High Shear Mixing with Ultrasonics
High shear mixers apply high shear forces into liquids and slurries in order to provide the uniform dispersing, blending, and emulsification of two or more liquid-solid or liquid-liquid phases. Ultrasonication generates high shear forces via acoustic cavitation, which occurs when high power ultrasound is coupled into liquids. Ultrasonic high-shear mixers are a superior mixing technology, which easily excels commonly used high shear blade mixers, multi-shaft mixers, high pressure homogenizers, colloid mills, and blade agitators.
The Benefits of Ultrasonic High-Shear Mixers
Ultrasonic high shear mixers are available from 50W lab homogenizers up to 16,000W industrial mixing systems. The broad portfolio from lab, bench-top and industrial ultrasonic high shear mixers makes it possible to choose the ideal ultrasonic high shear mixer for your application and production volume.
High amplitudes at the ultrasonic probe creates intense cavitation with liquid streams of high velocities and complex turbulences. The ultrasonically generated intense hydraulic and mechanical shear reduce particles and droplets to micron- and nano-size. Since sonication process parameters are precisely controllable and adjustable, the impact of mixing, milling, or dispersing can be precise adapted to the material and process goal. Ultrasonic high-shear mixers reduce the mixing / milling time and produce reliably fine and ultra-fine dispersions.
Ultrasonic mixer can be used for batch and inline-flow processes. The variety of ultrasonic flow cells and reactors allows for mixing streams at very different flow rates and viscosities. Ultrasonic high shear mixer can handle very high solid concentrations and even very abrasive particles are no problem.
How Does High-Shear Mixing by Sonication Work?
Ultrasonic high shear mixers use the same mechanical principle as industrial mixing systems such as high shear blade mixers, multi-shaft mixers, colloid mills, high pressure homogenizers, and blade agitators systems do. Ultrasonic mixing systems are used to disperse and mill particles, to emulsify oil and water phases, to solubilize solid matter and to produce homogeneous mixtures of any kind of materials in liquids and slurries. Ultrasonic shear mixers integrate an ultrasonic probe into a mixing vessel, such as into a batch tank or into a flow cell. The ultrasonic disintegrator probe vibrates in the liquid at a very high frequency and creates intense ultrasonic cavitation in the liquid. The collapse of the cavitation bubbles results in powerful shear forces, that disrupt and break droplets, agglomerates, aggregates, and even primary particles. As ultrasonic cavitation generates high-velocity cavitational streaming with up to 1000km/h, the cavitational liquid jets accelerate particles. When the accelerated particles collide with each other, the act as milling media. Subsequently, the colliding particles shatter and are are reduced to micron- or nano-size. In the ultrasonic cavitation field, pressures alternate quickly and repeatedly between vacuum and up to 1000bar. A rotary mixer with 4 mixer blades would need to operate at a staggering 300,000 RPM to achieve the same frequency of alternating pressure cycles. Conventional rotary mixers and rotor-stator mixers create no significant amount of cavitation because of their limitation in speed.
Processing Tip: Ultrasonic Mixing under Pressure
Applying pressure to the ultrasonic reactor or flow cell intensifies the acoustic cavitation. Hielscher Ultrasonics supplies various flow cell and reactor types, which can easily be pressurised up to 5 barg. Customized ultrasonic reactors can handle higher pressures of up to 300barg.
Ultrasonic High-Shear Mixers and Their Applications
Ultrasonic high shear mixers create intense shear forces, which have the required impact on particles such as solids, droplets, crystals, and fibers in order to disrupt and break them down to a targeted size, which can be in the micron or nano range. Depending on the materials hardness and brittleness, the ultrasonic process parameters can be exactly adjusted to achieve the aspired mixing result. When compared to alternative mixing methods such as high-shear blade agitators, high-pressure homogenizers, colloid / bead mills, shaft mixers etc. ultrasonic disintegrators offer some major advantages.
Advantages of Ultrasonic High Shear Mixers
- High-intensity cavitation and shear
- Uniform particle processing
- High solid concentrations
- No nozzles / no clogging
- No milling medium (i.e. beads) required
- Linear scalability
- Easy & safe operation
- Easy to clean
- Time- & energy-efficient
Ultrasonic High Shear Mixers for Particle Size Reduction
Ultrasonic disintegrators are used for particles size reduction and particle distribution, wether this means real comminution of primary particles (referred to as milling) or the breakage of agglomerates (referred to as deagglomeration / dispersion).
Read more about ultrasonic milling and dispersing of particles!
Ultrasonic High Shear Mixers for Emulsification
When two immiscible liquids (e.g., water and oil) are sonified using a probe-type ultrasonic mixer, ultrasonic cavitation disrupts the droplets – producing very small droplets of the two immiscible phases, which are then mixed together. As ultrasonic high shear mixers easily produce nano-sized droplets, stabilised ultrasonic emulsions exhibit a long-term stability and a clear transparent appearance.
Since any kind of emulsion has its specific emulsification / shear threshold, where optimal droplet size and characteristics are obtained, the precise adjustment of mixing parameters is crucial. Whilst shear too low results in too large droplets, which coalesce quickly and result in phase separation, shear too high can destroy the product. Ultrasonic high shear mixers can be precisely controlled and adjusted to process needs.
Click here to read more about ultrasonic nano-emulsification!
Ultrasonic High Shear Mixer UP200Ht for Emulsification
Ultrasonic High Shear Mixers for Blending and Dissolving
Ultrasonic high shear mixers are used to blend, mill, disperse, and dissolve particles such as powders, pigments and fibres in a rapid, reliable and easy process. Ultrasonically generated cavitation increases the mass transfer between solids and liquid. Ultrasonic cavitation has a strong impact on solid particles: The cavitational liquid streams erode the surface of solids and transports the eroded fragments into the liquid producing thereby a homogeneous suspension.
Click here to read more about ultrasonic dissolving!
Applications of Ultrasonic High Shear Mixers
- Milling & Grinding
- Deagglomeration & Dispersion
- Dissolving of powders
- Improving mass transfer
- Sonochemical reactions
High-Shear Mixers at Any Size
Hielscher Ultrasonics designs, manufactures and distributes high-performance high-shear mixers from the compact, yet powerful laboratory device to pilot and industrial high-shear mixers for the processing of large volume streams on commercial production level.
High Shear Mixers for the Laboratory
Probe-type ultrasonic mixers are established tools in every laboratory. Since ultrasonic processes can be linearly scaled up to large volume, Hielscher ultrasonic high-shear mixers are ideal to develop and optimize your process on small scale. Then, after establishing the optimum process parameters, the your mixing application can be upscaled linearly to pilot and bulk production.
Hielscher offers ultrasonic high shear mixers for lab scale work with a power range from 50 to 400 watts ultrasound mixing power.
High Shear Mixers for the Industry
Hielscher industrial high-shear mixers are high-power ultrasonic processors designed for milling, dispersing, emulsifying and blending large slurry streams under heavy duty. These industrial mixers easily handle high solid concentrations and abrasive particles. The probes (sonotrodes) of industrial ultrasonic high-shear mixers are equipped with a flange so that the mixer can be integrated into to steel tanks, glass vessels or plastic containers in any orientation. This allows to pressurize the sonication vessel. Applying pressure to the ultrasonic vessel or flow cell intensifies the acoustic cavitation and thereby the ultrasonic mixing process. Hielscher Ultrasonics offers industrial high-shear mixers from 500 to 16,000 watts. With the UIP16000, Hielscher offers the most powerful ultrasonic high-shear mixer worldwide.
High viscous materials? – No problem! All Hielscher ultrasonic processors in the bench-top and industrial categories can easily process viscous slurries of up to 250,000 centipoise. For viscosities higher than 2,000 cPs we recommend the use of flow-through cells in combination with progressive cavity pumps for improved coupling of the ultrasound waves into the fluid.
How to Find the Right Ultrasonic High Shear Mixer?
Hielscher Ultrasonics is long-time experienced manufacturer of powerful and reliable ultrasonic high-shear mixing systems, which are used to disperse and break particles, to prepare nanoemulsions, or to dissolve powders in liquids. Being market leader for ultrasonic mixers, Hielscher designs, manufactures and distributes ultrasonic high shear mixers and homogenizers from lab and bench top up to pilot and full-industrial scale.
Answering the following questions will help to find the most suitable high-shear mixer for your process:
- What is your target application?
- What is the typical volume that must be processed?
- What are the critical factors of the process?
- What are the quality standards, which must be achieved?
Our well trained and experienced staff will assist you with any questions and the conception of your mixing process. Hielscher Ultrasonics offers an in-depth consulting on ultrasonic processing to help our customers finding the most ideal ultrasonic high shear mixer. But Hielscher’s service does not end here, we train customers either at their facilities or in our ultrasonic process lab and technical center to assist them during process development, optimization and scale-up.
Hielscher Ultrasonics’ industrial ultrasonic processors easily deliver very high amplitudes, which are required to break hard particles and agglomerates or to process slurries with a high solid concentration. Hielscher industrial mixers easily run at amplitudes of up to 200µm continuously in 24/7 operation. If specific processes require even higher amplitudes, customized ultrasonic probes are available. Accessories such as booster horns, flow cells, sonication reactors and complete recirculation setups are readily available and allow to configure your ultrasonic mixing system adapted optimally to your process requirements. All sonotrodes and reactors, which are the only parts that get in contact with the medium, are CIP/SIP (cleaning and sterilization in place).
Sophisticated Ultrasonic High-Shear Mixers
Hielscher Ultrasonics focusses on high-performance cell disintegrators with highest user friendliness and state-of-the-art technical advances. This means that the standards of Hielscher lab disintegrators adapt more and more to the intelligence of industrial machinery. The user can control Hielscher’s digital ultrasonicators via browser remote control. The automatic data recording software writes all important ultrasonic parameters such as net power, total power, amplitude, temperature, pressure, time and date as CSV file on a built-in SD-card. Furthermore, the ultrasonic disintegrator can be programmed to automatic shut-off after a determined time or a specific energy input or program pulsating sonication modes. Pluggable temperature and pressure sensors allow for tracking the sample conditions carefully. Since temperature-control of heat-sensitive materials is a crucial factor for the quality of the process results, Hielscher offers various solutions to keep the process temperature in the targeted temperature range.
The sophisticated functions of Hielscher ultrasonicators assure the highest process control, reliable and reproducible sonication results, user-friendliness and working comfort.
Quality – Made in Germany
As a family-owned and family-run business, Hielscher prioritizes highest quality standards for its ultrasonic processors. All ultrasonicators are designed, manufactured and thoroughly tested in our headquarter in Teltow near Berlin, Germany. Robustness and reliability of Hielscher’s ultrasonic equipment make it a work horse in your production. 24/7 operation under full load and in demanding environments is a natural characteristic of Hielscher’s high-performance mixers.
You can buy Hielscher ultrasonic high-shear mixers in any different size and configured to your process. From treating fluids in a small lab beaker to the continuous flow-through mixing of slurries on industrial level, Hielscher Ultrasonics offers a suitable high-shear mixer for you! Please contact us – we are glad to recommend you the ideal ultrasonic mixer setup!
The table below gives you an indication of the approximate processing capacity of our ultrasonicators:
|Batch Volume||Flow Rate||Recommended Devices|
|1 to 500mL||10 to 200mL/min||UP100H|
|10 to 2000mL||20 to 400mL/min||UP200Ht, UP400St|
|0.1 to 20L||0.2 to 4L/min||UIP2000hdT|
|10 to 100L||2 to 10L/min||UIP4000hdT|
|n.a.||10 to 100L/min||UIP16000|
|n.a.||larger||cluster of UIP16000|
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Literature / References
- Pohl M.; Schubert H. (2004): Dispersion and deagglomeration of nanoparticles in aqueous solutions. International Congress for Particle Technology PARTEC 2004; Nuremberg, Germany.
- Thomas Leong, Muthupandian Ashokkumar, Sandra Kentish(2011): The Fundamentals of Power Ultrasound. – A Review. Acoustics Australia, 54 – Vol. 39 August 2011.
- Karl A. Kusters, Sotiris E. Pratsinis, Steven G. Thoma, Douglas M. Smith (1994): Energy-size reduction laws for ultrasonic fragmentation. Powder Technology, Volume 80, Issue 3, September 1994. 253-263.
- Pekarovicova, A.; Pekarovic, J. (2009): Emerging Pigment Dispersion Technologies. Pira International (2009).
- S.E. Karekar; B.A. Bhanvase; S.H. Sonawane; M.P. Deosarkar; D.V. Pinjari; A.B. Pandit(2014): Synthesis of zinc molybdate and zinc phosphomolybdate nanopigments by an ultrasound assisted route: Advantage over conventional method. Chemical Engineering and Processing 87; Nov. 2014.
Facts Worth Knowing
Ultrasonicators and their Use as High-Shear Mixers
Ultrasonicators are probe-type ultrasound devices, which are defined by transmitting the ultrasonic vibrations via an ultrasonic probe into the processing medium. The probe, also known as sonotrode, is a titanium rod that is vibrating in ultrasound frequency, e.g. 20kHz. Vibrating at 20 kHz means that the horizontal surface of the probe is expanding and contracting 20,000 times per second. These rapid movements in the ultrasonic frequency range at the tip of the probe are coupled into the fluid. In the fluid, the ultrasound waves travel through the medium and generate alternating high pressure / low pressure cycles. During the low pressure cycle, minuscule vacuum bubbles arise and grow over several pressure cycles until they reach a point, where they cannot absorb any further energy. At the point of maximum growth, the cavitation bubble bursts violently. The implosion results in an energy-dense field with very high temperatures and pressures, respective temperature and pressure differentials, liquid streams with velocities of up to 180m/sec and turbulences. This cavitational energy has a strong impact on liquids and slurries resulting in extraordinary mixing, blending, milling, dispersing and emulsifying results. Ultrasonic high-shear mixers easily produce nano-sized particles and droplets with a very narrow particle / droplet size distribution.
Common Industries for Ultrasonic High-Shear Mixers
- Dispersing, dissolving, mixing of solid/liquid formulations
- Material science
- Sample prep before analysis
- Nano-particle applications
- Particle functionalization
- Phase transfer reactions