Thermodynamic analysis of temperature dependence of the crystal growth rate of potassium sulfate

In this work, the effect of temperature on the crystal growth rate of potassium sulfate in aqueous K ₂SO ₄ and KCl-K ₂SO ₄ solutions is analyzed. The crystal growth rate equation of K ₂SO ₄ is developed on the basis of the difference of chemical potentials of K ₂SO ₄ at the solid-liquid interface. The Lu-Maurer model is used to predict the activity coefficient of K ₂SO ₄. The crystal growth rate of K ₂SO ₄ in aqueous K ₂SO ₄ solution decreases, then increases with increasing temperature, and reaches its lowest value around 303.15 K, which is in accordance with previous experimental results. Meanwhile, the optimal crystallization temperature of K ₂SO ₄ in aqueous KCl-K ₂SO ₄ solution is discussed. An effective method is found to increase the yield of K ₂SO ₄ by increasing the crystallization temperature to 333.15 K.