Raman microscopic studies of the liquid-liquid interface between an organic layer and an aqueous solution containing metal ions

Raman microscopic studies of liquid-liquid interfaces between an organic layer and aqueous solutions of metal ions containing extractants are described for the first time. Using a specially constructed cell, the observation of third-phase formation which hinders the mass transfer of metals from the aqueous to the organic layers has been monitored and the spectra discussed in terms of the processes involved and the molecular interactions. The system selected for study was tri-n-butylphosphate-odourless kerosene with zirconium(IV) in aqueous nitric acid solution, a model of an industrial process for nuclear fuels reprocessing. Particulate matter at the interface between the organic and aqueous layers was identified spectroscopically as a carbonate from wash solutions used in neutralisation of the aqueous acid component.