Dissertations, Theses, and Capstone Projects

Date of Degree

9-2023

Document Type

Dissertation

Degree Name

Ph.D.

Program

Chemistry

Advisor

Jennifer Shusterman

Advisor

Lynn Francesconi

Committee Members

Melissa Deri

Benjamin Burton-Pye

Subject Categories

Radiochemistry

Keywords

Isotope Harvesting, FRIB, NSCL, Zr-88

Abstract

Zr isotopes have various applications in nuclear science, such as 86Zr and 89Zr in nuclear medicine, 88Zr as a diagnostic isotope relevant to stockpile stewardship, and the fission product 95Zr useful as an s-process branch nucleus for study in astrophysics. To access these isotopes of interest, dedicated production methods and subsequent processing chemistry are required. Direct production routes can be technically challenging and difficult to obtain enough activity to meet demand. The processing chemistry of Zr isotopes is tedious due to the tendency for Zr to hydrolyze in solution without highly acidic conditions or a strong complexant. With the recent opening of the Facility for Rare Isotope Beams (FRIB), a new avenue is open to obtain Zr isotopes of interest in high yields from beam byproduct accumulation while avoiding hydrolyzing aqueous conditions.

During routine operation of the FRIB, radionuclides will accumulate in both the aqueous beam dump and along the beamline in the process of beam purification. These byproduct radionuclides, many of which are far from stability, can be collected and purified for use in other scientific applications in a process called isotope harvesting. In this work, the viability of harvesting Zr isotopes from solid components was investigated using several different separation methodologies. Initial work focused on the demonstration of solid-phase harvesting from a secondary 88Zr beam generated at the National Superconducting Cyclotron Laboratory (NSCL) that was stopped in a series of collectors comprised of Al, Cu, W, and Au foils. Total recovery of 88Zr was over three times higher recovery than in a previous aqueous-phase harvesting experiment by using anion-exchange and solvent extraction techniques.

Further investigation into other separation methodologies for harvesting Zr at FRIB was conducted to increase the extraction efficiency and target short-lived isotopes of Zr. Due to the complex nature of bulk metal matrices containing radionuclides of Zr, purification methods need to be tested under conditions that are amenable to the isotope harvesting facilities present at FRIB. In this work, a TOPO impregnated resin was synthesized for application to solid-phase isotope harvesting of trace Zr from bulk metal matrices at FRIB.

The chemistry developed for harvesting of Zr was adapted to a supported liquid membrane (SLM) system using 3D-printed microfluidic modules. Performing Zr extractions on the microfluidic scale is a rapid and efficient separation method applicable to harvesting short-lived Zr. The utility of solid-phase isotope harvesting to access elements such as Zr that readily hydrolyze in near-neutral pH aqueous conditions has been demonstrated using several approaches for application to harvesting from solid components at FRIB.

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