• Journal of the Korean Magnetics Society
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• v.19 no.6
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• pp.216-221
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• 2009

Y-type barium ferrite $Ba_2Co_2Fe_{12}O_{22}$ was synthesized by a solid state reaction method. Effects of metal ion mole ratio and calcination temperatures on magnetic properties and microstructures of the synthesized powders were investigated. Phase analysis and microstructure observation were performed with a XRD (X-ray diffractometer) and a FESEM (field effect scanning electron microscope), respectively. Magnetic properties of the powders were measured with a VSM (vibrating sample magnetometer). Single phase Y-type was synthesized when metal ion mole fraction $Fe^{3+}:\;Ba^{2+}:\;Co^{2+}$ was 6 : 1 : 1 and calcination temperature was $1050\;{^{\circ}C}$. High saturation magnetization value of 39.1 emu/g was obtained when metal ion mole fraction $Fe^{3+}:\;Ba^{2+}:\;Co^{2+}$ was 8 : 1 : 1 and calcination temperature was $1200\;{^{\circ}C}$.

• Journal of the Korean Chemical Society
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• v.43 no.5
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• pp.511-516
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• 1999

Shiff Base ligand such as [NOIPH] have been synthesized from 2-hydroxy-1-naphthaldehyde and arometic amine. Co(II), Ni(II), and Cu(II) complexes from the reaction metal salts with Tridentate Schiff Base [NOIPH] were sythesized. The ligand and metal(II) complexes were characterized by the elementary analysis, IR, UV-Vis, NMR spectra, and thermogravimetric analysis. Metal(II) complexes in solid state have been shown that the mole raio of Schiff base [NOIPH] as $N_2O$ type to Metal(II) is 2:1 and the metal(II) complexes of $N_2O$ ligand type were four-coordinated configuration.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.4
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• pp.231-236
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• 2011

The effects of magnesium and calcium ions on phosphorus removal by aluminium coagulation were investigated with various jar tests using settled raw sewage. Maximum TP (total phosphate) removal occurred at pH around 5~6 with aluminium coagulation, and it decreased above pH 6. TP and $H_nPO_4^{n-3}$ removal efficiencies, however, were kept above 95% at pH above 6 by adding the divalent metallic ions like magnesium or calcium ions on aluminium coagulation process. At molar ratio of Al/P ($Al^{3+}/H_nPO_4^{n-3}$) above 3, TP removal efficiency was as high as 80%, and residual TP less than 0.2 mg/L occurred at Al/P ratio above 6. TP removal efficiency was improved by adding magnesium or calcium ions and the optimum $Al^{3+}/Mg^{2+}$ and $Al^{3+}/Ca^{2+}$ ratios were about 2. The required dose of aluminium coagulant was reduced for equivalent amount of TP removal by adding magnesium or calcium ions, as a result sludge generation was also reduced.

• Analytical Science and Technology
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• v.9 no.3
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• pp.221-234
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• 1996

Basic studies for the effective extraction of dibenzylammonium dibenzyldithiocarbamate(DBADBDC) complexes of Ag(I), Pd(II), Au(III) and Pt(IV) into chloroform have been conducted. The effects of pH on the extraction of ligand itself and metal cemplexes showed that DBADBDC itself was uniformly extracted in the pH range of 2~9 and metal complexes were effectively extracted at the pH range as follows. That is, Ag(I) : in an acidic aqua medium, Pd(II) : > 4, Au(III) : wide range, and Pt(IV) : > 3. The distribution ratio and extractabilities were obtained from the partition and extraction equilibria of metal-DBDC complexes between aqueous solution and chloroform. Ag(I) : log D=4.226 : E(%)=99.9% in the aqueous solution of pH 0, Pd(II) : log D=1.804 : E(%)=98.5% at pH 4~7, Au(III) : log D=3.755 : E(%)=99.9% at pH 2~10, and Pt(IV) : log D=0.165 : E(%)=57.2% at pH 8.0. And also mole ratio of metal ion to ligand in complexes were determined by mole ratio method : 1 : 1 for Ag(I) and 1 : 2 for Pd(II), Au(III) and Pt(IV). $Cl^-$ was included as a coordination species in complexes of Au(III) and Pt(IV). Besides, extraction mechanisms of compleses sere examined in the presence of chloride ion in an aquous solution, and extraction reactions and estraction constants could be proposed and calculated, respectively.

• 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.27 no.5
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• pp.353-360
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• 1983

The adsorption behavior of 8-hydroxyquinoline (8HQ) on Amberlite XAD-4 and-7 resins was investigated by measuring its distribution coefficients under various experimental conditions, such as shaking time, pH and concentration of methanol in the medium. The application of 8HQ-impregnated-XAD resins for the absorption and separation of metal ions was studied. The maximum adsorption of 8HQ on XAD resins was observed in the 30% methanol solution having pH range from 6.0 to 9.0. The impregnation capacities of XAD resins for 8HQ were 3.81${\times}$10-2mmol, 8HQ/g, XAD-4 resins and 2.60${\times}$10-2mmol, 8HQ/g, XAD-7 resin, respectively. The 8HQ-impregnated-XAD resins were stable in pH range from 6.0 to 10.0 and the amount of 8HQ leached from XAD-4 resin by eluting with hydrochloric acid(above 5M) was negligible. The optimum pH range for the adsorption of metal ions on 8HQ-impregnated XAD resin was also 6.0 to 10.0, and the adsorption mole ratio of metal ion to 8HQ were 1 : 2 for Cu(II), Cd(II) and Ni(II), and 1 : 3 for Fe(III) at the above pH range. It was found that the absorbed metal ions on 8HQ-impregnated-XAD resins were recovered quantitatively with 5M HCl and 8HQ-impregnated-XAD-4 resin could be reusable over 5 times without decrease in its impregnation capacity.

• Analytical Science and Technology
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• v.10 no.5
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• pp.370-377
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• 1997

The several fundamental parameters on the solvent extraction of Co(II), Cu(II) and Zn(II) with dithizone were investigated. The value of $K_{a1}/K_p$ of dithizone(at $25^{\circ}C$) between an aqueous phase and a chloroform was found to be $4.72{\times}10^{-11}$. And the mole ratios of metal ion to dithizone in its metal complexes were determined by mole ratio method. The extractibilities(%) for metal-dithizone chelates were obtained from the extraction equilibria of metal-dithizone complexes between an aqueous phase and a chloroform as follows. Co(II) : 92.3% at pH 8.0 : Cu(II) : 97.1% at pH 4.0 and Zn(II) : 99.0% at pH 7.0. And also, in optimum experimental conditions the extraction constants of Co(II), Cu(II) and Zn(II) were examined.

• Analytical Science and Technology
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• v.5 no.4
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• pp.401-408
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• 1992

The ion-selectrodes based on calcium ferrite were prepared by mixing calcium oxide with ferric oxide on molar ratio of 0.6:1.4, 0.8:1.2, 1.0:1.0, respectively. The specimens were sintered at $1400^{\circ}C$ for 2hrs in $O_2$ and for 20min in $H_2$ atmosphere. The selectrode sintered in hydrogen atmosphere showed better responded potential and wider range of responded concentration than selectrode sintered in oxygen atmosphere. The ion-selectrodes base on calcium ferrite(0.6:1.4 molar ratio.) showed the highest potential to bivalent cations such as $Ca^{2+}$, $Ba^{2+}$, $Mg^{2+}$, $Zn^{2+}$ and halogen anions such as $I^-$, $Br^-$ in the range of $10^{-1}{\sim}10^{-7}M$. It showed good agreement with theoretical nernstian values.

• Journal of the Korean Chemical Society
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• v.28 no.6
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• pp.403-411
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• 1984

Amberlite XAD-7 and XAD-4 resins impregnated with DXHQ (5,7-dihalo-8-hydroxyquinoline) were prepared for the adsorption, separation and recovery of heavy metal ions from aqueous solutions. The characteristics of the impregnated resins, DXHQ (X : Cl, Br, I)-XAD were studied to find out the proper pairs of resin and DXHQ for the adsorption of metal ions. The increasing order of the impregnated amount of DXHQ onto XAD-7 resin was as follows: DCHQ < DBHQ < DIHQ. It was observed from the plot of log $K_d$ vs. pH that the optimum pH range for the adsorption of DIHQ onto XAD-4 resin was from 3.0 to 7.0. The stabilities of the DXHQ-XAD resins were investigated by measuring the amount of DXHQ remained on the XAD resin after shaking the DXHQ-XAD resins in various solutions of pH ranging from 2 to 12 and hydrochloric acid solutions. The impregnated resins were considerably stable in both acidic and neutral solutions. The amount of DIHQ leached from DIHQ-XAD-4 resin by eluting with various HCl solutions (1 ∼ 5M) was negligible, but in the case of XAD-7 resin it increases as the concentration of HCl solution increases. The optimum pH ranges, absorption mole ratio (M : DXHQ) and adsorption capacities (mmol metal per gram of resin) for the adsorption of metal ions onto the DXHQ-XAD resins were determined respectively. The stability of metal ion absorbed by the DXHQ-XAD resins was observed as the following order: M-DCHQ-XAD-7 < M-DBHQ-XAD-7 < M-DIHQ-XAD-7. The adsorbed metal ions were quantitatively recovered by eluting with HCl (0.5 ∼ 5M) and DXHQ-XAD resins could be reused over 5 times without re-impregnation of DXHQ.

• Polymer(Korea)
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• v.25 no.6
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• pp.765-773
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• 2001

In In order to remove harmful trace elements such as $Co^{2+}$, $Ni^{2+}$ , $Cr_2O_7\;^{2-}$ from water, we synthesized AN-co-(MMA/IA) according to various mole ratio of monomers and spun by wet-spinning. And multi-functional PAN ion exchangers were prepared by hydrolysis. We observed structure, degree of functionalization, ion exchange capacity, distribution coefficient and mechanical properties for ion exchanger. Anion exchange capacity decreased in 4.5 ~ 4.2 meq/g with increasing of IA content and cation exchange capacity increased in 1.8 ~ 2.2 meq/g. Tensile strength of the ion exchanger increased up to 0.008 mol% IA content and appeared maximum value by 216$kg/cm^2$Distribution coefficient for AN-co-(MMA/IA) ion exchanger appeared maximum value for Co(II), Ni(II) in pH 5-6 range and for Cr(III) in pH 3-4 range. And the adsorption capacity was in the order of Cr(III) > Co(II) > Ni(II) for multicomponent in continuous process.