Ultrasonic Homogenizers for Liquid Processing
Hielscher Ultrasonics specializes in the design and manufacturing of high power ultrasonic homogenizers for lab, bench-top and production level. Ultrasonic power is an effective and energy-efficient means to apply high shear and intense stress to liquids, powder/liquid mixtures and slurries. This makes it a strong alternative to high shear mixers, high pressure homogenizers and agitated bead mills.
Hielscher ultrasonic devices are in use worldwide as laboratory mixers, high shear mixing equipment, full-size in-line homogenizers or particle mills. The applications span mixing, dispersing, particle size reduction, extraction and chemical reactions. We supply to various industry segments, such as nano-materials, paints & pigments, food & beverage, cosmetics, chemicals and fuels. Read more about our devices and applications, or contact us now for the right ultrasonic systems for your process.
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While the scale-up of a process from the laboratory or bench-top level to full production is the most critical and hardest step for other mixing technologies, it is most simple with Hielscher ultrasonic equipment. This is because; during scale up we do not change any of the driving parameters, such as amplitude or pressure.
Ultrasonic batch mixing works well for volumes of up to 100L for some purposes, however ultrasonic in-line mixing using flow cell reactors and a feed pump is the more effective solution. In a flow cell the ultrasonic power is highly concentrated on a small volume resulting a more uniform processing and better product quality. A back pressure valve can be used to increase the pressure in the flow cell. This intensifies the sonication significantly resulting in higher hydraulic shear.
Ultrasonic Processes and Applications
Particle Size Reduction
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Particle Surface Cleaning
The surface of powder particles is a key factor for the interaction with the surrounding liquid. It is at such solid/liquid phase boundaries, where dissolving, chemical reactions or catalytical activity take place. Ultrasonic homogenization increases the exposure of particle surface to the liquid phase by uniform deagglomeration and particle size reduction. During catalytic and chemical reactions, the particle surface can be blocked by residue deposition, boundary layer formation, oxide layers and fouling. Ultrasonic cavitation causes high-speed liquid jets, high hydraulic shear and inter-particle collisions resulting in particle surface cleaning. Hielscher ultrasonic devices can be used in a batch or in-line to remove contaminations from particles in liquids.
Stirring is an often-underestimated process and requires reliable equipment, especially for increasing viscosities and volumes. Conventional agitators such as paddle mixers or rotor-stator mixers are limited by various factors, including viscosity and scalability. Therefore, high power ultrasonicators are the right choice for your mixing process due to their advantages in higher through-put, time saving, lower operational costs, safe operation (no moving parts) and simple maintenance.
When mixing dry powders, such as, pigments, thickeners or gums with liquids, the powder particles tend to form agglomerates, lumps or so-called “fish-eyes” (partially hydrated powder with a dry powder core). Agitators and stirrers will wash the surface of such agglomerates, only. This results in long mixing times and poor product quality. Ultrasonic mixing breaks agglomerates and lumps leading to an agglomerate-free solution. Furthermore, sono-chemical effects are well known to activate the particle surface area, which leads to advantages such as faster reactions and enhanced product quality.
For measurements by analytical instruments (e.g. HPLC, atomic spectrometer, etc.), generally most samples have to be liquefied. If the sample is soluble, the solute (such as sucralose, salts, e.g. in powder or tablet form) can be dissolved in a solvent (e.g. water, aqueous solvents, organic solvents etc.) resulting in a homogeneous mixture, composed of only one phase. The dissolving process can be carried out by manual or mechanical stirring, which is time-consuming and inefficient. Related problems are sample losses due to manipulation or lacking reproducibility by random errors and uneven mixing.
To initiate a chemical reaction, energy is required. The so-called activation energy is the amount of energy required to initiate a reaction and carry on spontaneously. By the input of ultrasonic energy, chemicals reaction can be initiated as attractive forces are overcome and free radicals are created. Typical chemical reactions that benefit from ultrasound are sono-catalysis (e.g. phase transfer catalysis), synthetic organic reactions, sonolysis as well as sol-gel-routes. Furthermore, ultrasonic forces create highly reactive surfaces, which is an important technique to increase catalyst activity.
The phenomenon of decreasing viscosity under increasing shear forces is termed shear thinning or thixotropic. The decrease of viscosity is of significant importance when the particle load of a medium should be modified. To achieve a higher solid load, in the first step viscosity must be lowered. After viscosity reduction, solids can be added and dispersed in the medium. High-shear forces created by ultrasonic cavitation cause shear-thinning and outstanding dispersing results. This application is mainly integrated before spray-drying or spray-freezing to increase the capacity of the spraying process or to influence the rheology of thixotropic material, e.g. polymers.
Sieving, Screening, Filtration
Separation of particles by size difference requires agitation of the screen or mesh. Ultrasonic agitation for sieving and screening is a proven tool, which increases sieving capacity and saves time as powders are enabled to pass the sieve faster and more complete. The result is a better final product quality with less material loss due to incomplete separation – and all within a shorter processing time. Read more about sieving and screening!
The control of bacteria and algae growth in water is for many industries a highly relevant upstream- or downstream-process for production. Powerful ultrasound waves are known for their effects on cell structures causing cell lysis and cell death as well as for their cleaning capability due to mechanical impact.
Furthermore, tanks, barrels, vessels and even filters can be successful cleaned from biofilms, residues, and debris in a very simple but efficient sonication step. Ultrasonically generated mechanical vibrations and cavitational shear forces remove the contamination. In general, cleaning agents are not necessary and the removed residues can be easily flushed away.
Industry Specific Solutions
Mostly, high power ultrasonicators are the only efficient tool to achieve the desired milling and dispersing results of nano particles (e.g. nanotubes, graphene, nanodiamonds, ceramics, metal oxides etc.). Alternatively, the ultrasonically assisted precipitation or so-called bottom-up synthesis is an efficient way to create pure nano crystals with unique properties. Especially, metallic nano particles, alloys and organometallic composites attract particular interest, as metals are of great importance in the industrial sector. Here too, sonication offers unique results such as the tin-coating of aluminum and titanium particles.
The precipitation or bottom-up synthesis describes the controlled formation of atoms, molecules and ions into larger chemical compounds. Precipitation is also useful for the purification of products. The advantage of precipitation is that by this method smallest particles of almost uniform form, particle/ crystal size and morphology are obtained. For the production of nano particles of high purity, precipitation and self-organization of molecular components is often the only way to achieve the desired quality. As precipitation is a very fast reaction, the efficient mixing of the reactants is essential. Ultrasonic mixing is the key for an even and fine mixed solution. Hielscher Ultrasonics supplies highly reliable ultrasonic equipment that guarantees complete control over the process parameters and a full reproducibility. Read more about precipitation!
Catalysts increase the conversion rate of chemical reactions and are needed to initiate a reaction or to keep the reaction running until a complete conversion is achieved. The fact that catalytic reactions are often slow and incomplete can be changed by high power ultrasound. Ultrasonication contributes to both, the homogeneous and heterogeneous catalysis and achieves faster conversion rates and higher yields. Ultrasonic forces create highly reactive surfaces and thereby increase the catalytic activity. Even though catalysts are not consumed themselves, surface depositions can lower the catalyst’s activity over the time. As solid catalysts often require rare and expensive metals, a long lifetime is an economically essential aspect. Ultrasound is a proven technique to remove fouling from the catalyst surface for reactivation to full catalytic capacity. Read more about sono-catalysis!
Chemical reactions are often slow and incomplete, thus the achievement of fuller utilization of the precursors is desirable. High-power ultrasonics cause physical effects in liquids, for instance enhanced mass transfer, emulsification, bulk thermal heating, and a variety of effects on solids (milling, deagglomeration, surface activation, modification). These physical effects significantly influence chemical reactions. In consequence, ultrasound contributes to manifold chemical reaction such as catalysis, synthesis & precipitation, sol-gel routes, emulsion chemistry and polymer chemistry. Hielscher ultrasonic devices a ideal for sonochemical application as Hielscher systems are capable to handle solvents, acids, bases and explosive materials (ATEX rated ultrasonicator UIP1000hd). All systems can be used for batch sonication as well as for inline sonication. A broad assortment of devices and accessories allows for matching the process requirements. Read more about sono-chemistry!
Ultrafine nano-sized particles and spherical shaped particles, thin film coatings, fibers, porous and dense materials, as well extremely porous aerogels and xerogels are highly potential additives for the development and production of high performance materials. Advanced materials, including e.g. ceramics, highly porous, ultra light aerogels and organic-inorganic hybrids can be synthesized from colloidal suspensions or polymers in a liquid via the sol-gel method. The material shows unique characteristics, since the generated sol particles range in the nanometer size. Via the ultrasonic sol-gel route, gels (so-called sono-gels) with smallest particle size, highest surface area and highest pore-volumes can be creates. The broad range of Hielscher’s ultrasonic equipment offers the ideal device configuration for specific materials and volumes. Read more about sol-gel processes!
Chemical waste imparting its recovery and degradation are a severe problem of industrial processes such as mining, chemicals manufacturing and landfill sites. Waste and pollutants (e.g. in soil, waste water…) have to be processed in terms to recycling, waste reduction or deposition. Sonochemical degradation is a highly potential process, which is characterized besides its outstanding and unique results by environmental friendliness and easy operation. Sonication can results in the cleavage of bondings, chain length reduction, molecular modification or activation. Thereby, it contributes to oxidation, sorption, sonolysis and leaching. Characteristic features of ultrasonically-assisted degradation are an increase of the chemical conversion rate as well as ultrasonic cavitation and the sonochemical effects provide a better mixing, initiation of reactions by energy input, creation of functional group (e.g. cleavage –OH hydroxyl groups) and radicals (e.g. H2O -> H+ and HO-).
Sonication has various effects on polymers: the effects of physical nature include mixing (such as emulsification, dispersing, deagglomeration, encapsulation) and bulk heating, whilst chemical effects create free radicals and change molecular structures. Ultrasound contributes in several ways to polymerization: High power ultrasound waves produce and disperse nano-size particles, emulsify non-miscible liquid phases and create free radicals which contribute to emulsion polymerization. Polymer nanocomposites and hydrogels can produced successfully by ultrasound. Furthermore, the surface functionalization of polymers plays an important role to enhance the performance of basic polymers and offers new approaches toward the development of tailored materials. The improvement of surface properties of commodity polymers is of high economical interest. Thereby, sonochemistry is the right way for successful polymer treatment.
Catalyst Reclamation / Regeneration
When reagents react at a catalyst particle surface, the products of the chemical reaction accumulate at the contact surface. This together with fouling and passivating layers blocks other reagent molecules from interacting at this catalyst surface. By ultrasonic cavitation and the thereby caused inter-particle collision, the residues on the particle surface are broken-off and washed away by ultrasonic streaming in the liquid. Cavitational erosion on particle surfaces generates unpassivated, highly reactive surfaces. Short-lived high temperatures and pressures contribute to molecular decomposition and increase the reactivity of many chemical species. Hielscher ultrasonic reactors can be used in the preparation, reclamation and regeneration of catalysts.
Sonoluminiscence describes the phenomenon of short bursts of light emission generated by imploding ultrasonic cavitation bubbles in a liquid medium. Although there are different theories that try to unveil the phenomenon of sonoluminiscence, until today scientists could not prove their theories, which include hotspot, bremsstrahlung radiation, collision-induced radiation and corona discharges, nonclassical light, proton tunneling, electrodynamic jets and fractoluminescent jets, quantum explanation (which is related to the Unruh or Casimir effect) or thermonuclear fusion reaction.
Biology & Microbiology
Hielscher Ultrasonics has the perfectly suitable ultrasonicator for each individual application. For smallest vials and test tubes, the VialTweeter is the device of your choice, whilst a lab probe device such as the UP200Ht or UP400S best treats larger samples. For bench-top and commercial applications, ultrasound systems from 500 watts up to 16,000 watts handle large volume streams easily. Various sonotrodes, flow cells and accessories complete the program and cover all requirements.
DNA, RNA & Chromatin Shearing
Desoyxribonucleic acid (DNA), ribonucleic acid (RNA) and chromatin are – along with proteins – the major macromolecules for all forms of life. DNA and RNA are the molecules that encode the genetic instructions of organisms. Chromatin is the combination of DNA and proteins where from the content of the cell nucleus is built. For research purpose, it is necessary to fragment these molecular building blocks into smaller components to investigate and analyze them or to rearrange them during immunoprecipitation and crosslinking. For DNA, RNA and chromatin shearing, the fragment size is very important. By full control over all important parameters, ultrasound enables for targeted molecule fragmentation. For instance, the ideal chromatin fragment length ranges between 200 and 1000 bp. Ultrasonic shearing is achieved by bursts in pulse mode. Due to intelligent devices and accessories, processing needs such as direct or indirect sonification, sample cooling, digital process recording are provided by Hielscher’s ultrasonic equipment. This ensures successful microbiological processing and operation comfort.
Paint & Ink, Pigments
For inks and ink jet inks, the particle size is the key quality mark: are the pigments too small, the ink loses its tinting strength – are the pigments too large, the printer nozzles clog resulting in poor printouts. Ultrasonication allows adjusting the processing parameters exactly to the aspirated milling and deagglomeration results. When the ideal ultrasonic processing parameters are once found, there is now reason to change them. The continuous inline production enables for an even output of highest product quality. The particle distribution within the formulation is vital for the expression of products’ attributes. Only if particle are dispersed evenly and uniform, the final product shows satisfactory quality such as transparency, UV resistance, or scratch resistance of coatings. Dispersing is one of the proven power applications of ultrasound.
Cosmetics & Personal Care
Bioethanol is a green fuel which is obtained when the starch and sugar of corn, crops, potatoes, cane, rice etc, is fermented by yeast cells into ethanol. By the application of power ultrasonics, the plant cells are disrupted and the intracellular material is extracted so that the feedstock is better available for the enzymatic digestion. Thereby, starch and sugars are better available for fermentation resulting in a faster and more complete conversion and higher yield.
Fuel, Energy, Oil & Gas
Food, Dairy & Beverage
Features and Benefits
- Sonication in batch or in-line mode
- Wetted sonication elements are Titanium
- Reactors are stainless (316L) or glass
- Low maintenance, no small orifices
- Ultrasonically assisted clean-in-place (CIP)
- 24hrs / 7days operation under full load
- High energy efficiency
Improved Digital Control
Our new devices come equipped with enhanced digital controls, such as touch screen, SD-card protocoling, temperature control and LAN interface for browser control. No software installation needed.
High Viscosity Slurries
Our bench-top and industrial homogenizers can process viscous slurries of up to 250,000 centipoise. For viscosities higher than 2,000 cPs we recommend the use of flow-cells with progressive cavity pumps for better coupling.
Easy-to-Clean / CIP
Hielscher ultrasonic mixers are available with sanitary fittings for easy access and cleaning. The ultrasonic cavitation assists clean-in-place procedures (CIP) – it is an extremely powerful ultrasonic cleaner in place.