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Activating Molecules, Ions, and Solid Particles with Acoustic Cavitation
Published on: April 11, 2014
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Hydroxyl radical formation in batch and continuous flow ultrasonic systems.
Hrvoje Juretic1, Melissa Montalbo-Lomboy2, J Hans van Leeuwen3
1Department of Agricultural and Biosystems Engineering, Iowa State University, Ames, IA 50011-3080, USA; Department of Energy, Power Engineering and Environment, Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Ivana Lucica 5, HR-10000 Zagreb, Croatia; Department of Civil, Construction and Environmental Engineering, Iowa State University, Ames, IA 50011-3232, USA.
Ultrasonics Sonochemistry
|August 5, 2014
Summary
Batch ultrasonic systems generate higher hydroxyl radical concentrations than continuous flow systems for pollutant degradation. Sonication time is the key factor influencing radical formation in both advanced oxidation technologies.
Area of Science:
- Environmental Chemistry
- Chemical Engineering
- Advanced Oxidation Processes
Background:
- Ultrasonic cavitation generates free radicals, driving pollutant degradation via advanced oxidation.
- Hydroxyl radicals are key reactive species in ultrasonic-based advanced oxidation technologies.
- Comparing batch and continuous flow ultrasonic systems is crucial for optimizing pollutant treatment.
Purpose of the Study:
- To compare hydroxyl radical formation in batch versus continuous flow ultrasonic systems.
- To investigate the influence of operational parameters like amplitude, sonication time, and flow rate.
- To assess the effect of saturating gases (helium and air) on radical generation.
Main Methods:
- Utilized terephthalic acid dosimetry to quantify hydroxyl radical formation.
- Conducted batch experiments in small and large reactors with a 20kHz titanium horn.
- Performed continuous flow experiments using a 20kHz, 3.3kW ultrasonic system with a titanium 'donut' horn.
Main Results:
- Batch systems produced higher hydroxyl radical concentrations than continuous flow systems at equivalent energy densities.
- Sonication time was identified as the primary factor affecting hydroxyl radical yield in both systems.
- Introducing helium or air did not enhance hydroxyl radical formation.
Conclusions:
- Batch ultrasonic reactors are more effective for hydroxyl radical generation compared to continuous flow systems.
- Optimizing sonication time is critical for maximizing radical production in ultrasonic advanced oxidation.
- Saturating gases do not significantly improve hydroxyl radical formation in these configurations.
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