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wangnavy11金虫 (小有名气)
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[求助]
化工方向的高手,尤其是超声方面的
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| 这是由于超声降解有机物的机制是超声空化效应，而只有当声强达到空化阈值时才能产生空化效应。随着声能密度的增加则空化效应加强，促进了A分子进入吸附剂孔道和扩散速度加快，从而促进了对A的去除。因此声强越大，降解效果越佳。但声强太高会使处理能耗增高，另外在高声强作用下，有可能破坏B分子；在某一极高声强下，空化泡在负声压相会变得很大，导致其在正压相不足以实现内破裂，空化泡崩溃不充分(形成了屏蔽)，系统对超声能量的利用率低。因此当超声声强增大时，去除率的提高幅度有所减小. |
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lxwqd
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【答案】应助回帖
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However the initial concentration of methanol affects its removal ratio, the adsorption reaction is close to equilibrium after 3min from beginning, and the increment of removal ratio is limited henceforth. The removed amount of methanol by B equal to the desorbed amount of methanol from the active sites of B. While the initial concentration of methanol is high and the usage amount of B is fixed, with the same adsorption sites and cavity position, more methanol molecules mean more competition and lower adsorption rate. As the initial concentration is low, less methanol molecules with less competition would be easierly come into the cavities of B aiding by the vibration of ultrasonic waves, resulting in a higher removal ratio. 这是由于超声降解有机物的机制是超声空化效应，而只有当声强达到空化阈值时才能产生空化效应。随着声能密度的增加则空化效应加强，促进了A分子进入吸附剂孔道 和扩散速度加快，从而促进了对A的去除。因此声强越大，降解效果越佳。但声强太高会使处理能耗增高，另外在高声强作用下，有可能破坏B分子；在某一极高声强下 ，空化泡在负声压相会变得很大，导致其在正压相不足以实现内破裂，空化泡崩溃不充分(形成了屏蔽)，系统对超声能量的利用率低。因此当超声声强增大时，去除率 的提高幅度有所减小. The reason is that the mechanism of ultrasonic degradation of organic matter is ultrasonic cavitation effect, and cavitation effect only occurs when the sound intensity reaches the cavitation threshold. With the increase in density of acoustic energy, cavitation effect would be strengthened that promote A molecules into the adsorbent pores and accelerate its diffusion rate, thereby promoting the removal of A. Thus, the greater the sound intensity, the better the degradation effect. However, if the sound intensity is too high, the operation energy consumption would increase, moreover, B molecules might be damaged under the impact of high sound intensity; under certain very high sound intensity, cavitation bubbles would become very large in negative acoustic pressure phase, and be insufficient to achieve the implosion in the positive pressure phase, resulting in the inadequate collapse of cavitation bubbles(forming a shield),and the low utilization rate of the system for the ultrasonic energy. So when the ultrasonic intensity continue to increase, the corresponding increment of the removal ratio decreases to some extent. |
2楼2012-09-27 20:53:55