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的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沉淀化学动力学模型来表示络合和沉淀的动力学。将这些模型与2La(NO3)3 + 3H2 = 3H2C2O4 + 6HNO3和Ca(OH)2 + H2SO4 = CaSO4 + 2H2O两种化学体系下的两阶段沉淀实验数据进行了比较。晶粒尺寸分布和晶粒形态与决定结晶动力学的条件有关。基于晶体形状的傅里叶级数描述符的一种新技术被应用于表征在这项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.