Abstract
The purpose of this study was to investigate the effects of competition between cobalt, europium and strontium for isosaccharinate, gluconate and picolinate. Systems where results indicated that competitive effects were significant have been identified. Thermodynamic calculations were performed for each system for comparison with the experimental results. Some exceptions may be due to precipitation of some species, or presence of species not in databases, or formation of mixed-metal complexes, or sorption to the solid phase(s). In some of the experiments, the complexity of the systems studied caused difficulty in identifying consistent trends. By concentrating on the results for simpler systems (i.e. for solubilities in the presence and absence of organic complexants and with just one competing metal ion), the evidence for competition effects has been investigated. Evidence for solubility enhancement due to organic ligands was apparent in the data for the systems Co with gluconate and Eu with isosaccharinate and gluconate. Of these above cases, the systems in which the effects of the competing ion are consistent with competition were limited to the cases of Eu with isosaccharinate and Sr as the competing ion, and Eu with gluconate and either Co or Sr as the competing ion.