An investigation into aqueous titanium speciation utilising electrochemical methods for the purpose of implementation into the sulfate process for titanium dioxide manufacture

Titanium dioxide, TiO₂, plays an important role in many areas of modern society due to its very high refractive index. In its powder form, it is most commonly found in paints, plastics, toothpaste, foods and medicines. Industrially, titanium dioxide has been mixed with glass or cement to produce superior materials. TiO₂ pigment is produced by two common methods, the Sulfate and Chloride Processes. This thesis will focus on the Sulfate process. During the sulfate process, the titanium ends up being in aqueous form in concentration acid, and little is known about the speciation of aqueous titanium. Therefore it is the focus of this thesis to investigate the electrochemistry of Ti(IV) reduction to Ti(III) in sulfuric acid media, using known electrochemical techniques, such as; cyclic voltammetry, impedance, RDE, polarography, to determine kinetic information, i.e. diffusion co-efficients, to better understand how titanium reacts in a sulfuric acid medium. The experimental results revealed that in sulfuric acid media, compared to other acid media, the sulfate ions form three different bridging species either as oligomers or monomers. These species depend on various solution conditions such as titanium and acid concentration as well as solution age. Indications of the best possible conditions have been provided.