Scientists have developed a method to efficiently clean water, contaminated with toxic mercury – one of the major causes of environmental damage and health problems worldwide.
According to the World Health Organization (WHO), mercury is one of the most harmful substances for human health. It can influence the nervous system, the development of the brain, and more.
Mercury also spreads very easily through nature and can enter the food chain. Freshwater fish, for example, often contain high levels of mercury.
According to the study published in the journal ‘Nature Communications,’ researchers from Chalmers University of Technology, Sweden, have come up with a new way to filter mercury from contaminated water through an electrochemical process.
All about the new method
1. The method works by extracting the heavy metal ions from water by encouraging them to form an alloy with another metal.
“Our new method makes it possible to reduce the mercury content in a liquid by more than 99 per cent. This can bring the water well within the margins for safe human consumption,” said lead researcher Bjorn Wickman, from the Chalmers University of Technology.
2. It involves a metal plate — an electrode that binds specific heavy metals to it.
3. The electrode is made of the noble metal platinum, and through an electrochemical process, it draws the toxic mercury out of the water to form an alloy of the two. In this way, the water is cleaned of the mercury contamination.
4. The alloy formed by the two metals is very stable, so there is no risk of the mercury re-entering the water.
“An alloy of this type has been made before, but with a totally different purpose in mind. This is the first time the technique with electrochemical alloying has been used for decontamination purposes,” said Cristian Tunsu, a researcher at Chalmers.
What is different about this technique?
- The electrode has a very high capacity. Each platinum atom can bond with four mercury atoms
- Furthermore, the mercury atoms do not only bond on the surface but also penetrate deeper into the material, creating thick layers
- This means the electrode can be used for a long time. After use, it can be emptied in a controlled way
- Thereby, the electrode can be recycled, and the mercury can be disposed of in a safe way
- This process is also very energy efficient
“Our technique is very selective. Even though there may be many different types of substance in the water, it just removes the mercury. Therefore, the electrode doesn’t waste capacity by unnecessarily taking away other substances from the water,” said Wickman.
The new innovation has already been bestowed with a number of prizes and awards, both in Sweden and internationally.
“We have already had positive interactions with a number of interested parties, who are keen to test the method. Right now, we are working on a prototype which can be tested outside the lab under real-world conditions,” Wickman added.
Uses of the new method
1. The technique could be used to reduce the amount of waste and increase the purity of waste and process water in the chemical and mining industries, and in metal production.
2. It can contribute to better environmental cleaning of places with contaminated land and water sources.
3. It can even be used to clean drinking water in badly affected environments because, thanks to its low energy use, it can be powered totally by solar cells. Therefore, it can be developed into a mobile and reusable water cleaning technology.
Occurrence of mercury
Mercury occurs naturally in the earth’s crust. It is released into the environment from volcanic activity, weathering of rocks and as a result of human activity.
Human activity is the main cause of mercury releases, particularly coal-fired power stations, residential coal burning for heating and cooking, industrial processes, waste incinerators and as a result of mining for mercury, gold, and other metals.
Health effects of mercury exposure
1. Elemental and methylmercury are toxic to the central and peripheral nervous systems.
2. The inhalation of mercury vapour can produce harmful effects on the nervous, digestive and immune systems, lungs and kidneys, and may be fatal.
3. The inorganic salts of mercury are corrosive to the skin, eyes and gastrointestinal tract, and may induce kidney toxicity if ingested.
4. Mercury is particularly harmful to children and can also be transmitted from a mother to a child during pregnancy.