Iron-cerium composites with high molybdenum sorption capability: potential application in low specific activity 99Mo/99mTc generators

^99mTc, as the most widely used radioactive nuclide in diagnostic imaging, whose supply heavily relies on the ⁹⁹Mo. Neutron activation technology, as an alternative to uranium fission technique, has become a pivotal route for producing ⁹⁹Mo. A critical aspect of its practical application lies in enhancing the sorption capacity of the column chromatography packing materials for the low specific activity molybdenum product. This study synthesizes two types of iron-cerium bimetallic composite materials, iron-cerium alkoxide (ICA) and iron-cerium oxide (ICO), as novel column chromatography packing materials compatible with low specific activity ⁹⁹Mo. Characterization techniques such as TEM, XRD, and BET were employed to reveal the surface morphology and mesoporous structure of ICA and ICO. An evaluation of their sorption performance showed that both ICA and ICO exhibited rapid sorption kinetics (< 10 min) and excellent sorption selectivity. Notably, ICA demonstrated a static sorption capacity of 207 mg Mo/g and a dynamic sorption capacity of 180 mg Mo/g, surpassing most reported adsorbents. Mechanistic studies using XPS, FT-IR, and zeta potential measurement suggest that the sorption of Mo onto both ICA and ICO is primarily governed by electrostatic interactions. Additionally, the sorption mechanism for ICA also includes ion exchange and surface complexation. With Re being the most common non-radioactive substitute for ^99mTc, desorption separation experiments revealed that ICA has a Re elution rate of over 75%, confirming its potential as a promising candidate material in low specific activity ⁹⁹Mo/^99mTc generators.