Phase distribution of iodine in the course of production of ⁹⁹Mo concentrate

Abstract

A novel procedure was suggested for studying the phase distribution of radioactive iodine in the liquid–gas system. Without redox reactions, the degree of iodine transfer into the gas phase is maximal for sulfuric and nitric acid solutions at pH ≤ 1.5. In weakly acidic, neutral, and alkaline solutions, the iodine transfer into the gas phase is insignificant (degree of transfer <0.05). Conditions for stabilization of iodine species (presence of redox reagents, solution acidity) were found. The most efficient purification of ⁹⁹Мо to remove iodine radionuclides is observed in sulfuric acid solutions, where the probability of formation of IО₃ ^– anions, exhibiting the highest affinity for titanium hydroxide, is minimal. Silver-modified Termoxid sorbents are suitable for selective sorption of iodine only from alkaline solutions (0.3–0.5 M NaOH), with the best result obtained for Т-5(Ag) (iodine distribution coefficient 2000–3000 mL g^–1). An additional step of purification of alkaline molybdenum concentrates to remove iodine on Т-5(Ag) sorbent was suggested; it allows the residual iodine content of the molybdenum concentrate to be decreased by a factor of 20.