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Sonochemical activity in ultrasonic reactors under heterogeneous conditions.
A Barchouchi1, S Molina-Boisseau2, N Gondrexon1
1Univ. Grenoble Alpes, CNRS, Grenoble INP, LRP, 38000 Grenoble, France.
Ultrasonics Sonochemistry
|December 18, 2020
Summary
Adding glass beads to heterogeneous media can decrease ultrasonic activity by scattering sound waves. Sonochemical activity depends on the surface area of these beads, with acoustic radiation power better reflecting this influence than calorimetric power.
Area of Science:
- Physical Chemistry
- Chemical Engineering
- Acoustics
Background:
- Ultrasound is utilized in industrial processes, particularly in heterogeneous media, owing to its physical and chemical effects.
- The heterogeneity of the medium can significantly impact the efficiency of ultrasonic applications.
Purpose of the Study:
- To investigate the effect of inert glass beads on sonochemical activity in an ultrasonic reactor.
- To understand how the surface area of solids influences ultrasonic power distribution and chemical effects.
Main Methods:
- Monitoring the formation rate of triiodide to quantify sonochemical activity.
- Measuring ultrasonic power using calorimetry and acoustic radiation techniques.
- Experimenting with various frequencies (20–1135 kHz) and glass bead sizes (8 µm–6 mm).
Main Results:
- Sonochemical activity decreases when the surface area of glass beads exceeds a critical value (approx. 10⁻² m²), attributed to wave scattering and attenuation.
- This phenomenon is consistent across a wide range of frequencies and bead sizes.
- Above a threshold surface area, only a portion of the supplied ultrasonic power contributes to chemical effects.
Conclusions:
- The surface area of inert solids is a critical factor influencing sonochemical activity in heterogeneous systems.
- Acoustic radiation power is a more suitable indicator than calorimetric power for assessing the impact of solids on sonochemical processes.
- Optimizing solid loading is crucial for maximizing ultrasonic efficiency in industrial applications.
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