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Magnetic field assisted nanoparticle dispersion

Identification

Key words magnetic field, hydrodynamic force, nanoemulsion, dispersion, aggregation, solubilisation, powder
Latest version 2011/04/27
Completed by KU Leuven LFT

How does it work?

Primary objective Deaggregation of nanoparticles to increase the surface area.
Working principle A magnetic field, even of moderate strength, alters the laminar flow profile of a electrically conducting solvent and enhances velocity gradients and shear rates (because of the parallel movement) near the walls of a channel. This is called the magnetohydrodynamic effect. It increases the attraction between particles and thus induces aggregation. These effects appear to be independent of the magnetic properties of the solid phase (1).

However, a permanent magnetic field can assist the break up of nanoparticle aggregates when these are suspended in a turbulent flow. Adequate magnetohydrodynamic forces can be obtained by applying an orthogonal magnetic field over a Venturi (flow is forced through a constriction section in the pipe) (2). Further research is required to understand the exact mechanism of magnetic field assisted emulsification (3).

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Additional effects
  • Low energy consumption in comparison to other techniques used to disperse nanoparticles (e.g. ultrasonic and ultraturrax techniques, planetary ball milling), as well as a simpler process design (2,4).
  • This technique can also be used to prepare oil-in-water or water-in-oil emulsions, possibly containing solid particles (2-4).
  • This technique can also be used to solubilise dry powders (by avoiding aggregation) (2,4).
Important process parameters the average size of the particles (or droplets in case of emulsions) depends on the magnetic strength. However, recirculation can also be applied to decrease the size as well as to improve the emulsion stability; linear flow rate (0.6-5 m/s) positively affects the emulsion stability (2-4).
Important product parameters viscosity; emulsifiers or surface-active agents can be added to improve the stability of the emulsion (2-4).

What can it be used for?

Products (Semi)liquid food products

Examples: mayonnaise (3)

Operations
  • Emulsification
  • Solubilisation of difficult-to-dissolve powders
Solutions for short comings This technology can offer an alternative for energy consuming high-shear, high-speed mixing for emulisification.

What can it NOT be used for?

Products Emulsions that need to be made under high shear.
Operations High-shear emulsification

Further research is required to establish what operations the technology can not be used for.

Other limitations Technical performance is somewhat lower than high pressure homogenizer.
Risks or hazards No hazards.

Implementation

Maturity Available at labscale and industrial scale.
Modularity /Implementation This technology can easily be implemented into an existing process line. Maintenance and investment costs are relatively low (2,4). Batch and continuous applications exist (3).
Consumer aspects None to be expected concerning the technology itself, as consumers are familiar with magnets. However, the general consumer attitude towards “nano” might be decisive.
Legal aspects No legal issues to be expected. Please check local legislation.
Environmental aspects This technology uses less energy than for instance ultrasonic technologies for dispersion (2,4).

Further Information

Institutes KU Leuven COK
Companies M4E
References 1. Busche et al. (1996) Magnetohydrodynamic Aggregation of Cholesterol and Polystyrene Latex Suspensions. Journal of Colloid and Interface Science 183, 528–538.

2. Stuyven et al. (2009) Magnetic field assisted nanoparticle dispersion. Chem. Commun. 47-49.

3. Kerkhofs et al. (2011) Mayonnaise production in batch and continuous process exploiting magnetohydrodynamic force. Journal of Food Engineering. 106, 35-39.

4. Nuyens et al (2009) Method for preparing emulsions. European Patent 1 560 641 B1.

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Created by LiesbethV on 27 April 2011, at 12:58