Rare earth element removing adsorbent and adsorptive separating method using the same

In order to capture rare earth elements containing TRU in a nitric acid solution efficiently, an adsorbent comprising a porous carrier impregnated with a mixture of carbamylmethylene phosphate (CMP) and carbamylmethylene phosphoric acid (CMPO) is used. As a porous carrier, a porous polymer carrier which is less cross-linked and has an appropriate pore diameter and a pore capacity is preferred so as to impregnate a large amount of the extracting agent uniformly. The adsorbent of the present invention has fast adsorption rate for rare earth elements, thereby enabling to separate TRU in radioactive liquid wastes by adsorption efficiently. (T.M.)