• Resources Recycling
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• v.7 no.3
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• pp.3-10
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• 1998

Simulated waste liquid containing 50 ppm cobalt ion was treated by adsorbing colloidal flotation using Fe(III) or Al(IlI) as flocclant and a sodium lamyl sulfate as a collector. Parameters such as pH, surfactant concentration, Fe(III) or Al(III) concentration, gas flow rate, etc., W앙e considered. The flotation with Fe(III) showed 99.8% removal efficiency of cohalt on the conditions of initial cobalt ion concentration 50 ppm, pH 9.5, gas flow rate 70 ml/min, and flotation time 30 min. When the waste solution, was treated with 35% $H_2O_2$ prior to adsorbing colloidal flotation, the optimal pH for removing cobalt shifted m to weak alkaline range and flotation could be applied in wider range of pH as compared to non-use of $H_2O_2$. Additional use of 20 ppm Al(III) after precipitation of 50 ppm Co(II) with 50 ppm Fe(III) made the optimal pH range for preferable flotation w wider. Foreign ions such as, $NO_3^-$, $SO_4^{2-}$, $Na^+$, $Ca^{2+}$ were adopted and their effects were observed. Of which sulfate ion was f found to be detrimental to removal of cob퍼t ion by flotation. Coprecipitation of Co ion with Fe(III) and Al(III) resulted in b better removal efficiency of cobalt IOn 피 the presence of sulfate ion.

• Journal of Integrative Natural Science
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• v.7 no.3
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• pp.188-192
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• 2014

Determination of cobalt(III) ion with a perfluorinated sulfonated polymer-ethylenediamine (nafion-en) modified glassy carbon electrode is studied. It is based on the chemical reactivity of an immobilized layer, nafion-en, to yield complex $[Co(en)_3]^{3+}$. The reduction peak potential by differential pulse voltammetry (DPV) is observed at $-0.437{\pm}0.047$ V (vs. Ag/AgCl). The linear calibration curve is obtained in cobalt(III) ion concentration range $1.0{\times}10^{-8}{\sim}1.0{\times}10^{-3}M$ ($5.893{\times}10^{-12}{\sim}5.893{\times}10^{-5}g/mL$).

• Journal of the Korean Chemical Society
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• v.19 no.2
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• pp.98-103
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• 1975

The synthesis of two new ligands, 1,10-dibenzyltriethylenetetraamine (1,10-$Be_2trien$) and 1,10-dibenzyl-5R-methyltriethylenetetraamine (1,10-$Be_2$-5R-Metrien), and the preparation of the dichloro cobalt(III) complexes of these ligands are reported. Both tetraamine ligands yield exclusively trans geometry upon coordination to the cobalt(III) ion.

• Bulletin of the Korean Chemical Society
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• v.18 no.8
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• pp.827-831
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• 1997

A novel ONNO-type tetradentate ligand, 1,3-diaminopropane-N,N'-di-α-(β-methyl)-pentanoic acid (H2apmp) and its cobalt(Ⅲ) complexes, [Co(apmp)X2]n+, (X=Cl-, NO2-, H2O, X2=CO32-, en, L-phenylalanine) have been synthesized. During the preparation of the dichloro cobalt(Ⅲ) complex of apmp, [Co(apmp)Cl2]-, the ligand has coordinated to the cobalt(Ⅲ) ion in a geometric selectivity to give only the uns-cis isomer and, during the substitution reaction between L-phenylalanine and [Co(apmp)Cl2]-, the L-phenylalanine has coordinated to the cobalt(Ⅲ) ion in a geometric selectivity to give only an uns-cis-meridional isomer. It is of interest that this is a rare case of the [Co(ONNO ligand)X2]n+-type complex preparations, which gives only an uns-cis isomer with geometric selectivity.

• Bulletin of the Korean Chemical Society
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• v.11 no.3
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• pp.251-253
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• 1990

L-Alanine(L-ala) and S-methyl-L-cysteine(L-mcy) cobalt(III) complexes of a flexible $N_2O_2$-type tetradentate ligand ethylenediamine-N,N'-di- -butyric acid(eddb), s-cis-[Co(eddb)(L-ala)] and s-cis-[Co(eddb)(L-mcy), have been prepared via the substitution reactions of the s-cis-$[Co(eddb)Cl_2]$-complex with, respectively, L-alanine and S-methyl-L-cysteine. Both L-alanine and S-methyl-L-cysteine are found to coordinate to the cobalt(III) ion via the nitrogen and oxygen donor atoms to give the meridional s-cis isomer. Electronic absorption, ir and pmr spectra are used to characterize the complexes obtained in this work along with elemental analysis data.

• Journal of the Korean Chemical Society
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• v.22 no.1
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• pp.25-29
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• 1978

Cobalt(III) complex containing ethylenediamine-triacetate and trimethylenediamine has been isolated from the reaction of ethylenediamine-tetraacetatocobaltate(III) with trimethylene-diamine in aqueous solution by Dowex 50W-X8, cation exchange resin in $H^+$ form. The ethylenediamine-triacetate($EDTRA^{3-}$) ligand coordinates to the cobalt(III) ion as a quadridentate with a free acetate branch. It has been observed that the complex has trans(O-O) (1) structure via the elemental analysis, UV, IR and NMR data.

• Journal of the Korean Chemical Society
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• v.10 no.1
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• pp.4-10
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• 1966

A new method of cobalt determination has been developed by employing ethylenediamine tetrabutyl acetate(EDTA-butyl ester) synthesized from EDTA and Butyl alcohol. The synthesized EDTA ester dissolved in butyl alcohol extracts various metal ions from aqueous solutions. Cobaltous ion extracted into organic phase containing EDTA ester to form Co (II)-EDTA butyl ester complex is back extracted into alkaline aqueous phase forming a stable pink colored complex of Co (III). The optimum condition for spectrophotometric determination of cobalt via the new complex has been established. The absorption peak occurs at 540$m{\mu}$ and Beer's law was obeyed over the concentration range of 0∼50 ${\mu}g/ml$ of cobalt.

• Journal of the Korean Chemical Society
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• v.33 no.2
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• pp.215-224
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• 1989

Electrochemical reductions of $trans-[Co(en)_2X_2](ClO_4)_n$ (where X is cyanide, nitrite, ammonia, and isothiocyanate) were investigated by cyclic voltammetry and polarography at mercury and glassy carbon electrode. $trans-[Co(en)_2(CN)_2]ClO_4$ was reduced to Co(II) complex followed by adsorption to the mercury electrode. Cyanide ion was not released from the reduced Co(II) complex but the cyanide and (en) were released after the reduction to metallic cobalt. The other complexes except $trans-[Co(en)_2(CN)_2]ClO_4$ were reduced to cobalt(II) complexes followed by release of monodendate ligand, and (en) was released at the reduction step to metallic cobalt. $trans-[Co(en)_2(NO_2)_2]ClO_4$ was reduced to cobalt(Ⅱ) complex, and $NO_2^-$ ion was released followed by electroreduction through ECE mechanism at pH 2. On glassy carbon electrode, all complexes of Co(III) were reduced to Co(II) complexes with irreversible one-electron diffusion controlled reaction in which (en) was not released at this step. Increasing absorption wave number of complexes caused to negative shift of peak potential.

• Journal of the Korean Chemical Society
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• v.30 no.4
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• pp.377-382
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• 1986

Racemic tris-oxalatocobaltate (III) complex ions were optically resolved by an optical active complex, ${\Delta}$-tris-ethylenediamine cobalt (III), and then racemization of ${\bigwedge}-[Co(ox)_3]^{3-}$ obtained was investigated in various mixed solvent such as water-organic solvent (organic solvents=ethanol, iso-propyl alcohol, acetone, and dioxane). The rate of racemization was increased with following order; water < ethanol < acetone < isopropyl alcohol < dioxane; which is the same order for polarizability of organic solvent added. Considering ${\Delta}H^{\neq},\;{\Delta}S^{\neq}$ and above facts for the racemization of ${\bigwedge}-[Co(ox)_3]^{3-}$, it seems to be twist mechanism of plausible mechanisms.

• Journal of the Korean Chemical Society
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• v.26 no.5
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• pp.310-319
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• 1982

Cobalt(III) complexes with sexidentate ligands, N,N,N',N'-tetrakis(2-amino-ethyl)-1,2-ethanediamine (ten), -1,3-propanediamine (ttn), -1,4-butanediamine (ttmd), -(R,R)-and -(R,S)-2,4-pentanediamine (tptn) were prepared, and the characterization of d-d absorption band on the variation of chelate ring size and conformation of these complexes were studied by means of electronic spectra. The first d-d absorption bands of $[Co(L)]^{3+}$ complexes are shifted to smaller wave numbers in the order. ttn > (R,R)-tptn > ten > ttmd${\simeq}$(R,S)-tptn for (L). The UV, $^{13}C$ NMR, and Circular Dichroism studies indicate that the R,S-tptn ligand of $[Co(R,S-tptn)]^{3+}$ complex coodinates to cobalt(Ⅲ) ion as a sexidentate with one methyl group in axial position.