To see other variants and accessories, please enter the webcode on our website. webcode 501 KNOWLEDGE SONOPULS ULTRASONIC HOMOGENISERS Selecting the right device The electric power is not suitable to be the only criteria for selectinganultrasonichomogeniser. This valueonly states thepower of the ultrasonic generator, but not the energy inserted into the sample. The decisive factor for the result of the exposure to sonic waves is the amplitude at the soundradiating surface of the sonotrode with regard to the sample amount to be exposed. Mode of operation Ultrasonic generator: Converting the incoming power into ultrasonic power with 20 kHz operating frequency. Ultrasonic converter: Converting the electric energy from the generator intomechanical waves of the same frequency. Standard horn and booster horn: They enhance the amplitude emitted by the ultrasonic converter, based on their special design. Probes: As work peaks, they transfer the sonic power into the sample. As microtips, tapered tips or titanium flat tips with a diameter from 2 to 38 mm for different amplitudes and volumes. Probes are made of a very solid titanium alloy. This has the advantage that they are very stable compared to dynamic alternating loads and show great consistency towards aggressive and corrosive media. Sample preparation in the laboratory The main area of application of ultrasonic homogenisers is sample preparation. This includes homogenising, emulsifying and suspending different substances, accelerating chemical reactions, disrupting cells as well as extracting cell contents. By means of ultrasonic homogenisers, certain substances can be systematically destroyed, long treatment processes can be shortened and the profits of many reactions can be increased. Because of these advantages, new applications continue to be added. The comparison with other treatment devices in the laboratory such as pebble mills, rotorstator or split homogenisers shows that ultrasonic homogenisers work with higher efficiency and guarantee reproducible results at the same time. Disruption of cells and micro-organisms Modern laboratories use ultrasonic homogenisers for disrupting cell walls in order to reach cell contents, e.g. proteins. A part of the energy entered in cell suspension is always converted into heat. In order to avoid thermal damage to the cell contents, the sample is either exposed to sounds cyclically with interruptions (with or without cooling) or only in a cooling container. It is especially advantageous to expose microorganisms to sonic waves in rosette cells. These are sonic vessels made of glass, which ensure a permanent circulation of the sample liquid due to their form. If in addition they are placed in an ice bath, the content is efficiently cooled in a rosette cell due to its great glass surface. Dispersing Particles of solid substances or liquids can be dispersed in another liquid medium with ultrasonic energy. For example, nanostructured powders such as titanium oxide or pyrogenic silica are more and more widely used to produce paints and varnishes or for polishing little body surfaces due to their great specific surface and the therefore increasing chemical reaction potential. At the same time, these substances tend to agglomerate, which worsens flow and wetting behaviour. The pictured agglomerates can be destroyed with an ultrasonic homogeniser, while the dispersion is permanently stabilised against a reagglomeration. To analyse the particle size, dispersing is important for the accuracy of the measurement. The particles can only be detected in the extent in which they appear in the measurement zone as detectable measurement signal. This means that agglomerates which have not been dispersed lead to erroneous measurements. By means of ultrasound, the particles are divided and prepared for the following measurement. During emulsifying with ultrasound, two liquids which cannot be mixed with each other, such as oil and water, are processed into a homogenous liquid (see pict.). Compared to conventional methods with rotors or mills, it is possible to create very disperse emulsions with very low droplet size and very high stability by means of ultrasound. The droplets do not form clots or grapes and they do not sediment. When using rotors or stirrers, slow stirring often causes an isolation of the liquids, whereas fast stirring leads to undesired air bubbles. Ultrasonic homogenisers are often used in pharmacies for the highquality small production of salves. Homogenisation The technical application areas of ultrasonic homogenisers ranges from paint and varnish productions and homogenisation of sewage and soil samples for analytical purposes to sample preparation for grit size analyses. In environmental laboratories for example, industrial sewage is constantly examined for heavy metals, fats or oils in order to be able to immediately introduce measures in case the concentration is exceeded. For representative water analyses, it is necessary to put the samples in a homogenous state. This is carried out by means of ultrasonic homogenisation within a very short period of time. before after Oil-water emulsification www.sonopuls.info
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