Potentiometric titration

Published: 14 October 2008

Potentiometry of suspensions of solids (or complex solutions) is a way to achieve indirect information of surface (or aqueous) complexation reactions.

Usually, the proton exchange is recorded but the exchange of other ions can also be detected by the use of ion selective electrodes.

The information on surface speciation can then be used to predict the surface – aqueous or surface – surface interactions in various environments as, for example, an agglomeration process or the fate of organic materials or metal ions in natural environments.

Modelling of data in aqueous solutions is relatively straightforward, where data usually can be explained with a definite model. For surface reactions, the situation is more complicated since several Surface Complexation Models (SCMs) are used for the evaluations. The background for this is the difficulties to accurately describe the behavior of the surface potential on solid/aqueous interface double layer in various environments. Most work at our division has been focused on high ionic strength systems, in which the Constant Capacitance Model has shown to give consistent models.

Several PhD dissertations have been produced during the years using potentiometry as main research method.  The most recent is: Mathias Jarlbring: Surface Reactions in Aqueous Suspension of Fluorapatite and Iron Oxides, 2006.