Research Initiation: A Study of the Effect of Chemical Complexation in Precipitation and Crystallization Processes

研究了在强酸介质中加入弱酸阴离子时，化学络合作用对金属阳离子沉淀的影响。采用基于二级连续反应的化学沉淀动力学模型来描述络合和沉淀的动力学。用2La(NO3)3 3H2=3H2C2O4 6HNO3和Ca(OH)2HSO4=CaSO42H2O两步沉淀实验数据与模型进行了比较。颗粒大小分布和颗粒形态与决定结晶动力学的条件有关。一种基于傅立叶级数描述晶体形状的新技术被应用于表征在本工作中形成的晶体的形状。

The effect of chemical complexation on the precipitation of metal cations in a strong acid medium by the addition of anions of a weak acid is investigated. Chemical kinetic models of precipitation based on second order consecutive reactions are used to represent the kinetics of complexation and precipitation. These models are compared with data from two stage precipitation experiments using the following chemical systems: 2La(NO3)3 + 3H2 = 3H2C2O4 + 6HNO3 and Ca(OH)2 + H2SO4 = CaSO4 + 2H2O. The particle size distribution and particle morphology are correlated with the condition which determines the crystallization kinetics. A novel technique based on Fourier series descriptors of the crystal shape is applied to characterize the shapes of the crystals formed in this work.