Magnetic soap created
2 Feb 2012 by Evoluted New Media
A soap that can be controlled by magnets has been created by scientists at the University of Bristol, who hope it can be used to clean up after oil spills.
Researchers dissolved iron in a range of inert liquid surfactant containing chloride and bromide ions similar to those found in everyday mouthwash or fabric conditions. The addition of iron createes metallic centres within the soap particles, which responds to a magnetic fields when placed in solution.
When the team - led by Professor Julian Eastoe - introduced a magnet to a test tube containing their new soap beneath a less dense organic solution, the iron-rich soap overcame both gravity and surface tension between the water and oil. It levitated through the organic solvent.
“As most magnets are metals, from a purely scientific point of view these ionic liquid surfactants are highly unusual, making them a particularly interesting discovery,” said Eastoe.
Once the surfactant was shown to be magnetic, it was taken to the Institut Laue-Langevin (ILL) where it was subjected to neutron scattering. This showed the soap’s magnetic properties result from tiny iron-rich clumps - micelles - that sit within the watery solution.
“The particles of surfactant in solution are too small to see using light, but are easily revealed by neurton scattering which we use to investigate the structure and behaviour of all types of materials at the atomic and molecular scale,” said Dr Isabelle Grillo, head of the Chemistry Laboratories at ILL.
Magnetic surfactants have a wide range of uses. Their responsiveness to external stimuli allows a range of properties - electrical conductivity, melting point, size and shape of aggregates and how readily it dissolves in water - to be altered by a simple magnetic on and off switch. These factors - key in the effective application of soaps in industrial settings - could only be controlled by adding an electric charge, changing the pH, temperature or pressure of the system.
The magnetic properties make it easier to round up and remove from a system, suggesting that in may have applications in environmental clean ups and water treatment. It may also make experiments which require precise control of liquid droplets easier.
