Abstract
The possibility to concentrate, then redisperse colloidal suspensions is not only of great theoretical interest, but is also relevant to the industrial process of solid-liquid separation, which must often be followed by a redispersion stage. Up to now, these consecutive operations were unrealizable in the presence of polymers, since flocculation and adsorption were generally considered irreversible in this case. Previous studies have pointed out the occurrence of two main flocculation mechanisms: charge neutralization and interparticle bridging. The use of copolymers makes it possible to take into account these two different mechanisms together. Using this fact we prepared new copolymers of acrylamide with N-vinylimidazole via radical polymerization and characterized them by light scattering, viscometry, potentiometric titrations, and UV studies. One peculiarity of the chosen system is its dependence on pH: actually the degree of neutralization of such cationic polyelectrolytes does vary with pH, especially near the pK value. This paper shows that these copolymers may induce reversible flocculation of negatively charged suspensions, e.g., silica suspensions, by simple pH adjustment. Performances of the system were followed by various physico-chemical methods. The observed results are explained in terms of flocculation mechanisms as a function of pH.
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References
Derjaguin BV, Landau L (1941) Acta Phys Chem 14:633
Verwey EJW, Overbeek JThG in: Theory of the stability of lyophobic colloids, Elsevier Ed, Amsterdam, p
Kruyt HR, Klompe MAM (1943) Kolloid Beih. 54:507
Vincent B (1978) J Chem Soc Faraday Trans I 74:337
Frens G, Overbeek JThG (1971) J Colloid Interface Sci 36:2
Durand-Piana G, Lafuma F, Audebert R (1987) J Colloid Interface Sci 119:474
Wang TK, Piana G, Lafuma F, Audebert R (1987) in: Flocculation in Biotechnology and Separation Systems, Elsevier Science, Amsterdam, pp 165:173
Wang TK, Audebert R (1987) J Colloid Interface Sci 119:459
Wang TK, Audebert R (1988) J Colloid Interface Sci 121:32
Katchalsky A, Spitnik P, J Polymer Sci 2, 4:432–446
Gold D, Gregor H (1958) Z Physik Chem Neue Folge 15:103
Tan JS, Sochor AR (1981) Macromolecules 14:1700
Hesselink FTh (1977) J Colloid Interface Sci 60:448
Evers OA, Fleer GJ, Scheutjens JMHM, Lyklema J (1986) J Colloi Interface Sci 111:446
Rubio J, Kitchener JA (1976) J Colloid Interface Sci 57:132
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Vaslin-Reimann, S., Lafuma, F. & Audebert, R. Reversible flocculation of silica suspensions by water-soluble polymers. Colloid & Polymer Sci 268, 476–483 (1990). https://doi.org/10.1007/BF01411007
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DOI: https://doi.org/10.1007/BF01411007