• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.10 no.S_2
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• pp.79-88
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• 2001

Humic acids react with chlorine to produce Trihalomethanes(THMs), known as carcinogens, during disinfection, the last stage in water purification. Currently, the removal of organic humic acids is considered the best approach to solve the problem of THM formation. Accordingly, the current study examined the adsorption of organic compounds of humic acids onto an inorganic carrier prepared from oyster shell waste. The adsorbent used was activated oyster shell powder(HAP) and silver ion-exchanged oyster shell powder(HAP-Ag), with CaCO$_3$ as the control. The adsorbates were phthalic acid, chelidamic acid, catechol, dodecylpyridinium chloride(DP), and 2-ethyl phenol(2-EP). The adsorption experiments were carried out in a batch shaker at $25^{\circ}C$ for 15 hours. The equilibrium concentration of the adsorbate solution was analyzed using a UV spectrophotometer and the data fitted to the Langmuir isotherm model. Since the solution pH values were found to be greater than the pKa values of the organic compounds used as adsorbates, the compounds apparently existed in ionic form. The adsorptive affinities of the organic acid and phenolic compounds varied depending on the interaction of electrostatic forces, ion exchange, and chelation. More carboxylic acids and catechol, rather than DP and 2-EP, were adsorbed onto HAP and HAP-Ag. HAP and HAP-Ag exhibited a greater adsorptive affinity for the organic compounds than CaCO$_3$, used as the control.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.3
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• pp.112-117
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• 2017

Ion exchange fiber, PADD was synthesized by the reaction between PAN based acrylic fiber and DETA with $AlCl_3{\cdot}6H_2O$, and was analyzed by FT-IR and SEM to investigate its characteristics. The experimental results of Cr(VI) removal by PADD were better fitted with Langmuir adsorption isotherm, and the maximum uptake value ($Q_{max}$) was calculated to be 6.93 mmol/g. The kinetic data can be well described by Lagergen pseudo-second order rate model. The Cr(VI) adsorption capacity of PADD was 4.11 mmol/g at pH 2, which shows the effect of pH changes on the removal of Cr(VI). The adsorption selectivity of Cr(VI) was higher than phosphate and As(V). Total ion exchange capacity of PADD was 4.70 mmol/g, which was measured by acid-base back titration.

• Journal of the Korean Applied Science and Technology
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• v.16 no.1
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• pp.75-81
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• 1999

HF purification performance of an ion exchange membrane(IEM) was evaluated with 0.5% HF spiked with 10ppb of Fe, Ni and Cu nitrates. The result show that after less than five turnovers through an IEM, the metallic impurity concentration drops below 1ppb. The decrease rate can be fitted to a model assuming the experimental tanks to be continuously stirred tank reaction and that the metallic impurity concentration after the IEM is a function of the single-pass purification efficiency of the membrane, the concentration before purification and the metals desorbed form the IEM. The Concentration after purification was investigated up to a cumulative Fe loading of 300ppb in the 23 liter recirculated loop. It increases linearly vs. cumulative loading and can be explained by the Langmuir theory resulting in a purification efficiency at the equilibrium of close to 99.5% in this loading regime.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.10
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• pp.895-900
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• 2016

Remaining useful life (RUL) estimation of the Li-ion battery has gained great interest because it is necessary for quality assurance, operation planning, and determination of the exchange period. This paper presents the RUL estimation of an Li-ion battery for an energy storage system using exponential function for the degradation model and Markov Chain Monte Carlo (MCMC) approach for parameter estimation. The MCMC approach is dependent upon information such as model initial parameters and input setting parameters which highly affect the estimation result. To overcome this difficulty, this paper offers a guideline for model initial parameters based on the regression result, and MCMC input parameters derived by comparisons with a thorough search of theoretical results.

• Journal of Korean Society of Water and Wastewater
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• v.33 no.2
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• pp.131-140
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• 2019

This study used a packed column reactor and a horizontal flow mesh reactor to examine the removal of copper ions from aqueous solutions using pine bark, a natural adsorbent prepared from Korean red pine (Pinus densiflora). Both equilibrium and nonequilibrium adsorption experiments were conducted on copper ion concentrations of 10mg/L, and the removals of copper ions at equilibrium were close to 95%. Adsorption of copper ions could be well described by both the Langmuir and Freundlich adsorption isotherms. The bark was treated with nitric acid to enhance efficiency of copper removal, and sorption capacity was improved by about 48% at equilibrium; mechanisms such as ion exchange and chelation may have been involved in the sorption process. A pseudo second-order kinetic model described the kinetic behavior of the copper ion adsorption onto the bark. Regeneration with nitric acid resulted in extended use of spent bark in the packed column. The horizontal flow mesh reactor allowed approximately 80% removal efficiency, demonstrating its operational flexibility and the potential for its practical use as a bark filter reactor.

• YAKHAK HOEJI
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• v.28 no.3
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• pp.139-147
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• 1984

L-PHA, a lectin having lymphoagglutinating activity but devoid of erythroagglutinability which is contained in Korean white kidney bean (Phaseolus vulgaris L.), was isolated and purified through several techniques such as ion exchange chromatography, hydroxyapatite column and affinity chromatography. Purified L-PHA was identified as a single band by polyacrylamide disc gel electrophoresis. The molecular weight of the L-PHA was estimated about 125, 000 daltons by polyacrylamide gel electrophoresis and it was turned out having one subunit (probably dimer of the Yachnin's model) of Mr~60, 000. Immunochemical studies also tried and these results reconfirmed the purity of this L-PHA.

• Journal of Microbiology and Biotechnology
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• v.14 no.1
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• pp.29-34
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• 2004

Biosorption technology is recognized as an economically feasible alternative for the removal and/or recovery of metal ions from industrial wastewater sources. However, the structure of biosorbents is quite complex when compared with synthetic ion-exchange resins, which makes it difficult to quantify the ion-binding sites. Accordingly, this report describes a well-defined method to characterize the pK values and numbers of biomass functional groups from potentiometric titration data. When the proposed method was applied to Sargassum polycystum biomass as a model biosorbent, it was found that the biomass contained three types of functional groups. In addition, the carboxyl group (pK=$3.7{\pm}0.09$) was found to be the major binding sites ($2.57{\pm}0.06 mmol/g$) for positively-charged heavy-metal ions.

• Polymer(Korea)
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• v.30 no.1
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• pp.45-49
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• 2006

In this study, it was investigated on the boron separation ken synthetically prepared seawater. ion exchange resin used in the experiments was Amberlite IRA 743, containing glucamine functional group. The experiments were carried out as a function of the conditions of the pH, boron initial concentration and temperature of seawater in a batch reactor. As a result, optimum conditions for boron adsorption were at pH 8.5 and 313 K, respectively. The adsorption rate was increased very fast with increasing the temperature, but decreased with increasing the initial concentration of boron. Also, the kinetics for boron adsorption applied the pseudo-second order model, as follows: $$\frac{X}{1-X}=780[C_0]^{-1.65}t^{1.48}\;exp\;({-\frac{17883}{RT}}\)\;;\;pH8.5$$

• Korean Chemical Engineering Research
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• v.57 no.3
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• pp.338-343
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• 2019

The water transport and water content of the electrolyte membrane greatly affect the performance of the membrane in PEMFC(Proton Exchange Membrane Fuel Cell). In this study, the parameters (electroosmotic coefficient, water diffusion coefficient) of polymer membranes for water transport were measured by a simple method, and water flux and ion conductivity were simulated by using a model equation. One dimensional steady state model equation was constructed by using only the electro-osmosis and diffusion as the driving force of water transport. The governing equations were simulated with MATLAB. The electro-osmotic coefficient of $144{\mu}m$ thick polymer membranes was measured in hydrogen pumping cell, the value was 1.11. The water diffusion coefficient was expressed as a function of relative humidity and the activation energy for water diffusion was $2,889kJ/mol{\cdot}K$. The water flux and ion conductivity results simulated by applying these coefficients showed good agreement with the experimental data.

• Korean Journal of Environmental Agriculture
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• v.39 no.4
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• pp.281-288
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• 2020

BACKGROUND: Generally, ammonia occurs from agricultural waste disposal. Ammonia is known as a harmful substance to the human body and has a bad influence such as eutrophication on the ecosystem. It is possible to remove the ammonia by ammonia adsorption method using natural zeolite, without external influence. However, due to the natural zeolite shape, it is hard to reuse. METHODS AND RESULTS: Electrospinning method can produce fiber with constant diameter. Moreover, electrospinning method has no limitation for selecting the material to make the fiber, and thus, it is valuable to reform the surface of adsorbent. In this study, reusable membrane was made by electrospinning method. The highest removal efficiency was shown from the membrane with 20% of zeolite included, and it has been verified that it is possible to reuse the membrane through chemical treatment. The highest ammonia removal efficiency was about 92.4%. CONCLUSION: In this study, ammonia adsorption characteristics of zeolite fibers were studied. Electrospinning method can produce zeolite fiber with even distribution. Ammonia can be removed efficiently from ion exchange ability of the natural zeolite. The result of adsorption isotherm indicated that both Freundlich model and Langmuir model provided the best fit for equilibrium data. And study on desorption has demonstrated that the ion exchange from zeolite was reversible when 0.01 M NaCl and KCl solution were used.