Keihei Ueno

A Novel Colorimetric Reagent for Potassium Based on Crown Ether Complex Formation

Abstract The extraction study of alkali metal ions was made with a new type of crown ether, 4′-picrylaminobenzo-15-crown-5 (HL). Upon dissociation in alkaline medium orange-colored HL gives blood-red anion, L−, and extracts selectively K+ (and to a lesser extent Rb+) ion into chloroform as a colored complex of composition ML·HL. A colorimetric determination of 10 - 400 ppm K+ in the presence of < 2000 ppm Na+ was possible using this new crown ether reagent.

Preparation and Adsorption Properties of λ-MnO2-Cellulose Hybrid-Type lon-Exchanger for Lithium Ion. Application to the Enrichment of Lithium Ion from Seawater

Abstract spherical beads of a hybrid-type ion-exchanger (HIE) have been prepared by dispersing microcrystalline λ-MnO2 in macroporous cellulose gel beads. The beads were 0.1 to 0.3 mm in diameter and contained 0.71 g λ-MnO2/g dry HIE. The ion-exchange behaviors of HIE for lithium and sodium ions were investigated by batch and column methods. The uptakes for lithium and sodium ions were 2.8 and 0.1 mmol/g dry HIE, respectively, at pH 12.3 by the batch method and 1.0 and 0.1 mmol/g dry HIE at pH 11.6-11.8, respectively, by the column method. When 1.52 L seawater was passed through a column containing 0.05g wet HIE at a flow rate of 0.3 mL/min, 2.0 mg lithium/g dry HIE was recovered, indicating that the enrichment ratio for lithium ion was 1.3 × 104 mL/g and the enrichment factors for lithium ion to sodium, potassium, calcium, and magnesium ions were 7.1 × 104, 1.7 × 103, 1.0 × 103, and 6.9 × 103, respectively.

Liquid-liquid extraction of group IB metal ions by thioethers

Abstract Liquid-liquid extraction of metal ions by means of organic extractants possessing divalent sulfur (thioethers) is discussed. it is shown that 1,2-bis(hexylthio)ethane (BHTE) and 13,14-benzo-1,4,8,11-tetrathiacyclopentadecane (TTX) are powerful extractants for soft metal ions such as copper(I), Silver(I), and gold(I). The same is true for the trivalent phosphorus compounds, triphenylphosphine and phosphite tristers, which were studied for comparison. Copper(II) and gold(III) are efficiently extracted with thioethers in combination with reducing agents. From an equilibrium study for the extraction of copper(I) and silver(I) by BHTE (L), a complex of the type ML2X (M+, metal ion; X−, anion) was proved to be extracted. In the extraction of gold, the combined use of a thioether and phosphite enhanced the extractability of the metal, compared with the independent use of these extractants; the synergism is discussed. Further, the reductive extractions of copper(II) and gold(III) were coupled with a photo-redox reaction, leading to light-induced extraction of these metal ions.

Selective Separation of Arsenic(III) and (V) Ions with Ferric Complex of Chelating Ion-Exchange Resin

Abstract Trace levels of aqueous arsenic(III) and (V) ions were adsorbed selectively onto the ferric complex of a chelating resin, Uniselec UR-10. The adsorption was markedly dependent upon the pH of the aqueous phase. The distribution ratio and the specific adsorption capacity of arsenic(III) were 23,000 and 0.47 mmole/g, respectively, at the optimum pH for the adsorption, 9.2. The corresponding values of arsenic(V) were 22,000 and 0.53 mmole/g at the optimum pH 5.5. In the column operation the adsorption of the arsenic ions was also dependent upon the flow velocity and the size of the resin particle. A velocity of 60 cm/hr and 100 to 200 mesh size afforded satisfactory results. Adsorbed arsenic was recovered quantitatively by eluting the resin with 2 N hydrochloric acid, where the complexed iron was also eluted. A trace level of arsenic in wastewater from a geothermal power plant was successfully separated in the presence of a large excess of diverse cations and anions. Trace arsenic in natural seawater...

Selective Adsorption of Arsenic Ions on Silica Gel Impregnated with Ferric Hydroxide

Abstract Selective adsorption of trace arsenite- and arsenate anions in an aqueous solution by ferric hydroxyde supported on silica gel particles was investigated. Silica gel particles were loaded with ferric hydroxide of the range of 1 – 3 wt. % in terms of Fe based on the dry gel, and the extent of adsorption of arsenite or arsenate ion measured by batch- and column processes, being the highest at pH 6 in the presence of diverse foreign ions. With the use of silica gel containing 3.3 wt. % Fe, as much as 0.07 m mol of arsenic per gram of dry gel was adsorbed.

Chromogenic crown ether reagents for spectrophotometric determinations of sodium and potassium

Abstract Crown ethers carrying a phenolic group, 2-hydroxyphenoxymethyl-15-crown-5 and -18-crown-6, were synthesized. Introduction of nitro groups in the 3- and 5-positions of the aromatic nucleus or introduction of a 4-nitrophenylazo group in the 5-position gives a series of chromogenic reagents suitable for the extraction spectrophotometry of sodium and potassium. Sodium in human blood serum was successfully determined by using the (2-hydroxy-3,5-dinitrophenyl)oxymethyl-15-crown-5 reagent. The molar absorptivity of the sodium complex is 14 000 l mol -1 cm -1 at 423 nm.

Bioaccumulation of Arsenic by Freshwater Algae and the Application to the Removal of Inorganic Arsenic from an Aqueous Phase. Part I. Screening of Freshwater Algae Having High Resistance to Inorganic Arsenic

Abstract Several freshwater alga having resistance to arsenic were screened from microorganisms which had been sampled at sites polluted with arsenic from a geothermal electric power plant and old mines and smelters of arsenic ores. The alga thus screened could grow in the liquid medium (Modified-Detmer culture medium) containing sodium arsenate at levels up to 2000 ppm as elemental arsenic concentration. Some mixed systems of alga grew rapidly in the media at the higher levels of arsenic ranging from 50 to 2000 ppm. The mixed systems of alga screened included predominantly blue-green algae, green algae, and diatom, and also included protozoa, rotifera, and bacteria as minor components. One pure algal culture was obtained by means of an agar plate culture, and the algae isolated was identified as Chlorella vulgaris Beijerinck var. vulgaris. The growth of C. vulgaris in a pure culture was unaffected by 100 ppm of arsenic.

Simple semiquantitative determination of trace metal ions by use of reagent gel columns—I: Determination of mercury with dithizone gel

Mercury(II) at the sub-ppm level was determined by using a column packed with gel beads containing dithizone stabilized as the zinc complex. The beads turned from pink to green when the acidified sample solution was passed through the column. If the solution contained mercury (II), the colour of the gel beads turned to orange owing to the formation of mercury dithizonate. The length of the coloured zone was proportional to the amount of mercury in the sample. With 0.01% dithizone gel, as little as 0.1 ppm of mercury(II) could be determined in a 20-ml sample at a flow-rate of 1 ml/min.

Analytical application of organic reagents in hydrophobic gel media—I: General principle and the use of dithizone gel☆

Two types of hydrophobic gel particles containing dithizone were prepared, either by the swelling of low cross-linkage polystyrene beads with a dithizone solution in chlorobenzene, or by the gelatinization of a dithizone solution with dibenzalsorbitol. The extraction capacity of the gel particles for metal ions such as mercury, cadmium, zinc and lead from dilute aqueous solution, was investigated at various dithizone concentration and pH values. A column packed with such gel particles is found to be useful for the selective preconcentration or the selective trapping of specific metal ions at low concentration levels.

Spectrophotometric determination of sodium by ion-pair extraction with crown ether complexes and monoanionic dyes☆

Abstract A highly selective photometric procedure for the determination of sodium in blood serum is proposed, based on the ion-pair extraction of a sodium—cryptand complex. A comparative study of cryptands with various cavity sizes, different pairing anions and extraction solvents is described. The use of cryptand 211, picrate and toluene, as ligand, pairing anion and extraction solvent, respectively, allows sodium to be determined at the μg ml−1 level. A 350-fold amount of potassium (by weight) does not interfere, nor do other alkali metals. Possible interferences by multivalent cations are masked by EDTA.