Investigation of hydrodynamic cavitation induced reactive oxygen species production in microchannels via chemiluminescent luminol oxidation reactions. (15th July 2022)

• Record Type: Journal Article
• Authors: Podbevšek, Darjan; Ledoux, Gilles; Dular, Matevž
• Is Part Of: Water research. Volume 220(2022)
• Publication Date: 2022-07-15
• Subjects: Cavitation cloud shedding -- Free radicals -- Photon counting -- Microscale cavitation -- Luminol chemiluminescence -- Convergent-divergent channels; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2022.118628
• Languages: English
• ISSNs: 0043-1354

Abstract

Highlights: Contactless, in situ chemiluminescence-based radical quantification. Radical generation in micro convergent-divergent channels. Geometry and flow parameters in micro-milli transition scale examined. Dominant radical yielding vapor structures identified by single photon counting. The cavitation cloud collapse was found not to be the source of the chemical yield. Abstract: Hydrodynamic cavitation was evaluated for its reactive oxygen species production in several convergent-divergent microchannel at the transition from micro to milli scale. Channel widths and heights were systematically varied to study the influence of geometrical parameters at the transitory scale. A photomultiplier tube was used for time-resolved photon detection and monitoring of the chemiluminescent luminol oxidation reactions, allowing for a contactless and in situ quantization of reactive oxygen species production in the channels. The radical production rates at various flow parameters were evaluated, showing an optimal yield per flow rate exists in the observed geometrical range. While cavitation cloud shedding was the prevailing regime in this type of channels, the photon arrival time analysis allowed for an investigation of the cavitation structure dynamics and their contribution to the chemical yield, revealing that radical production is not linked to the synchronous cavitation cloud collapse events. Instead, individual bubble collapses occurring throughout the cloud formation were recognized to be the source of the reactive oxygen species. Graphical abstract: Image, graphical abstract