A novel wastewater treatment process, acoustic cavitation assisted plasma (ACAP) is proposed in this study aiming at expanding the treatable range of water pollutants due to a synergetic effect of ultrasound irradiation and high voltage plasma discharge. In this process, the role of acoustic cavitation is not only to provide generation of chemically active OH⋅ radicals, as for example in conventional ultrasonic wastewater treatment techniques, but also to ensure conditions for stable plasma generation in wastewater and, thus, to extend the treatable range of water pollutants. Rhodamine B (RhB) was used as a model pollutant in experiments examining effects of ultrasound amplitude, RhB initial concentration, output voltage, solution pH and electrical conductivity on the RhB degradation efficiency. The results revealed that the ultrasound-assisted plasma generation requires lower output voltages and allows to increase the acceptable range of electrical conductivity of treatable solutions up to 1000 μS/cm, that is about 24 times higher than in the case of conventional plasma discharge treatment. The alkaline and acid medium were found to be favorable for higher degradation efficiency. Additional measurements and results of recent investigations concerning underwater plasma showed that microbubbles presented in cavitation zone could serve as “bridges” making the pulse discharge propagation between the electrodes easier than in the conventional case. Besides, acoustic cavitation assists a faster transition of plasma discharge from ineffective streamer type to more effective spark type that further contributes to the improvement of the treatment performance.

本研究提出了一种新颖的废水处理工艺，即声空化辅助等离子体（ACAP），其目的是通过超声辐射和高压等离子体放电的协同作用来扩大水污染物的可处理范围。在此过程中，声空化的作用不仅是提供化学活性OH⋅自由基的产生（例如在常规超声废水处理技术中），而且还可以确保在废水中稳定产生等离子体的条件，从而扩展可处理范围的水污染物。罗丹明B（RhB）被用作模型污染物，用于检查超声振幅，RhB初始浓度，输出电压，溶液pH值和电导率对RhB降解效率的影响。结果表明，超声辅助等离子体的产生需要较低的输出电压，并允许将可处理溶液的可接受的电导率范围提高到1000μS/ cm，这是常规等离子体放电处理情况下的约24倍。发现碱性和酸性介质有利于更高的降解效率。最近有关水下等离子体的研究的其他测量和结果表明，空化区域中出现的微气泡可以充当“桥”，这使得脉冲放电在电极之间的传播比传统情况更容易。除了，