A soap that responds to magnetic fields could be used to clean up oil spills without leaving behind detergents that can harm surrounding wildlife.
Researchers at the University of Bristol, UK dissolved iron particles in water that contained chlorine and bromine ions, materials which are commonly found in household products such as mouthwash or fabric cleaner. This created a metallic centre within the soap particles that could be influenced by a nearby magnetic field.
The team tried out their new soap by placing it in a test tube beneath layers of water and an oil-like substance. Using a magnet, they were able to overcome both gravity and surface tension to lift the soap through the layers and out of the tube.
This test shows that it is much easier to remove magnetic soaps from mixtures of other liquids, suggesting they could be used in response to environmental disasters such as oil spills, where concerns have been raised about the cleaning substances in use. A magnetic soap could easily be collected after cleaning, reducing the environmental impact.
Magnetic soaps could also have a range of industrial applications thanks to their ability to change properties such as electrical conductivity or melting point at will with a magnetic on/off switch. These properties are normally altered by adding an electric charge or changing the pH, temperature or pressure of the substance, meaning they can not be reversed.