• Journal of the Korean Chemical Society
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• v.27 no.4
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• pp.287-293
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• 1983

Free radical-initiated copolymerizations of diethyl ${\alpha}$-phenylvinyl phospbate (DEPVP) with acrylonitrile (AN) and maleic anhydride (MAnh) were studied. The monomer reactivity ratios for AN/DEPVP pair, determined at $70^{\circ}C$ in bulk using benzoyl peroxide as an initiator, were;$ r_1(AN) = 0.77, r_2(DEPVP) = 0.002$. The values of the Alfrey-Price constants, Q and e, for DEPVP were calculated to be 0.012 and -1.35, respectively. Free radical-initiated copolymerization of MAnh/DEPVP pair in chloroform at $70^{\circ}C$ produced 1 : 1 alternating copolymers regardless monomer feed composition with the highest copolymerization rate at the molar ratio of MAnh : DEPVP = 7 : 3. The equilibrium constant of a charge-transfer complex between DEPVP and MAnh in deutrated chloroform, determinated at room temperature by transformed Benesi-Hildebrand NMR method, was 0.085 l/mol. The reduced viscosity of copolymers of AN/DEPVP pair decreased as the content of DEPVP units increased, while that of MAnh/DEPVP pair remained more or less constant.

• Journal of the Korean Chemical Society
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• v.55 no.3
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• pp.346-353
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• 2011

Base hydrolysis of 7-hydroxy-2H-chromen-2-one (HC) and 7-hydroxy-2H-chromen-2-one-4-acetic acid (HCA) in aqueous-methanol and aqueous-acetone mixtures were studied kinetically at temperature range from 283 to 313 K. The activation parameters of the reactions were evaluated and discussed. Moreover, the change in the activation energy barrier of the investigated compounds from water to water-methanol and water-acetone mixtures was estimated from the kinetic data. It is observed that the change in activation barriers is more or less the same for the hydrolysis of HC and HCA. Base hydrolysis of HC and HCA follows a rate law with $k_{obs}=k_2[OH^-]$. The decrease in the rate constants of HC and HCA as the proportion of methanol or acetone increases is due to the destabilization of $OH^-$ ion. The high negative values of entropy of activation support the proposal mechanism, i.e. the investigated reaction takes place via the formation of an intermediate complex. Moreover, these values refer to the rigidity and stability of the intermediate complex. Thus, the ring opening of the intermediate complex would be the rate controlling step.

• Journal of the Korean Chemical Society
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• v.40 no.1
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• pp.59-64
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• 1996

The 7F0→5D0excitation spectra of Eu(Ⅲ) complexed with polyfunctional monocarboxylic acid(glycolic acid, glycine and thioglycolic acid) containing a terminal O, N and S neutral donors and propionic acid were investigated using Eu(Ⅲ) luminescence spectroscopy. In the excitation spectra of Eu(Ⅲ)-propionate system, the stepwise appearance of the peaks was observed at 579.0, 579.2 and 579.5 nm with increasing in the ligand-to-metal ratio, which correspond to the formation of Eu(propionate)2+, Eu(propionate)2+ and Eu(propionate)3 species. Three maximum peaks were also obtained for Eu(Ⅲ)-glycolate, Eu(Ⅲ)-glycinate and Eu(Ⅲ)-thioglycolate systems and were found to be quite similar to those of Eu(Ⅲ)-propionate system. The q values (number of coordinated water molecules of Eu(Ⅲ) ion) obtained from the luminescence decay constants of Eu(Ⅲ)-glycolate and Eu(Ⅲ)-thioglycolate were 7.0 and 7.1, and compare well with 7.3 for Eu(Ⅲ)-propionate: Each ligand units replace around two coordinated water molecules. These results show that the polyfunctional monocarboxylates behaves like the propionate for Eu(Ⅲ) ion coordination.

• Journal of the Korean Chemical Society
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• v.28 no.5
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• pp.309-314
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• 1984

The species and equilibria of uranium and vanadium have been investigated in the various concentration of perchloric, hydrochloric and sulfuric acid by anion exchange chromatography. In the concentration range of $0.01\;{\sim}\;0.5M$ hydrochloric and $0.01\;{\sim}\;0.5M$ perchloric acid, uranium seems to be $UO_2^{2+}$species and in higher concentration than 0.5M hydrochloric acid $UO_2^{2+}$seems to form the chloride complex ion as $UO_2Cl^+$, $UO_2Cl_2$, $UO_2Cl_3^-$ and $UO_2Cl_4^{2-}$ according to the increase of the hydrochloric acid concentration. In the dilute(0.01N) sulfuric acid the adsorbability of uranium on anion exchange resin is strong and then decreases with increasing the sulfuric acid concentration. From this result we conclude that $UO_26{2+}$ formed the complex ion as $UO_2(SO_4)_2^{2-}$. In the perchloric acid of $0.01\;{\sim}\;0.5N$ concentration the existing equilibrium of vanadium and its constant calculated at $20^{\circ}C$ is $1.9{\times}108$ for $H_2V_{10}O_{28}^{4-}$ + $14H^+$ = $10VO_2^+ + 8H_2O$. The elution behaviors of vanadium in the hydrochloric and sulfuric acid are smiliar to those in perchloric acid.

• Journal of the Korean Chemical Society
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• v.11 no.3
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• pp.89-93
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• 1967

The interactions of fluorobenzene with iodine monochloride, iodine monobromide, bromine and chlorine in carbon tetrachloride solution have been examined through ultraviolet spectrophotometric measurements. The results indicate the formation of one to one molecular complexes, $C_6H_5F{\cdot}ICl$, $C_6H_5F{\cdot}IBr$, $C_6H_5F{\cdot}Br_2$, and $C_6H_5F{\cdot}Cl_2$ in solution. The equilibrium constants obtained at room temperature for the formation of these four complexes are 0.161, 0.072, 0.045 and 0.035 l $mole^{-1}$, respectively. Comparison of these results with those reported in the literature on other complexes of similar type reveals that the relative stabilities of these complexes decrease in the following orders: ICl>IBr>$I_2$>$Br_2$>$Cl_2$ $C_6H_6$>$C_6H_5Br$>$C_6H_5Cl$>$C_6H_5F$

• Journal of Environmental Science International
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• v.4 no.2
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• pp.223-232
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• 1995

New two macrocyclic compounds using as carriers of liquid emulsion menbrame, have been synthesized. These reuslts provide evidance for the usefulness of the theory in designing the systems. The efficiency of selective transport for heavy metal ions have been discussed from the membrane systems that make use of $SCN^-$,<>,$I^-$,CN- and $Cl^-$ ion as co-anions in source phase and make use of $S_2O_3^{2-}$ and $P_2O_7^{4-}$ ion as receiving phase, respectively. The transport rate of M(II) was highest when a maximum amount of the M(II) in the source phase was present as$Cd(SCN)_2$$(P[SCN^-]= 0.40M)$, $Hg(SCN)_2([SCN^-]=0.40M)$ and Pd(CN)$([CN^-]= 0.40M)$. The Cd(II) and Pb(II) over each competitive cations were well transprted with 0.3M-S2032- and 0.3M-P2O74-, respectively in the receiving phase. Results of this study indicate that two criteria must be met in order to have effective macrocycle-mediated transport in these emulsion system. First one must effective extraction of the $M^{n+}$ into the toluene systems. The effectiveness of this extraction is the greatest if locK for $M^{n+}$macrocycle interaction is large and if the macrocycle is very insoluble in the aqueous phase. Second, the ratio of the locK values (or Mn+-receiving phase ($S_2O_3^{2-}$- or $P_2O_7^{4-}$) to $M^{n+}$-macrocycle (($L_1$이나 $L_2$) interaction must be large enough to ensure quantitative stripping of Mn+(($Cd^{2+}$,$Pb^{2+}$)at the toluene receiving Phase interface. $L_1$(3.5-benzo-10,13,18,21-tetraoxa-1,7,diazabicyclo(8,5,5) eicosan) forms a stable ($Cd^{2+}$ and >,$Pb^{2+}$ complexes and $L_1$ is very insoluble in water and its $Cd^{2+}$ and >,$Pb^{2+}$ complex is considerably less stable than $Cd^{2+}$-(S2O3)22- and $Pd^{2+}-P_2O_7^{4-}$ complexes. On the other hand, the stability of the $Hg^{2+}$)+-$L_1$( complex exceed that of the $Hg^{2+}$- (S2O3)22- and Hg2+-P2O74-, and the distribution coefficient of $L_2$(5,8,15,18,23,26-hexaoxa-1,12- diazabicyclo-(10,8,8) octacosane) is much smaller than that of $L_1$. Therefore, the partitioning of Lr is favored by the aqueous receiving Phase, and little heavy metal ions transport is seen despite the large logK for $Hg^{2+}$+-$L_1$ and $Mn^+$($Cd^{2+}$+, $Pb^{2+}$+ and $Hg^{2+}$)-$L_2$ interactions. Key Words : macrocycles, transport, heavy metal, co-anion, source phase, receiveing, complex separation, interaction, destribution coefficient.

• Analytical Science and Technology
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• v.7 no.2
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• pp.225-232
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• 1994

The podands I-VII, acyclic polyethers, expected high extractability for $Ag^+$ against $Pb^{2+}$ were designed and synthesized with high yields. Using podands I-VII as extractants, the %extraction(%Ex) of $Ag^+$ and $Pb^{2+}$ as picrates were determined in water/chloroform systems. The stability constants(log K) for the complexation of $Ag^+$ with podands I-VII were also determined by potentiometry. %Ex($Ag^+$) were proportional to the numbers of substituted sulfur donor atoms. Podand VI(log K : 7.65) having 3 substituted sulfur and podand VII(log K : 9.15) having 4 substituted sulfur, however, exhibited almost 100% of extractability, respectively. In %Ex($Ag^+/Pb^{2+}$, oxygen-sulfur mixed donor podands(IV-VII) showed the higher values. Otherwise, the values of log K and %Ex($Ag^+$) largely depended on the variation of donor-site of sulfur. From the results of NMR experiments, it seems that it is due to the ${\pi}-{\pi}$ stacking interaction between the aromatic end-groups.

• Analytical Science and Technology
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• v.17 no.6
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• pp.481-488
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• 2004

Solvent extraction of Ni(II) into a chloroform by using salen[N,N'-Bis (salicylidene)-ethylenediamine] as a ligand has been studied. Salen was synthesized from ethylenediamine and salicylaldehyde by simple condensation reaction in an ethanol. Salen formed a 1 : 1 complex with Ni(II) and its extraction constant was $10^{5.12}$. For the determination of Ni(II) in sea water samples, some experimental conditions such as pH of solution, amount of salen, acid type and concentration for back extraction, extraction time, and influence of foreign ions were optimized by using a synthetic sea water. The sea water of which the composition was similar to a natural sea water was synthesized in this laboratory. Trace Ni(II) was extracted into the chloroform in the weak basic solution above pH 8. And the nickel could be quantitatively extracted with the concentration of salen higher than $1.2{\times}10^{-4}mol/L$. This concentration was more than 180 times of Ni(II) in the solution with a mole ratio. Real samples of Korean coastal sea water were analyzed under optimized conditions. Even though Ni(II) was not detected in these samples. Recoveries more than 98% were obtained in the samples which 40 ng/mL of Ni(II) was spiked. And detection limit of proposed method was 1.3 ng/mL. From these results, it could be known that salen of this type would be applied for the determination of trace metals as an organic chelating reagent.

• Economic and Environmental Geology
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• v.38 no.1
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• pp.23-31
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• 2005

This study was performed to investigate the effect of humic acid on the adsorption of arsenic onto hematite and its binding mechanism through the chemical speciation modeling in the binary system and the adsorption modeling in the ternary system. The complexation modeling of arsenic and humic acid was suitable for the binding model with the basis of the electrostatic repulsion and the effect of bridging metal. In comparison with the experimental adsorption data in the ternary system, the competitive adsorption model from the binary intrinsic equilibrium constants was consistent with the amount of arsenic adsorption. However, the additive rule showed the deviation of model in the opposite way of cationic heavy metals, because the reduced organic complexation of arsenic and the enhanced oxyanionic competition diminished the adsorption of arsenic. In terms of the reaction mechanism, the organic complex of arsenic, neutral As(III) and oxyanionic As(V) species were transported and adsorbed competitively to the hematite surface forming the inner-sphere complex in the presence of humic acid.