Factors influencing the stability of the polysucrose/alumina system

The influence of such factors as polymer concentration (10–800 ppm), pH of the solution (3–9), and ionic strength of the background electrolyte (0.001–0.1) and the presence of surfactants (SDS, CTAB, TX-100) on the stability of the colloidal suspensions alumina/polysucrose were measured spectrophotometrically. The obtained results, discussed together with the adsorption, the surface charge density, and the surface tension data, showed that the measured suspensions are unstable and flocculate quite easily. Although due to the fact that polysucrose (PS) considered to be neutral proved to be slightly negatively charged, there is a chance to control the stability using the abovementioned factors. The most effective way to obtain stable Al₂O₃/PS suspensions was the addition of SDS to the system. Because of the competitive adsorption between PS and sodium dodecyl sulfate (SDS) at the alumina surface, the larger number of free macromolecules of PS is present in the bulk solution, what leads to the depletion stabilization process. The other examined factors such as the polymer concentration, pH of the solution, and the ionic strength of the electrolyte have minor influence on the stability of the Al₂O₃/PS suspensions. The obtained results create new possibilities in the fields of functionalized materials such as adsorbents and catalysts.