Publication

Coupled Biogeochemical Processes Governing the Stability of Bacteriogenic UO2

2006
Posters

Abstract

Introduction: The chemical stability of bacteriogenic UO2 is the seminal issue governing its success as an “in-situ waste form” in the subsurface. The goals of this project are to identify key molecular-scale processes that mediate the stability and oxidation of bacteriogenic UO2 in the subsurface and to measure their rates at the meter scale. We will eventually develop coupled (bio)geochemical conceptual process models describing the effects of these processes on U(VI) release from UO2 in heterogeneous subsurface media. Hypotheses: We postulate that: (I) the stability of bacteriogenic UO2 is enhanced by cation substitution into UO2 ; (II) that sulfides may locally buffer the redox potential of ground water and protect UO2 from oxidation; and (III) that subsurface bacterial Mn(II) oxidation may catalytically enhance UO2 oxidation.

Official source

https://infoscience.epfl.ch/entities/publication/7e3ea21d-f379-4a1d-b39f-60b0fbc8ec53

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2006
Posters

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/7e3ea21d-f379-4a1d-b39f-60b0fbc8ec53

About this result

Related concepts (32)

Reduction potential

Redox potential (also known as oxidation / reduction potential, ORP, pe, , or ) is a measure of the tendency of a chemical species to acquire electrons from or lose electrons to an electrode and thereby be reduced or oxidised respectively. Redox potential is expressed in volts (V). Each species has its own intrinsic redox potential; for example, the more positive the reduction potential (reduction potential is more often used due to general formalism in electrochemistry), the greater the species' affinity for electrons and tendency to be reduced.

Redox

Redox (ˈrɛdɒks , ˈriːdɒks , reduction–oxidation or oxidation–reduction) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a decrease in the oxidation state. There are two classes of redox reactions: Electron-transfer – Only one (usually) electron flows from the atom being oxidized to the atom that is reduced. This type of redox reaction is often discussed in terms of redox couples and electrode potentials.

Standard electrode potential

In electrochemistry, standard electrode potential , or , is a measure of the reducing power of any element or compound. The IUPAC "Gold Book" defines it as: "the value of the standard emf (electromotive force) of a cell in which molecular hydrogen under standard pressure is oxidized to solvated protons at the left-hand electrode". The basis for an electrochemical cell, such as the galvanic cell, is always a redox reaction which can be broken down into two half-reactions: oxidation at anode (loss of electron) and reduction at cathode (gain of electron).

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Coupled Biogeochemical Processes Governing the Stability of Bacteriogenic UO2

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