Fine Grain Size Ammonium Paratungstate

Fine grain size ammonium paratungstate may be prepared by microwave-ultrasonic cooperative evaporation crystallization at higher temperature and without addition of surfactant.

A fine single crystal APT-4 with average particle size of 7.6μm, uniform particle size distribution and complete crystal form can be obtained under the following conditions:
Not stirred by machinery or under magnetism; No addition of surfactants; Under better APT preparation conditions - ultrasonic frequency of 25kHz, power of 1000W, microwave power of 700W, temperature of 80°C, ammonium tungstate (WO3) concentration of 212g/L, and the cooperative time of 15min.fine grain size ammonium paratungstate picture
Characteristics of Microwave-ultrasonic Cooperative Evaporation Crystallization to Prepare APT
1. The crystal structure of APT did not change according to the results of SEM, XRD and thermogravimetry - differential thermal analysis.
2. Particle size of fine APT:
(1) Increase with the increase of temperature;
(2) Decrease with the increasing concentration of ammonium tungstate;
(3) Decrease in the beginning and then increase as the increase of microwave-ultrasonic cooperative power;
(4) First increase and then decrease as the increase of microwave-ultrasonic cooperative time.
3. Overcome the shortcomings of the traditional APT process (crystallization process) such as slow crystallization rate and the influence of surfactant on the purity of APT.

More details, please visit:
http://www.ammonium-paratungstate.com/english/index.html

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