Researchers have proposed a new technique that can capture indestructible chemicals, known as "eternal chemicals," from water and break down the chemical bonds that make these substances so resistant. The new method relies on a membrane that uses hydrogen and the metal palladium to perform the task.
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According to the study, the disappearance of the pollutant from the water does not necessarily mean its destruction, while the removal of fluorine from the molecule's structure provides evidence that the bonds that give these substances their ability to survive have already begun to break down.
Bruce Rotman, professor of environmental engineering at the Sweet Center for Environmental Biotechnology at Arizona State University in the United States and lead author of the study, explains that the difficulty in getting rid of the eternal materials is mainly due to the extremely strong bond between carbon and fluorine atoms.
This same strength is what made those materials useful in water- and grease-resistant products, such as some non-stick cookware, food packaging materials and fire-fighting foams, but it also made them one of the hardest pollutants to destroy once they reach water and the environment.
According to the researcher, this process occurs in two successive stages. First, the membrane captures the pollutant and places it in the appropriate location. Then, the active hydrogen begins to remove fluorine atoms one by one and replace them with hydrogen. Comparative experiments confirmed that hydrogen alone could not break down the substances, while palladium alone was able to attract some of the substance from the water without breaking it down. This means that the success of the process depends on the combined action of palladium and hydrogen.
Success in the lab, but hesitation in the application.
Not all the indestructible chemicals were equally easy to remove. Researchers found that compounds with longer molecular chains were more likely to adhere to the film and degrade, while some materials resisted the process more due to their different chemical structures. However, the system was still able to remove these materials and some of the fluorine they contained.
Bruce points out that these results don't mean the solution is ready for drinking water treatment plants, as the concept is still working in the lab. It's not yet certain that it can treat drinking water on a city-wide scale at the same cost that existing water treatment plants can afford. The researcher explains, "The experiments were conducted in a small device under controlled conditions, and the concentrations of the substances used in the continuous operation test were higher than those typically found in many drinking water sources, which helped to accurately measure the chemical changes."
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