Analele ştiinţifice ale Universităţii "Al. I. Cuza" din Iaşi

The behavior of aqueous dispersion of inorganic oxides is of great importance in industrial and laboratory applications. Point of zero charge is of fundamental importance in surface sciences; for example, in the field of environmental science, it determines how easily a solid substrate is able to adsorb potentially ions. It also has applications in colloids science, e.g., flotation of minerals. Point of zero charge (pH_PZC) for a given oxide surface is the pH value at which it surface has a net neutral charge. The significance of the pH_PZC value is that a given oxide surface will have a positive charge in the acid pH domain (and the value is less than the point of zero charge) and a negative charge in the alkaline pH domain.

The point of zero charge (pH_PZC) for titanium dioxide reported in the literature cover almost all pH domain, from 2 to almost 9. In this paper, we used the acid-base titration method to determined the pH_PZC for a TiO₂ sample. Results obtained for three different electrolite solutions show that value of point of zero charge is 5.5, in a very good correlation with the data from the literature.