Heteroflocculation of kaolin pre-treated with oppositely charged polyelectrolytes

Seppänen, Rauni; Ström, Gōran; Elftonson, J.

doi:10.1016/s0927-7757(99)00213-7

Cited by 7 publications

(4 citation statements)

References 24 publications

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“…A change in the polymer/solid ratio can easily be simulated by varying the polymer concentration and holding the solid concentration at the same level. Therefore, the flocculation performance of polymers has often been evaluated with experiments in which the added polymer concentration to a suspension was varied 2, 4, 6, 23. However, the validity of this approach has not been demonstrated to date.…”

Section: Resultsmentioning

confidence: 99%

Chitosan‐graft‐acrylamide polyelectrolytes: Synthesis, flocculation, and modeling

Laue¹,

Hunkeler²

2006

J of Applied Polymer Sci

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A series of chitosans have been grafted with quaternary ammonium cationic monomers, as well as acrylamide using Ce(IV) to induce macroradical formation on the polysaccharide backbone. The materials, which have long chain branches per molecule between 0.3 and 5.5, are shown to provide very high specific flocculation efficiency, at the very least equal to the entirely synthetic materials which have been previously documented in the literature. A charge ratio, determined from the polymer concentration at which flocculation takes place, the charge density of the polymer, and the surface charge of the suspended matter are proposed as metrics to evaluate the occurrence of charge neutralization and bridging or charge patch flocculation mechanism. Furthermore, a window of application (WA) for flocculants, which characterizes the region of concentration wherein the polyelectrolyte can remove 99% of the supernatant turbidity, has been defined. It was shown to depend on the square root of the ionic strength and varies inversely with the Debye length, providing a fundamental basis for the concept of the WA. A mathematical expression is presented which links the WA with the salt concentration and the number of branches of the grafted polymer. Grafted chitosans have been shown to be more robust than polyacrylamides in testing against model kaolin suspensions.

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Section: Resultsmentioning

confidence: 99%

Chitosan‐graft‐acrylamide polyelectrolytes: Synthesis, flocculation, and modeling

Laue¹,

Hunkeler²

2006

J of Applied Polymer Sci

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“…In many colloidal systems, dispersion of substrates is achieved by controlling the adsorption and conformation of polymers on the surface of the dispersed particulates. , In addition to possible modification of the van der Waals forces by the adsorbed polymer, various interaction forces such as steric, , depletion, − bridging, , and electrostatic − have been identified as acting in a variety of their combinations . These forces, if relevant, are all components of the general thermodynamic description of colloidal interaction, which requires that interparticle forces relate directly to the dependence of the adsorption isotherms of solutes (adsorption as a function of chemical potential) on the interparticle separation. − …”

Section: Introductionmentioning

confidence: 99%

Reversible Flocculation of Silica Across the Phase Boundary of Poly(vinyl caprolactam) in Aqueous Solution

Qiu

Somasundaran

2005

Langmuir

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The colloid stability of silica dispersions in water in the presence of poly(vinyl caprolactam) (PVCAP) has been studied below and above the lower consolute temperature (LCT) of its solutions. The dispersion sediments slowly without PVCAP in the temperature range studied (26-40 degrees C) or with PVCAP below the LCT ( approximately 30 degrees C). In contrast, with PVCAP above the LCT, rapid flocculation occurs at acid pH, with re-dispersal on cooling. Reversible flocculation is also obtained above the LCT by cycling the pH from alkaline to acid and back. The flocculation observed above the LCT may also be regarded as heterocoagulation between the silica particles and the aggregates of the polymer.

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“…According to the molar mass and the concentration of the second polymer, this phenomenon can lead to the formation of a new protective layer or to the destabilization of the system by bridging flocculation [6,[8][9][10][11]. Moreover, heteroflocculation has been observed between particles covered by different layers for complexation [3,12,13]. The interparticle complex formation between protective layers and a second polymer was mentioned, but briefly examined from a mechanistic point of view.…”

Section: Introductionmentioning

confidence: 99%

Interactions of hairy latex particles with cationic copolymers

Borget

Lafuma

Bonnet-Gonnet³

2005

Journal of Colloid and Interface Science

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Heteroflocculation of kaolin pre-treated with oppositely charged polyelectrolytes

Cited by 7 publications

References 24 publications

Chitosan‐graft‐acrylamide polyelectrolytes: Synthesis, flocculation, and modeling

Chitosan‐graft‐acrylamide polyelectrolytes: Synthesis, flocculation, and modeling

Reversible Flocculation of Silica Across the Phase Boundary of Poly(vinyl caprolactam) in Aqueous Solution

Interactions of hairy latex particles with cationic copolymers

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