【摘要】 通过缓慢滴加焦磷酸钾的硝酸溶液到钼酸铵溶液中制得了大颗粒磷钼酸铵(AMP)。研究了AMP的成核速率(G)与晶体生长速率。与晶体生长速率相比成核速率的反应级数更高。最初,大颗粒磷钼酸铵的结晶过程处于相变反应控制的动力学区域,此时溶液的过饱和生成速率比过饱和消除速率高。晶体线生长速率与溶液的过饱和度先增加后降低。在滴加中期,过饱和消除速率增长到与其生成速率相当。在滴加后期,晶体成核速率快速增高,而晶体的线生长速率下降。晶体的成核速率成为过饱和消除的唯一控制步骤。因此,AMP成核大部分是在首先接触到滴加液的局部溶液中完成的。更多还原

【Abstract】 Large particle ammonium molybdophosphate(AMP) was prepared by slowly dropping a nitric acid solution of potassium pyrophosphate into an ammonium molybdate solution. The nucleation rate( G) and crystal growth rate for AMP were studied. Compared with crystal growth, the nucleation has a higher reaction order.Initially, large particle AMP crystallizes in the kinetic region controlled by phase transfer reaction when the growing speed of supersaturation is higher than the removing speed. The crystal linear growth rate( L) and supersaturation degree(ΔC) of the solution increases first and decreases thereafter. In the medium dropping stage, the increase in removing speed of supersaturation is the same as the growing speed. During the late dropping stage, the nucleation rate rises rapidly when the crystal linear growth rate decreases and the nucleation rate is the only control step for the removing speed of supersaturation. Therefore, the nucleation of AMP almost completes in local solution as soon as meeting the nitric acid solution.更多还原