• Korean Journal of Environmental Agriculture
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• v.37 no.1
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• pp.21-27
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• 2018

BACKGROUND: Although 1 M $NH_4OAc$ (pH 7.0) is predominantly used as the extractant of exchangeable cations in agricultural soils, this method is unsuitable for extracting the cations in saline and calcareous soils. This study was performed to select a proper method to determine exchangeable cations in vinyl greenhouse soils. METHODS AND RESULTS: Exchangeable cations (Ca, Mg, K, Na) in saline vinyl greenhouse soils were determined after extraction with 1 M $NH_4OAc$ (pH 7.0 and 8.5) and 1 M alcoholic $NH_4Cl$ (pH 8.5). Sum of exchangeable cations of the soils extracted with 1 M $NH_4OAc$ at pH 7.0 was 1.9-2.5 times greater than soil cation exchange capaity determined at pH 7.0, even though soluble salts were pre-removed. A similar result was found when the cations were extracted with 1 M $NH_4OAc$ at pH 8.5. Those results are mostly due to the overestimation of exchangeable Ca and Mg, linked to a partial dissolution of sparingly soluble salts in $NH_4OAc$ solution. When extracted with 1 M alcoholic $NH_4Cl$ at pH 8.5, extractable Ca and Mg decreased significantly due to the lower solubility of Ca and Mg carbonates in the extractant. And the sum of exchangeable cations was very close to the corresponding exchange capacity of soils. CONCLUSION: Alcoholic $NH_4Cl$ (pH 8.5) is proposed as a reliable extractant in determination of exchangeable cations in saline vinyl greenhouse soils. And soluble salts should be removed prior to the extraction of exchangeable cations.

• Journal of Environmental Science International
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• v.8 no.3
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• pp.399-409
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• 1999

The three domestic natural zeolites(Yong dong-ri (Y), Daesin-ri (D), Seogdong-ri (S)) harvested in Kyeongju-shi and Pohang-shi, Kyungsangbug-Do, were pretreatd with each of the NaOH, $Ca(OH)_2$ and NaOH following HCl solutions, and the removal performances of divalent haevy metals(Cu, Mn, Pb, and Sr) for natural and pretreated zeolites were investigated and compared in the single and mixed solutions. The natural zeolite-heavy metal system attained the final equilibrium plateau within 20 min, irrespective of initial heavy metal concentration. The heavy metal uptakes increased with increasing initial heavy metal concentration and pH. The heavy metal uptakes for natural zeolites decreased in the following sequences : D>Y>S among the natural zeolites; Pb>Cu>Sr>Mn among the heavy metals. The pretreated zeolites showed higher heavy metal removal performances than natural zeolites and decreased in the order of NaOH, NaOH following HCl, $Ca(OH)_2$ treatment among the pretreatment methods. The heavy metal ion exchange capacity by natural and pretreated zeolites was described either by Freundlich equation or Langmuir equation, but it followed the former better than the latter. The heavy metal uptakes for natural zeolites decreased in the mixed solution, in comparing with those in the single solution and especially, the manganese uptake decreased greatly in the mixed solution. The pretreated zeolites showed the improved removal performances of heavy metals in the mixed solution than in the single solution and the heavy metal uptakes by those in the mixed solution showed the same trends in the single solution among the chemical treatment methods and heavy metals.

• Proceedings of the Korean Biophysical Society Conference
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• 2003.06a
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• pp.37-37
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• 2003

We have shown the $Ca^{2+}$-activated chloride current is present in cardiac myocyte in rabbit pulmonary vein (Kim et al., 2002). This current amplitude was increased as [N $a^{+}$]$_{i}$ was increased and we suggested this chloride current may be involve in the spontaneous action potential frequency change. Since this current is activated by the increase of intracellular $Ca^{2+}$, we would like to test what is the inducer of the increase of [C $a^{2+}$]$_{i}$ between a L-type $Ca^{2+}$-current or a reverse mode of N $a^{+}$-C $a^{2+}$ exchange current. White rabbit (1.5 kg) was used and anesthetized with Ketamin (100 mg/kg). Pulmonary vein (PV) was isolated and sleeve area between left atrium and PV was dissected. Using collagenase (Worthington 0.7 mg/cc), single cardiac myocytes were isolated. In the presence of 15 mM of N $a^{＋}$, three steps of voltage pulses were applied (holding potential : -40 ㎷, -80 ㎷ for 50 msec, 30 ㎷ for 5 msec, 10 ㎷ steps from -70 ㎷ to 60 ㎷). The inward and outward tail current was activated after brief 5 msec prepulse. The outward tail current was blocked by the removal of extracellular chloride substituted by glucuronic acid or by a chloride channel blocker, 5 mM 9-AC. But the inward tail current was still remained even though the amplitude was decreased. The reversal potentials were changed to the direction of the change of chloride equilibrium potential ( $E_{Cl}$ ) but the shift of equilibrium potential was not enough to match to the theoretical equilibrium potential shift. In the presence of L-type $Ca^{2+}$ channel blocker, nifedipine 1 uM, inward tail currents were greatly reduced but the outward current tail currents were still remained. In the presence of N $a^{+}$-C $a^{2+}$ exchange current blocker, 10 uM KB-R7943, the inward and outward tail currents were blocked almost completely. We tried to test the $Ca^{2+}$sensitivity of the chloride current with various [C $a^{2+}$]$_{i}$ in pipette solution from 100 nM to 1 uM but we failed to activate $Ca^{2＋}$-activated chloride currents even though the cell became contracted in the presence of 1 uM $Ca^{2+}$. From these results, we could conclude that the increase of [C $a^{2+}$]$_{i}$ to activate the outward $Ca^{2+}$-activated chloride current was mainly induced by the activation of the reverse mode of N $a^{+}$-C $a^{2+}$ exchanger, But for the increase of [C $a^{2+}$]$_{i}$ to activate the inward tail current, L-type $Ca^{2+}$ current may be the major provoking current. Since the cytosolic increase of [C $a^{2+}$]$_{i}$ through pipette solution have failed to activate $Ca^{2+}$-activated chloride current, this chloride current may have very low $Ca^{2+}$ sensitivity or a comparmental increase $Ca^{2+}$ such as in subsarcolemmal space may activate the chloride current. Since there are several reports and models that the increase of $Ca^{2+}$ in subsarcolemmal space would be over several to tens of uM, both possibility may be valid together.uM, both possibility may be valid together.

• Korean Journal of Crystallography
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• v.11 no.4
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• pp.224-230
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• 2000

We have been investigated the flaking mechanism of the soda-line glass. The pH of aqueous solution approached to 10 and increased with reaction time by ion exchange reaction between Na/sup +/ ion of glass and H/sup +/ ion of aqueous solution under the conditions of below pH 9 of start solution. The relationship between the pH of solution and reaction time shows logarithm. Total dissolution reaction of glass components by OH/sup -/ ion in aqueous seems to be dominant after the pH solution reached to 10 and the dissolution rate linearly increased with reaction time. The above tow reactions are simultaneously occurred. The dissolved Ca/sup 2+/ ions are reprecipitated on the glass surface to Ca-compound. The flakes are formed by the separation of leached layer of glass due to the different thermal expansion coefficient.

• 보존과학연구
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• s.35
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• pp.5-23
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• 2014

The possibility of non-destructive inspection glass beads for verification. Conduct a comparative analysis of the Chungcheong area with glass beads excavated Age-specific characteristics of the glass beads shall be classified by region. Trace amounts of ingredients such as CaO, $Al_2O_3$ (stabilizer), MgO, the difference is negligible. $SiO_2$ (subjects), $Na_2O$ (flux) analysis and the difference between the values was greater than in the other ingredients. Composition differences occurred rough surface to a non-uniform cross-section analysis is considered. Minimize the error value, such as the surface of carbon-coated Study, there are additional requirements. Produced at the time of the social and cultural characteristics of ancient glass and important archaeological materials, and to inform the process of cultural exchange between each region in the production of glass technology era according to the level of science and technology, arts and crafts, can be identified.

• Journal of Soil and Groundwater Environment
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• v.22 no.3
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• pp.10-17
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• 2017

In this study, the evolution and origin of major dissolved constituents of crystalline bedrock groundwater in a coastal area were evaluated using multivariate statistical and groundwater quality analyses. The groundwater types mostly belonged to the $Na(Ca)-HCO_3$ and $Ca-HCO_3$ types, indicating the effect of cation exchange. Stable isotopes of water showed two areas divided by first and secondary evaporative effects, indicating a pattern of rapid hydrological cycling. Saturation indices of minerals showed undersaturation states. Thus, the degree of evolution of groundwater is suggested as in the low to intermediate stage, based on field and laboratory analytical conditions. According to the principal component analysis (PCA) results, the chemical components of EC, $Ca^{2+}$, $Mg^{2+}$, $K^+$, $HCO_3{^-}$, $SO{_4}^{2-}$ (PCA 1), $F^-$ (PCA 3), $SiO_2$ (PCA 4), and $Fe^{2+}$ (PCA 5) are derived from various water-rock interactions. However, $NO_3{^-}$, $Na^+$, and $Cl^-$ (PCA 2) represented the chemical characteristics of both anthropogenic sources and natural sea spray.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.22 no.3
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• pp.287-299
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• 2024

Technetium has been identified as an element of interest for the safety assessment of a deep geological repository for used nuclear fuel. In this study, the sorption of Tc(IV) onto MX-80 bentonite, illite, and shale in ionic strength (I) 0.1-6 mol·kgw^-1 (m) Na-Ca-Cl solutions at pH_m = 4-9 and limestone at pH_m = 5-9 was studied. Tc(IV) sorption on MX-80 increased with pH_m from 4 to 6, reached the maximum at pH_m = 6-7, and then gradually decreased with pH_m from 7 to 9. Tc(IV) sorption on illite gradually increased with pH_m from 4 to 7, and then decreased as pH_m increased. The sorption properties of Tc(IV) on shale were quite similar to those on illite. Tc(IV) sorption on limestone slightly increased with pH_m from 5 to 6 and then seemed to be constant at pH_m = 6-9. Tc(IV) sorption on all four solids was independent of ionic strength (0.1-6 m). The 2 site protolysis non-electrostatic surface complexation and cation exchange model successfully simulated the sorption of Tc(IV) onto MX-80 and illite and the optimized values of surface complexation constants were estimated.

• Korean Chemical Engineering Research
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• v.52 no.2
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• pp.175-181
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• 2014

Microbial fuel cells (MFC) were operated with livestock wastes and PEMFC (Proton Exchange Membrane Fuel Cells) MEA (Membrane and Electrode Assembly). OCV of MFC with mixtures of microbial was higher than that of MFC with single microbial. MFC using pig wastes showed highest OCV (540 mV) among cow waste, chicken waste and duck waste. And the power density of MFC using pig waste was $963mW/m^2$. Contamination of MEA with $Na^{2+}$, $Ca^{2+}$, $K^+$ ion and impurities was the one cause for low performance of MFC during operation.

• Environmental Engineering Research
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• v.23 no.3
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• pp.330-338
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• 2018

This study investigated the possibility of using potassium titanate oxide ($K_2Ti_4O_9$) and acrylic acid-grafted polypropylene fabric (PP-g-AA) as adsorbents capable of removing strontium from aqueous solutions. $K_2Ti_4O_9$ showed the highest rate of strontium removal in the weak alkaline range, while the PP-g-AA increased strontium removal in the neutral range. Moreover, the adsorption capacity of the $K_2Ti_4O_9$ was not affected by the coexistence of K and Na ions, while the adsorption capacity decreased when Ca and Mg ions were present at the same concentration as that of strontium. When coexisted at the same concentration as strontium, Na, K, Ca, and Mg ions strongly reduced the adsorption capacity of the PP-g-AA. The results also indicated that the adsorption of strontium on $K_2Ti_4O_9$ was consistent with both the Langmuir and Freundlich adsorption isotherms. In contrast, the adsorption of strontium on the PP-g-AA was more consistent with the Langmuir isotherm model. Moreover, the adsorption equilibrium time of $K_2Ti_4O_9$ was generally 12 h, while that of the PP-g-AA was 5 h, indicating that the adsorption rates were consistent with the pseudo-second order kinetics model. $K_2Ti_4O_9$ and the PP-g-AA could be regenerated by simple washing with 0.5 N HCl.

• Bulletin of the Korean Chemical Society
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• v.19 no.1
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• pp.98-103
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• 1998

The crystal structure of dehydrated $Rb^+$-exchanged zeolite X, stoichiometry $Rb_{71}Na_{21}-X\; (Rb_{71}Na_{21}Si_{100}Al_{92}O_{384})$ per unit cell, has been determined from single-crystal X-ray diffraction date gathered by counter methods. The structure was solved and refined in the cubic space group Fd3, a=25.007(3) Å at 21(1) ℃. The crystal was prepared by ion exchange in a flowing stream using a 0.05 M aqueous RbOH solution (pH=12.7). The crystal was then dehydrated at 360 ℃ and $2{\times}10^{-6}$ torr for two days. The structure was refined to the final error indices, $R_1=0.047$ and $R_2=0.040$ with 239 reflections for which I> 3σ(I). In this structure, 71 $Rb^+$ ions per unit cell are found at six different crystallographic sites and 21 $Na^+$ ions per unit cell are found at two different crystallographic sites. Four and a half $Rb^+$ ions are located at site Ⅰ, the center of the hexagonal prism. Nine $Rb^+$ ions are found at site Ⅰ' in the sodalite cavity (Rb-O=2.910(15) Å and O-Rb-O=78.1(4)°). Eighteen $Rb^+$ ions are found at site Ⅱ in the supercage (Rb-O=2.789(9) Å and O-Rb-O=92.1(4)°). Two and a half $Rb^+$ ions, which lie at site Ⅱ', are recessed ca. 2.07 Å into the sodalite cavity from their three O(2) oxygen planes (Rb-O=3.105(37) Å and O-Rb-O=80.6(5)°). Thirty-two $Rb^+$ ions are found at site Ⅲ deep in the supercage (Rb-O=2.918(12) Å and O-Rb-O=71.9(4)°), and five $Rb^+$ ions are found at site Ⅲ'. Seven $Na^+$ ions also lie at site Ⅰ. Fourteen $Na^+$ ions are found at site Ⅱ in the supercage (Na-O=2.350(19) Å and O-Na-O=117.5(6)°).