UK scientists claim to have developed the world’s first magnetic soap as a way of helping clean up oil spills.
A team from Bristol University has created a soap composed of iron-rich salts dissolved in water, which responds to a magnetic field when placed in solution and so can be more easily removed after it’s been applied.
As well as finding use in industrial cleaning products, the soap could provide a way of removing spilt oil from the sea without leaving polluting chemicals behind.
The Bristol scientists, led by Prof Julian Eastoe, produced the soap by dissolving iron in a range of inert ‘surfactant’ materials containing chloride and bromide ions, similar to those found in products such as mouthwash and fabric conditioner.
Surfactants are compounds used as detergents that lower the surface tension of liquids, enabling them to mix more easily with substances they would usually repel, for example, oil and water.
The addition of iron to the surfactants created metallic centres within the soap particles that reacted to a magnetic field. It was previously assumed that these centres would be too isolated within the solution to make the liquid magnetically reactive.
Prof Eastoe said: ’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, although 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, from water treatment to industrial cleaning products.’
Scientists at the international neutron research centre Institut Laue-Langevin (ILL) in Grenoble, France, were able to explain why the soap took on magnetic properties by firing beams of neutrons at it to analyse its structure.
They used a technique called small angle neutron scattering (SANS) to show that the clumps of particles that form when surfactants are added to water created the magnetic properties when they contained iron.
Dr Isabelle Grillo of ILL’s chemistry labs said: ‘The particles of surfactant in solution are small and thus difficult to see using light but are easily revealed by SANS, which we use to investigate the structure and behaviour of all types of materials with typical sizes ranging from the nanometre to the tenth of micrometre.’
By making surfactants magnetic, scientists can now alter a range of the materials’ properties, including electrical conductivity, melting point and ability to dissolve in water, simply by turning a magnetic field on or off.
These factors have traditionally been controlled in order to make industrial soaps more effective using electricity, or changing the pH or temperature of the system. These changes, however, irreversibly alter the system’s composition and cost money to remediate.