Hydrolytic precipitation of vanadium compounds in the MVO3-VOSO4-M2SO4-H2O (M = Rb, Cs) systems

In the MVO 3 -VOSO 4 -M 2 SO 4 -H 2 O (M = Rb, Cs) systems, acid hydrolysis at 90°C results in the following phases: M 4 ′ x V 6 O 1 6 ′ δ .nH 2 O and Rb x V 6 O 1 6 - δ .nH 2 O (1.7 ≤x≤2.0, 0 < δ ≤ 0.3),Cs x V 6 O 1 6 - δ .nH 2 O (1.4 ≤ x ≤ 1.6, 0.2 ≤ δ ≤ 0.3), Rb x V 1 2 O 3 1 - δ . nH 2 O (1.7 ≤ x ≤ 2.0, 0.9 ≤ δ ≤ 1.5), Cs x V 1 2 O 3 1 - δ . nH 2 O (1.4 ≤ x ≤ 2.0, 1.2 ≤ 8 ≤ 1.4), and Cs 2 - x V 4 O 1 1 - δ (0 < x ≤ 0.2, 0 < δ ≤ 0.2). Adding M 2 SO 4 to a solution with the ratio MVO 3 /VOS0 4 = 1 results in two-phase samples Rb x V 1 2 O 3 1 - δ . nH 2 O + Rb x V 6 O 1 6 - δ . nH 2 O and M x V 6 O 1 6 - δ . nH 2 O + MV 5 O 1 3 - δ .nH 2 O and the Cs x V 6 O 1 6 - δ . nH 2 O phase (1.5 ≤ x ≤ 1.9, 0.2 ≤ δ ≤ 0.9). The kinetics of formation of M x V 6 O 1 6 - δ . nH 2 O phases is studied as a function of temperature, pH of solutions, and additions of M 2 SO 4 and VOSO 4 .