# Temperature and time dependence on extraction of Molybdenum-99 hot atoms from neutron-irradiated β-molybdenum trioxide particles into water

## TL;DR

This study explores how temperature and heating time affect the extraction of Molybdenum-99 from neutron-irradiated particles into water, improving radiopharmaceutical production.

## Contribution

The first investigation of temperature and time dependence in extracting 99Mo hot atoms, suggesting a hydrated phase accelerates extraction.

## Key findings

- Extraction efficiency of 99Mo increased from 20.31% to 66.88% with higher temperature and longer heating.
- The activation energy for extraction is lower than atomic diffusion but higher or close to hydrated phase processes.
- A hydrated MoO3 phase is suggested to accelerate 99Mo extraction.

## Abstract

This study presents a novel perspective by examining the influence of temperature and heating time on the extraction of 99Mo into water, contributing to a better understanding of its extraction kinetics. β-MoO3 particles were synthesized via thermal evaporation and subsequently characterized using X-ray diffraction and transmission electron microscopy. These particles were then neutron-irradiated at the Kyoto University Research Reactor facility, after which the activity of the 99Mo in the particles was analyzed by a high-purity germanium semiconductor detector. The irradiated β-MoO3 particles were dispersed in water at temperatures of 20, 30, 40 or 50 °C for durations of 1, 2.5 or 5.5 h to extract 99Mo. The associated β-MoO3 solutions were also analyzed by a high-purity germanium semiconductor detector. The 99Mo extraction efficiency was increased from 20.31 ± 1.24% to 66.88 ± 1.42% upon raising the water temperature and increasing the heating duration. The activation energy for this extraction process was found to be lower than that for simple atomic diffusion in crystalline MoO3 and higher or close to that for the formation of or proton conduction in a hydrated MoO3 phase. This result suggests that a hydrated MoO3 phase accelerated the extraction of 99Mo. To the best of our knowledge, this is the first research to investigate the temperature and time dependence in the extraction of 99Mo hot atoms, providing a promising approach for large-scale production of 99Mo/99mTc radiopharmaceuticals.

The new extraction process significantly improves the extraction of Molybdenum-99 hot atoms/Tc-99m