Technetium has been identified as an element of interest for the safety assessment of a deep geological repository for used nuclear fuel. In this study, the sorption of Tc(IV) onto MX-80 bentonite, illite, and shale in ionic strength (I) 0.1–6 mol·kgw−1 (m) Na-Ca-Cl solutions at pHm = 4–9 and limestone at pHm = 5–9 was studied. Tc(IV) sorption on MX-80 increased with pHm from 4 to 6, reached the maximum at pHm = 6–7, and then gradually decreased with pHm from 7 to 9. Tc(IV) sorption on illite gradually increased with pHm from 4 to 7, and then decreased as pHm increased. The sorption properties of Tc(IV) on shale were quite similar to those on illite. Tc(IV) sorption on limestone slightly increased with pHm from 5 to 6 and then seemed to be constant at pHm = 6–9. Tc(IV) sorption on all four solids was independent of ionic strength (0.1–6 m). The 2 site protolysis non-electrostatic surface complexation and cation exchange model successfully simulated the sorption of Tc(IV) onto MX-80 and illite and the optimized values of surface complexation constants were estimated.

1. Introduction
2. Experimental
    2.1 Materials
    2.2 Sorption Experiment
3. Results and Discussion
    3.1 Sorption Kinetics
    3.2 Sorption on MX-80
    3.3 Sorption on Illite
    3.4 Sorption on Shale and Limestone
4. Conclusions
Conflict of Interest
Acknowledgements
REFERENCES

• Shinya Nagasaki(McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L7, Canada) Corresponding author
• Zhiwei Zheng(McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L7, Canada)
• Jianan Liu(McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L7, Canada)
• Jieci Yang(McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4L7, Canada)
• Tammy (Tianxiao) Yang(Nuclear Waste Management Organization, 22 St. Clair Ave. East, 4th Floor, Toronto, ON, M4T 2S3, Canada)