Ion Exchange and Other Studies of Some Compounds of Thorium.

The aim of the work described in this thesis has been to further the knowledge of the behaviour of thorium in acid solutions. In connection with this object, a review of the literature showed that there was some disagreement, particularly as to the behaviour of thorium in nitric acid, and in addition, there was little evidence con-cerning the reactions of thorium in phosphoric acid media. The various sytems were investigated by means of ion exchange methods and the position has been clarified to a large extent with respect to the types of species present. Structures for the complex ions present are tentatively proposed and possible explanations of the observed phenomena are discussed. During the course of the work it was necessary to design methods for the preparation of pure solutions of thorium perchlorate and thorium phosphate. In addition no accurate method was available for the quantitative determination of thorium in the presence of phosphate or for sulphate in the presence of thorium. Two methods of separation have been designed to enable these determinations to be carried out accurately. The phenomenon of the co-precipitation of thorium with barium sulphate which was encountered in the course of a survey of analytical methods was found to be worthy of fuller investigation, particularly as the published information was scanty. Studies including those utilizing X-ray diagrams indicate that complex formation is not involved but a final explanation of this process has not proved to be forthcoming