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Effect of agitation and molecular weight on polymer adsorption and deflocculation


  • Abstracted from the Ph.D. dissertation of L. Jankovics, Columbia University, New York, 1961.


The rates of adsorption of PAM's were measured on calcium phosphate at various intensities of agitation. Vigorous mechanical stirring promotes the adsorption by degrading the floccules, thus providing new surfaces available for further adsorption of polymers. The rising parts of the rate curves correspond to the breaking up of flocs or “deflocculation” by the applied mechanical stirring. The flat portions of the curves in the high stirring time range indicate complete redispersion; no further surfaces are available for the adsorption of polymer flocculants. The effect of the intensity of agitation upon adsorption was investigated. Increasing the number of revolutions of the stirrer causes the adsorption curves to rise more sharply. This suggests that the deflocculation also becomes more rapid. At equimolar initial concentrations the rates of adsorption and deflocculation decrease with increasing molecular weight.

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