Takaharu Itagaki

Effect of Shape and Size of Amidoxime-Group-Containing Adsorbent on the Recovery of Uranium from Seawater

Abstract An amidoxime-group-containing adsorbent for the recovery of uranium from seawater was synthesized by radiation-induced graft polymerization of acrylonitrile onto polypropylene fiber of round and cross-shaped sections. The tensile strength and elongation of the synthesized adsorbent, both of which were one-half those of the raw material, were not affected by the shape of the fiber. The deterioration of the adsorption ability induced by immersing the adsorbent in HC1 was negligible because of the short immersion time required for the desorption with HC1. The concentration factors for uranium and transition metals in 28 days were in the order of 105, while those for alkali metals and alkaline earth metals were in the order 10−1-101. The recovery of uranium with the cross-shaped adsorbent was superior to that of the round-shaped one. XMA line profiles show that the distribution of uranium is much restricted to the surface layer when compared with that of alkaline earth metals. Diminishing the diamete...

Binding Properties of a Polymer Having Amidoxime Groups with Proton and Metal Ions

Abstract The proton-binding behavior of a polymer having amidoxime groups was examined by the potentiometric titration method. Adsorptive properties of the polymer for UO2(VI), Mg(II), Fe(II), Ni(III), Co(II), Ni(II), Cu(II), and Zn(II) were also examined at very low concentrations in the 1–9 pH range. The amidoxime polymer possesses adsorptive affinities of the following order: (Mg(II), Ca(II)) < Zn(II) < Co(II) < Ni(II) < Cu(II) < UO2(VI). These adsorptive affinities are reasonably explained by the proton-binding and the metal ion-complexing abilities of the ligand, and are discussed from the standpoint of uranium recovery from seawater.

Selective Elution of Uranium from Amidoxime Polymer. II

Abstract The separative elution of uranium from an amidoxime polymer was examined by the column method with hydrochloric acid solutions. The amidoxime polymer was immersed in seawater for 40 d for preparation of an uranium-loaded polymer sample for the elution experiments; the metal ions adsorbed were Mg(II), Ca(II), Fe(III), Ni(II), Cu(II), and Zn(II) as well as UO2(VI). It was found from the pH dependence of elution extent by a batch method that the order of elution pH values is Fe(III) < UO2(VI) < Cu(II) < Ni(II) < Zn(II) < Ca(II) < Mg(II). In the elution by a column method, Mg(II), Ca(II), Zn(II), and Ni(II) were eluted completely by 0.1 M HC1 and the eluate of enriched uranium was obtained by a succeeding elution with 0.5 or 1 M HC1. This eluate contained Cu(II). and Fe(III), which could be removed in the succeeding step. The elution treatment with hydrochloric acid solutions hardly affected the adsorptivity for uranium in seawater. It was suggested that the elution of uranium with hydrochloric acid ...

Adsorption equilibrium of uranium from aqueous [UO2(CO3)3]4– solutions on a polymer bearing amidoxime groups

The adsorption equilibrium of uranium from aqueous solutions containing tricarbonatouranate(VI) ions on a polymer bearing amidoxime groups was examined at pH 8–9. It is suggested that the adsorption proceeds by ligand exchange of three carbonate ions on the central uranyl(VI) ion with two amidoxime groups, accompanied by deprotonations. The uranyl(VI) complex formed with the polymer was found to be more stable than that with acetamidoxime as a ligand, suggesting that the amidoxime polymer has potential for the recovery of uranium from sea-water.

Kinetics of Adsorption of Uranium on Amidoxime Polymers from Seawater

Abstract Distributions of uranium adsorbed on amidoxime polymers crosslinked with tetraethyleneglycol dimethacrylate (4EGDM) and/or divinylbenzene (DVB) from seawater were examined by x-ray microanalysis in order to elucidate the diffusion behavior of uranium into the polymer matrix. The uniform distribution of the ligands on the polymers was confirmed by the distribution of Cu(II) adsorbed from copper(II) dichloride solutions. It was found that the distribution of uranium adsorbed is changed significantly by the composition of 4EGDM and DVB. Thus, the polymer crosslinked with 4EGDM exhibits a uniform distribution of uranium; however, as the ratio of DVB to 4EGDM increases, a more predominant distribution of uranium near the periphery of the polymer particle appears and the intensity decreases. This suggests that the adsorption rate of uranium is governed by the diffusion of uranium into the polymer matrix, explaining well the dependence of the adsorption rate on the hydrophilicity of the polymer. On the ...

Binding ability of acetamide oxime with proton, copper(II), and dioxouranium(VI) in aqueous solutions

The equilibrium constant of acetamidoxime (acetamide oxime) with proton in aqueous solutions was determined using the potentiometric method. The compositions and stability constants of the complexes of this ligand with CuII and UVIO2 in aqueous solutions were also determined. Acetamidoxime forms 1 : 1 and 1 : 2 complexes with CuII and UVIO2. Furthermore, the UVIO2 complexes were found to be more stable than those of CuII; these characteristic properties of the ligand are discussed in relation to the recovery of uranium from sea water.

Sepabeads® FP series: new highly porous hydrophilic supports for protein separation

Abstract The use of the new chromatographic packing material, Sepabeads® FP series , has been examined in industrial-scale separations. They showed sufficient stability and have a highly porous hydrophilic nature which makes them suitable for the purification of biopolymers such as proteins. It was found that the protein adsorption capacity strongly depends on the porosity, i.e., mean pore radius, of the packing as well as on the type of attached functional groups. Using Sepabeads FP series, industrial-scale separations of biopolymers in various chromatographic modes have become practical. Basic properties of Sepabeads FP series and some applications to the separation of proteins are briefly described.