Bestimmung der freien säure in plutonium-, uran- und thorium-lösungen

Preparation of acid standards for and determination of free acid in concentrated plutonium-uranium solutions

“…This is especially true for ions such as Pu(IV) which begin to undergo hydrolysis at quite low pH; Kh = 0.054 for Pu(IV) (1) indicates approximately 10% hydrolysis at 0.5 M H+ in noncomplexing aqueous solution. Most of the procedures which have been reported in the literature for the determination of free acid in the presence of plutonium or uranium have been based on two concepts: (1) the removal of the Pu and/or U from the solution by precipitation (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13), ion exchange (14,15), or solvent extraction (16) without altering the free acid content or (2) the complexing of the Pu and/or U in the solution adequately to prevent hydrolysis up to the end-point pH of an acidimetric titration (5,(17)(18)(19)(20)(21). In both cases these procedures are followed by titration with standardized base.…”