钼酸铵结晶动力学参数与溶液同多酸根组成变化的关系

RELATION BETWEEN KINETICAL PARAMETERS OF AMMONIUM MOLYBDATE CRYSTALLIZATION AND COMPOSITION VARIATION OF HOMOPOLYMOLYBDATE RADICAL

研究了钼酸铵中和结晶过程成核速率 ( N)与晶体线生长速率 ( L)与溶液中同多酸根离子组成的变化关系。结果表明 :AQM的 N和 L随溶液中 [MO8O2 64 -]的升高以及 [MO7O2 4 6-]和 pH的降低而增大。在加入酸量相同的情况下 ,酸化速度快的溶液由于偏离缩合平衡较大 ,其 [Mo8O2 64 -]始终较高 ,[Mo8O2 4 6-]和 [MoO4 2 -]较低。AQM的 L高峰值出现在 [Mo8O2 64 -]较低 ,而 [Mo7O2 4 6-]较高的结晶初期 ,其主要原因是此阶段首先接触到无机酸的局部溶液中成核数量较少 。

The relation between the kinetical parameters,such as the nucleation rate ( ) and the linear rate ( ) of crystal growth,and the composition variation of homopolymolybdate radical in the neutralized crystallization of AQM was studied.Results showed that and of AQM increased with the rising concentration of Mo 8O 26 4- and the reducing concentration of Mo 7O 24 6- and the reducing pH value.The concentration of Mo 8O 26 4- was much higher from beginning to end and the concentrations of Mo 7O 24 6- and MoO 4 2- were much lower because of considerable deviation from the polymerization equlibrium in the solution with a high rate of acidification in the case of identical amount of acid added. of AQM reached the peak value in the initial crystallization stage when the concentration of Mo 8O 26 4- was much lower and the concentration of Mo 7O 24 6- was much higher,because the amount of AQM nucleation was low and the oversaturation lasted for a long time in the local solution which met inorganic acid first in this stage.