Ammonium metatungstate solution is an aqueous solution of ammonium metatungstate (AMT), which may be prepared using ammonium tungstate solution as raw material by Bipolar Membrane Electrodialysis (BMED). AMT solution may be used as raw material for producing its downstream products by liquid phase process. AMT is extremely easily soluble in water, and its solubility in water increases with the increase of temperature.
BMED is a new membrane separation technology, which has been widely applied in the preparation of acid, alkali, organic acid and other fields. Under the action of electric field, water dissociation occurs within the bipolar membrane and H+ and OH- are provided on both sides of the membrane respectively. The BMED process is stable and easy to operate.
BMED to Prepare Ammonium Metatungstate Solution
Under optimized conditions, continuous BMED tests were performed to investigate the influence of current density, initial NH4HC03 concentration in alkali chamber, WO3 concentration in feed liquid, and pH value of salt chamber solution on the BMED process. The results showed that:
The average current efficiency of BMED process is 72.50%. DC power consumption is only 0.877kWh/kg W03 and the recovery of WO3 reaches 99.97% under the following conditions:
1. Current density is 700 A/m2;
2. WO3 concentration in ammonium tungstate solution is 172.3g/L;
3. Initial NH4HC03 concentration in alkali chamber is 1.5 mol/L;
4. Electrodialysis time is 600min;
5. PH value of salt chamber solution is 2.8±0.1;
6. Temperature is (31±0.5) °C.
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