• Analytical Science and Technology
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• v.12 no.3
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• pp.203-208
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• 1999

The ion-pair high performance liquid chromatographic elution behavior of salicylic acid and its derivatives was studied with measuring capacity factor, k', changing the concentration of ion-pairing reagent (tetrabutylammonium chloride, TBACl) in mobile phase. As a result, it was found that k' of the samples increase at pH 7.2 as the TBACl concentration increases. The derivatives of salicylic acid were separated each other at an optimum mobile phase condition which was found from the observation of the retention behavior. The optimum mobile phase condition was methanol solution($MeOH:H_2O_2$ 30:70) containing 20 mM TBACl for the determination of salicylic acid and methanol solution($MeOH:H_2O_2$ 20:80) containing 40 mM TBACl for p-aminosalicylic acid at pH 7.2. The method has been applied for the analysis of the contents of salicylic acid derivatives in an aspirin tablet and a tuberculosis curing agent.

• Proceedings of KOSOMES biannual meeting
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• 2004.05b
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• pp.81-84
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• 2004

Control of Sediment is very important in prawn farm due to the eruption of toxic material such as W1ionized H2S, NH3 and NO2-. In this study, column test study, column with filter media such as activated carbon, zeolite, oyster shell and iron chloride to evaluate the reduction of toxicity from sediment ammonia-N(NH3) was effectively removed by Zeolite and oyster shell. It was indicated that ammonium ion(NH4+) was removed by ion exchange of zeolite. And the ammonia in the column of oyster shell was existed as the form of NH4+, which is not toxic for prawn because oyster shell was stably kept around pH 8. Therefore, some of ammonia(NH3) was reduced by oyster shell. Hydrogen sulfide and COD were effectively removed by adsorption of activated carbon and a partial removal of hydrogen sulfide was accomplished by Oyster shell. Phosphorous was removed by activated carbon, oyster shell and iron chloride. In prawn farm, the concentration of ammonia was increased with increase of pH by algae photosynthesis in the column of activated carbon, zeolite and iron chloride, but it was revealed that pH was stably kept in the column of oyster shell.

• Journal of the Korean Recycled Construction Resources Institute
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• v.12 no.2
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• pp.206-213
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• 2024

The present study concerns the inhibition of Calcium Nitrite Inhibitor(Ca(NO₂)₂) in mortar contaminated by chloride ions. Thus, the corrosion resistance and chloride transport were measured for the mortar containing calcium nitrite inhibitor. As a result, an increase in the dosage of calcium nitrite inhibitor resulted in an increase in the chloride threshold concentration for reinforcement corrosion, while the rate of chloride transport was accelerated. However, the calcium nitrite inhibitor could not guarantee the time to corrosion, due to the increased mobility of chlorides. To ensure the passivity of steel, the dosage of calcium nitrite inhibitor must exceed a certain dosage, ranging from 2.0~3.0 % by cement weight.

• Journal of the Korea Concrete Institute
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• v.16 no.4 s.82
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• pp.485-492
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• 2004

In this study, ASTM C 1202 which is most commonly used for evaluating the penetration resistance into the concrete is reviewed. The test results by ASTM C 1202 showed that the passed charge could be underestimated as the $OH^-$ ion concentration in the concrete is lowered when the concrete is mixed with the admixtures. Therefore, the modified method using the distilled water was proposed in the paper. According to the test results, the modified method is not susceptible to $OH^-$ ion and temperature rise. In addition, the long term emersion test for the concrete mixed with the admixtures in the NaCl solution showed that the chloride diffusion coefficient tested by the modified method have higher correlation compared to the conventional ASTM method.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.663-668
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• 2003

In this paper, an environmental factor and a durability resistance factor which adapts the concept of the Load Resistance Factor Design for safety design of RC structures is derived and a basic principle of a durability evaluation for RC structures using the factors is proposed. It is shown that durability of RC structures can be evaluated by comparing predicted value of chloride ion concentration with limit value of concentration for steel corrosion generation in reinforcement steel position and the durability of concrete manufactured for the RC structures can be also evaluated by comparing characteristic diffusion coefficient of concrete with predicted diffusion coefficient during mixture design.

• Bulletin of the Korean Chemical Society
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• v.7 no.3
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• pp.163-166
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• 1986

A new paraffin salt bridge was developed for the concentration cell in high pressure system. The emf values of the concentration cells were measured to calculate the activity coefficients of the electrolytic ions depending upon the pressure of the system. The activity coefficients of sodium, chloride and bromide ions increase with the temperature of the cell and decreased, nearly half at 2500 bars, $20^{\circ}C$, with the pressure. These results can be explained to be attributed to the volume change of the hydrated ion due to the electrostriction. The volume change decreased with pressure due to an increase in the degree of the hydration.

• Bulletin of the Korean Chemical Society
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• v.26 no.1
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• pp.51-56
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• 2005

A PVC membrane electrode for lead ion based on 1-phenyl-2-(2-quinolyl)-1,2-dioxo-2-(4-bromo) phenylhydrazone (PQDBP) as ionophore was demonstrated. The optimum composition of the membrane was 30 wt% poly(vinyl chloride), 60 wt% dibutyl phthalate as a plasticizer, 4 wt% ionophore and 6 wt% sodium tetraphenylborate as additive. The electrode exhibits a Nernstian response (28.7 mV decade$^{-1}$) for Pb$^{2+}$ over a wide concentration range (1.0 ${\times}$ 10$^{-1}$ to 1 ${\times}$ 10$^{-6}$ M) with a detection limit of 6.0 ${\times}$ 10$^{-7}$ M. This sensor has a short response time and can be used for at least 2 months without any divergence in potentials. The proposed electrode could be used in a pH range of 3.0-6.0 and revealed good selectivities for Pb$^{+2}$ over a wide variety of other metal ions. It was successfully applied as an indicator electrode for the potentiometric titration of lead ion with potassium chromate and for the direct determination of lead in mine.

• Journal of Electrochemical Science and Technology
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• v.5 no.4
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• pp.115-127
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• 2014

Cd-Pb thin films were electrodeposited from a diluted chloride solution using stainless steel rotating disc electrode. The linear sweep voltammograms of the single metallic ions show that electrodeposition of these ions was mass transfer control due to the plateau observed for different rotations at concentration (50 and 200 ppm). The voltammograms of binary system elucidate that electrodeposition process always start at cathodic potential located between the potential of individual metals. Currents transients measurements, anodic linear sweep voltammetry (ALSV) and atomic force microscopy (AFM) were used to characterize the electrocryatalization process and morphology of thin films. ALSV profiles show a differentiation for the dissolution process of individual metals and binary system. Two peaks of dissolution Cd-Pb film were observed for the binary system with different metal ion concentration ratios. The model of Scharifker and Hills was used to analyze the current transients and it revealed that Cd-Pb electrocrystalization processes at low concentration is governed by three-dimensional progressive nucleation controlled by diffusion, while at higher concentration starts as a progressive nucleation then switch to instantaneous nucleation process. AFM images reveal that Cd-Pb film electrodeposited at low concentration is more roughness than Cd-Pb film electrodeposited at high concentrated solution.

• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.4
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• pp.227-238
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• 2013

The purpose of this study is to develop a process technology to produce high hardness drinking water which meet drinking water standard, remaining useful minerals like magnesium and calcium in the seawater desalination process while removing the sulfate ions and chloride ions. Seawater have been separated the concentrated seawater and desalted seawater by passing on Reverse Osmosis membrane (RO). Using Nano-filtration membrane (NF), We were prepared primary mineral concentrated water that sodium chloride were not removed. By the operation of electro-dialysis (ED) having ion exchange membrane, we were prepared concentrated mineral water (Mineral enriched desalted water) which the sodium chloride is removed. We have produced the high hardness water to meet the drinking water quality standards by diluting the mineral enriched desalted water with deionized water by RO. Reverse osmosis membranes (RO) can separate dissolved material and freshwater from seawater (deep seawater). The desalination water throughout the second reverse osmosis membrane was completely removed dissolved substances, which dissolved components was removed more than 99.9%, its the hardness concentration was 1 mg/L or less and its chloride concentration was 2.3 mg/L. Since the nano-filtration membrane pore size is $10^{-9}$ m, 50% of magnesium ions and calcium ions can not pass through the nano-filtration membrane, while more than 95% of sodium ions and chloride ions can pass through NF membrane. Nano-filtration membrane could be separated salt components like sodium ion and chloride ions and hardness ingredients like magnesium ions and calcium ions, but their separation was not perfect. Electric dialysis membrane system can be separated single charged ions (like sodium and chloride ions) and double charged ions (like magnesium and calcium ions) depending on its electrical conductivity. Above electrical conductivity 20mS/cm, hardness components (like magnesium and calcium ions) did not removed, on the other hand salt ingredients like sodium and chloride ions was removed continuously. Thus, we were able to concentrate hardness components (like magnesium and calcium ions) using nano-filtration membrane, also could be separated salts ingredients from the hardness concentration water using electrical dialysis membrane system. Finally, we were able to produce a highly concentrated mineral water removed chloride ions, which hardness concentration was 12,600 mg/L and chloride concentration was 2,446 mg/L. By diluting 10 times these high mineral water with secondary RO (Reverse Osmosis) desalination water, we could produce high mineral water suitable for drinking water standards, which chloride concentration was 244 mg/L at the same time hardness concentration 1,260 mg/L. Using the linked process with reverse osmosis (RO)/nano filteration (NF)/electric dialysis (ED), it could be concentrated hardness components like magnesium ions and calcium ions while at the same time removing salt ingredients like chloride ions and sodium ion without heating seawater. Thus, using only membrane as RO, NF and ED without heating seawater, it was possible to produce drinking water containing high hardness suitable for drinking water standard while reducing the energy required to evaporation.

• Resources Recycling
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• v.17 no.6
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• pp.17-23
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• 2008

In order to simulate the leaching solution of copper sulfide ore in $FeCl_3$ solutions, synthetic solutions with composition of $FeCl_3$-$FeCl_2$-$CuCl_2$-CuCl-NaCl-HCl-$H_2O$ were prepared. The concentration of iron and copper chloride was varied from 0.1 to 1 m in synthetic solutions. The effect of composition on the mixed solution pH and potential at $25^{\circ}C$ was measured. When HCl concentration was constant, the increase of CuCl concentration increased solution pH. The increase of other solutes excluding HCl and CuCl decreased solution pH owing to the increase of the activity coefficient of hydrogen ion. A high CuCl concentration favored the redox equilibrium in the direction of Cu(I), while $FeCl_3$ had the opposite effect.