Volt Equivalent diagrams as a means of displaying the electrochemical thermodynamics of the sulfur-water system

In this paper, we describe the use of Volt-Equivalent Diagrams (VEDs) to display the electrochemical thermodynamics of one of the most complicated chemical systems in nature; the S-H2O system, as it relates to the use of copper for the isolation of high level nuclear waste (HLNW) in granitic repositories in Sweden. The complexity stems from this element having oxidation states that vary from -2 to +8 including a multitude of fractional oxidation states. The volt equivalent describes the reactivity of a species and foretells the various chemical transformations that may occur between different sulfur-containing species in the system. (C) 2013 Elsevier Ltd. All rights reserved.