Properties of the Na3VO4-HCl-H2O system in the dependence on acidity and concentration of the sodium vanadate solution

Concentration of free hydrogen ions and the composition of sediments emerging in the Na3VO4 solution by addition of Sm3+ ions were studied as influenced by acidity and concentration of the solution. The system was studied at five constant concentrations of vanadium (0.08, 0.12, 0.175, 0.22 and 0.32 g.ion/l) at different pH. Samarium vanadate was precipitated from the Na3VO4-HCl-H2O equilibrium system by equimolecular solutions of Sm(NO3)3 in the ratio 1:1. In the alkaline region the processes of protonization and dimerization in diluted sodium vanadate solutions were simultaneous. In more concentrated solutions these processes were separated, since the increase in V concentration promoted protonization rather than dimerization, especially in aklakine solutions