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Thermodynamics of cation exchange on smectites

Cation exchange reactions buffer the fluid chemistry of pore fluids, which should be taken into account for modelling the evolution of the pore fluid chemistry during dissolution and precipitation reactions. This requires, however, detailed knowledge about the usually non-linear behaviour of A-B-exchange reactions, where the selectivity may change with the ratio A/(A+B) and where changes in the ionic strength induces concentration-valency effects. In a first step, well-characterized smectites will be used for measuring binary exchange isotherms of common pore fluid cations at ambient temperatures. Since very little is known about the impact of temperature on exchange reactions, these experiments will then be extended to typical reservoir temperatures.

Start of work: Immediately
Supervision: Helge Stanjek
Level: MSc, AGW preferred, a liability to chemistry is essential