超声波场强化解吸速率的机理及场协同分析

Mechanism and Fields Synergism Analysis of Desorption Enhancement by Ultrasonic Field

从分子动力学原理出发,提出了外场作用下的解吸动力学模型,分析讨论了超声场强化解吸速率的机理及超声场与吸附相分子振动之间的协同作用。根据超声条件下吸附相分子的受迫振动和非吸附相分子的波动,分别讨论了吸附相分子及非吸附相分子在超声波场中获得的能量并进行了数量级分析和比较。结果表明,在超声波场中吸附相分子比非吸附相分子获得更多的能量,一般要大10个数量级以上,这正是超声波场强化解吸速率的本质所在。进一步理论分析表明,对一定频率的超声波,能流越大解吸速率越大,这是与实验相符的;同时,在超声波能流一定的情况下,可使超声波频率达到吸附相分子的固有频率而使解吸速率强化,这是超声波场与吸附相分子振动之间协同的结果。

A dynamical model of desorption under external physical field was established on the basis of molecular dynamics. The mechanism of desorption enhanced by ultrasonic field was expatiated. The effect of synergism of the ultrasonic field and the molecule vibration of adsorpted phase on the desorption was discussed. According to the fact that when ultrasonic field is exerted on the adsorption system, the molecules in fluid phase are fluctuated and the molecules of the adsorpted phase are forced to vibrate, the energy obtained separately by the molecules of the fluid phase and the molecules of the adsorpted phase was theoretically analyzed and compared. The results indicate that the energy obtained by the molecules of the adsorpted phase is 10 magnitude orders higher than that of obtained by the molecules of the fluid phase under the same ultrasonic field. The results of theoretical analysis also further show that the desorption rate increases as the ultrasonic energy flow is increased at the same ultrasonic frequency, which is in good agreement with experimental results, and if the ultrasonic frequency comes up to the natural frequency of the adsorpted molecules under the definitive ultrasonic energy flow, the desorption would be enhanced due to the synergism of the ultrasonic field and the vibration of the molecules of the adsorpted phase.