For the first time ever, a magnetic soap was developed

Scientists from the University of Bristol have developed a soap consisting of iron-rich salts dissolved in water that react to a magnetic field when placed in a solution. Implementing this feature in finished soaps could alleviate concerns about the use of soaps to clean up oil spills and could bring about a revolution in industrial cleaning products.

"]Scientists from the University of Bristol have developed a soap consisting of iron-rich salts dissolved in water that react to a magnetic field when placed in a solution. Implementing this feature in finished soaps could alleviate concerns about the use of soaps to clean up oil spills and could bring about a revolution in industrial cleaning products.

Scientists have been searching for a long time for a way to control soaps from the moment they are introduced into a solution in order to increase their ability to dissolve oils in water and in the next step to remove them from the mixture. The team of researchers from the University of Bristol previously studied soaps that are sensitive to light, carbon dioxide or changes in acidity, temperature or pressure. The team's latest breakthrough, as published in the scientific journal Angewandte Chemie, relates to the development of the first ever soap sensitive to a magnetic field.

It has been proposed that soaps from the group of ionic liquids, consisting mainly of water and a number of transition metal conjugates (heavy metal atoms such as iron bound to halides such as bromine or chlorine), could be used as materials that can be controlled by means of magnets for a long time, but researchers have always believed that the metallic centers are too isolated within the solution , a property that prevents them from long-range interactions required for magnetic activity.

The researchers from the University of Bristol created their magnetic soap by dissolving iron in a variety of inert soaps consisting of chlorine and bromine ions similar to those found in mouthwash or common household hair conditioners. The addition of the iron created metallic centers within the soap particles.

In order to test the properties of their innovative product, the researchers put the soap in a test tube and placed it under a less compressed organic solution. When the researchers introduced a magnet into this mixture, the iron-rich soap was able to overcome both gravity and the surface tension between the water and the oil, while rising through the organic solvent and reaching the source of the magnetic energy, a demonstration that proves the soap's magnetic properties.

It is known that when soap substances are put into water they form tiny sticky aggregates (particles called micelles). The researchers used an advanced method (small angle neutron scattering, SANS) in order to verify that the creation of these tiny particles of the iron-rich material is responsible for obtaining these magnetic properties. The lead researcher explains: "The particles of the soap, which are in the solution, are very tiny, so it is difficult to see them with the help of light, but this can be easily done with the help of the above-mentioned method used to study the structure and behavior of all types of materials with characteristic sizes ranging from one nanometer to one tenth of a micrometer."

The potential of magnetic soap applications is huge. Their ability to respond to external stimuli provides the possibility to change a number of properties, such as electrical conductivity, melting point, the size and shape of the aggregates and their degree of dissolution in water, with the help of a simple external magnetic switch. Normally, these factors, which form the basis for the efficient application of soaps in a variety of industrial systems, were previously subject to control only through the activation of an electric charge or a change in the system's acidity level, temperature or pressure - all factors that change the system irreversibly and which are expensive to implement.

The magnetic properties of the soap also facilitate its collection and removal from the system from the moment it is added to it, a feature that provides the possibility for additional applications in the fields of environmental cleaning and water and wastewater treatment. Scientific experiments that require precise control of liquid drops can also be easily carried out with the help of the addition of these soaps and the activation of a magnetic field.

One of the researchers explains: "Since most magnets are composed of metals, from a purely scientific point of view, these soaps from the family of ionic liquids are particularly unusual, making them a very interesting discovery. Any system that only reacts following exposure to an external stimulus that does not affect its internal assembly is a major breakthrough since it is possible to produce products that only work after receiving the stimulus."
The news about the study

Magnetic soap: a magnet pulls the soap out of various solutions, including oil and water.
[Courtesy: Institut Laue-Langevi]