| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2005: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2004: ¥2,600,000 (Direct Cost: ¥2,600,000)
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| Research Abstract |
Introduction : Room-temperature ionic liquids (ILS) have recently attracted increasing attention as environmentally benign alternative to conventional organic solvents in a variety of synthetic, catalytic, and electrochemical applications, owing to their unique physical and chemical properties such as no measurable vapor pressure, non-flammability, high thermal stability, excellent solvating properties for organic and inorganic materials. In this study, the distribution behavior of N-benzoyl-N-phenylhydroxylamine (BPHA or HL) between an IL,1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim][PF_6]) and an aqueous phase, and the extraction behavior of lanthanides (Ln^<3+>) into IL was investigated with BPHA as an extractant.
Results and Consideration : 1)Chemical species of BPHA existing in ionic liquid. The BPHA solution is colorless when BPHA is dissolved as a protonated species, HL, in non-polar solvents, such as chloroform, carbon tetrachloride and benzene, whereas the BPHA soluti
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on shows pale yellow to yellow when BPHA is dissolved as a deprotonated species, L-, in 0.1 mol dm^<-3> sodium hydroxide solution of 50% ethanol-aqueous mixture. BPHA dissolved in IL shows pale yellow to yellow under dissolution conditions, during shaking and ultrasonic agitation at a dissolution temperature. From these results, it was presumed that BPHA in IL is mainly present as the deprotonated type, L-, and is partly present as the protonated type, HL. The distribution coefficients of the deprotonated and the protonated types of BPHA will be K_<D,HL>》K_<D,L>. High concentration of deprotonated type of BPHA in aqueous phase is favorable for the chelate formation in an aqueous phase. Such a distribution behavior of BPHA may contribute to the extractability of metal ions. In fact, the deeper yellow color of BPHA in II can improve the better extractability of lanthanides(III).
2)Extraction procedure of lanthauides(III) with BPHA. Two cm^3 of aqueous solutions containing 1 x 10^<-4> mol dm-<-3> of lanthanide ions was prepared in a stoppered test tube ; their pHs were adjusted by adding acetate buffer solutions, and tartrate ion as masking agent was added. The solution was shaken with 2 cm^3 of IL containing BPHA by a bioshaker at the constant temperature of 25℃ and the shaking rate of 200 r/min for 1 hr. Then the mixture was centrifugation for 3 min at 1000 rpm to achieve phase separation. After the phase separation, the concentration of lanthanide ion in the aqueous phase was measured by ICP-AES. The extraction behavior of Pr^<3+>,Eu<3+> and Yb<3+> with BPHA using IL as an organic phase were studied, for the comparison with the data in chloroform as the extraction solvent. The extractabilities with IL were much superior to these with chloroform. Ionic liquids have the potential to replace traditional volatile organic solvent in liquid/liquid extraction of lanthanide ions. Less
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