Sonochemistry Ultrasonics Research Group

The Sonochemistry Ultrasonics Research Group (SURG) works with the propagation of ultrasound waves through a liquid medium that can lead to the creation of acoustic cavitation bubbles.

These cavitation bubbles can emit light (sonoluminescence) and undergo violent collapse to generate extreme temperatures (> 5000 k), pressures (> 1000 atm) and jet velocities (up to 120 m/s has been reported).

It is these remarkable conditions that allow ultrasound to create unusual physical and chemical properties ideal for degradation of pollutants, synthesis of polymers and nanomaterials. However, to capitalise on these effects, one needs to understand how the physical and chemical properties vary under different solution and sonication conditions such as frequency and power.

Ultrasonic processing has applications in heterogeneous and homogeneous environments, and is able to augment chemical processes via the well-known mechanoacoustic and sonochemical effects from the cavitation bubbles. This can enhance radically driven processes, as well as mixing, emulsification and molecular accessibility.

The mechanism and level of enhancement is influenced by the reactor configuration (geometry, transducer type, frequency, flow, power) and the characteristics of the medium (gases present, solid loading, form of the solute, pH etc). Therefore it is of interest to investigate the effect of these parametric variations to further capitalise on the bubble dynamics to enhance the desired ultrasonic effects.

The equipment available at SURG is able to investigate the various parametric effects of ultrasound on a multitude of processes, aimed at understanding the fundamental interactions toward process improvement and optimisation.

Research areas

Crystallisation is a common technique adopted by many industries for separation and purification operations. However, this method can suffer from unpredictable nucleation rates and inconsistencies in product qualities.  To remediate this, seeds are often added, but this can pose additional issues such as product contamination.

Ultrasound induced cavitation have shown to facilitate and control nucleation of crystals (sonocrystallisation), resulting in a more consistent and narrower size distribution of products. However, crystallisation and acoustic cavitation are two complex dynamic systems and when coupled together in this manner, the complexity is compounded.  For this reason, mechanism behind crystallisation is still contentious.

At SURG, we are interested in understanding the mechanism of sonocrystallisation and determining the effective application of ultrasound in crystallisation processes.  Some of the systems we are currently looking into are sodium chloride, paracetamol, lactose and dairy whey by-products.

Ultrasonic effects have potential applications in the processing of lignocellulose at various stages along the conversion process. Within SURG, we have interest in ultrasonic pretreatment of lignocellulose, as well as the ultrasonic enhancement of the conversion of fractionation products.

Pretreatment of lignocellulose occurs in a heterogeneous solution where the collapse of cavitation bubbles can enhance the accessibility of biomass components from pits and cracking observed on the surface of the biomass. In addition, the chemical effects of ultrasound have applications for enhanced purification of the polymeric component of the lignocellulosic biomass.

The unique chemical and physical effects created by ultrasound cavitation bubbles provides an ideal environment for effective chemical synthesis of materials. Here in SURG we are interested in the use of ultrasound to synthesis, but not limited to, protein shelled microbubbles, nanoparticles and metal organic frameworks (MOFs).

A sonochemically active bubble within a solution has three areas of interest, inside the bubble, the bubble-liquid interface and the bulk solution. The inner bubble may be considered as a little reactor with plasma-like reactions facilitated within the extreme conditions present.

The characteristics of the bubble are effected by the wave frequency and power, solution characteristics and gases present.  What happens in the inner bubble, will then effect which species are produced and diffuse into the interfacial region, which is characteristically at less extreme conditions than the inner bubble. Then, the bulk reactions are in turn a result of a combination of the inner bubble and interfacial reaction chemistry.

A focus of our research is to elucidate these effects under various gas atmosphere using a systematic method aimed at the identification of the most influential parameters. This can lead to an ability to control the reaction mechanism to obtain tuneable mini bubble reactors for targeted applications.

Ultrasound is able to effect cells in physically from microjetting and shear forces and chemically via ultrasonically-produced radicals. The microjets and shear forces produced in the sonicated solution are able to break the cell wall, killing or deactivating the cell.

This can enhance cell breakage or deactivation of cell growth In addition the shear forces from the cavitating bubble can lead to a pulsation of the cell which can weaken the cell wall and enhance the permeability of the cell membrane. This has application in the ability of the delivery of drugs in the case of cancerous cells, or for delivery of anti-microbial in the case of bacteria.

The cells are also subject to the radical oxidative species (ROS) produced by ultrasound. The production of ROS can enhance anti-microbial effects of ultrasound on bacteria and can interact positively with therapeutic agents or antibiotics that work via a ROS – initiated mechanism.

The efficacy of ultrasound is dependent on the targeted application, and can be influenced by the means and mode of the ultrasound applied to the cells of interest. Within SURG we have teamed up with the BB group (link) to investigate ultrasound in different biological applications. This includes the deactivation of bacteria in food systems and the treatment of pancreatic cancer using novel therapeutic agents.

With fresh water making up less than 1% of the world’s water, coupled with the ever growing demand and increase in water pollution, industries are forced to meet strict waste water discharge guidelines.

The radicals produced by cavitation bubbles have shown to accelerate the degradation of certain pollutants and within SURG we are investigating the use of ultrasound for the advance oxidation of per- and polyfluoroalkyl substance (PFAS) contaminated waters, abattoir waste, sulphates as well as phenols.


The ultrasonic bath is commonly found in labs and used for cleaning applications. The cavitation within a bath can be demonstrated with a simple aluminium foil test and provides a good comparison of ultrasonic applications, repeatability and effects at low frequencies and powers.

The ultrasonic field can be calibrated using different methods. At SURG we use and have the ability to perform iodide dosimetry, with spectrophotometric analysis; imagery analysis, visualising sonoluminescnce or sonochemiluminescence (Andor ixon X3 low light camera); hydrophone pressure measurements (Teledyne RESON TC4038-1), and calorimetric analysis.

Ultrasonic horn is a high power, low frequency means of introducing ultrasound into solution. The tip of the horn is interchangeable with a micro-tip and is used for emulsification applications, cell deactivation.

The pilot scale test rig was donated by Bio-Sep Ltd. The flow through cell allows for larger scale ultrasonic applications at elevated temperatures and pressures. 

These three sets consist of an amplifier, transducer, impedance matching and different reactor options. These allow for more specialised work that may require gas environments or sparging, separated chemical solutions, flow through cells or immersed applications.

Frequencies available include 22, 44, 98, 128, 139, 200, 300, 400, 500, 760 kHz, 1 and 2 MHz.


Lee, J. Y. (2016). Importance of Sonication and Solution Conditions on the Acoustic Cavitation Activity. In M. Ashokkumar (Ed.), Handbook of Ultrasonics and Sonochemistry (pp. 137-175). Springer. doi: 10.1007/978-981-287-278-4

Wood RJ, Lee J, Bussemaker MJ. (2017) 'A parametric review of sonochemistry: control and augmentation of sonochemical activity in aqueous solutions'. Ultrasonics Sonochemistry, doi: 10.1016/j.ultsonch.2017.03.030

Kezia, K., Lee, J., Zisu, B., Weeks, M., Chen, G., Gras, S., Kentish, S. (2016). Crystallisation of minerals from concentrated saline dairy effluent. WATER RESEARCH101, 300-308. doi:10.1016/j.watres.2016.05.074

Bhangu, S. K., Ashokkumar, M., & Lee, J. (2016). Ultrasound Assisted Crystallization of Paracetamol: Crystal Size Distribution and Polymorph Control. CRYSTAL GROWTH & DESIGN16(4), 1934-1941. doi:10.1021/acs.cgd.5b01470

Hallez, L., Lee, J., Touyeras, F., Nevers, A., Ashokkumar, M., & Hihn, J. Y. (2016). Enhancement and quenching of high-intensity focused ultrasound cavitation activity via short frequency sweep gaps. Ultrasonics Sonochemistry29, 194-197. doi:10.1016/j.ultsonch.2015.09.019

Pflieger, R., Lee, J., Nikitenko, S. I., & Ashokkumar, M. (2015). Influence of He and Ar Flow Rates and NaCl Concentration on the Size Distribution of Bubbles Generated by Power Ultrasound. Journal of Physical Chemistry B Materials119(39), 12682-12688. doi:10.1021/acs.jpcb.5b08723

Jiao, J., He, Y., Kentish, S. E., Ashokkumar, M., Manasseh, R., & Lee, J. (2015). Experimental and theoretical analysis of secondary Bjerknes forces between two bubbles in a standing wave.. Ultrasonics58, 35-42. doi:10.1016/j.ultras.2014.11.016

Jiao, J., He, Y., Yasui, K., Kentish, S. E., Ashokkumar, M., Manasseh, R., Lee, J. (2015). Influence of acoustic pressure and bubble sizes on the coalescence of two contacting bubbles in an acoustic field.. Ultrasonics Sonochemistry22, 70-77. doi:10.1016/j.ultsonch.2014.06.022

Bussemaker MJ, Zhang D. (2014) 'A phenomenological investigation into the opposing effects of fluid flow on sonochemical activity at different frequency and power settings. 2. Fluid circulation at high frequencies'. Ultrasonics Sonochemistry, 21 (2), pp. 485-492. doi: 10.1016/j.ultsonch.2013.09.011

Bussemaker MJ, Zhang D. (2014) 'A phenomenological investigation into the opposing effects of fluid flow on sonochemical activity at different frequency and power settings. 1. Overhead stirring.'. Ultrason Sonochem, Netherlands: 21 (1), pp. 436-445. doi: 10.1016/j.ultsonch.2013.07.002

Lee, J., Ashokkumar, M., & Kentish, S. E. (2014). Influence of mixing and ultrasound frequency on antisolvent crystallisation of sodium chloride.. Ultrasonics Sonochemistry21(1), 60-68. doi:10.1016/j.ultsonch.2013.07.005

Bussemaker MJ, Xu F, Zhang D. (2013) 'Manipulation of ultrasonic effects on lignocellulose by varying the frequency, particle size, loading and stirring.'. Bioresour Technol, England: 148, pp. 15-23. doi: 10.1016/j.biortech.2013.08.106

Bussemaker MJ, Mu X, Zhang D. (2013) 'Ultrasonic pretreatment of wheat straw in oxidative and nonoxidative conditions aided with microwave heating'. Industrial and Engineering Chemistry Research, 52 (35), pp. 12514-12522. doi: 10.1021/ie401181f

Bussemaker MJ, Zhang D. (2013) 'Effect of ultrasound on lignocellulosic biomass as a pretreatment for biorefinery and biofuel applications'. Industrial and Engineering Chemistry Research, 52 (10), pp. 3563-3580. doi: 10.1021/ie3022785

Jiao, J., He, Y., Leong, T., Kentish, S. E., Ashokkumar, M., Manasseh, R., Lee, J. (2013). Experimental and Theoretical Studies on the Movements of Two Bubbles in an Acoustic Standing Wave Field. The Journal of Physical Chemistry Part B: Condensed Matter, Materials, Surfaces, Interfaces and Biophysical117(41), 12549-12555. doi:10.1021/jp404886h

Lee, J., zisu, B., Chandrapala, J., Bhaskaracharya, R., Palmer, M., Kentish, S. Ashokkumar, M. (2011). Effect of ultrasound on the physical and functional properties of reconstituted whey protein powders. Journal of Dairy Research78(2), 226-232. doi:10.1017/S0022029911000070

Towata, A., Lee, J., Yasui, K., Tuziuti, T., Kozuka, T., & Iida, Y. (2011). Fabrication of silver nanoparticles deposited on boehmite sol for surface enhanced Raman scattering. Applied Surface Science257(14), 6010-6015. doi:10.1016/j.apsusc.2011.01.098

Lee, J., Ashokkumar, M., Yasui, K., Tuziuti, T., Kozuka, T., Towata, A.,Iida, Y. (2011). Development and optimization of acoustic bubble structures at high frequencies. Ultrasonics Sonochemistry18(1), 92-98. doi:10.1016/j.ultsonch.2010.03.004

Kozuka, T., Yasui, K., Hatanaka, S., Tuziuti, T., Lee, J., & Towata, A. (2010). Study of an acoustic field in a microchannel. Japanese Journal of Applied Physics45(7S). doi:10.1143/JJAP.49.07HE14

Ashokkumar, M., Lee, J., Iida, Y., Yasui, K., Kozuka, T., Tuziuti, T., Towata, A. (2010). Spatial distribution of acoustic cavitation bubbles at different ultrasound frequencies.. ChemPhysChem: a European journal of chemical physics and physical chemistry11(8), 1680-1684. doi:10.1002/cphc.200901037

Lee, J., Vakarelski, I. U., Yasiui, K., Tuziuti, T., Kozuka, T., Towata, A., Iida, Y. (2010). Variations in the spatial distribution of sonoluminescing bubbles in the presence of an ionic surfactant and electrolyte. Journal of Physical Chemistry B114(8), 2572-2577. doi:10.1021/jp907329z

Ashokkumar, M., Bhaskaracharya, R., Kentish, S., Lee, J. Y., Palmer, M., & Zisu, B. (2010). The ultrasonic processing of dairy products – An overview. Dairy Science and Technology90(2), 147-168. doi:10.1051/dst/2009044

Iida, Y., Ashokkumar, M., Tuziuti, T., Kozuka, T., Yasui, K., Towata, A., Lee, J. (2010). Bubble population phenomena in sonochemical reactor: I Estimation of bubble size distribution and its number density with pulsed sonication - Laser diffraction method. Ultrasonics Sonochemistry17(2), 473-479. doi:10.1016/j.ultsonch.2009.08.018

Iida, Y., Ashokkumar, M., Tuziuti, T., Kozuka, T., Yasui, K., Towata, A., Lee, J. (2010). Bubble population phenomena in sonochemical reactor: II. Estimation of bubble size distribution and its number density by simple coalescence model calculation. Ultrasonics Sonochemistry17(2), 480-486. doi:10.1016/j.ultsonch.2009.08.017

Yasui, K., Tuziuti, T., Lee, J., Kozuka, T., Towata, A., & Iida, Y. (2010). Numerical simulations of acoustic cavitation noise with the temporal fluctuation in the number of bubbles. Ultrasonics Sonochemistry17(2), 460-472. doi:10.1016/j.ultsonch.2009.08.014

Ashokkumar, M., Lee, J., Iida, Y., Yasui, K., Kozuka, T., Tuziuti, T., Towata, A. (2009). The detection and control of stable and transient acoustic cavitation bubbles.. Physical Chemistry Chemical Physics11(43), 10118-10121. doi:10.1039/b915715h

Ashokkumar, M., Lee, J., Zisu, B., Bhaskaracharya, R., Palmer, M., & Kentish, S. (2009). Sonication Increases the Heat Stability of Whey Proteins. Journal of Dairy Science92(11), 5353-5356. doi:10.3168/jds.2009-2561

Yasui, K., Lee, J. Y., Tuziuti, T., Towata, A., Kozuka, T., & Iida, Y. (2009). Influence of the bubble-bubble interaction on destruction of encapsulated microbubbles under ultrasound. Journal of Acoustical Society of America126(3), 973-982. doi:10.1121/1.3179677

Tuziuti, T., Yasui, K., Lee, J., Kozuka, T., Towata, A., & Lida, Y. (2009). Influence of surface active solute on ultrasonic waveform distortion in liquid containing air bubbles. Journal of Physical Chemistry A113(31), 8893-8900. doi:10.1021/jp901898p

Iida, Y., & Lee, J. (2009). Protein microbubbles: Ultrasonic fabrication, chemical treatment and their characterization. Materials Integration22(6), 30-34. Retrieved from

Iida, Y., Lee, J., Kozuka, T., Yasui, K., Towata, A., & Tuziuti, T. (2009). Optical cavitation probe using light scattering from bubble clouds. Ultrasonics Sonochemistry16(4), 519-524. doi:10.1016/j.ultsonch.2008.12.003

Lee, J., Yasui, K., Tuziuti, T., Kozuka, T., Towata, A., & Iida, Y. (2008). Spatial distribution enhancement of sonoluminescence activity by altering sonication and solution conditions. Journal of Physical Chemistry B112(48), 15333-15341. doi:10.1021/jp8060224

Yasui, K., Tuziuti, T., Lee, J., Kozuka, T., Towata, A., & Iida, Y. (2008). The range of ambient radius for an active bubble in sonoluminescence and sonochemical reactions. Journal of Chemical Physics128(18). doi:10.1063/1.2919119

Tuziuti, T., Yasui, K., Lee, J., Kozuka, T., Towata, A., & Iida, Y. (2008). Mechanism of enhancement of sonochemical-reaction efficiency by pulsed ultrasound. Journal of Physical Chemistry A112(22), 4875-4878. doi:10.1021/jp802640x

Vakarelski, I. U., Lee, J., Dagastine, R. R., Chan, D. Y., Stevens, G. W., & Grieser, F. (2008). Bubble colloidal AFM probes formed from ultrasonically generated bubbles.. Langmuir24(3), 603-605. doi:10.1021/la7032059

Lee, J., Tuziuti, T., Yasui, K., Kentish, S., Grieser, F., Ashokkumar, M., Iida, Y. (2007). Influence of surface-active solutes on the coalescence, clustering, and fragmentation of acoustic bubbles confined in a microspace. The Journal of Physical Chemistry Part C: Nanomaterials and Interfaces111(51), 19015-19023. doi:10.1021/jp075431j

Ashokkumar, M., Lee, J., Kentish, S., & Grieser, F. (2007). Bubbles in an acoustic field: an overview.. Ultrasonics Sonochemistry14(4), 470-475. doi:10.1016/j.ultsonch.2006.09.016

Kentish, S., Lee, J., Davidson, M., & Ashokkumar, M. (2006). The dissolution of a stationary spherical bubble beneath a flat plate. Chemical Engineering Science61(23), 7697-7705. doi:10.1016/j.ces.2006.08.071

Lee, J., Ashokkumar, M., Kentish, S., & Grieser, F. (2006). Effect of alcohols on the initial growth of multibubble sonoluminescence.. Journal of Physical Chemistry B110(34), 17282-17285. doi:10.1021/jp063320z

Lee, J., Ashokkumar, M., Kentish, S., & Grieser, F. (2005). Determination of the size distribution of sonoluminescence bubbles in a pulsed acoustic field.. Journal of the American Chemical Society127(48), 16810-16811. doi:10.1021/ja0566432

Lee, J., Kentish, S., Matula, T. J., & Ashokkumar, M. (2005). Effect of surfactants on inertial cavitation activity in a pulsed acoustic field.. Journal of Physical Chemistry B109(35), 16860-16865. doi:10.1021/jp0533271

Lee, J., Kentish, S., & Ashokkumar, M. (2005). Effect of surfactants on the rate of growth of an air bubble by rectified diffusion.. Journal of Physical Chemistry B Materials109(30), 14595-14598. doi:10.1021/jp051758d

Lee, J., Kentish, S. E., & Ashokkumar, M. (2005). The effect of surface-active solutes on bubble coalescence in the presence of ultrasound.. Journal of Physical Chemistry B109(11), 5095-5099. doi:10.1021/jp0476444

Research students

Richard Wood

Thesis title: Parametric Control and Augmentation of Sonchemical Activity in Aqueous Solutions.

Supervised by Madeleine Bussemaker and Judy Lee.

Sylvia Nalesso

Thesis title: Ultrasound simulated crystallisation of functional materials.

Supervised by Judy LeeMadeleine BussemakerRichard Sear and Mark Hodnett (NPL).

Katie Costello

Thesis titleListeria growth in structured food models: towards modelling microbial kinetics and potential antimicrobial resistance in structured cheese models as affected by emerging technologies.

Supervised by Eirini VelliouMadeleine BussemakerGorge Gutierrez and Jan Van Impe (KU Leuven).

Pello Alfonso Muniozguren

Thesis title: Application of advanced oxidation assisted processes for industrial wastewater treatments.

Supervised by Judy LeeDevendra SarojRalph Chadeesingh and Madeleine Bussemaker.

Timothy Sidnell

Thesis title: Ultrasonic degradation of Per- and Polyfluoroalkyl Substances.

Supervised by Madeleine Bussemaker, Dr Ian Ross (Arcadis) and Judy Lee.

Who we collaborate with