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Using Light Scattering to Screen Polyelectrolytes (PEL) Performance in Floccula...
Rasteiro, Maria G.; Pinheiro, Ineide; Garcia, Fernando A. P.; Ferreira, Paulo; Hunkeler, DavidFlocculation of precipitated calcium carbonate (PCC) was monitored using light diffraction spectroscopy (LDS). Four cationic polyacrylamides of high molar mass and with different degrees of branching, all copolymers of acrylamide (AM) and acryloyloxyethyltrimethyl ammonium chloride (Q9), were tested. LDS supplied information about the kinetic curves for flocs growth and also for the flocs structure evolution. F...
Modeling the Turbulent Flow of Pulp Suspensions
Ventura, Carla A.F.; Garcia, Fernando A.P.; Ferreira, Paulo J.; Rasteiro, M. GraçaPulp fiber suspensions are complex systems because the components present singular and complex interactions between them. A mechanistic model for the turbulent flow regime of industrial pulp suspensions was developed on the basis of a CFD code, using the chemical engineering module of COMSOL Multiphysics software. The standard k-ε turbulence model, chosen to simulate turbulence, was tested and validated using f...
Use of New Branched Cationic Polyacrylamides to Improve Retention and Drainage ...
Antunes, Elisabete; Garcia, Fernando A. P.; Ferreira, Paulo; Blanco, Angeles; Negro, Carlos; Rasteiro, M. GraçaCationic polyacrylamides of very high molecular weight and with different charge densities and degrees of branching have been investigated as retention aids for papermaking. The effects of polymer charge density and polymer branching on drainage and retention of a suspension containing fibers and precipitated calcium carbonate have been correlated with flocs properties. Additionally, the effects of flocculant d...
Effect of Water Cationic Content on flocculation, flocs resistance and refloccu...
Antunes, Elisabete; Garcia, Fernando A. P.; Ferreira, Paulo; Blanco, Angeles; Negro, Carlos; Rasteiro, M. GraçaIn papermaking, mill water closure may result in a significant increase of inorganic salts in the white water. The effect of these contaminants on the performance of retention aids was evaluated, in this study, through flocculation of Precipitated Calcium Carbonate (PCC) with three very high molecular weight cationic polyacrylamides (C-PAM) of medium charge density and with different degrees of branching. Furth...
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