• The Korean Journal of Pesticide Science
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• v.4 no.1
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• pp.19-25
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• 2000

The adsorption and leaching of organophosphorus pesticide, EPN (O-ethyl-O-4 -nitrophenyl phenyl phosphonothioate) were investigated in Namwon soil(black volcanic soil), Aewol soil(very dark brown volcanic soil) and Mureung soil(dark brown nonvolcanic soil) in Cheju Island. The residue of EPN was surveyed on coastal environment of Cheju in Aug. 1996. The organic matter of Namwon soil, Aewol soil and Mureung soil was 19.8, 6.2 and 2.4%, respectively. The cation exchange capacity of Namwon soil, Aewol soil and Mureung soil was 24.8, 13.0 and 9.5 meq/100 g, respectively. The Freundlich constant, k value, was 89.4, 26.9 and 9.25 for Namwon soil, Aewol soil and Mureung soil, respectively. The k value of Namwon soil with very high organic matter content and cation exchange capacity was the highest for Aewol soil and Mureung soil. The Freundlich constant, 1/n, show a high correlation with organic matter content, i.e. it is less than unity for organic matter rich soil of Namwon soil and greater than unity for organic matter poor soil of Mureung soil. The leaching of EPN was slower for Namwon soil with high k values, and faster for Mureung soil with low k values. The results of the study was demonstrated the potential of pollution for EPN have little leached into soil environment. EPN was not detected in seawater and sediment in the coastal environment in Cheju Island. EPN used in the farm on tile Cheju island were not residued in the coastal environment.

• Journal of the Korean Ceramic Society
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• v.39 no.8
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• pp.728-734
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• 2002

Stabilization behavior of Cr, Cd, Cu, Pb, Fe and Zn heavy metals in the EAF dust was investigated by adding EAF dust to clay or white clay, respectively, up to 50 wt% with 10 wt% intervals and sintering at temperatures between 200 and $1200^{\circ}C$ with $200^{\circ}C$ intervals with an aid of ICP-AES followed by TCLP test to evaluate heavy metal cation exchange capacity of the clay or the white clay. The clay or the white clay had a better Cr ion exchange capacity than that of zeolite. The TCLP leaching test for the sintered specimens showed that Cr and Fe were rarely detected for all the specimens and the concentration of Cd and Zn decreased with increasing sintering temperature and decreasing EAF dust contents respectively. When the clay or the white clay were mixed with EAF dust, cation exchange may occur between the clay and the EAF dust so that the first stabilization of the mixtures containing semistabilized heavy metals may happen. Stabilization of heavy metals in the ceramic bodies was further completed probably due to the eutectic reaction caused by the sintering of semi-stabilized mixtures. It was conceivable that the white clay rather than the clay may be a better stabilizer for the EAF dust containing heavy metals.

• Korean Journal of Mineralogy and Petrology
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• v.36 no.4
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• pp.313-321
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• 2023

Numerous studies have investigated the adsorptive sequestration of radioactive cesium in the natural environment. Among these studies, adsorption onto minerals and high-temperature treatment stand out as highly effective, as demonstrated by the use of zeolite. In this study, cesium was ion-exchanged with birnessite and subsequently underwent high-temperature treatment up to 1100℃ to investigate both mineral phase transformation and the leaching characteristics of cesium. Birnessite has a layered structure consisting of MnO₆ octahedrons that share edges, demonstrating excellent cation adsorption capacity. The high-temperature treatment of cesium-ion-exchanged birnessite resulted in changes in the mineral phase, progressing from cryptomelane, bixbyite, birnessite to hausmannite as the temperature increased. This differs from the phase transformation observed in the tunneled manganese oxide mineral todorokite ion-exchanged with cesium, which shows phase transformation only to birnessite and hausmannite. The leaching of cesium from cesium-ion-exchanged birnessite was estimated by varying the reaction time using both distilled water and a 1 M NaCl solution. The leaching quantity changed according to the treatment temperature, reaction time, and type of reaction solution. Specifically, the cesium leaching was higher in the sample reacted with 1 M NaCl compared to the sample with distilled water and also increased with longer reaction time. For the samples reacted with distilled water, the cesium leaching initially increased and then decreased, while in the NaCl solution, the leaching decreased, increased again, and finally nearly stopped like the sample in the distilled water for the sample treated at 1100℃. These changes in leaching are closely associated with the mineral phases formed at different temperatures. The phase transformation to cryptomelane and birnessite enhanced cesium leaching, whereas bixbyite and hausmannite hindered leaching. Notably, hausmannite, the most stable phase occurring at the highest temperature, demonstrated the greatest ability to inhibit cesium leaching. This results strongly suggest that high-temperature treatment of cesium-ion-exchanged birnessite effectively immobilizes and sequesters cesium.

• Korean Journal of Soil Science and Fertilizer
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• v.16 no.3
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• pp.235-241
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• 1983

Major cation uptake by the rice plant and its leachates in submerged condition were studied at 3 different levels of potassium and nitrogen application with three texture soils (Clay loam, Loam, Sandy loam) by pot experiment. The results are as follows. 1. Potassium uptake and grain yields of rice plant were increased and calcium and magnesium uptake of rice plant were decreased by application of potassium. 2. The potassium application caused to increase Ca, Mg, K and $NH_4$ Content in leachate. 3. In the rice leaf at heading stage, the optimum cation ratios of K/Ca, K/Mg in me and $K_2O/N$ in % at N 3.3g/pot level were 1.59, 4.26 and 3.62, respectively, but the ratios were increased to 1.65, 4.32 and 3.94 at high level of nitrogen. 4. Similar trends of cation ratios were found in rice straw. leaching soil solution and soils after harvest by potassium application.

• Journal of Environmental Science International
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• v.10 no.4
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• pp.305-310
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• 2001

pH($H_2O$), pH(KCI), CEC(cation exchange capacity), O.M.(organic matter) and exchangeable cations(K, Na, Ca, Mg) of paddy soil, upland soil and forest soil in Kumi city were investigated for the purpose of knowing soil acidification and the correlation between soil acidification and leaching of inorganic salts. The mean pH($H_2O$) values of paddy soil were 5.23(surface soil) and 5.69(subsoil) and 4.74(subsoil). The were 6.37(surface soil) and 6.11(subsoil), and those of forest soil were 4.67(surface soil) and 4.74(subsoil). The mean pH(KCl) values of paddy soil were 4.59(surface soil) and 4.98(subsoil) were 5.48(surface soil) and 5.04(subsoil), and those of forest soil were 3.82(surface soil) and 3.89(subsoil). The acidification of forest soil was more rapid than that of paddy soil and upland soil/ The total mean amounts of exchangeable cations(K, Na, Ca, Mg) in paddy soils were 6.14me/100g(surface soil) and 5.64me/100g(subsoil), and those in upland soils were 6.86me/100g(surface soil) and 6.65me/100g(subsoil), and those in forest soils were 4.06me/100g(surface soil) and 3.34me/100g(subsoil). The contents of inorganic salts in forest soil were much less than those of paddy soil and upland soil. The correlation coefficients(r) between pH($H_2O$) values and the total amounts of exchangeable cations in soils were $0.6635^{**}$(surface soil) and $0.6946^{**}$(subsoil), and those between pH(KCl) values and exchangeable cations in soils were 0.6629(surface soil) and $0.5675^{**}$(subsoil). The correlation between soil acidification and leaching of inorganic salts in soil was positively significant at 1% level.

• Journal of the Korean Chemical Society
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• v.30 no.5
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• pp.488-492
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• 1986

The $Ca^{++}$ and $Mg^{++}$ released during Ca, Mg-Na exchange on Kampo 78 montmorillonite which was treated with various concentrations of NaCl solution, were measured with EDTA titration metbod in the leaching solutions. Lanthanide montmorillonite was prepared with various neutral lanthanide ions from sodium montmorillonite in which the exchangeable ions are displaced from the exchanger, such as the displacement of $Na^+$ by $Ln^{3+}$ ions, Cation exchange capacity (CEC) is determined on remaining lanthanides in the leaching solutions with E. D. T. A titration method. As a results of this study, there were no difference of C. E. C in series of lanthanide contraction, but C. E. C depends on charge density of montmorillonite. When we conformed the structure of Ln-montmorillonite by X-ray diffraction. It was found that there was much difference of pattern between Na-montmorillonite and Ln-montmorillonite.

• Resources Recycling
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• v.11 no.3
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• pp.3-9
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• 2002

Relnoval of ammonia from aqueous solutions has been studied with zeolite and bentonite minerals. Zeolite and bentonite powder were supplied by a domestic company and used as delivered without further purification. The aqueous pH was found to increase by addition of zeolite or bentonite up to pH 8.5 from initial pH of 5.5∼5.7. From the C.E.C. measurement by ammonium acetate leaching method, the values of C.E.C. of zeolite and bentonite sample were observed to be 129.7 meq/100 gr and 65.1 meq/100 gr, respectively and Na+ ion accounted for the major part of total C.E.C. in both cases. In the removal of ammonia with zeolite and bentonite, physical adsorption of ammonium ion onto minerals was believed to contribute to the removal of it as well as the intrinsic cation exchange reaction. Finally, zeolite was found to be superior to bentonite in the removal of ammonia from aqueous solutions.

• Journal of the Korean earth science society
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• v.32 no.2
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• pp.170-179
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• 2011

Fly ashes derived from coal fired power plants have unique chemical and mineralogical characteristics. The objective of this research was to study how indigenous bacteria affected heavy metal leaching in fly ash slurry during the fly ash-seawater interactions in the ash pond located in Yeongdong seashore, Korea. The in-situ pH of ash pond seawater was 6.3-8.5. For this study, three sites of the ash pond were chosen to collect a sample of fly ash slurry. Three samples that had a mix of fly ash (0.4 L) and seawater (1.6 L) were collected at each site. First sample was autoclaved ($120^{\circ}C$, 2.5 atm), second one was inoculated with glucose to stimulate the microbial activity, and the last sample was kept in the natural condition. Compared with other samples including autoclaved and natural samples, the glucose added sample showed sharp increase in its alkalinity after 15 days, cation concentration change such as Ca, Mg, and K seemed to increase in early stage, and then decrease 15 days later in slurry solution of glucose added sample, and a possibly considerable decrease in $SO_4^{2-}$ in the fly ash slurry samples when glucose was added to stimulate the microbial activity. Geochemical data of this study is likely to be related to the activity of bacteria at the ash pond. The result may be used to understand about the characteristic of bacteria.

• Journal of the Korean Ceramic Society
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• v.25 no.3
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• pp.251-260
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• 1988

Ion-exchange porous glasses were prepared by heat treatment and subsequently hydro thermalor acid leaching treatment $10Li_2O$.$(90-x)B_2O_3$.$xSiO_2$ base glasses containing various amount of $Al_2O_3$ or $MoO_3$. It was investigated how the phase separation and the cation exchange capacity(CEC) were affected by the addition of $Al_2O_3$ or $MoO_3$. The optimum condition of phase separation in these glasses was about 48$0^{\circ}C$ for 10 hrs. The degree of phase separation was rapidly suppressed by the addition of $Al_2O_3$ up to 10 mol% and thereafter suppression effect was decreased. The maximum value of CEC, about 252meq/100g, was observed with the $1OLi_2O$.$45B_2O_3$.$45SiO_2＋7.5Al_2O_3$ porous glass prepared by hydrothermal treatment and its mean pore radius was about 16.3A. The addition of $MoO_3$ accelerated phase separation and leaching rate. Looking at the remakable increment of pore diameter and pore volume of these porous glasses by the addition of $MoO_3$, the effect of $MoO_3$ may be ascribed to the lowering of silica concentration in the borate phase and to the forming of water-soluble complex with silica during the leaching treatment.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.4
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• pp.545-550
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• 2011

Urea intercalated into montmorillonite (MT) exhibits remarkably enhanced N use efficiency, maintaining its fast effectiveness. This study dealt with the release property of urea from metal-urea-clay hybrid with MT (MUCH) under continuous-flow conditions and the cumulative impacts of its successive application on physicochemical properties of soils. Releases of urea were completed within 4 hrs under continuous-flow condition regardless of the types and the leaching solutions. However, urea release property was significantly affected by both the form of fertilizer and the presence of electrolytes in solution. The fast release property of urea from MUCH in continuous-flow condition was not significantly affected by soil properties such as soil pH and soil texture. In addition, its successive application did not lead to any noticeable change in soil physicochemical properties, water stable aggregate rate, water holding capacity and cation exchange capacity in both sandy loam and clay loam soils. Therefore, this study strongly supported that urea intercalated into MT could be applied as fast-effective N fertilizer, in particular for additional N supply.