Dispersion stability of titanium dioxide in aqueous isopropanol with polymer dispersant

Two polymer dispersants, polyester dispersant (PD) and sodium polyacrylate (NaPAA), were used to disperse titanium dioxide in 10% aqueous isopropyl alcohol (IPA). The effect of pH and zeta potential on the dispersibility of the titanium dioxide (TiO 2 ) was studied via sedimentation. An optimum pH value of 8 for the two polymer dispersants in aqueous IPA suspension was found. The isoelectric point of the TiO 2 particles was at pH 5.1 and pH 5.3 and shifted to lower pH in the presence of PD or NaPAA, with a greater decrease in zeta potential for the NaPAA suspension (− 36.5 to − 64.1 mV) due to the high degree of ionization compared with PD (− 36.5 to − 60.6 mV). The conformations of PD and NaPAA were strongly pH dependent: Their adsorption was highest at low pH and lowest at high pH, with the maximum adsorption of PD and NaPAA being 44.0 and 39.2 mg g −1 at pH 3, respectively. It was shown that the stability of the suspensions was not only dependent on the pH but also on the zeta potential and molecular structure of the dispersant.