Regions with naturally occurring resources containing rare metals are unevenly distributed throughout the world. The Kuroshio, or Black Current, transports various rare metals dissolved in seawater. For example, the amounts of vanadium and molybdenum annually transported by the Kuroshio are 300- and 400-fold, respectively, compaved to the amounts annually consumed in Japan. The reactors of the Fukushima Daiichi Nuclear Power Plant, which were damaged by the Great East Japan Earthquake, caused a meltdown of nuclear fuel and a subsequent hydrogen explosion. By injecting seawater into the reactors for cooling, hundreds of thousands of tons of seawater containing radioactive species was produced. It was stored in the nuclear power plant, but some of it was released to the ocean. Radioisotopes, such as cesium-137, iodine-131, and strontium-90, dissolved in seawater pose a great risk to sea life and thus should be removed and safely confined. We have developed a new preparation technology for fibrous adsorbents capable of selectively collecting ionic species of rare metals in seawater. The fibrous adsorbents containing functional moieties exhibited a high adsorption rate, high adsorption capacity, and are easy use with seawater. Here, the adsorption performance of the novel adsorptive fiber in braid form for the recovery of rare metals and the removal of radioisotopes has been described.
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