Ion exchange of H+/Na+ in polyantimonic acid, doped with vanadium ions

Abstract

Abstract The influence of doping of polyantimonic acid with vanadium ions on the ion exchange H+/Na+ kinetics is determined. With the help of the X-ray analysis it is shown that doped compounds H2Sb2-x V x O6-δ · nH2O, where x = 0.14; 0.36; 0.48 have the pyrochlore-type structure. With the increase of the amount of vanadium in a sample there is a decrease of a unit cell parameter. It is determined that there is a reduction of a unit cell frame, formed by antimonic and vanadium ions, and a size reduction of hexagonal cavities, in which protons are located. It is shown that during the ion exchange of H+/Na+ there is a change of the unit cell plane without a symmetry breaking of a crystal structure, which demonstrates solid solution formation. With the increase of the amount of vanadium in the sample there is a decrease of the ion-exchange capacity, which is connected with the decrease of the channel’s section size. The ion exchange H+/Na+ kinetics has been studied with the approximation of the Boyd’s model for the intergrain diffusion. Diffusion coefficients had the order 10−13 m2/s and decreased with the increase of the amount of vanadium in the sample.