Large-scale ultrasonic irradiation

Large-scale ultrasonic irradiation is extant technology. Liquid processing rates of 200 liters/minute are routinely accessible from a variety of modular, in-line designs with acoustic power of several kW per unit (83). The industrial uses of these units include (1) degassing of liquids, (2) dispersion of solids into liquids, (3) emulsification of immiscible liquids, and (4) large-scale cell disruption (74). While these units are of limited use for most laboratory research, they are of potential importance in eventual industrial application of sonochemical reactions. 

In cases where low intensity irradiation is needed batch treatment could be as simple as using a large-scale ultrasonic cleaning bath as the reaction vessel. However the tank would need to be constructed of a material which was inert towards the chemicals involved. An appropriate grade of stainless steel might prove adequate or plastic tanks could be used. In the latter case however the transducer would need to be bonded onto a stainless or titanium plate and this assembly then bolted to the tank. A useful variant to this and indeed one which offers greater flexibility in use is the sealed, submersible transducer assembly (Fig. 7.17). With either system some form of additional (mechanical) stirring would almost certainly be needed. 

At times the net rates of chemical/physical processing achieved using ultrasonic irradiations are not sufficient so as to prompt towards industrial scale operation of sonochemical reactors. This is even more important due to the possibility of uneven distribution of the cavitational activity in the large scale reactors as discussed... 

Industry uses special devices similar to ultrasonic baths and probes but appropriately scaled up in size and ultrasound irradiation power. The UIP16000 model from Hielscher Ultrasound Technology is by far the most powerful ultrasonic processor available worldwide the apparatus is capable of delivering a continuous power of 16000 W at efficiency above 80%. Such powerful systems have been developed in response to the demand for the ultrasonic treatment of liquids on a large scale in fact, the ultrasound power required usually increases in proportion to the amount of liquid to be treated within a certain time. 

The selective reductive cleavage of the P—C bond between phosphorus and a phenyl group is a slow reaction especially for large scale preparations.Recent findings report that ultrasonic irradiation accel-... 

Nucleation can often be induced by agitation, mechanical shock, friction and extreme pressures within solutions and melts, as shown by the early experiments of Young (1911) and Berkeley (1912). The erratic effects of external influences such as electric and magnetic fields, spark discharges, ultra-violet light. X-rays, 7-rays, sonic and ultrasonic irradiation have also been studied over many years (Khamskii, 1969) but so far none of these methods has found any significant application in large-scale crystallization practice. 

Ultrasound is currently employed in the preparation of emulsions on an industrial scale. In this case, the reagents are pumped through a minisonic homogenizer or whistle reactor (Fig. 17). Cavitation occurs as the fluid flows across a vibrating plate and the power obtainable is limited by this factor. Most of the chemical effects observed arise from the vast increase in interfacial area rather than the ultrasonic irradiation itself. However, its advantages stem from its proven ability to process large quantities of material in this manner. 

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