In the sonochemical degradation of nonvolatile compounds, the free radicals must be delivered into the aqueous solution from the cavitation bubble to initiate reduction–oxidation reactions. The penetration depth in the liquid becomes an important parameter that influences the radical delivery efficiency and eventual treatment performance. However, the transport of radicals in the liquid phase is not well understood yet. In this paper, we focus on the most reactive OH radical and numerically simulate its penetration behavior. This is realized by solving the coupled equations of bubble dynamics, intracavity chemistry, and radical dispersion in the aqueous phase. The results present both the local and global penetration patterns for the OH radicals. By performing simulations over a wide range of acoustic parameters, we find an undesirable phenomenon that the penetration can be adversely suppressed when strengthening the radical production. A mechanistic analysis attributes this to the excessively vigorous recombination reactions associated with high radical concentrations near the bubble interface. In this circumstance, the radicals are massively consumed and converted into molecular species before they can appreciably diffuse away. Our study sheds light on the interplay between radical production inside the bubble and dispersion in the outside liquid. The derived conclusions provide guides for sonochemical applications from a new perspective.

在非挥发性化合物的声化学降解中，自由基必须从空化气泡中输送到水溶液中以引发还原-氧化反应。液体中的渗透深度成为影响自由基递送效率和最终治疗性能的重要参数。然而，自由基在液相中的传输还不是很清楚。在本文中，我们关注最具反应性的 OH 自由基并对其渗透行为进行数值模拟。这是通过求解气泡动力学、腔内化学和水相中的自由基分散的耦合方程来实现的。结果显示了 OH 自由基的局部和全局渗透模式。通过对广泛的声学参数进行模拟，我们发现一个不良现象，即在加强自由基生产时，渗透会受到不利抑制。机械分析将此归因于与气泡界面附近的高自由基浓度相关的过度剧烈的重组反应。在这种情况下，自由基在它们可以明显扩散之前被大量消耗并转化为分子种类。我们的研究阐明了气泡内部自由基的产生与外部液体中的分散之间的相互作用。得出的结论从一个新的角度为声化学应用提供了指导。机械分析将此归因于与气泡界面附近的高自由基浓度相关的过度剧烈的重组反应。在这种情况下，自由基在它们可以明显扩散之前被大量消耗并转化为分子种类。我们的研究阐明了气泡内部自由基的产生与外部液体中的分散之间的相互作用。得出的结论从一个新的角度为声化学应用提供了指导。机械分析将此归因于与气泡界面附近的高自由基浓度相关的过度剧烈的重组反应。在这种情况下，自由基在它们可以明显扩散之前被大量消耗并转化为分子种类。我们的研究阐明了气泡内部自由基的产生与外部液体中的分散之间的相互作用。得出的结论从一个新的角度为声化学应用提供了指导。