Kousaburo Ohashi

Cloud point extraction of iron(III) and vanadium(V) using 8-quinolinol derivatives and Triton X-100 and determination of 10−7 mol dm−3 level iron(III) in riverine water reference by a graphite furnace atomic absorption spectroscopy

The cloud point extraction behavior of iron(III) and vanadium(V) using 8-quinolinol derivatives (HA) such as 8-quinolinol (HQ), 2-methyl-8-quinolinol (HMQ), 5-butyloxymethyl-8-quinolinol (HO(4)Q), 5-hexyloxymethyl-8-quinolinol (HO(6)Q), and 2-methyl-5-octyloxymethyl-8-quinolinol (HMO(8)Q) and Triton X-100 solution was investigated. Iron(III) was extracted with HA and 4% (v/v) Triton X-100 in the pH range of 1.70-5.44. Above pH 4.0, more than 95% of iron(III) was extracted with HQ, HMQ, and HMO(8)Q. Vanadium(V) was also extracted with HA and 4% (v/v) Triton X-100 in the pH range of 2.07-5.00, and the extractability increased in the following order of HMQ < HQ < HO(4)Q < HO(6)Q. The cloud point extraction was applied to the determination of iron(III) in the riverine water reference by a graphite furnace atomic absorption spectroscopy. When 1.25 x 10(-3)M HMQ and 1% (v/v) Triton X-100 were used, the found values showed a good agreement with the certified ones within the 2% of the R.S.D. Moreover, the effect of an alkyl group on the solubility of 5-alkyloxymethyl-8-quinolinol and 2-methyl-5-alkyloxymethyl-8-quinolinol in 4% (v/v) Triton X-100 at 25 degrees C was also investigated.

Cloud point extraction equilibrium of lanthanum(III), europium(III) and lutetium(III) using di(2-ethylhexyl)phosphoric acid and Triton X-100.

The cloud point extraction behaviors of lanthanoids(III) (Ln(III)=La(III), Eu(III) and Lu(III)) with and without di(2-ethylhexyl)phosphoric acid (HDEHP) using Triton X-100 were investigated. It was suggested that the extraction of Ln(III) into the surfactant-rich phase without added chelating agent was caused by the impurities contained in Triton X-100. The extraction percentage more than 91% for all Ln(III) metals was obtained using 3.0x10(-5)moldm(-3) HDEHP and 2.0% (v/v) Triton X-100. From the equilibrium analysis, it was clarified that Ln(III) was extracted as Ln(DEHP)(3) into the surfactant-rich phase. The extraction constant of Ln(III) with HDEHP and 2.0% (v/v) Triton X-100 were also obtained.

Effect of alkyl substitueras in hydrophobic 8-quinolinol on the extraction of gallium(III) and applications to the separation of gallium(III) from aluminum(III).

The extraction of gallium(III) with newly prepared 5-alkyloxymethyl-8-quinolinol derivatives with alkyl substituent at the 2-position in 8-quinolinol moiety has been studied. The Ga(III)-5-octyloxymethyl-8-quinolinol (HO(8)Q), Ga(III)-2-methyl-5-octyloxymethyl-8-quinolinol (HMO(8)Q), Ga(III)-2-methyl-5-hexyloxymethyl-8-quinolinol (HM-O(6)Q), and Ga(HI)-2-n-butyl-5-hexyloxymethyl-8-quinolinol (HNBO(6)Q) complexes extracted in heptane from a perchloric acid medium were Ga(O(8)Q)(3), Ga(OH)(H(2)O)(MO(8)Q)(2), Ga(OH)(H(2)O)(MO(6)Q)(2) and Ga(OH)H(2)O)(NBO(6)Q)(2), respectively. The 2-tert-butyl-5-hexyloxymethyl-8-quinolinol did not exhibit any reactivity toward gallium(III). The extraction constants for Ga(O(8)Q)(3) (K(ex) = [Ga(O(8)Q)(3)](org) [H(+)](3)/[Ga(3+)][HO(8)Q](org)(3)), Ga(OH)(H(2)O)(MO(8)Q)(2) (K(ex) = [Ga(OH) (H(2)O)(MO(8)Q)(2)](org) [H(+)](3)/[Ga(3+)][HMO(8)Q](org)(2)), Ga(OH)(H(2)O)(2)(MO(6)Q)(2) and Ga(OH)(H(2)O)(NBO(6)Q)(2), which were extracted in heptane from an acidic solution, are 10(3.21 +/- 0.12), 10(-4.24 +/- 0.16), 10(-3.84 +/- 0.16) and 10(-4.07 +/- 0.07), respectively at I = 0.1 M and 25 degrees C. HNBO(6)Q exhibited very high selectivity toward gallium(III) in the presence of aluminum(III). Even in the presence of a 100 fold excess of aluminum(III) to gallium(III) (1.43 x 10(-5) M), gallium(III) was completely extracted and the distribution ratio of aluminum(III) was found to be less than 2.0 x 10(-3).

Effect of 1,10-phenanthroline on the extraction and separation of lithium(I), sodium(I) and potassium(I) with thenoyltrifluoroacetone

Abstract The extraction of Li + with thenoyltrifluoroacetone (Htta) in the presence of 1,10-phenanthroline (phen) has been studied in various organic solvents. The remarkable enhancement of the extraction of Li + , that is a synergistic effect, was observed by the addition of phen, and the high extractability of Li + was attained in toluene, benzene, chlorobenzene and o -dichlorobenzene. The extraction equilibrium of Li + , Na + and K + (denoted as M + ) in the presence or absence of phen in chlorobenzene and the adduct formation reaction in the organic phase were studied in detail. The adduct of Li + was Li(tta)(phen) in the wide concentration range of phen in the organic phase, while in Na + and K + M(tta)(phen) 2 also exists in the high concentration region. The maximum value of the separation factor between Li + and Na + was observed in the present system and was larger than that in the Htta–trioctylphosphine oxide (TOPO)–benzene system reported previously.

Simultaneous kinetic determination of phosphate and silicate based on heteropoly blue formation

Abstract Small amounts of phosphate (0.08–1.16 μg ml-1) and larger amounts of silicate (12–60 μg ml-1) can be determined simultaneously by a kinetic method based on the difference in the rates of the heteropoly blue formation with molybdenum (V)—molybdenum (VI) mixtures in 0.28 M perchloric acid. The interference of large amounts of iron(III) on the determination of phosphate can be eliminated by masking with sodium hydrogen sulfite; this method is applicable to reagent-grade iron(III) chloride.

Solvent effect on distribution ratio of Pd(II) in supercritical carbon dioxide extraction and solvent extraction using 2-methyl-8-quinolinol

The distribution ratio (D(M)) of Pd(II) by the extraction with 2-methyl-8-quinolinol (HMQ) was determined using the supercritical carbon dioxide medium (SF-CO(2)) and organic solvent media such as perfluoro-methylcyclohexane, heptane, cyclohexane, carbon tetrachloride and benzene. From experimental results of the slopes of logD(M) versus pH plot and logD(M) versus HMQ concentration plot, the extracted species both in the SF-CO(2) extraction (SFE) and the solvent extraction (SE) were determined to be Pd(MQ)(2). The distribution constant of HMQ (K(D,HMQ)) in the SFE and SE systems were determined from the dependence of the distribution ratio of HMQ (D(HMQ)) on the pH. A linear relationship was observed between logK(D,HMQ) and the solubility parameter (delta) of the extraction medium based on the regular solution theory in both the SFE using SF-CO(2) at the pressure of 8.5-40 MPa and the SE systems. The difference in the slope of the logK(D,HMQ) versus delta plot between the SFE and the SE systems is attributable to the extent of the specific interaction of the solute HMQ with the solvent molecules, i.e. CO(2) molecules and the organic solvent molecules. The D(M) versus delta plot obtained under a given extraction condition using SF-CO(2) (11-40 MPa) and organic solvents showed clear linearity. The D(M) obtained using SF-CO(2) at relatively low pressure range from 8.5 to 11 MPa was independent of the pressure and the delta of SF-CO(2), which coincides with the experimental fact that the solubility of Pd(MQ)(2) in the SF-CO(2) at 8.5-11 MPa was practically constant.

Supercritical carbon dioxide extraction equilibrium of gallium(III) with 2-methyl-8-quinolinol and 2-methyl-5-butyloxymethyl-8-quinolinol.

This work performed fundamental studies for the extraction of gallium(III) with 2-methyl-8-quinolinol (HMQ) and 2-methyl-5-butyloxymethyl-8-quinolinol (HMO(4)Q) into supercritical carbon dioxide (SF-CO(2)) from a weakly acidic solution. The distribution constants of HMO(4)Q between aqueous and SF-CO(2) phases were determined at 45 degrees C, 8.6-20.4 MPa and I=0.1 M (H, Na)NO(3) (M=mol dm(-3)). At 45 degrees C and 15.7 MPa, gallium(III) was hardly extracted with HMQ into SF-CO(2), but was quantitatively extracted with HMO(4)Q in the pH range of 2.20-2.84. The extraction constant, K(ex, SF-CO(2)) (=[Ga(OH)(MO(4)Q)(2)](SF-CO(2))[H(+)](3)[Ga(3+)](-1)[HMO(4)Q](SF-CO(2))(-2)), of gallium(III) with HMO(4)Q was determined to be 10(-2.6+/-0.1) at 45 degrees C, 15.7 MPa and I=0.1 M (H, Na)NO(3), which was 63 times larger than that in heptane at 45 degrees C and 0.10 MPa. It was also found that the addition of 3,5-dichlorophenol as a synergist enhanced the extractability of gallium(III) with HMO(4)Q into SF-CO(2).

Stability constants of inner- and outer-sphere complexes of hydrated tris(1-(2-thienyl)-4,4,4-trifluoro-1,3-butanedionato) lanthanide(III) with tris(2,4-pentanedionato) cobalt(III)

Abstract Binuclear complexation between hydrated tris(1-(2-thienyl)-4,4,4-trifluoro-1,3-butanedionato)lanthanide(III) (Ln(tta) 3 ) and tris(2,4-pentanedionato)cobalt(III) (Co(acac) 3 ) in benzene has been studied by a liquid–liquid distribution method and spectroscopic methods such as electronic absorption for d–d transition, IR for OH vibration of coordinated water molecules, and 59 Co NMR. The stability constants of a binuclear complex ( β s,1 ) across the lanthanide series were determined by both distribution and spectrophotometric methods. The β s,1 values for La to Nd were close to each other and much higher than those for Er to Lu, which were almost constant. As a result, there was the large difference in β s,1 between the light and the heavy Ln. The spectrochemical studies by IR and 59 Co NMR suggested that the binuclear complex has two different structures with inner- and outer-sphere coordination. In the former Co(acac) 3 displaces the coordinated water molecules in the Ln chelate and directly coordinates to the central Ln ion through the coordinating oxygen atoms of the acac ligands. In the latter hydrogen-bonding is formed between the coordinating oxygen atoms in Co(acac) 3 and hydrogen atoms of coordinated water molecules in the Ln chelate. Both binuclear complexes coexist in the solution of light Ln, while the outer sphere type mostly exist in heavy Ln.

Newly developed decontamination technology based on gaseous reactions converting to carbonyl and fluoric compounds

A new gas-phase decontamination technology is developed based on gaseous reactions utilizing the volatile properties of the carbonyl and fluoric compounds of radioactive transition elements and actinides (corrosion products, fission products, and transuranium) on a materials surface. The feasibility of this new technology is determined by removing nonradioactive (Co, Cr, Ni, Re, Mo, Mn, Ru, and Zn) and radioactive ( 60 Co, 63 Ni, and 103 Ru) nuclide transition elements as gaseous forms under high CO pressure (50 to 200 atm) and high temperature (∼350°C). Experiments involving U and using fluoric gases are also performed. For radioactive nuclides existing in an oxide layer of stainless steel, pretreatment with supercritical CO 2 + I 2 + H 2 O is used to remove the oxide layer completely, and by the subsequent gaseous reaction, 95 to 99% of 60 Co is removed from the layer by CO gas treatment at a pressure of 200 atm. The plasma treatment using fluorine gas results in U being removed with high efficiency (∼60%) after only 5 min, even at a reduced pressure of I Torr and at room temperature. When the carbonyl and fluoric species generated from a nontoxic gas mixture (1 Torr) of CF 4 and O 2 is used, U and 60 Co are removed simultaneously with high removal efficiencies of 80 and 100% for 60 Co and U, respectively. The data provide evidence that chemically reactive plasma treatment is available as a gas-phase decontamination method that can be conducted using nontoxic gases under safe and mild conditions such as reduced pressure, shorter time periods, and ambient temperature. Finally, a fluoric chemical reaction can be used to remove solid U deposits by converting them to gaseous U compounds at room temperature and without using plasma treatment. The pressure of ClF 3 gradually affects the higher removal efficiency of U, and the removal efficiency is >90% under the conditions of 30 min and >100 Torr. The results verify that chemical reactions involving carbonylation and fluorination reactions can be utilized for gas-phase decontamination, and the potential for this new idea for decontamination is affirmed. If gas-phase decontamination technology is further developed, it will be not only convenient but also economically advantageous because decontaminating and treating the large volume of nuclear wastes-especially nonincinerable radioactive wastes-are currently very difficult.

Equilibrium and ab initio computational studies on the adduct formation of 1,3-diketonato-lithium(I), -sodium(I) and -potassium(I) with 1,10-phenanthroline and its 2,9-dimethyl derivatives.

Highly effective and selective synergistic extraction of Li+ has been found using 2-naphthoyltrifluoroacetone (Hnta) as an acidic chelating agent and 2,9-dimethyl-1,10-phenanthroline (dmp) or 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (dmdpp) as a neutral ligand (denoted as L) in toluene. The synergism was ascribed to the adduct formation in the organic phase, and the composition and the formation constants of the adducts for alkali metal ions (M+) were determined by the extraction equilibrium analysis. The adducts found were M(nta)L for Li+ and Na+, while M(nta)L and M(nta)L2 for K+. To understand thermodynamics of the adduct formation with the bidentate amines, quantum chemical calculations of the 1:1 and 1:2 adduct formations with dmp and 1,10-phenanthroline (phen) were performed. The electronic and steric effects of the methyl groups at 2,9-positions of phen on the thermodynamic functions of adduct formation as well as the high lithium selectivity were quantitatively elucidated.