Phase formation in the system Zn(VO3)2-HCl-VOCl2-H2O

The phase and chemical compositions of precipitates formed in the system Zn(VO3)(2)-HCl-VOCl2-H2O at pH 1-3, molar ratio V4+: V5+ = 0.1-9, and 80A degrees C were studied. It was shown that, within the range 0.4 ae V4+: V5+ ae 9, zinc vanadate with vanadium in a mixed oxidation state forms with the general formula ZnxV4+ V-y(5+) O-2-y(5) a (TM) nH(2)O (0.005 ae x ae 0.1, 0.05 ae y ae 0.3, n = 0.5-1.2). Vanadate ZnxV2O5 a (TM) nH(2)O with the maximum tetravalent vanadium content (y = 0.30) was produced within the ratio range V4+: V5+ = 1.5-9.0. Investigation of the kinetics of the formation of ZnxV2O5 a (TM) nH(2)O at pH 3 determined that tetravalent vanadium ions VO2+ activate the formation of zinc vanadate, and its precipitation is described by a second-order reaction. It was demonstrated that, under hydrothermal conditions at pH 3 and 180A degrees C, zinc decavanadate in the presence of VOCl2 can be used as a precursor for producing V3O7 a (TM) H2O nanorods 50-100 nm in diameter.