Coagulation of bentonite suspension by polyelectrolytes or ferric chloride / E. Barbot in Chemical engineering journal, Vol. 156 N° 1 (Janvier 2010)  

Public ISBD [article]  inChemical engineering journal > Vol. 156 N° 1 (Janvier 2010) . - pp. 83-91 Titre : Coagulation of bentonite suspension by polyelectrolytes or ferric chloride : floc breakage and reformation Type de document : texte imprimé Auteurs : E. Barbot, Auteur ; P. Dussouillez, Auteur ; J. Y. Bottero, Auteur Année de publication : 2010 Article en page(s) : pp. 83-91 Note générale : Génie Chimique Langues : Anglais (eng) Mots-clés : Coagulation Flocculation Ferric chloride Polyelectrolytes Shear stress Laser granulometry Index. décimale : 660 Résumé : Coagulation process usually involves different hydrodynamic conditions, in particular when it is followed by a filtration step. In this study, coagulation performance was investigated under a wide range of shear stress. Floc behaviour was followed in-line by laser granulometry to determine size distribution and structure. Synthetic suspension of bentonite in tap water was used as a reference for mineral solids in surface water. Three cationic polymers (polyamine based and polyDADMAC) and ferric chloride were tested using different coagulation reactor geometries. Jar-test indicated coagulation performance under mild hydrodynamic conditions and Taylor–Couette reactors were used to create shear stresses up to 8 Pa. Flocs formed with ferric chloride are not able to grow under middle shear stress like 1.5 Pa. On the contrary, polyelectrolytes lead to large flocs, dense (Df = 2.6) and resistant to shear stress. A qualitative comparison of floc resistance to shear depending on hydrodynamic conditions and coagulant type is given through the calculation of the strength factor. Fractal dimension measurements indicate a mechanism of particle erosion when flocs are subjected to a higher shear stress in Taylor–Couette reactor. Floc re-growth is also investigated, and breakage appears to be non-reversible regardless of coagulant and conditions experimented. DEWEY : 660 ISSN : 1385-8947 En ligne : http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TFJ-4XF840K-1&_user=6 [...] [article] Coagulation of bentonite suspension by polyelectrolytes or ferric chloride : floc breakage and reformation [texte imprimé] / E. Barbot, Auteur ; P. Dussouillez, Auteur ; J. Y. Bottero, Auteur . - 2010 . - pp. 83-91. Génie Chimique Langues : Anglais (eng) in Chemical engineering journal > Vol. 156 N° 1 (Janvier 2010) . - pp. 83-91 Mots-clés : Coagulation Flocculation Ferric chloride Polyelectrolytes Shear stress Laser granulometry Index. décimale : 660 Résumé : Coagulation process usually involves different hydrodynamic conditions, in particular when it is followed by a filtration step. In this study, coagulation performance was investigated under a wide range of shear stress. Floc behaviour was followed in-line by laser granulometry to determine size distribution and structure. Synthetic suspension of bentonite in tap water was used as a reference for mineral solids in surface water. Three cationic polymers (polyamine based and polyDADMAC) and ferric chloride were tested using different coagulation reactor geometries. Jar-test indicated coagulation performance under mild hydrodynamic conditions and Taylor–Couette reactors were used to create shear stresses up to 8 Pa. Flocs formed with ferric chloride are not able to grow under middle shear stress like 1.5 Pa. On the contrary, polyelectrolytes lead to large flocs, dense (Df = 2.6) and resistant to shear stress. A qualitative comparison of floc resistance to shear depending on hydrodynamic conditions and coagulant type is given through the calculation of the strength factor. Fractal dimension measurements indicate a mechanism of particle erosion when flocs are subjected to a higher shear stress in Taylor–Couette reactor. Floc re-growth is also investigated, and breakage appears to be non-reversible regardless of coagulant and conditions experimented. DEWEY : 660 ISSN : 1385-8947 En ligne : http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TFJ-4XF840K-1&_user=6 [...]

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