New Superhydrophobic Material can Purify Water Effectively from Oil Products

A novel material with the ability to effectively purify water from oil products has been developed by researchers at Tomsk Polytechnic University in collaboration with the University of Lille (France). This material is based on a usual household polyurethane sponge.

The material samples. Image Credit: Tomsk Polytechnic University.

The researchers made it superhydrophobic, that is, it repels water, while absorbing oil product molecules effectively. The study outcomes were reported in the Separation and Purification Technology journal.

New oil production methods, especially the ones related to production on the seabed and ocean floor, raise up the risk of spills. We all know about the environmental impact of the accident that happened on a drilling platform in the Gulf of Mexico in 2010. Therefore, one of the most urgent scientific problems is to obtain selective sorbents capable to extract oil products from a water-oil mixture, avoiding interactions with water.

Pavel Postnikov, Associate Professor, TPU Research School of Chemistry and Applied Biomedical Sciences, Tomsk Polytechnic University

Postnikov added, “The latter point is crucially important since interactions with water basically result in some resultant products to end up in the water and affect the ecosystem. Furthermore, water saturation drops the sorbent effectiveness. Therefore, we had to find affordable material and make it hydrophobic and efficient for the mentioned goal. We decided in favor of a regular washing sponge.”

The sponge was made hydrophobic by using special organic compounds called diazonium salts. The sponge was immersed in an aqueous solution with diazonium salts and heated to a temperature of 60 °C.

The resulting active radicals acted on the sponge and formed new organic groups with hydrophobic properties on the surface. These organic groups are sensitive to oil products at the same time. They serve as sorbents that selectively absorb oil molecules.

The second issue is to find an efficient way to remove this material from water. We chose a magnetic sorbent collection. We added iron nanoparticles in the structure of the sponge, obtained by our original method and characterized by increased susceptibility to nonpolar molecules. We also added hydrophobic organic groups. As a result, we obtained material that almost does not interact with water despite the fact that it is a sponge.

Pavel Postnikov, Associate Professor, TPU Research School of Chemistry and Applied Biomedical Sciences, Tomsk Polytechnic University

In water, petroleum products exist in an emulsion form. This indicates that their microscopic droplets are distributed in a different liquid, which, in this case, is water. The researchers say in reality, such emulsions are highly stabilized in general, making it hard to isolate them into separate components.

We tested our material with both highly stabilized and low stabilized emulsions. The experiments demonstrated that the material is excellent. We also tested its effectiveness on industrial oils that can pollute natural water bodies. The material also showed its high efficiency.

Pavel Postnikov, Associate Professor, TPU Research School of Chemistry and Applied Biomedical Sciences, Tomsk Polytechnic University

Moreover, the studies revealed that it is possible to reuse the novel material repeatedly for several times.

Pavel stated, “In experiments, we used it at least five times and there was no drop in its efficiency.”

The study was funded by the Russian Science Foundation (No. 17-73-20066).

Source: https://tpu.ru/en

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