Crystallization Kinetics and Mechanism of Magnesium
Ammonium Phosphate Hexahydrate:
Experimental Investigation and Chemical Potential Gradient Model Analysis
and Prediction
posted on 2020-07-15, 15:08authored byKai Ge, Yuanhui Ji, Shuai Tang
The
influence of various factors (e.g., temperature, stirring speed,
pH, and alginic acid concentration) on the crystallization kinetics
of magnesium ammonium phosphate hexahydrate (MAP) was evaluated. The
chemical potential gradient models were used to analyze the MAP crystallization
mechanism and predict MAP crystallization kinetics. It was found that
the temperature and stirring speed mainly influenced the kinetic rate
constant, while alginic acid additives mainly influenced the thermodynamic
driving force of MAP. The pH mainly influenced both the rate constant
and the thermodynamic driving force, which is the key influencing
factor of the crystallization rate and performance of MAP. The theoretical
modeling indicated that the MAP crystallization mechanism was dominated
by the adhesive-type growth mechanism. Furthermore, the crystallization
kinetics of MAP was successfully predicted as a function of alginic
acid concentration with high accuracy. This work is expected to provide
important information for selecting appropriate operating parameters
to control the performance of MAP in practical applications.