超声场对种分反应动力学过程的影响

研究了在无超声场及在 2 0kHz和 33kHz超声场 3种条件下的种分动力学方程。结果表明 ,在超声场作用下进行种分过程 ,可以大幅度提高分解速度 ,缩短分解时间。在 2 0kHz和 33kHz超声场中的种分动力学模型与无超声场中的种分动力学模型一致 ,但是反应的活化能分别降低了 2 2kJ/mol和 33kJ/mol。超声场强化种分过程的机理是反应体系吸收了超声场中的空化能量 ,降低了反应的能量势垒。

Effect of ultrasound on kinetics of aluminium trihydroxide precipitation Bayer process

The precipitation rate is increased and the precipitation time is reduced remarkably under ultrasound. The kinetic model of precipitation without ultrasound is in accordance with those of other researches. It is a second order rate equation model that relates the instantaneous rate of hydrate precipitation to the supersaturation of sodium aluminate solution. The activation energy found in experiments is 68?kJ/mol, closing to the values published before. Furthermore, the kinetic models of precipitation under 20?kHz and 33?kHz ultrasound are the same as those without ultrasound, with exception of activation energies reduction and the frequency factors changed. Compared with the activation energy without ultrasound, it is reduced by 33?kJ/mol and 22?kJ/mol under 33?kHz and 20?kHz ultrasound respectively.