Takehiro Kojima

Separation of uranium(vi) by liquid-solid extraction with tri-n-octylphosphine oxide diluted with naphthalene

Abstract Liquid-liquid distribution with tri-n-octylphosphine oxide (TOPO)and molten naphthalene has been investigated for the extraction of 20 metals from nitric acid and hydrochloric acid solutions. Uranium is quantitatively extracted from 1 M nitric acid or hydrochloric acid by using 100 mg of TOPO and 200 mg of naphthalene and shaking for 5 min at 80°C, and separated from transition metals, alkaline earth metals and rare earth metals (except scandium). Addition of naphthalene increases the extraction efficiency.

Adsorption behaviour and separation of copper(II) ions on cellulose triacetate polymer containing α-hydroxy oxime compounds

Abstract A series of α-hydroxy oxime compounds was synthesized and characterized. A new type of adsorbent, cellulose triacetate (TAC) powder (20–60 mesh) containing five kinds of α-oxime compounds such as α-benzoin oxime and 2-hydroxyphenyl ethyl ketone oxime (HPEKO), was prepared by dissolving cellulose triacetate with α-oxime in dichloromethane and pouring the mixture into hot water. The adsorption behaviour with α-oxime—TAC powders was examined for seven metal ions from solution of pH 2–10. Copper(II) was quantitatively retained on the HPEKO—TAC in the pH range 4–10 in batch experiments, whereas negligible adsorption was obtained for cobalt(II), iron(III) and iron(II); palladium(II) was also quantitatively adsorbed. The retention capacity of copper(II) and nickel(II) on the loaded adsorbent was about 1.4 and 1.1 mg g −1 at pH 5.9 and 8.1, respectively. Copper(II) retained on the column was completely eluted with 50 cm 3 of 0.25 mol dm −3 hydrochloric acid, and separated from nickel(II) and iron(III).

Extraction of complexes of iron(III) and other metals with bis(2-ethylhexyl)phosphoric acid into molten biphenyl/naphthalene

Abstract The extraction behaviour of twelve metals as function of the concentration of nitric or hydrochloric acid is described; bis(2-ethylhexyl)phosphoric acid (BEHPA) and 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester are used as the extractants with 3:1 (w/w) biphenyl/ naphthalene (m.p. 52°C) as the molten solvent which is easily separated by cooling to room temperature. Scandium (III) and zirconium (IV) can be separated from uranium (VI), rare earth metals and some transition metals with BEHPA. The extraction behaviour of iron with both extractants is described in detail.

Spectrophotometric determination of uranium(VI) by solvent extraction with trioctylphosphine oxide and a molten mixture of biphenyl and naphthalene

Uranium in ores has been determined spectrophotometrically after extraction with trioctylphosphine oxide (TOPO) into a molten mixture of biphenyl and naphthalene. By addition of salting-out agents such as sodium nitrate to the aqueous phase and cooling, the organic phase can be obtained as a solid lump on the surface of the aqueous phase, making its collection simple. The uranium can then be determined directly in the organic phase with 1-(2-pyridylazo)-2-naphthol or 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol.