Recovery of Molybdenum Precursor Material in the Cyclotron-Based Technetium-99m Production Cycle

Abstract

A closed-loop technology aiming at recycling the highly 100Mo-enriched molybdenum target material has been developed in the framework of the international research efforts on the alternative, cyclotron-based 99mTc radionuclide production. The main procedure steps include (i) 100Mo-based target manufacturing; (ii) irradiation under proton beam; (iii) dissolution of 100Mo layer containing 9×Tc radionuclides (produced by opened nuclear reaction routes) in concentrated H2O2 solution; and (iv) Mo/Tc separation by the developed radiochemical module, from which the original 100Mo comes as the “waste” alkaline aqueous fraction. Conversion of the residual 100Mo molybdates in this fraction into molybdic acids and MoO3 has been pursued by refluxing in excess of HNO3. After evaporation of the solvent to dryness, the molybdic acids and MoO3 may be isolated from NaNO3 by exploiting their different solubility in water. When dried in vacuum at 40 °C, the combined aqueous fractions provided MoO3 as a white powder. In the last recovery step MoO3 has been reduced using a temperature-controlled reactor under hydrogen overpressure. An overall recovery yield of ~90% has been established.