Separation and preconcentration of perrhenate from ionic solutions by ion exchange chromatography

Abstract

Technetium poses an environmental hazard because of its radioactivity and long half-life. It exists in the form of pertechnetate in the environment and can be modeled by the nonradioactive ion perrhenate, since pertechnetate and perrhenate have the same geometry and similar chemical properties. In this research, a new zinc cyclen resorcinarene cavitand (ZCR) column was used in ion chromatography (IC) to efficiently separate perrhenate. Ion chromatography has the advantage of requiring almost no sample preparation for water samples. The ZCR column demonstrated the ability to separate anions: fluoride, chloride, nitrate, sulfate, phosphate, perchlorate, and perrhenate by gradient 2–60 mM NaOH. Unlike other columns, the new column material was selective in retaining perrhenate. The ZCR column also gave a linear range from 2.0 to 1000 mg L−1 for perrhenate with R2 > 0.997. There was a logarithmic relationship between the concentration of perrhenate and its retention time. Excellent perrhenate recovery was achieved on the ZCR column when river water was spiked with perrhenate and perrhenate was preconcentrated. The efficient separations of perrhenate by the ZCR column will potentially assist in pertechnetate separations.