Ultrafine ammonium paratungstate may be prepared by microwave-ultrasonic cooperative evaporation crystallization method.
Microwave-ultrasonic Cooperative Evaporation Crystallization to Prepare Ultrafine Ammonium Paratungstate
1. Experimental Equipment
(1) XH-300A computer ultrasonic and microwave combined synthesis extraction instrument;
(2) ZK-82B electric constant temperature drying oven;
(3) UK Malvern laser particle size analyzer;
(4) Miniflex X-ray diffractometer;
(5) Netherlands Philips XL30 scanning electron microscope;
(6) Diamond 6000 thermo-differential thermal analyzer.
2. Experimental Procedures
A certain volume of ammonium tungstate solution with a concentration of WO3 266g/L was poured into the synthesis extraction instrument. The ultrasonic frequency was set to 25 kHz, and the microwave and ultrasonic power were adjusted to the specified values. Ultrasound cooperated with microwave was used to heat the solution to evaporate and crystallize at a specified temperature for a certain period of time and then filter while it is still hot. After filtering, the filter should be washed with deionized water for 2 to 3 times. And then the filtered material is dried in an electric oven at 100°C for 2 hours.
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