The nucleation kinetics of ammonium metavanadate precipitated by ammonium chloride

Abstract The nucleation kinetics of ammonium metavanadate (NH 4 VO 3 ) was investigated under conditions of the simulated process for precipitation of NH 4 VO 3 from the vanadium-containing solution. Induction periods for the nucleation of NH 4 VO 3 were experimentally determined as a function of supersaturation at temperatures from 30 to 45 °C. Using the classical nucleation theory, the interfacial tension between NH 4 VO 3 and supersaturated solution, the nucleation rate and critical radius of nucleus for the homogeneous nucleation of NH 4 VO 3 were estimated. With temperature increasing, the calculated interfacial tension gradually decreased from 29.78 mJ/m 2 at 30 °C to 23.66 mJ/m 2 at 45 °C. The nucleation rate was found to proportionally increase but the critical radius of nucleus exponentially decreased, with increase in supersaturation ratio at a constant temperature. The activation energy for NH 4 VO 3 nucleation was obtained from the relationship between temperature and induction period, ranging from 79.17 kJ/mol at S =25 to 115.50 kJ/mol at S =15. FT-IR and Raman spectrum indicated that the crystals obtained in the precipitation process were NH 4 VO 3 .