High-temperature thermodynamics of ZnO-NH4Cl-H2O system

On the basis of the principles of simultaneous equilibrium, conservation of mass, and aqueous electronic charge neutrality and the correspondence principle of ion entropy, the high-temperature thermodynamics of the ZnO-NH4Cl-H2O system was studied to predict solubility and construct Zn species distribution. The model was constructed precisely by using the MATLAB program. The total Zn2+ concentration in the solution was affected significantly by temperature and total ammonium concentration. ZnNH3Cl3 was the predominant species in the ZnO-NH4Cl-H2O system. The solubility of zinc diammine chloride in NH4Cl solution (>2 mol.L-1) in the temperature range of 303-353 K was determined using equilibrium experiments, which had results that agreed well with the theoretical value. The data and high-temperature thermodynamic model used in this paper are reliable. (C) 2020 The Author(s). Published by Elsevier B.V.