Synthesis and Solubility Behavior of Magnesium Ortho-, Meta-, and Pyrovanadates

Magnesium vanadates are important chemical products for luminescent materials and energy storage and also important intermediate substances during vanadium extraction, whose solubility behavior is, however, ambiguous and controversial. In this work, three common magnesium vanadates, namely, magnesium ortho-, pyro-, and metavanadate, were synthesized by a solid-solid synthesis method with MgO and V2O5 as raw materials. In optimum synthesis conditions, the obtained pure magnesium vanadates are confirmed using x-ray diffraction analysis. Then, their solubilities in water and in acidic solution in the pH range of 0-7.0 were systematically investigated at different temperatures. Results show that magnesium vanadates are readily soluble in acidic solution but are only slightly soluble in water, while in both cases magnesium metavanadate has higher solubility than orthovanadate and pyrovanadate. This work provides the fundamental data to improve understanding of the vanadium extraction mechanism and the performance control of magnesium vanadate materials.