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Different Setups to Implement Flow-Through Ultrasonic Processing

Author: Paresh Shah
by Paresh Shah
Posted: Nov 25, 2014

Ultrasonic probe sonication has multifaceted applications, ranging from dispersion and emulsification, to blending and degassing across several industries, including laboratory research, pharmaceutical, biochemistry, food processing, and cosmetics manufacturing, amongst others. When large volume of material needs to be sonicated, an open-system ultrasonication setup has its own set of limitations. Open-system setup works well for small batch processing in laboratories; however, a continuous ‘flow-through’ ultrasonic processing setup is required for large-volume processing. An ultrasonic reactor (also known as an ultrasonic flow cell) forms an important part of a continuous (inline) flow-through ultrasonic processing system.

In addition to a generator (ultrasonic power supply), a transducer (piezoelectric converter), and a probe (horn), a flow-through ultrasonication system features a flow cell. Compared to the batch-type sonication, this inline flow-through setup provides greater uniformity in ultrasonic exposure, better temperature stability, and ability to process larger capacities. Depending on the application and the sample volume to be processed, one can adjust the horn amplitude and the flow rate of the liquid to control the degree of processing.

There are three different setups that can be used for flow-through or inline ultrasonic liquid processing: single-pass; recirculation (also known as loop); and multi-reactor. An overview of each setup is explained below:

Single-Pass Setup

In single-pass configuration, a premix solution is pumped through an inlet of the ultrasonic reactor chamber and subjected to the cavitation zone. Once the cavitation cycle is complete, the final material is flows out into a container through an outlet. If this setup is used as a part of a multistep processing system, then the sonicated solution may enter its subsequent step for further processing. The single-pass setup is common for low viscosity mixes that require fast ultrasonic processing. In the food processing industry, this configuration is used to remove dissolved gases from liquid foods.

Recirculation or Loop Setup

In the loop setup, the solution to be sonicated is recirculated through the flowcell for subsequent cycles of sonication. This is done to increase the material’s exposure time to the cavitation zone and is recommended for challenging procedures, such as preparation of oil-in-water nanoemulsions in cosmetics and skin care industry. Another area which uses this configuration is the development of plastic composites wherein nanoparticles are required to be dispersed into liquid resins. More often than not, a cooling liquid is circulated through the cooling jacket to prevent the heat build-up and keep the temperature stable.

Multi-Reactor Setup

This setup consists of more than one ultrasonic reaction chambers and provides the advantages of both the single-pass and loop processing configurations. Whilst multiple sonication cycles take place in loop as well as multi-reactor systems, the latter setup facilitates the solution to undergo a single sonication cycle per flowcell. Difficult and challenging procedures, such as nanocrystallisation use the multi-reactor configuration for ultrasonic liquid processing. This setup of multiple ultrasonic reactor chambers offers productivity advantage over other two configurations as scaling up production is directly proportional to the number of reactors used.

About the Author

Paresh Shah is a Director at Life-Care Equipments Pvt. Ltd., a leading manufacturer and distributor of a wide range of ultrasonic cleaning systems.

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Author: Paresh Shah

Paresh Shah

Member since: Jun 27, 2014
Published articles: 10

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