The dispersion stability (the relative absorbance) of the kaolin in the presence of CPC as a function of
equilibrium concentration at pH 9 is shown in Figure 3 together with the key data in Table 2. In the
absence of added surfactant, the dispersions of the kaolin were stable. When CPC alone was added,
stability nearly complete flocculation occurred at an equilibrium concentration of about 0.02 to 0.03 mM.
This concentration corresponds roughly with the first rapid rise in adsorbed amount in the adsorption
isotherm. This result is consistent with that of Panya, et al,[1]. However, when the equilibrium amount of
CPC was greater than about 0.4 to 0.5 mM, the suspensions were completely stabilized. No flocculation
occurred at concentrations where the adsorbed amount of CPC reached its maximum. Similar stability
behavior was observed when PVA was pre-adsorbed onto the kaolin. In this case, the stability of the
suspensions re-stablilsed at higher concentrations of CPC as well (about 0.5 to 0.6 mM). The
restabilisation corresponds to the increase in adsorbed amount up to the maximum adsorbed amount of
CPC onto the kaolin that was pre-adsorbed with PVA.