Induction of titanium reduction using pyrrole and polypyrrole in the ionic liquid ethyl-methyl-imidazolium bis(trifluoromethanesulphonyl)amide

The electrowinning of titanium currently involves high temperature processing and quite extreme condition. As part of a project investigatingthe use of ionic liquids to refine titanium, we have investigated the use of a polymeric nucleating agent to assist the electro-depositionof the metal. Initial attempts focussed on polypyrrole coatings on the working electrode. These were unsuccessful due to the lowconductivity of the conducting polymer in the IL at the reductive potentials required to deposit the titanium. However, it was found thatpyrrole was a very successful additive able to induce deposition of titanium species from a TiCl4 containing ionic liquid electrolyte([emim][Ntf2]). Well characterised titanium containing polypyrrole co-deposits have been achieved, when pyrrole was introduced, howeverbulk metallic titanium was not observed. The presence of titanium species in these deposits was confirmed by XPS. It is thought thatthe growing pyrrole oligomers form nucleation sites either in situ at the electrodeliquid interface or as a thin film on the electrode allowingco-precipitation of reduced Ti species from solution.