Interactions of Tc(IV) with citrate in NaCl media

Abstract

AbstractThis paper presents the experimental determination of the stability constant for the citrate complexes with TcO(OH)+and TcO(OH)20at different ionic strengths (NaCl), using a solvent extraction method. Data show that the stability constants for the formation of TcO(OH)Cit2−and TcO(OH)2Cit3−are 107.5 ± 0.2and 102.8 ± 0.2, respectively, at zero ionic strength, with an average of 106.5 ± 0.3and 102.8 ± 0.2, respectively, in the 1.0–3.0 M ionic strength range. PHREEQC calculations based on these stability constants show that the TcO(OH)Cit2−is the predominant species between pH 3 and 8 and that 50 mM citrate leads to a Tc(IV) solubility of 2 × 10−5 M at pH 5.