Solution viscosity and flocculation characteristics of linear polymeric flocculants in various media

• Published in: Chemical engineering research & design Vol. 89; no. 7; pp. 1037 - 1044
• Main Authors: Chimamkpam, T.O., Rasteiro, M.G., Garcia, F.A.P., Antunes, E., Ferreira, P., Hunkeler, D., Wandrey, C.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-07-2011; Elsevier
• Subjects: Applied sciences; Cationic polyelectrolyte; Charge density; Chemical engineering; Copolymers; Exact sciences and technology; Flocculating; Flocculation; Industrial use water; Mathematical models; Media; Organic polymers; Papermaking; Physicochemistry of polymers; Pollution; Polyelectrolytes; Properties and characterization; Rheological properties; Rheology; Solution and gel properties; Strength; Water treatment and pollution; Cationic polyelectrolyte; Copolymers; Rheology; Papermaking; Flocculation; Shear; Distilled water; Paper mill; Modeling; Charge density; Polyelectrolyte; Industrial water; Shear viscosity; Polymer solutions; Flocculation reagent; Ionic strength; Electrokinetic potential; Chemical composition
• ISSN: 0263-8762
• DOI: 10.1016/j.cherd.2010.10.022

▶ Rheological characterization of a new set of cationic copolymers of acrylamide (AM and Q9) differing in molar mass and ratio Q9/AM. ▶ Water characteristics have got a strong influence on the solution viscosity of the different polyelectrolytes (PEL). ▶ PEL behaviour in distilled water is compared with its behaviour in a highly cationic water from a paper mill. The influence of water quality on viscosity is dependent on the PEL characteristics (molar mass and charge density). ▶ Solution viscosity has been correlated with performance on flocculation of PCC particles used as filler in papermaking. ▶ The influence of water quality on solution viscosity could be correlated with differences detected on flocculation performance in the two media.
Rheological characteristics of linear copolymers of acrylamide (AM) and acryloyloxyethyltrimethyl ammonium chloride (Q9), differing in molar mass and chemical composition, have been studied in distilled water (DW) and industrial water (IW) obtained from a paper mill. For all copolymers, the shear viscosity, μ, was much lower as the ionic strength of the water increased, with near Newtonian behaviour observed at high ionic strengths. In DW, the polymer solutions were yield pseudoplastic. Comparison of the behaviour of all flocculants at the same shear rate in the two media was accomplished by modelling the rheological data.
The characteristics of the copolymers could be related with their flocculation performance in IW. The rate of flocculation in the IW was generally higher than in the DW. In general, flocculants with higher charge density were effective at lower concentrations exhibiting a lower value for the optimum PEL dosage. The flocculation data were supported with zeta potential measurements. In all cases flocs break under shear with an inability to recover the floc size with time. Overall, the polyelectrolyte behaviour in flocculation as a function of molar mass, charge density and quality of the medium could be correlated. This is of particular importance for papermaking due to the modern tendencies for water closure.