Mechanism of Ultrasonic Effect on the Crystallazition of Ammonium Molybdate in Aqueous Solution
超声对钼酸铵溶液结晶过程的影响机制

The effect of ultrasonic wave on the crystallization of ammonium molybdate aqueous solution was studied. The crystalline and thermochemical property under ultrasonic effect were discussed. It is indicated that ultrasonic has a great effect on the reaction system of preparing b-type ammonium tetramolybdate. The crystallization time was shortened from 1~2 d to 10~20 min under ultrasonic and the crystalline form became microcrystal-type under ultrasonic. The total energy and condensation of atoms of H2Mo7O244 and (MoO2)(MoO3)x1]2+(x=1, 2, 3) were computed at the HF/ 321G, STO3G level, and their geometrical structures were optimized using the molecular mechanics optimization method. The calculation results show that the reason of transformation from H2Mo7O244 to (MoO2)(MoO3)x1]2+ at pH 2.3~2.5 is the effect of ultrasonic. All ab initio calculations were performed with the Gaussian98 program.