Physico-chemical behaviour of V(V) in a concentrated phosphoric acid

Tests show that the conducitivity and viscosity of solutions of phosphoric acid (54% P2O5) change as increasing quantities of vanadium are added, indicating that the metallic cation interacts with the phosphoric acid molecule. This behaviour is confirmed by measurements of acidity. Determination of R0 (H) shows that the acidity of the environment increases as a function of the concentration of V (V), suggesting that the interaction between the vanadium and the phosphoric acid molecule releases H+ protons. Spectrophotometric measurements are used to determine the type of interaction, the nature of the species resulting from the interaction between the vanadium and the phosphoric acid molecule, and the number of protons involved. (c) 2005 Elsevier B.V. All rights reserved.