Electrostatic Stabilization of Ultrafine Titania in Ethanol

The colloidal stability of a suspension of very fine titania (TiO 2 ) powder in ethanol has been investigated. The electrokinetic behavior and stability ratios were determined as a function of operational pH and salt concentration. We show that the stability is strongly dependent on ionic strength; the TiO 2 suspensions will aggregate relatively rapidly at ionic strengths >10 −3 M , while suspensions exhibiting long‐term stability can be made at ≤10 −4 M , providing that the zeta potential of the TiO 2 particles is sufficiently high, i.e., |ζ|= 40–50 mV. Theoretical estimates of the stability based on electrostatic repulsion show a relatively good correlation with the experimental results, in particular in the acidic operational pH (pH*) range.