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May 26, 1998 　Researchers at the Japan Atomic Energy Research Institute (JAERI) have developed a new material which efficiently adsorbs useful metals dissolved in seawater. They have succeeded in recovering high yields of such rare metals as vanadium and uranium. 　The functional material research group led by Mr. Takanobu Sugo, Head of Radiation Processing Development Laboratory, Dept. of Material Development of the JAERI Takasaki Radiation Chemistry Research Establishment, has been studying the application of radioactive rays to polyethylene fiber (nonwoven fabric) that is currently used for oil fences, etc., aiming to develop functional materials for the selective adsorption of metals. 　They conducted adsorption tests several times by mooring the material (12kg) in the sea and separating it with an acid solution. As a result, 20g of powdered vanadium oxide and 16g of uranium oxide were collected. 　Rare metals are dissolved in Seawater, such as vanadium dissolves rare metals such as vanadium, cobalt, and uranium, which Japan rarely produces. As the concentration of these materials is very low, several milligrams per one tonne of seawater, it has been quite difficult to develop technology for recovering those metals at an economical cost. The adsorbent developed by the Takasaki Research establishment is quite different from conventional ones. It possesses a high capability to selectively adsorb rare metals, and is able to concentrate the metals in seawater by 1 million to 10 million times as well as being capable of repeated use due to its high stability in seawater. This discovery introduces the possibility of obtaining such rare metals at an economical cost by processing seawater with this efficient adsorbent. The possibility of this new metal resource is very large when one considers the massive volume of rare metals, as much as several tens of millions of tonnes continually flowing into the neighboring waters of Japan transported by the Black Stream. If a very small portion of this volume (0.1%〜0.2%) can be captured by an adsorbent moored in the Black Stream, it will be sufficient to meet domestic demand. 　The JAERI is planning to conduct technical tests to study the possibility of developing a practical recovery system of the metals.

Development of the Adsorbent at the Takasaki Research Establishment

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Fig.1:	Synthesis process for amidoxime adsorbent
Fig.2(a):	Principle of metal caputure by amidoxime group
Fig.2(b):	Structure of amidoxime adsorbent and model for metal recovery
Fig.3:	Amount of vanadium and uranium recovered from seawater
Fig.4:	Adsorption offshore the Sekine coast, Mutsu Bay
Fig.5:	Vanadium and uranium recovered from seawater

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For further information, please contact:

Mr. Takanobu Sugo Head of Radiation Processing development Laboratory Section, Dept. of Material Development Takasaki Radiation Chemistry Research Establishment JAERI Tel: +81-27-346-9380 Fax: +81-27-346-9687