Composition and Formation Kinetics of Sodium Polyvanadates
in Vanadium(IV, V) Solutions

N. V. Podval’naya and V. L. Volkov

Institute of Solid State Chemistry, Ural Division, Russian Academy of Sciences,
ul. Pervomaiskaya 91, Yekaterinburg, 620219 Russia

Received March 7, 2005

Abstract—We study how VO²⁺ ions affect the composition and formation kinetics of polyvanadate precipitates
in solutions with 1 3 at 80–90°C. The compounds have the general formula Na_2.1xHO₃₁ ·
nH₂O (0 x 1.1, 0.2 y 2.3, 0.1 1.4). The maximal vanadium(IV) concentration in the precipitates
(y= 2.2 and 2.3) is achieved for the V⁴⁺/V⁵⁺ ratio in the solution equal to 0.5 and 0.3 and pH of 1.7 and 3.0,
respectively. The polyvanadate precipitation at pH 1.7 has a long induction period, which is not observed when
V⁴⁺/V⁵⁺ > 0.02. In the solutions with pH 3.0, the precipitation occurs only when VO²⁺ are added. The processes
are controlled by second-order reactions on the polyvanadate surface.

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