Editing Ultrasound (section)

===Processing===
{{main|Sonication}}
Ultrasonication offers great potential in the processing of liquids and slurries, by improving the mixing and chemical reactions in various applications and industries. Ultrasonication generates alternating low-pressure and high-pressure waves in liquids, leading to the formation and violent collapse of small [[vacuum]] bubbles. This phenomenon is termed [[cavitation]] and causes high speed impinging liquid jets and strong hydrodynamic shear-forces. These effects are used for the deagglomeration and milling of micrometre and nanometre-size materials as well as for the disintegration of cells or the mixing of reactants. In this aspect, ultrasonication is an alternative to high-speed mixers and agitator bead mills. Ultrasonic foils under the moving wire in a paper machine will use the shock waves from the imploding bubbles to distribute the cellulose fibres more uniformly in the produced paper web, which will make a stronger paper with more even surfaces. Furthermore, chemical reactions benefit from the free radicals created by the cavitation as well as from the energy input and the material transfer through boundary layers. For many processes, this sonochemical (see [[sonochemistry]]) effect leads to a substantial reduction in the reaction time, like in the [[transesterification]] of oil into [[biodiesel]].{{Citation needed|date=July 2020}}
[[File:Schematic of bench and industrial-scale ultrasonic liquid processors produced by Industrial Sonomechanics, LLC.jpg|thumbnail|Schematic of bench and industrial-scale ultrasonic liquid processors]]

Substantial ultrasonic intensity and high ultrasonic vibration amplitudes are required for many processing applications, such as nano-crystallization, nano-emulsification,<ref name = "nanoemulsion paper">{{cite journal | vauthors = Peshkovsky AS, Peshkovsky SL, Bystryak S | title = Scalable high-power ultrasonic technology for the production of translucent nanoemulsions. | journal = Chemical Engineering and Processing: Process Intensification | date = July 2013 | volume = 69 | pages = 77–82 | doi = 10.1016/j.cep.2013.02.010 | bibcode = 2013CEPPI..69...77P }}</ref> deagglomeration, extraction, cell disruption, as well as many others. Commonly, a process is first tested on a laboratory scale to prove feasibility and establish some of the required ultrasonic exposure parameters. After this phase is complete, the process is transferred to a pilot (bench) scale for flow-through pre-production optimization and then to an industrial scale for continuous production. During these scale-up steps, it is essential to make sure that all local exposure conditions (ultrasonic amplitude, [[cavitation]] intensity, time spent in the active cavitation zone, etc.) stay the same. If this condition is met, the quality of the final product remains at the optimized level, while the productivity is increased by a predictable "scale-up factor". The productivity increase results from the fact that laboratory, bench and industrial-scale ultrasonic processor systems incorporate progressively larger [[ultrasonic horn]]s, able to generate progressively larger high-intensity cavitation zones and, therefore, to process more material per unit of time. This is called "direct scalability". It is important to point out that increasing the power of the ultrasonic processor alone does ''not'' result in direct scalability, since it may be (and frequently is) accompanied by a reduction in the ultrasonic amplitude and cavitation intensity. During direct scale-up, all processing conditions must be maintained, while the power rating of the equipment is increased in order to enable the operation of a larger ultrasonic horn.<ref name = "horn paper">{{cite journal | vauthors = Peshkovsky SL, Peshkovsky AS | title = Matching a transducer to water at cavitation: acoustic horn design principles | journal = Ultrasonics Sonochemistry | volume = 14 | issue = 3 | pages = 314–22 | date = March 2007 | pmid = 16905351 | doi = 10.1016/j.ultsonch.2006.07.003 | doi-access = free | bibcode = 2007UltS...14..314P }}</ref><ref name = "book section">{{cite book | vauthors = Peshkovsky AS, Peshkovsky SL | chapter = Industrial-scale processing of liquids by high-intensity acoustic cavitation-the underlying theory and ultrasonic equipment design principles | veditors = Nowak FM | title = Sonochemistry: Theory, Reactions and Syntheses, and Applications | location = Hauppauge, NY | publisher = Nova Science Publishers | date = 2010 }}</ref><ref name = "book">{{cite book | vauthors = Peshkovsky AS, Peshkovsky SL | title = Acoustic cavitation theory and equipment design principles for industrial applications of high-intensity ultrasound | location = Hauppauge, NY | publisher = Nova Science Publishers | date = 2010 | series = Physics Research and Technology }}</ref>