Synthesis of perrhenic acid using solvent extraction

The paper presents results of investigations into production of perrhenic acid from aqueous solutions of ammonium perrhenate of concentration 25 g/L by solvent extraction method. It was demonstrated that perrhenic acid can be obtained by extraction of ReO4− with 50% tributyl phosphate (TBP) solution in toluene from aqueous solution of ammonium perrhenate acidified with sulphuric(VI) acid to pH of 1.0 and further stripping of ReO4− from organic phase by water of temperature 80 °C. Complete separation of rhenium from ammonium ions was possible after repeated extraction and repeated stripping. In the result perrhenic acid of concentration about 70 g/L Re was obtained, which then was concentrated to reach the level of 300 g/L Re. Thus produced perrhenic acid of concentration 300 g/L Re contained no more than 0.01 g/L of impurities composed of metal (sodium, potassium, magnesium) and ammonium ions.