Chemical effects in hydrodynamic cavitation on a chip: The role of cavitating flow patterns

Amongst the advanced oxidation processes (AOPs), hydrodynamic cavitation (HC) has emerged as one of the most cost-efficient, simple and ecologically friendly approaches in the recent decade. This type of the cavitation, in contrast to its counterpart (acoustic cavitation), has a huge potential to upscale to the industrial levels. In the recent years, the micro-scale HC (HC on a chip concept) has exhibited favorable efficacy in terms of nucleation type, surface effects and flow pattern dominancy. In this study, the chemical effects of the HC on a chip concept are shown for the first time by considering the effects of the cavitating flow patterns. So, this is the first attempt to understand the effects of the inception and developed cavitating flow patterns on the chemical reactions during the bubble collapse in the micro-scale. In addition, a particular attention is paid to the chemical reaction effects before the cavitation bubble observation in this investigation. Our results indicated that the triiodide releasing amount was interestingly maximum before the inception occurred, especially at the first cycle. The released amount decreased at the inception and increased for the case of the developed twin cavities. We also showed that, comparing to our previous studies, the cavitation arrived at a relatively lower upstream pressure in the open loop cavitation test rig. Therefore, the outcome of this approach reveals the significance of the in-depth investigations of the complex and very transient nature of the cavitation at different flow patterns. Furthermore, this study implied that reactors benefitting HC on a chip concept will be environmentally friendly tools for producing products from the wastes and worthless materials in the near future.

Automated summary

Hydrodynamic cavitation (HC) has emerged as a cost-efficient and environmentally friendly approach in the field of advanced oxidation processes (AOPs). This study investigates the chemical effects of the HC on a chip concept and highlights the importance of understanding the complex nature of cavitation at different flow patterns. The results show that the triiodide releasing amount is highest before the inception of cavitation and decreases afterwards, except for the case of developed twin cavities where it increases. This study suggests that reactors utilizing the HC on a chip concept could be environmentally friendly tools for waste and material conversion.