Toxic heavy metals in water are a serious problem all over the world. The World Health Organization (WHO) lists 10 chemicals of major Public Health concern, and four of them are metal or metalloid: mercury, lead, cadmium, and arsenic.
Researcher Chalmers University of Technology in Sweden. have developed a new technique to efficiently and easily clean water contaminated with toxic mercury one of the major causes of environmental damage and health problems worldwide.
What is Mercury ??
Mercury is a naturally occurring element found in rocks, soil, water, air and living things. It is also found in some products. Exposure to mercury can cause health effects. Mercury spreads very easily through nature, and can enter the food chain. Freshwater fish, for example, often contain high levels of mercury.
It is particularly harmful for Young children (under 15 years old) and fetuses are more sensitive to mercury. Too much mercury can cause long lasting problems with understanding and learning. For that reason, pregnant women and women of child-bearing age should avoid mercury exposure.
The newly invented techniques/ method “ 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 Bjorn Wickman, from Chalmers University of Technology in Sweden.
This technique is fully described in the journal Nature Communications, works via extracting the heavy metal ions from water by encouraging them to form an alloy with another metal.
Elemental mercury is typically released from industrial processes, agricultural processes, household, commercial and medical products containing mercury, sewage discharge and sediment.
In water, micro-organisms transform mercury into a highly toxic organic molecule - methyl mercury - which is readily absorbed into the bodies of algae and plankton.
“Today, cleaning away the low, yet harmful, levels of mercury from large amounts of water is a major challenge for us. Industries need better methods to reduce the risk of mercury being released in nature,” said Wickman.
The new method involves a metal plate an electrode that binds specific heavy metals to it. 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 up mercury contamination. 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, researcher at Chalmers. One strength of the new cleaning technique is that the electrode has a very high capacity.
Each platinum atom can bond with four mercury atoms. Further more, 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 disposed of in a safe way.
A further positive for this process is that it is very energy efficient. “Another great thing with our technique is that it 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 mercury-removal process helps to fulfill mission of finding more efficient, less expensive ways to clean the environment, mercury. This process will save time and money while removing mercury more efficiently than any other process.