Estimating Na+ and K+ concentrations of the pore solution based on ex-situ leaching tests and thermodynamic modeling

Ex-situ leaching (ESL) methods have typically yielded higher sodium and potassium concentrations than pore solutions obtained using the conventional high-pressure extraction approach since ESL concentrations require a back-calculation to account for dilution. This paper proposes a new method for adjusting the concentrations obtained from ESL. Thermodynamic calculations were used to determine the total pore solution content, and a pore partitioning model was then used to separate the total solution into gel and capillary assignments. Using the refined pore solution volumes to adjust the concentrations from ESL improved the correlation to PSE concentrations.