Batch preparation of ammonium isopolymolybdate solution from ammonium molybdate solutions using bipolar membrane electrodialysis

The disadvantage of the traditional ammonium tetramolybdate (ATM) production process is a large consumption of nitric acid. Therefore a novel process for the generation of ammonium isopolymolybdate solution from ammonium molybdate solution using bipolar membrane electrodialysis (BMED) was developed and the batch experiment was carried out in this paper. The BMED process was studied to optimize various parameters such as initial base solution, final electrolytic pH value of salt solution, current density, initial NH4HCO3 concentration of base solution and Mo concentration in feed solution. The average current efficiency was 82%, the power consumption was 0.058 kWh/mol NH4+ or 0.887 kWh/mol Mo, and the recovery rate of Mo reached 99.4% under the optimal conditions of a current density of 500 A/m2, an initial Mo concentration of 173 g/L in the salt compartment, an initial NH4HCO3 concentration 2.0 mol/L in the base compartment, an initial (NH4)2CO3 concentration of 1.0 mol/L in the electrode solution and 32 ± 0.5 °C and a final solution pH of 4.0 in the salt compartment.