Nucleation and growth kinetics of struvite in a fluidized bed reactor

• Published in: Journal of crystal growth 2008-03, Vol.310 (6), p.1187-1194
• Main Authors: Bhuiyan, M. Iqbal H., Mavinic, D.S., Beckie, R.D.
• Format: Article
• Language: English
• Subjects: A1. Crystallization; A1. Kinetics; A1. Models; A1. Nucleation; A2. Growth; B1. Struvite; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Equations of state, phase equilibria, and phase transitions; Exact sciences and technology; Growth from solutions; Materials science; Methods of crystal growth; physics of crystal growth; Physics; Solid-solid transitions; Specific phase transitions; Theory and models of crystal growth; physics of crystal growth, crystal morphology and orientation
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2007.12.054

Kinetics of struvite crystallization were studied to gain a better understanding of intentional struvite formation in fluidized bed reactors. Mechanisms controlling nucleation were studied in the laboratory by induction time experiments. pH monitoring proved to be an effective method of induction time determination, during the induction period. The induction period, when nucleation was the controlling process for struvite crystal formation, was found to be primarily reaction controlled, with minor transport influence. The metastable region for struvite was explored in this study. The solubility and supersolubility curves, which are the boundaries of the metastable region, were observed to be almost parallel straight lines in the concentration range studied. The growth rate of struvite determined in a fluidized bed reactor was mainly transport controlled. With the determination of the mass-transfer coefficient and surface-reaction coefficient for a specified condition, a two-step linear growth rate model for struvite growth determination in a fluidized bed reactor has been proposed.