Quarternary amine-based sodalite sorbent for selective removal of Tc-99 and I-129
Technetium-99 and Iodine-129 are risk-driven contaminants of high priority to DOE-EM office. Both radionuclides are prevalent at DOE nuclear waste sites. Because these radionuclides greatly affect the catalytic redox extraction process of uranium and plutonium in the fuel cycle, their removal from spent nuclear solution is highly desirable for efficient recovery of uranium and plutonium, and mitigation of potential releases of these radionuclides to the environment. The goals of this project were to develop advance sorbents for simultaneous capture of Tc-99 and I-129 from contaminated groundwater and nuclear waste streams. This research examined modification of porous commercial and synthesized aluminosilicate minerals (zeolite) for enhanced retention of radionuclides. Herein we report the development of a sorbent that: (1) binds pertechnetate ($TcO_4^-$) with a sorption efficiency (Kd) greater than any other sorbent materials previously reported in literature, (2) exhibits fast sorption kinetics and (3) uptakes $TcO_4^-$ under acidic and oxidizing conditions where Tc-99 retention is problematic. Thus, the use of quaternary-amine modified mesoporous zeolite as an amendment and/or permeable reactive barrier would be a robust strategy for Tc-99 remediation. Moreover, further modification of the evaluated zeolite materials with silver is envisioned to promote effective retention of both Tc-99 and I-129 and this study was slated for fiscal year 2019.