The nucleation kinetics of ammonium metavanadate precipitated by ammonium chloride

• There are a few reports on the nucleation kinetics of NH4VO3 in aqueous solutions.
• The induction periods for the nucleation of NH4VO3 in solutions containing NH4Cl and NaCl were experimentally determined.
• The interfacial tensions between NH4VO3 and supersaturated solutions were estimated using classical nucleation theory.
• The effects of supersaturation and temperature on the nucleation kinetics of NH4VO3 were investigated.

The nucleation kinetics of ammonium metavanadate (NH4VO3) was investigated under conditions of the simulated process for precipitation of NH4VO3 from the vanadium-containing solution. Induction periods for the nucleation of NH4VO3 were experimentally determined as a function of supersaturation at temperatures from 30 to 45 °C. Using the classical nucleation theory, the interfacial tension between NH4VO3 and supersaturated solution, the nucleation rate and critical radius of nucleus for the homogeneous nucleation of NH4VO3 were estimated. With temperature increasing, the calculated interfacial tension gradually decreased from 29.78 mJ/m2 at 30 °C to 23.66 mJ/m2 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 NH4VO3 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 NH4VO3.