Effects of Ultrasound on Crystal Nucleation of Na_2SO_4

Na2SO4 has a special dissolution and crystallization property.An induction time of Na2SO4 is measured under ultrasound both in heating and cooling crystallization.The interface energy value is calculated by classic formula.In order to investigate the dynamics of ultrasonic cavitation and ultrasonic effects on the thermodynamics and kinetics properties of crystallization,the micro-mechanism is analyzed from the ultrasonic cavitation bubbles motion process.With local high temperature and pressure when ultrasound bubbles collapse,the interface energy value is reduced and nucleation is hastened,indicating that the promotion of nucleation by ultrasound may occur in the process of compression or expansion.