Adsorption of molybdenum-99 on Co(II)–Fe(III) layered double hydroxide and evaluation of ⁹⁹ Mo/ ^99m Tc separation: column study

Abstract The efficient and high-purity separation of 99m Tc from 99 Mo is essential for its widespread use in nuclear medicine diagnostics. This work explores the potential of cobalt–iron layered double hydroxide (Co–Fe LDH) as an alternative sorbent compared to the traditional one, alumina (Al 2 O 3 ) for the separation of 99m Tc from 99 Mo in a fixed-bed column system. Co–Fe LDH was synthesized via co-precipitation and comprehensively characterized by Fourier-transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET) surface area analysis and thermogravimetric and differential thermal analysis (TGA-DTA). The characterization confirmed its mesoporous structure, reasonable surface area (67.7 m 2 /g), and thermal stability up to 600 °C. Static batch experiments were conducted to assess the Co–Fe LDH uptake efficiency for 99 Mo (VI) under varying conditions. The maximum sorption capacity reached 229 mg/g at pH 3, which is higher than many reported sorbents. Furthermore, Co–Fe LDH maintained excellent performance after exposure to gamma irradiation up to 120 kGy, confirming its radiation stability and suitability for radioactive applications. Dynamic column experiments were performed under different experimental conditions to optimize the separation process. The optimal conditions, pH 3, 50 mg/L initial 99 Mo concentration, 0.5 g Co–Fe LDH, and a flow rate of 1 mL/2 min produced a high 99m Tc yield with minimal 99 Mo contamination. The Mo/Tc ratio under these conditions was as low as 0.006 %, demonstrating excellent separation performance.