extension of an axial dispersion model, including control parameters (screw speed and flow rate) and geometrical parameters (screw profile and die design). Simulations were performed for various operating and geometrical conditions so as to illustrate possibilities offered by the proposed model. Validation was conducted for two different...
Tipo: Text Palavras-chave: Alginate; Extraction; Extrusion; Mathematical modelling; Residence time distribution; Simulation; Laminaria digitata.
Ano: 2010 URL: http://archimer.ifremer.fr/doc/00005/11592/8985.pdf
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Kinetics modeling of alginate alkaline extraction from Laminaria digitata ArchiMer
Vauchel, Peggy; Le Roux, Karine; Kaas, Raymond; Arhaliass, Abdellah; Baron, Regis; Legrand, Jack.
Alginates being depolymerized during their alkaline extraction, reducing extraction time could help producing higher rheological quality alginates. The purpose of the present work is to study fresh Laminaria digitata destructuration during alkaline extraction and its link to extraction kinetics. Both alginate extraction yield and mean diameter of algae particles were followed for different values of agitation level and initial size of algae pieces. Results highlighted the existence of a link between extraction yield and algal destructuration. Those elements and the specificity of L. digitata structure have been taken into account to propose a kinetics model based on a fluid-particle reaction with decreasing size particles. The model parameters have been...
Tipo: Text Palavras-chave: Model; Laminaria digitata; Alkaline extraction kinetics; Alginate.
Ano: 2009 URL: http://archimer.ifremer.fr/doc/2009/publication-6315.pdf
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Optimisation de procédés innovants pour l'obtention de phycocolloïdes ArchiMer
Vauchel, Peggy.
Alginates are polysaccharides which are naturally present in the cell wall of brown algae and extracted because of their rheological properties. The alginate industry uses an extraction protocol, which central step, the carbonatation, is conducted in batch reactors. It is a high water, reagent and time demanding process. The main objective of this thesis is to optimize the alginate extraction process. A study of the existing process, focused on carbonatation step, enabled to highlight points which could be enhanced to optimize the extraction yield and the quality of extracted alginates. Stirring intensity and algae pieces size have been identified as parameters having an influence on the carbonatation reaction kinetics. A specific analysis on medullar and...
Tipo: Text Palavras-chave: Alginate; Extraction; Laminaria digitata; Extrusion réactive; Optimisation; Modélisation; Distribution des temps de séjour; Cinétique; Rendement; Propriétés rhéologiques; Alginate; Extraction; Laminaria digitata; Reactive extrusion; Optimization; Modeling; Residence time distribution; Kinetics; Extraction yield; Rheological properties.
Ano: 2007 URL: http://archimer.ifremer.fr/doc/00002/11364/7937.pdf
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