• Journal of Soil and Groundwater Environment
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• v.16 no.1
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• pp.82-90
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• 2011

Reactive reductants of cement/Fe(II) systems in dechlorinating chlorinated hydrocarbons have not been identified. The previous studies showed that a hematite/CaO/Fe(II) system had TCE degradation characteristics similar to those of cement/Fe(II) systems with regard to degradation kinetics and that lime (CaO) plays an important role in enhancing the reactivity for TCE dechlorination. The current study shows identified the formation of gypsum ($CaSO_4$) in the hematite/CaO/$FeSO_4$ system through the XRD analysis. The amounts of the gypsum increased with increment of the initial CaO dose. However, when CaO in the hematite/CaO/$FeSO_4$ system was replaced with gypsum, TCE degradation was not observed. Ca-removed Portland cement extracts (CPCX) in combination with $FeSO_4(CPCX/FeSO_4)$ showed no TCE degradation. On the other hands, the Portland cement extracts (PCX) in the presence of $FeSO_4(PCX/FeSO_4)$ and CPCX/CaO/$FeSO_4$ systems degraded 0.2 mM TCE within 5 days, indicating that CaO also played an important role dechlorination reactions in the systems. The pseudo-first-order rate constants (k) of the CPCX/CaO/$FeSO_4$ systems were 0.20, 0.24, and 0.72 $day^{-1}$, when the CaO dosages were 25, 50 and 75 g/L, respectively. The XRD analyses showed identified the common peaks having the d-values of 3.02, 2.27, and 1.87 in the reaction systems that showed TCE degradation. However, it was not possible to clearly identify the crystalline minerals having the three peaks from the references in JCPDS cards. This study reveals that the reactive agents in the cement/Fe(II) and the hematite/Fe(II) systems are likely to be those containing CaO and Fe(II).

• Journal of the Korean GEO-environmental Society
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• v.20 no.2
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• pp.69-79
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• 2019

The coastal area forms various sedimentary layers according to the environmental conditions such as the topography and geological features of the upper region of the river, ocean currents, and river mouth. Therefore, identifying the characteristics of the marine clay deposited in the coastal area plays a key role in the investigation of the formation of soft ground. In general, alluvial grounds are formed by a variety of factors such as changes in topography and natural environment, they have very diverse qualities depending on the deposited region or sedimentation conditions. The most important thing for the construction of social infrastructures in soft ground areas is economical and efficient treatment of soft ground. In this study, the author collected data from diverse laboratory and field tests on five areas in western and southern offshore with relatively high reliability, and then statistically analyzed them, thereby presenting standard constants for construction design. Correlation between design parameters such as over consolidation ratio, preconsolidation pressure was analyzed using linear and non-linear regression analyses. Also, proposed distribution characteristics of design parameters in consideration of each region's uncertainty through statistical analyses such as normality verification, outlier removal.

• Journal of the Korean Chemical Society
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• v.31 no.4
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• pp.334-343
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• 1987

The Chemical reactions between $NiL_m{^{2+}}\{$Ni(rac-1[14]7-diene)^{2+},\;Ni(meso-1[14]7-diene)^{2+},\;Ni(1[14]4-diene)^{2+},\;{\alpha}-Ni(rac-[14]-decane)^{2+},\;{\beta}-Ni(rac-[14]-decane)^{2+},\;and\;Ni(meso-[14]-decane)^{2+}$}\and\ CN^-$ ion were studied by the spectrophotometric method. The equilibrium constants (K_1$) for the 1:1 complex ion, $[NiL_m(CN)]^+\;with\;NiL_m{^{2+}}\;and\;CN^-$ ion were determined in the range of 3 to $25^{\circ}C$. The $K_1\;for\;Ni(rac-1[14]7-diene)^{2+},\;Ni(meso-1[14]7-diene)^{2+},\;Ni(1[14]4-diene)^{2+},\;{\alpha}-Ni(rac-[14]-decane)^{2+},\;{beta}-Ni(rac-[14]-decane)^{2+},\;and\;Ni(meso-[14]-decane)^{2+}\;at\;15^{\circ}C$ was 4.7, 5.3, 6.2, 7.5, 9.4, and 9.8, respectively. The values of $K_1$ decreased with increasing temperature. From the temperature effect on equilibrium constant ($K_1$), thermodynamic parameters $({\Delta}H^{\circ},\;{\Delta}S^{\circ},\;{\Delta}G^{\circ})$ for reaction were evaluated and the reaction of $NiL_m{^{2+}}\;and\;CN^-$ ion was exothermic. $NiL_m{^{2+}\;reacts\;with\;CN^-$ ion to give $Ni(CN)_4{^{2-}}$ ion and macrocyclic ligand $(L_m)$. The kinetics of formation of the $Ni(CN)_4{^{2-}}$ ion of varying the $[CN^-],\;[HCN],\;and\;[OH^-]$ have been investigated at 3∼$25^{\circ}C\;and\;0.5M\;NaClO_4$. Maintaining a constant $[CN^-],\;k_{obs}/[CN^-]^2$ increases linearly with increasing [HCN]. In the presence of large quantities of $[OH^-],\;k_{obs}/[CN^-]^2$ also increases linearly with $[OH^-]$. From the temperature effect on kinetic constant (k_{obs})$, parameter of activation $({\Delta}H^{\neq},\;{\Delta}S^{\neq})$ of reaction of $NiL_m{^{2+}}\;with\;CN^-$ ion were determined. For the $Ni(rac-1[14]7-diene)^{2+},\;Ni(meso-1[14]7-diene)^{2+},\;{\alpha}-Ni(rac-[14]-decane)^{2+},\;{\beta}-Ni(rac-[14]-decane)^{2+},\;and\;Ni(meso-[14]-decane)^{2+}\;series\;{\Delta}H^{\neq}$ gradually decrease as the d-d transition energy, $ν(cm^{-1})$ decrease. And the reaction of the five $NiL_m{^{2+}}\;with\;CN^-$ ion take place by way of equal paths.

• Korean Journal of Environmental Agriculture
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• v.12 no.1
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• pp.51-57
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• 1993

Objective of this research was to assess the influence of reaction time on the heavy metal-organic ligand complexation by employing kinetic models. Aqueous solutions of humic (HA) or fulvic acid (FA) were reacted with metal solutions with 1:1 ratio to form complexes. Efficiency of organic ligand on metal removal was determined by separating the precipitates from solution using $0.45\;{\mu}m$ filter paper. Complexation between Cu or Pb and HA or FA followed the first- or multiple first order kinetics, largely depending on metal concentration and kind of organic ligand. Amounts of precipitates were increased proportionally with reaction time but reached to quasiequilibrium where rate of precipitate formation was not varied with time. Copper-ligand complexation was, irrespective of ligand, fitted to the single first order kinetics at Cu concentrations lower than $300{\mu}M$, but this was fitted to the multiple first order kinetics at Cu concentrations higher than $300{\mu}M$. As increasing Cu concentrations, the precipitates formed more readily, judging from the increased rate constants (${\kappa}$). In the multiple first order kinetics, ${\kappa}$ was decreased as reaction steps proceeded. Most of Cu-ligand precipitates were formed within 15 min. FA precipitated Cu more rapidly than HA did. ${\kappa}$ for Pb-HA complexation was decreased but that for Pb-FA reaction was increased, as increasing Pb concentration. Most of Pb-organic ligand complexation occurred within 30 min. Afterwards, ${\kappa}$ values were relatively small and not affected much by time. Pb was precipitated by humic acid more readily than Cu when metal concnetrations were $200{\sim}300{\mu}M$. However, when metal concentrations were in the ranges of $400{\sim}500{\mu}M$, a reversed tendency was observed.

• Analytical Science and Technology
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• v.8 no.3
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• pp.321-334
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• 1995

Basic studies for the effective extraction of ammonium pyrrolidine dithiocarbamate(APDC) complexes of Co(II), Ni(II) and Cu(II) into a solvent have been performed. The maximum distribution ratio was appeared (log D=1.3543) at pH 2.0 and the partition coefficient was 2.489 in the extraction of $4{\times}10^{-5}M$ APDC itself into chloroform. From the UV/visible spectra of metal-chelates in aqueous and organic solutions, the pH to form stable 1:2 metal-ligand complexes were Co(II):5.0, Ni(II):8.0 and Cu(II):8.0, respectively and only 1 minute was enough to be partitioned into the chloroform. Besides, the partition and extraction equilibria of the complexes were investigated by back-extracting $10.0{\mu}g/ml$ metal-chelates from the solvent into an aqueous solution beacuse of their slight solubilities in the aqueous solution. The distribution coefficients and extractabilities were as follows : at pH 6.5~8.5 of the aqueous solution, log D=2.834 : E(%)=99.9% for $Co(PDC)_2$, at pH 11, log D=5.699 E%=100 for $Ni( PDC)_2$, and at pH 6.0, log D=2.025 : E(%)=99.1% for $Cu(PDC)_2$. And the extraction and formation constants were log $K_{ex}=9.671$ : log ${\beta}_2=6.938$ for $Co(PDC)_2$, log $K_{ex}=9.646$ : log ${\beta}_2=7.071$ for $Ni( PDC)_2$, and log $K_{ex}=9.074$ : log ${\beta}_2=7.049$ for $Cu(PDC)_2$, respectively. From these results, an optimum extraction procedure can be constructed for the separative concentration of trace metallic ions, and the quantitative determination of them in advanced materials and environmental samples will be expected without any influence of sample matrixes.