The aqueous chemistry of polonium and its relationship to mineral processing streams

Abstract

Polonium-210 is a radioactive daughter of uranium-238. It has a relatively short half-life and, as a consequence, it is very dangerous to handle even in microgram quantities because of intense radiation effects. These properties have made it difficult to obtain reliable data on its chemical behaviour and in particular its aqueous chemistry is poorly understood. To overcome the shortfalls in our knowledge of polonium behaviour, this thesis has addressed pertinent issues by the undertaking of extensive research to develop a thermochemical database for the element. Such data is vital in trying to predict and understand the behaviour of the element in solution for a given set of conditions. Because of the paucity of reliable data in the literature, much of the data presented here has been derived theoretically using linear free energy relationships. To validate the derived data, pH-potential diagrams were constructed for several practical systems. The pH-potential diagram provides a compact, pictorial summary of electron-transfer, proton-transfer and electron-and-proton-transfer reactions, favoured on thermodynamic grounds. Use of these diagrams, in conjunction with pratical observations and measurements, has resulted in a better understanding of the aqueous chemistry of polonium in both the simple metal-water system and the more complicated systems of many industrial processes. In particular, the work highlighted that the chemistry of polonium is often similar to that of lead. This is in contrast with the literature which has indicated that the behaviour of polonium is analogous to that of its Group(VI) homologues, tellurium and selenium. The present work has shown that polonium has characteristics of both lead and tellurium, depending upon conditions.

Date of Award	2001
Original language	English