• Journal of the Korean Chemical Society
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• v.29 no.4
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• pp.397-405
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• 1985

The adsorption behaviors of some oxime compounds well known as metal chelating agents on the Amberlite XAD resins were compared by measuring their distribution coefficients (log Kd) in various media, respectively. Among the oxime compounds, salicylaldoxime (SAO) and $\alpha-benzoinoxime(${\alpha}$-BzO)$ which showed large log Kd values were chosen. The characteristics of XAD-4 resins impregnated with SAO and ${\alpha}$-BzO have been studied to apply them for the adsorption and recovery of minute quantities of metal ions in aqueous solution. The optimum conditions for adsorption of SAO and ${\alpha}$-BzO on the resin were 30% methanol media having pH range of 1~8(for SAO) and 1~9 (for ${\alpha}$-BzO), respectively. The distribution coefficients of two oxime compounds were decreased as temperature increased. From the adsorption enthalpy data of SAO and ${\alpha}$-BzO, ranging from 4.96 to 6.66 Kcal/mol, it is suggested that their adsorption mechanism on XAD-4 resin is likely due to molecular adsorption equivalent to dipole-dipole interaction. The impregnated resins were considerably stable in the aqueous solutions of pH 5.0~10.0 and in 0.1~5M hydrochloric acid solutions. The former is the medium for adsorption of metal ions, while the latter is for recovery of the adsorbed metal ions. The adsorption mole ratio of Mn(II), Co(II), Ni(II), Zn(II) ions on SAO-XAD-4 and ${\alpha}$-BzO-XAD-4 resins were about 1 : 2 at the optimum conditions, respectively. The adsorbed metal ions were recovered completely by eluting with 3M HCl-50% methanol solution

• Journal of the Korean Chemical Society
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• v.17 no.6
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• pp.434-438
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• 1973

Distribution coefficients (C) of some transition metal ions such as Ni(II), Cu(II), Cd(II), Zn(II), and Hg(II) have been determined in methanol-, ethanol-, isopropanol-, acetone-, and dimethylsulfoxide-water mixtures by using Rexyn 101 (Na-form) resin and 0.2 M sodium chloride solution. The log C values of the metallic ions decrease almost straightly with the increase in reciprocal values of the dielectric constants of the mixed solvents. In the solvents having the same dielectric constants, the distribution coefficients of the metallic ions decrease with the increase in the basicity of the aprotic organic molecule and with the decrease in the molecular size of the protic organic molecule. The separation of the metallic ions has been accomplished with the eluting agent suggested by the C values.

• Journal of the Korean Chemical Society
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• v.23 no.6
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• pp.385-391
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• 1979

It was found that cupric ion selective electrode, which was prepared by mixing CuS and $Ag_2S$ with the ratio four to one and PVC, was hard and durable. The response potentials were reproducible and linear in the range from 1.0 ${\times}$ $10^{-1}M$ to 1.0 ${\times}$ $10^{-5}M$ copper (II) solution and its slope was 25.0 mV per decade concentration at $298^{\circ}K$, slightly different from Nernstian slope. The copper (II) indicating electrode was applied in precipitation titration of 1.0 ${\times}$ $10^{-2} M Cu(II)$ sample solution containing proper amounts $NaNO_3$ with 0.1 M NaOH standard solution. Also, this electrode could be used in complex titration of Zn(II), Mg(II), Ca(II) with EDTA and stability constant of EDTA complex of Ca(II) and Mg(II) was calculated by using known Cu-$EDTA^{2-}$ stability constant.

• Analytical Science and Technology
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• v.12 no.5
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• pp.397-402
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• 1999

The open-chain hexadentate $N_6$, ligand containing two pyridyl groups, 1,15-bis(2-pyridyl)-2,6,10,14-tetraazapentadecane (bpyped) has been synthesized as its tetrahydroehloride salt and characterized by EA, IR, NMR, and Mass. Its proton dissociation constants($logK{^n}_H$) and stability constants ($log\;K_{ML}$) for Co(II), Ni(II), Cu(II) and Zn(II) ions were determined at $25^{\circ}C$ and ionic strength 0.10 M($KNO_3$) in aqueous solution by potentiometry and compared with those or analogous $N_6$ ligands contain one or two propylenic spacers, which make six-membered chelate rings, between the aliphatic nitrogen atoms.

• Journal of the Korean Chemical Society
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• v.33 no.4
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• pp.357-365
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• 1989

The positional parameters of framework atoms, cations, and water molecules in hydrated and dehydrated $Mg_4Na_4-A$, $Ca_6-A$, $Zn_5Na_2-A$ and $Co_4Na_4-A$ were determined by the optimization technique using some potential energy functions and VAIOA optimization program. Upon dehydration, cations in hydrated states move toward the framework oxygens of 6 rings. Frameworks of fully dehydrated zeolite A are more stable than those of fully dehydrated divalent cation exchanged Zeolite A. There are three different kinds of water molecules in divalent cation exchanged Zeolite A; W(III) (water molecules having hydrogen bonds), W(II) (water molecules associated with $Na^+$ ions), and W(I) (water molecules associated with divalent cations). Three different DTA endothermic peaks were observed corresponding to the dehydration of three different kinds of water molecules in divalent cation exchanged Zeolite A.

• Journal of the Korean GEO-environmental Society
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• v.2 no.3
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• pp.17-35
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• 2001

In this study, we conducted a combined adsorption-sequential extraction analysis(CASA) to investigate temperature effects of single adsorption of lead, copper, zinc and cadmium on natural clays. As a result, it was found that in a single adsorption of lead and copper, about 50% of adsorption was occluded in carbonate phase, and in case of cadmium, about 80% of adsorption was occluded in exchangeable phase. At temperature below $25^{\circ}C$ about 60% of zinc was occluded in exchangeable phase but above $40^{\circ}C$ about 50% of zinc was occluded in carbonate phase. The effect of temperature on each occluded phase was largely observed in Fe-oxide, Mn-oxide and organic occluded phases. Besides, the adsorption of metals on natural clays was an endothermic reaction with the exception of exchangeable phase adsorption.

• Analytical Science and Technology
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• v.11 no.6
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• pp.440-447
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• 1998

Polydentate Schiff base ligands 5-Br-BSDT(bis(5-bromosalicylaldehyde)diethylenetriamine) having $N_3O_2$ atoms, 5-Br-BSTT(bis(5-bromosalicylaldehyde)triethylenetetramine) having $N_3O_2$ atoms, 5-Br-BSTP(bis(5-bromosalicylaldehyde)tetraethylenepentamine) having $N_3O_2$ atoms were synthesized. Stability constants of the complexes between these ligands and the metal ions such as Cu(II), Ni(II) and Zn(II) were measured in DMSO by a polarographic method. It was observed that all metal(II) ions employed in this study formed 1 : 1 complexes with Schiff base ligands. Stability constants for the ligands were in the order of Cu(II)>Ni(II)>Zn(II), and for complex formation were in the order of 5-Br-BSTP>5-Br-BSTT>5-Br-BSDT according to the increasing in the number of donor atoms. Both enthalpy and entropy changes are obtained in negative valves. Exothermicity for the complex formation indicated tight binding between the ligands and metal ions. The negative entropy change would be related to the fact that solvent molecules are strongly interacting with the metal complexes.

• Journal of the Korean Chemical Society
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• v.46 no.5
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• pp.407-411
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• 2002

A method to determine lead ion in aqueous media using an optical sensor loaded on a fluorescent optode membrane incoporating a metal ion-selective ionophore, a proton-selective chromoionophore and lipophilic anionic sites has been studied. The effects of pH and thickness of membrane on the fluorescence intensity were investigated. The effects of foreign ions such as $Na^+$, $K^+$, $Mn^{2+}$ and $Zn^{2+}$ on the determination of lead ion were also studied. The linear range in the calibration curve for the determination of lead ion was found to be 5.0${\times}10^-7$ to 5.0${\times}$$10^-3$M and the correlation coefficient in this range was -0.99107 under the optimal experimental conditions. The relative standard deviation of the blank signals was 3.0% and the detection limit of lead ion was 5.0${\times}$$10^-9$M.

• Journal of the Korean Chemical Society
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• v.37 no.8
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• pp.723-729
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• 1993

Cu(II) ion-responsive chemically modifed electrodes (CMEs) were constructed by incorporating 1-(2-pyridylazo)-2-naphthol (PAN) into a conventional carbon-paste mixture of graphite powder and Nujol oil. Cu(II) ion was chemically deposited on the surface of the PAN-chemically modified electrode in the absence of an applied potential by immersion of the electrode in a buffer solution (pH 3.2) containing Cu(II) ion, and then reduced at a constant potential in 0.1 M KNO$_3$. And a well-defined voltammetric peak could be obtained by scanning the potential to the positive direction. The electrode surface could be regenerated with exposure to acid solution and reused for the determination of Cu(II) ion. In 5 deposition / measurement / regeneration cycles, the response could be reproduced with 6.1${\%}$ relative standard deviation. In case of using the differential pulse voltammetry, the calibration curve for Cu(II) was linear over the range of 2.0 ${times}$ 10$^{-7}$ ∼ 1.0 ${times}$ 10$^{-6}$ M. And the detection limit was 6.0 ${times}$ 10$^{-8}$ M. Studies of the effect of diverse ions showed that Co, Ni, Zn, Pb, Mg and Ag ions added 10 times more than Cu(II) ion did not influence on the determination of Cu(II) ion, except EDTA and oxalate ions.

• Analytical Science and Technology
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• v.6 no.3
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• pp.329-334
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• 1993

The formation of Mo(VI)-alizarin red S chelate ion its extraction into an organic solvent by ion-pairing for the separarive determination of trace Mo(VI) in natural water was applied in seawater samples. Removed Fe(III) and Zn(II), and Cu(II) by precipitating with anthranilic acid at pH 4.0 and 2.0, seawater 100mL was sampled in 250mL separatory funnel. After Mo(VI)-ARS chelate ion was formed by adding 0.01M alizarin red S solution 1.0mL to the water sample of pH 4.6, 0.6% aliquat-336 chloroform solution 10mL was added and the solution was vigorously shaked for about 30 seconds to form the ion-pair between Mo(VI)-ARS and aliquat-336 perfectly. The solution was stood for about 30 minutes. And the organic phase was taken for the absorbance measurement of the ion-pair at 520nm. The content of Mo(VI) was obtained from the standard calibration curve. Several extraction conditions such as pH, adding amounts of alizarin red S and aliquat-336, and shaking and standing times were optimized and the interferences and release of concomitant ions was also studied. This procedure was applied to the analysis of Eastern and Yellow seawaters. It could be confirmed from the recoveries of over 85% in samples spiked with a given amount of Mo(VI) that this method was also quantitative in the determination of trace Mo(VI) in a seawater.