• Analytical Science and Technology
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• v.13 no.4
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• pp.428-432
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• 2000

A PVC membrane electrode based on upper-rim calix[4]crown as ionophore was prepared using dioctyl sebacate (DOS) as a plasticizer. The potential response of this membrane electrode to alkali, alkaline earth metal cations were examined. This membrane electrode exhibited a Nemstian response to $10^{-5}-10^{-1}M$ of CsCI with a slope of 52.3 mV/decade in Tris-buffer(pH 7.20). Its response time ($t_{90%}$) was 10s and it could be used for at least 2 months.

• Journal of the Korean Ceramic Society
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• v.47 no.6
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• pp.583-589
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• 2010

In this paper, the properties of reclaimed ash(RA) from various domestic thermal power plants(S, D and H) were analyzed, and the possibility of fabricating the artificial lightweight aggregate(ALA) using RA was studied. The chemical compositions of RA are similar to the clay, but it had higher concentrations of alkali earth metal oxides(CaO, MgO) and unburned-carbon. The TCLP(Toxicity Characteristic Leaching Procedure) results showed that the dissolution concentrations of heavy metal ions of RA were below the limitation defined by the enforcement regulation of wastes management law in Korea. The results of IC analysis showed that leaching concentration of $Cl^-$ ion was 124 ppm for RA of HN and ${SO_4}^{2-}$ ion was leached a few hundreds ppm for all RA in this study. The ALAs with various mass ratio of clay to reclaimed ash(RA:Clay = 7:3, 6:4, 5:5, 4:6, 3:7) were sintered with a electric muffle furnace at the temperature of $1050{\sim}1200^{\circ}C$. The specific gravity and water absorption(%) of the sintered ALAs were 1.1~1.8 and 10~30% respectively. The ALA sintered in the rotary kiln at $1125^{\circ}C$ showed a bulk density of 1.7 and water absorption of 15.2%.

• The Journal of Engineering Geology
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• v.15 no.4 s.42
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• pp.391-405
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• 2005

Chemical and isotopic analysis for stream water, shallow groundwater, intermediate groundwater and deep groundwater was carried out to grasp hydrogeochemical characteristics of groundwater in the Heunghae area, Pohang city. Water type of stream water and shallow groundwaters is typified as Ca-Cl type, intermediate groundwater is $Na-HCO_3$, and deep groundwater is prominent in Wa-Cl type. $HCO_3^-\;and\;SiO_2$ in shallow groundwater are originated from weathering of silicate minerals, whereas those of deep groundwaters are resulted from weathering of carbonate minerals. Ca and Mg ions in both shallow and deep groundwaters are resulted from weathering of calcite and dolomite. $SO_4^{2-}$ in shallow groundwater is originated mainly from pyrite oxidation. As well depth increases, pH and TDS increase, but Eh and DO decrease. Alkali metal contents(K, Na, Li) increases as well depth increases, but alkali earth metal(Mg, Ca) and hi concentrations increase as well depth decreases. Anions, halogen elements(F, Cl, Br), and $HCO_3$ contents increase as well depth increases. The average stable isotope value of the groundwater of each depth is as follows; deep groundwater: ${\delta}^{18}O=-10.1\%o,\;{\delta}D=-65.8\%_{\circ}$, intermediate groundwater: ${\delta}^{18}O=-8.9\%_{\circ},\;{\delta}D=-59.6\%_{\circ}$, shallow groungwater : ${\delta}^{18}O=-8.0\%_{\circ},\;{\delta}D=-53.6\%_{\circ}$, surface water : ${\delta}^{18}O=-7.9\%_{\circ},\;{\delta}D=-53.3\%_{\circ}$ respectively.

• Applied Chemistry for Engineering
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• v.10 no.7
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• pp.996-1002
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• 1999

The oxalate precipitation of lanthanide and actinide by oxalic acid was investigated in the simulated radioactive liquid waste, which was composed of 17 elements of alkali, alkaline earth(Cs, Rb, Ba, Sr), transition metal(Zr, Fe, Mo, Ni, Pd, Rh), lanthanide(La, Y, Nd, Ce, Eu) and actinide(Np, Am) in nitric acid solution. The effect of concentrations of nitric acid and ascorbic acid on the precipitation yield of each element in the simulated solution was examined at 0.5 M oxalic acid concentration. The precipitation yields of the elements were usually decreased with nitric acid concentration, nevertheless, the precipitation yields of lanthanide and actinide were more than 99%. Palladium was precipitated due to the reduction of Pd(II) into Pd metal by the addition of ascorbic acid in the oxalate precipitation and then, the precipitation yields of Mo, Fe, Ni, Ba decreased by 10~20% with concentration of ascorbic acid. The reductive precipitation of Pd(II) into Pd metal by the addition of ascorbic acid into the simulated radwaste occurred at below 1 M nitric acid concentration and its yield showed maximum at the ascorbic acid concentration of 0.01~0.02 M. The hydrazine suppressed the reductive precipitation of Pd by the ascorbic acid.

• Journal of the Korean Chemical Society
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• v.44 no.2
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• pp.115-119
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• 2000

A PVC membrane electrode based on upper-rim calix[4] crown as ionophore was prepared using dioctyl sebacate (DOS) as a plasticizer. The potential response of this membrane electrode to alkali, alka-line earth and transitionmetal metal cations were examined. This membrane electrode exhibited a Nernstian response to $10^{-6}{\sim}10^{-2}M\;Pb(NO_3)_2$ with a slope ot 27.0 mV/decade. Its response time ($t_{90}$) was 10s and it could be used for at least 2 months. Also, the potential was maintained constantly in the rage of ph $2.0{\sim}12$.

• Journal of the Korean Chemical Society
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• v.42 no.5
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• pp.531-538
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• 1998

The ion selective membrane electrode made of calix[4]arene-based host 1 as ionophore, poly (vinyl chloride) (PVC) as matrix and dioctylsebacate (DOS) as a plasticizer was studied. The potential responses of this membrane electrode to alkali, alkaline earth and transition metal cations were investigated. Especially this membrane electrode was turned out to be affinitive for $Pb^{2+}$ in the deionized water. It was observed that the response was linear in the concentration range from $1.0 \times 10^{-1} M to 1.0 \times 10^{-6} M of Pb^{2+}$ and its slope (26.5 mV/decade) was near to the sub-Nernstian response in deionized water. Also, the potential was maintained constantly in the range of pH $4.00 \sim 12.00$, which supports the potential usage as $Pb^{2+}$ affinitive electrode in the deionized water.

• Transactions of the Korean hydrogen and new energy society
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• v.28 no.4
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• pp.323-330
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• 2017

Ash remaining after coal combustion was used as a catalyst support for tar steam reforming with various proportions of $Al_2O_3$ added for higher reforming efficiency. At a constant Ni content of 12 wt%, a coal ash and $Al_2O_3$ were mixed at a ratio of 5:5, 7:3, 9:1. As a result, the catalytic activity for toluene steam reforming was improved by adding $Al_2O_3$ at $500-600^{\circ}C$. The catalysts with ratio 7:3 and 5:5 reached toluene conversion of 100% above $700^{\circ}C$. When comparing the catalysts in which the coal ash and $Al_2O_3$ mixed at a ratio of 5:5 and 7:3 with the Ni/Al catalyst, it was concluded that this coal ash catalyst has efficient catalytic performance.

• Bulletin of the Korean Chemical Society
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• v.26 no.4
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• pp.579-584
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• 2005

The 3-[(2-furylmethylene)amino]-2-thioxo-1,3-thiazolidin-4-one (FTT) was used as an excellent ionophore in construction of a $Zn^{2+}$ PVC-based membrane sensor. The best performance was obtained with a membrane composition of 30% poly(vinyl chloride), 62% nitrobenzen (NB), 3% FTT and 5% sodium tetraphenyl borate (TBP). This membrane sensor shows very good selectivity and sensitivity towards $Zn^{2+}$ over a wide variety of cations, including alkali, alkaline earth, transition and heavy metal ions. The membrane sensor revealed a great enhancement in selectivity coefficients for $Zn^{2+}$ ions, in comparison to the previously reported $Zn^{2+}$ membrane sensors. Theoretical studies also showed the selective interaction of TFF and $Zn^{2+}$ ions. The proposed membrane sensor exhibits a Nernstian behavior (with slope of 29.3 ${\pm}$ 0.3 mV per decade) over a wide concentration range (1.0 ${\times}$ $10^{-6}$-1.0 ${\times}$ $10^{-2}$) with a detection limit of 8.5 ${\times}$ $10^{-7}$ M (52 ng mL$^{-1}$). It shows relatively fast response time, in the whole concentration range ($\lt$ 20 s), and can be used for at least 10 weeks in a pH range of 3.0-7.0. The proposed membrane sensor was successfully used in direct determination of $Zn^{2+}$ ions in wastewater of industrial zinc electroplating companies, and also as an indicator electrode in titration with EDTA.

• Bulletin of the Korean Chemical Society
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• v.32 no.8
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• pp.2643-2647
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• 2011

Efficient ditopic receptor, uranyl(II) N,N'-(ethylenedioxy)benzenebis(salicylideneimine) (3) for beryllium ion has been obtained upon functionalization of 1,2-ethylenedioxybenzene (1) with a uranyl-salphen (salphen = N,N'-phenylenebis(salicylideneimine)) unit. Binding affinities of the receptor, 3 in AN-DMSO (v/v 95:5) solution have been measured for alkali and alkaline earth metal ions by conductometry comparing 1. The results showed that both monotopic 1 and ditopic receptor 3 were selective for $Be^{2+}$ ions over other cations, while especially 3 that can complex both with cations (coordinated to basic oxygen of ethylenedioxybenzene) and anions (coordinated to the Lewis acidic uranyl center) results in an increase of the stability constants by a factor of $10^{2.42}$ with respect to 1. Furthermore, the $Be^{2+}$-3 interactions are demonstrated by $^1H$ NMR experiments in highly polar solvent medium, DMSO-$d_6$. Higher selectivities were also observed for $Be^{2+}$ when the ditopic receptor, 3 was incorporated into PVC membranes and tested as ion selective electrodes at neutral pH.

• Journal of Sensor Science and Technology
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• v.1 no.1
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• pp.85-92
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• 1992

A new potassium sensitive field effect transistor modified with 4'-aminobenzo-15-crown-5 was prepared and its response characteristics were evaluated. The response slope of $K^{+}-ISFET$ for pH was 30.0 mV/decade and the response time was mere than 3 minutes. And the response slope and time of the $K^{+}-ISFET$ for potassium ion as $19.5{\pm}0.2{\;}mV/decade$ and about 3 minutes, respectively. The linear response range of the sensor for potassium ion was $2.0{\times}10^{-4}{\sim}1.0{\times}10^{-2}M$. The selectivity coefficients of the $K^{+}-ISFET$ for the alkali and alkaline earth metal ions were also evaluated. Sodium, ammonium and calcium ions exhibited relatively significant interference. The long term stability of the sensor was remarkably improved and it could be used for more than 50 days.