Fluorinated Diluents- A Review

The history of the development of fluorinated compounds as potential diluents in solvent extraction processes is described. Fluorinated diluents were first investigated in the former Soviet Union and later in the United States and Europe. Fluorinated diluents represent a class of compounds that can be used as primary diluents or as phase modifiers. They are of particular utility when extractant solubility is limited in traditional hydrocarbon diluents and a polar diluent is needed. The chemical and physical characterisitics of fluorinated diluents are provided for a broad range of compounds. Other properties such as toxidcity and resistance to radiolysis are described. Fluorinated compounds have been studied for over 40 years and have been used at industrial scale as a primary diluent for cesium and strontium extraction in Russia and as a phase modifer for an insustrial-scale cesium extraction process in the United States. The advantages and disadvantages of traditional hydrocarbon diluents are compared with chlorinated diluents, chlorinated and fluorinated diluents, and a number of different types of fluorinated diluents. Developing trends for teh use of fluorinated diluents in solvent extraction processes are discussed. This article should provide assistance to researchers investigating new or improved solvent extraction processes where traditional hydrocarbon diluents may not be appropriate.