January 24, 2012
Scientists Announce World’s First Magnetic Soap
University of Bristol scientists have developed a magnetic soap that could potentially one day be useful in oil spills and revolutionize cleaning products.
The soap is produced by dissolving iron in a range of inert surfactant materials composed of chloride and bromide ions -- much like those found in mouthwash or fabric softener. This means the soap and the materials that it dissolves can be readily removed by applying a magnetic field.
Details of the new magnetic soap are reported in the chemistry journal Angewandte Chemie, a peer-reviewed journal of the German Chemical Society.
It is very similar to ordinary soap, except for the fact that it contains iron atoms that help form tiny particles that are easily removed through magnetization.
“If you'd have said about 10 years ago to a chemist: ℠Let´s have some soap that responds to magnets℠, they´d have looked at you with a very blank face,” co-author Julian Eastoe of the University of Bristol, told BBC News. “We were interested to see, if you went back to the chemical drawing board with the tool-kit of modern synthetic chemistry, if you could...design one.”
To test it, they introduced a magnet to a test tube containing the soap, covered by a less dense organic solution. When they introduced the magnet, the iron-rich soap overcame gravity and surface tension between the water and oil, rising through the organic solvent towards the magnet.
The soap´s electrical conductivity, melting point, size and shape of aggregates and how readily it dissolves in water can be altered by a simple magnetic on and off switch, making the possibilities for a wide range of applications a foreseeable reality.
In the past, one had to add an electric charge or change the pH, temperature or pressure of the system -- all changes that permanently alter the system composition and cost money. The new on/off method will make it much easier to round up and remove soap from a system once it has been added, making it a natural for environmental clean ups and water treatment.
“Any systems which act only when responding to an outside stimulus that has no effect on its composition is a major breakthrough as you can create products which only work when they are needed to,” said Peter Dowding, an industrial chemist not involved in the research. “The ability to remove the surfactant after it has been added widens the potential applications to environmentally sensitive areas like oil spill clean ups where in the past concerns have been raised.”
Soap is made of long molecules with ends that behave differently: one end of the molecule is attracted to water and the other is repelled by it. The “detergent” action of soap comes from its ability to attach to oily, grimy surfaces, with the “water-hating” end breaking up water molecules at that surface. The soap molecules then gather up into droplets in which all the “water-loving” ends face outward.
Once the scientists successfully developed the surfactant and it proved to be magnetic, Eastoe and his colleagues took the samples to the Institut Laue-Langevin, in Grenoble, France, where an intense beam of sub-atomic particles known as neutrons shed light on the matter. ILL scientists used the technique to confirm the iron-rich surfactant brought about the magnetic properties in the soap.
“The particles of surfactant in solution are too small to see using light but are easily revealed by neutron scattering which we use to investigate the structure and behavior of all types of materials at the atomic and molecular scale,” said Dr. Isabelle Grillo, head of the Chemistry Laboratories at ILL.
“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. From a commercial point of view, though these exact liquids aren´t yet ready to appear in any household product, by proving that magnetic soaps can be developed, future work can reproduce the same phenomenon in more commercially viable liquids for a range of applications,” Eastoe told BBC News.
“The research at the University of Bristol in this field is about how we can take the ordinary and give it extraordinary properties by chemical design,” said Eastoe. “We have uncovered the principle by which you can generate this kind of material and now it´s back to the drawing board to make it better.”
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