Gielen B, Marchal S, Jordens J, Thomassen L C J, Braeken L, Van Gerven T
KU Leuven, Department of Chemical Engineering, Celestijnenlaan 200 f box 2424, 3001 Leuven, Belgium; KU Leuven, Faculty of Industrial Engineering, Lab(4)U, Agoralaan Building B box 8, 3590 Diepenbeek, Belgium.
KU Leuven, Department of Chemical Engineering, Celestijnenlaan 200 f box 2424, 3001 Leuven, Belgium.
Ultrason Sonochem. 2016 Jul;31:463-72. doi: 10.1016/j.ultsonch.2016.02.001. Epub 2016 Feb 2.
In the present work, the influence of gas addition is investigated on both sonoluminescence (SL) and radical formation at 47 and 248 kHz. The frequencies chosen in this study generate two distinct bubble types, allowing to generalize the conclusions for other ultrasonic reactors. In this case, 47 kHz provides transient bubbles, while stable ones dominate at 248 kHz. For both bubble types, the hydroxyl radical and SL yield under gas addition followed the sequence: Ar>Air>N2>>CO2. A comprehensive interpretation is given for these results, based on a combination of thermal gas properties, chemical reactions occurring within the cavitation bubble, and the amount of bubbles. Furthermore, in the cases where argon, air and nitrogen were bubbled, a reasonable correlation existed between the OH-radical yield and the SL signal, being most pronounced under stable cavitation at 248 kHz. Presuming that SL and OH originate from different bubble populations, the results indicate that both populations respond similarly to a change in acoustic power and dissolved gas. Consequently, in the presence of non-volatile pollutants that do not quench SL, sonoluminescence can be used as an online tool to qualitatively monitor radical formation.
在本研究中，研究了在47kHz和248kHz频率下添加气体对声致发光（SL）和自由基形成的影响。本研究中选择的频率会产生两种不同类型的气泡，从而能够将所得结论推广至其他超声反应器。在这种情况下，47kHz产生瞬态气泡，而在248kHz时稳定气泡占主导。对于这两种气泡类型，添加气体时羟基自由基和声致发光产率的顺序为：氩气>空气>氮气>>二氧化碳。基于热气体性质、空化气泡内发生的化学反应以及气泡数量的综合情况，对这些结果给出了全面解释。此外，在通入氩气、空气和氮气的情况下，OH自由基产率与声致发光信号之间存在合理的相关性，在248kHz的稳定空化条件下最为明显。假设声致发光和OH自由基源自不同的气泡群体，结果表明这两个群体对声功率和溶解气体变化的响应相似。因此，在存在不淬灭声致发光的非挥发性污染物时，声致发光可作为一种在线工具来定性监测自由基的形成。
