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A new efficient way to extract Cesium-137 (¹³⁷Cs) from seawater was developed by researchers of Far Eastern Federal University (FEFU) and the Institute of Chemistry of the Far Eastern Branch of the Russian Academy of Sciences (FEB RAS). The researchers suggested to use sorbents based on the nickel-potassium ferrocyanide and natural chitosan made from the shells of crustaceans. The invention was tested during the ACE Maritime University international marine expedition in the Atlantic Ocean and was honored with a diploma at the conference of the National Research Center "Kurchatov Institute" (Moscow).

According to Eduard Tokar, the expedition participant, postgraduate student at the Department of Nuclear Technologies, School of Natural Sciences, Far Eastern Federal University, Cesium-137 is one of the most dangerous radioactive elements. As a result of accidents at nuclear power plants (NPPs), it can enter the ocean, and then into the human body, having a disastrous effect.

"At present, there are several techniques for extracting Cesium from seawater, but each one has its own shortcomings. We proposed a new method and at the moment it is optimal and allows Cesium to be concentrated with an efficiency of up to 99%. The sorbent consists of natural chitosan made from the shells of crustaceans—crabs, shrimps and others—and nickel-potassium ferrocyanide substance, reacting with which Cesium forms a precipitate," explained Eduard Tokar.

The development was tested during the oceanic expedition organized by the Swiss Polar Institute (SPI). During the voyage from Bremenhafen (Germany) to Cape Town (South Africa), the FEFU postgraduate student studied the radioactivity of the waters of the North Sea, the English Channel, the Bay of Biscay, and the coast of Africa. Places with an inflated radioactivity of Cesium were identified with the help of the new sorbent near the shores of Great Britain, at Cape la Hague (France), north of Cape Town and elsewhere. FEFU researchers intend to conduct similar studies during the Pacific expedition scheduled for 2018.

"Most of the existing and under construction nuclear power plants in the Asia-Pacific region are located in the coastal zone and use seawater for direct cooling. This poses a risk of the release of radioactive substances into the World Ocean in the event of an accident. Therefore, the extraction of Cesium-137 from water is an important technological task for the region's environmental monitoring," added Eduard Tokar.

The research is supported by the FEFU Competitiveness Enhancement Program and the Russian Foundation for Basic Research. The authors of the development are the employees of the FEFU School of Natural Sciences and the FEB RAS Institute of Chemistry: Eduard Tokar, Andrey Yegorin, Larisa Zemskova, Valentin Avramenko, and Ivan Tananaev. A patent is being processed for the new technology.