Preparation and Properties of an Aqueous Ferrofluid

Ferrofluids are colloidal suspensions of surfactant-coated magnetic particles in a liquid medium. This paper describes a simple synthesis of an aqueous-based ferrofluid that may be used in an introductory science or engineering laboratory. Magnetite (Fe3O4) particles are precipitated by combining Fe...

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Veröffentlicht in:Journal of chemical education 1999-07, Vol.76 (7), p.943
Hauptverfasser: Berger, Patricia, Adelman, Nicholas B, Beckman, Katie J, Campbell, Dean J, Ellis, Arthur B, Lisensky, George C
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Sprache:eng
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Zusammenfassung:Ferrofluids are colloidal suspensions of surfactant-coated magnetic particles in a liquid medium. This paper describes a simple synthesis of an aqueous-based ferrofluid that may be used in an introductory science or engineering laboratory. Magnetite (Fe3O4) particles are precipitated by combining FeCl3 and FeCl2 in a 2:1 stoichiometric ratio in aqueous ammonia solution. The resulting particles, ~10-20 nm in diameter based on powder X-ray diffraction, are then treated with aqueous tetramethylammonium hydroxide, which acts as a surfactant. When the resulting ferrofluid is placed near a magnet, it forms conical spikes. This paper also describes a method for repelling both oil- and water-based ferrofluid from solid surfaces that would otherwise be stained by the fluid. Finally, a demonstration of the interaction between ferrofluid and magnetic fields, in which ferrofluid is induced to leap upward by a stack of magnets, is described.
ISSN:0021-9584
1938-1328
DOI:10.1021/ed076p943