Sorption of Pd on illite, MX-80 bentonite and shale in Na-Ca-Cl solutions

This paper examines sorption of Pd(II) onto illite, MX-80 bentonite, and Queenston shale in Na-Ca-Cl solutions of varying ionic strength (IS) from 0.01 to 6.0 mol/L (M) and pHc ranging from 3 to 9 under atmospheric conditions. A 2-site protolysis non-electrostatic surface complexation and cation exchange model was applied to the Pd sorption onto illite and MX-80 using PHREEQC, and the model results were compared to the experimental ones obtained in this work. Surface complexation and cation exchange constants were estimated for both illite and MX-80 through the optimization process to bring the predicted distribution coefficients from the model into alignment with the experimentally derived values. These optimized surface complexation constants were compared to existing linear free energy relationships (LFER). (C) 2020 Korean Nuclear Society, Published by Elsevier Korea LLC.

Automated summary

This study investigates the sorption of Pd(II) onto different minerals in Na-Ca-Cl solutions with varying ionic strength and pH. A 2-site protolysis non-electrostatic surface complexation and cation exchange model is used to describe the sorption behavior, with surface complexation and cation exchange constants optimized to align with experimental results. The impact of surface complexation constants on the sorption behavior is highlighted, with comparison to existing linear free energy relationships.