超声场影响钼酸铵结晶机制的理论分析

Theoretical Analysis of Effect of Ultrasonic on Crystallization Mechanism of Ammonium Molybdate

利用量子化学计算方法在HF/3 2 1G和STO 3G水平上计算了钼酸铵结晶过程涉及到的H2 Mo7O2 4 4- ,[(MoO2 ) (MoO3) x - 1 ] 2 + (x =1,2 ,3 ) ,2 (NH4 ) 2 Mo4 O1 3,H8Mo8O30 4 - 等的总能量、原子净电荷和集居数。各计算模型均用分子结构最优化方法进行了几何优化。结果表明 :四钼酸铵的 3种可能结构中 ,以 8个MoO6 八面体公用棱的结构总能量最低 ,较稳定 ;超声波作用下所产生的高能环境 ,可能使pH值为 2 .0～ 2 .5时溶液中的H2 Mo7O2 4 4- 变成 [(MoO2 ) (MoO3) x - 1 ] 2 + (x =1,2 ,3 ) ,从而生成微粉型四钼酸铵。

The total energy, atomic charges and condensed population of atoms of H 2Mo 7O 24 4- , [(MoO 2)(MoO 3) x -1 ] 2+ ( x =1, 2, 3), 2(NH 4) 2Mo 4O 13 , H 8Mo 8O 30 4- etc., were computed at the HF/3 21G, STO 3G level using Gaussian 94 program, and their geometrical structures were optimized using the molecular mechanics optimization method. The calculation results show that the transformation from H 2Mo 7O 24 4- to [(MoO 2)(MoO 3) x -1 ] 2+ ( x =1, 2, 3) at pH=2.0～2.5 is reasonable caused by ultrasonic. The structure of ammonium tetramolybdate with eight MoO 6 is more stable.