• Korean Chemical Engineering Research
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• v.43 no.2
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• pp.249-258
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• 2005

A two-column six-step pressure swing adsorption(PSA) process was to study separation of hydrogen from hydrogen and methane($60_{vol}%/40_{vol}%$) binary system onto activated carbon adsorbent. The effects of the feed gas pressure, the feed flowrate and the P/F(purge to feed) ratio on the process performance were evaluated. The cyclic steady-states of PSA process were reached to after 15 cycles. $H_2$ purity increases according as the P/F ratio and pressure increase and the feed flow rate decreases; however, $H_2$ recovery shows an opposite phenomena to the purity. PSA process simulation studied to find optimum operation condition. In the results, 22 LPM feed flowrate, 11 atm adsorption pressure and 0.10 P/F ratio might be optimal values to obtain more than 75% recovery and 99% purity hydrogen. In this study was non-isothermal and non-adiabatic model considering linear driving force(LDF) model and Langmuir-Freundlich adsorption isotherm considered to compare between prediction and experimental data.

• Analytical Science and Technology
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• v.10 no.1
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• pp.53-59
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• 1997

Chloride form anion exchange resin was used to separate one of the elements from the rare earth mixture using respectable Ln-EDTA eluent. $Sm^{3+}$, $La^{3+}$ or $Ce^{4+}$ complexed with EDTA was passed through the resin column and eluted with a Sm-EDTA solution as an eluent. Here all the rare earth element ions except $Sm^{3+}$ were passed. Adsorbed $Sm^{3+}$ in resin was eluted with 1.0 M HCl solution. If La-EDTA solution as an eluent was used to separate lanthanum ions, lanthanum ions were eluted together with other rare earth elements. When Ce-EDTA solution was also used for separation of $Ce^{4+}$, it was eluted in the region of other rare earth elements. In the case of Sm-EDTA elution, the elution mechanism was as follows : Absorption : $RCl+Ln-Y^-{\leftrightarrows}RLnY+Cl^-$, Sm-EDTA elution : $RLnY+Sm-Y^-{\leftrightarrows}RSmY+Ln-Y^-$, HCl elution : $RSmY+HCl{\leftrightarrows}RCl+Sm-Y^-$.

• Journal of the Korean Society of Food Science and Nutrition
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• v.11 no.3
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• pp.1-4
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• 1982

By high performance liquid chromatography, separation and quantification of glucoalkaloids $({\alpha}-chaconine$and${\alpha}-solanine)$ from potato (Solanum tuberosum, var. May Queen) was established using periderm and cortex. $Nucleosil-NH_2\;(10{\mu}m)$ was packed in two stainless steel columns ($4.0\;ID{\times}15\;cm$ and $4.0\;ID{\times}25\;cm$) which were connected in sequence and eluted with the mixture of tetrahydrofuran, phosphoric acid buffer and acetonitrile (50 : 25 : 25, v/v/v) at the flow rate of 1ml/min. and the absorbance were read at 208 nm. Retention time was 6.92 min. for ${\alpha}-chaconine$ and 10.96 min. for ${\alpha}-solanine$ with complete separation. This method took 12 min. per sample and seemed best. ${\alpha}-Chaconine$ and ${\alpha}-solanine$ were found much in periderm than in cortex.

• Membrane Journal
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• v.11 no.3
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• pp.133-139
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• 2001

The hydorgen ions in PVA/SSA membranes were substituted with monovalent metal ions, $Li^{+}$, $Na^{+}$, $K^{+}$, divalent metal ion forms, $Mg^{2+}$, $Ca^{2+}$, $Ba^{2+}$, trivalent metal ion forms, $Al^{+}$. The effect of exchange with metal ions was investigated through the swelling measurement and pervaporative experiments for water-ethanol and water-methanol mixtures at various operating conditions. In addition, ESCA analysis was carried out to study the substitution of the metal ions in membranes. The swelling ratio decerased in the sequence of $Li^{+}$, $Na^{+}$, $K^{+}$ and this might be due to the 'salting-out` effect while the swelling ratios for divalnet and trivalent ion-substituted membranes were affected by the combined effect of salting-out, electrostatic crosslinking and extent of metal ion substitution. For the pervaporation performance, PVA/SSA-$H^{+}$membrane showed the lowest flux and highest separation factor for all aqueous ethanol solutions. The typical results of the flux, 59 g/$m^{2}$hr and the separation factor, 44 were obtained at $50^{\circ}C$ for 90% ethanol aqueous mixture. For water-methanol solutions, the PVA/SSA membranes substituted with monovalent PVA/SSA membranes substituted with divalent and tribalent metal ions, both `salting-out` and electrostatic effects affected the pervaporative results.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.17 no.5
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• pp.368-372
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• 1984

This paper deals with a rapid method for determination of ATP and its related compounds in fish and shellfish products using high performance liquid chromatography(HPLC). The HPLC used is a HPLC/ALC-224 equiped with UV-spectrophotometer (254 nm) as detector and integrator (Yanagimoto system-1000). The column used is a stainless steel tubing ($30.0\;cm{\times}3.9\;mm\;i.d.$) packed with ${\mu}-Bon-dapak\;C_{18}$. A mixture of $1\%$ triethylamine-phosphoric acid(pH6.5) was used as an eluent and the flow rate of the eluent was controlled at 2 ml/min. For the separation of ATP and its related compounds, a standard mixture of ATP, ADP, AMP, IMP, inosine and hypoxanthine was subjected to HPLC under the above mentioned conditions. Six peaks were obtained with retention times within 20 min, and elution order were hypoxanthine, IMP, inosine, AMP, ADP and ATP. But 5'-IMP and 5'-GMP fractions were not separated by this method. In generally, IMP content in boiled-dried fish and shellfish products purchased from the market was comparatively higher than that of other nucleotides. Especially, boiled-dried big eye herring marked higher value in IMP content than other boiled-dried ones. Hypoxanthine and inosine were major components of ATP-related compounds in dried products and seasoned-dried ones. And IMP content in seasoned-dried products was higher than that of dried ones. This fact is suggested that a part of IMP in seasoned-dried ones was derived from flavoring matter (MSG, 5'-IMP and 5'-GMP) which is added during the seasoning treatment.

• Korean Chemical Engineering Research
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• v.47 no.6
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• pp.740-746
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• 2009

In the present study, the drowning-out crystallization of L(+)-calcium lactate was investigated in order to develop the crystallization separation process. The crystallization of the calcium lactate was induced by injecting the alcoholic anti-solvent into the aqueous solution of calcium lactate and the control of the calcium lactate crystal size during the crystallization was primarily investigated under the consideration of the anti-solvent species, anti-solvent composition and agitation speed as the key operating factors. Alcohols of methanol, ethanol, n-propanol and i-propanol were used as the anti-solvent for the drowning-out crystallization. Prior to the crystallization experiment, the solubility of calcium lactate in the water-alcohol mixture was measured along with the variation of the alcohol species and composition, which was necessary to estimate the supersaturation level of the crystallization. By the drowning-out crystallization, the calcium lactate crystals of the fabric shape were obtained. Using the ethanol as the antisolvent, the fabric crystals close to the needle shape were produced. However, the hairy crystals were obtained by using the propanol as the anti-solvent. Due to such morphological features, the crystals was highly apt to form the aggregates. The aggregation of the crystals was intensified as increasing the alcohol fraction in the water-alcohol mixture. Meanwhile, the agitation caused the breakage of crystals, resulting in the decrease of the crystal size. Therefore, the crystal size in the crystallization was predominantly determined by the competition between the crystal aggregation and breakage.

• Membrane Journal
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• v.32 no.2
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• pp.150-162
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• 2022

In the field of water treatment and pharmaceutical bio an alumina hollow fiber membrane used for mixture separation. However, due to the lack of strengths it is very brittle to handle and apply. Therefore, it is necessary to study and improve the bending strength of the membrane to 100 MPa or more. In this study, as the mixing ratio of the nano-particles increased to 0, 1, 3, and 5 wt%, the viscosity of the fluid mixture increased. The pore structure of the hollow membrane produced by interrupting the diffusion exchange rate of the solvent and non-solvent during the spinning process suppresses the formation of the finger-like structure and gradually increases the ratio of the sponge-like structure to improve the membrane mechanical strength to more than 100 MPa. As a result, an interparticle space was ensured to improve the porosity of the sponge-like structure with high permeability, and it showed excellent N2 permeability of about 100000 GPU and high water permeability of 3000 L/m² h. Therefore, it can be concluded, that the addition of γ-Al₂O₃ nanoparticles as sintering aid is an important method to enhance the mechanical strength of the α-alumina hollow fiber membrane to maintain high permeability.

• Applied Chemistry for Engineering
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• v.25 no.1
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• pp.116-120
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• 2014

Light cycle oil (LCO), one of the by-products of the catalytic cracking gasoline manufacturing process, contains a lot of valuable aromatics. In particular, 2,6-dimethylnaphthalene (2,6-DMN) contained in LCO has been becoming important as the basic material of polyethylene naphthalate plastic and liquid crystal polymer, etc. If it were possible to separate and purify the valuable aromatic hydrocarbons (such as 2,6-DMN) from LCO, which have only been used as fuel mixed with heavy oil, it would be very meaningful in terms of the efficient use of resources. We investigated the high-purity purification of 2,6-DMN by the combined method of melt crystallization (MC) and solute crystallization (SC). The enriched DMN isomer mixtures (concentration of 2,6-DMN : 10.43%) recovered from LCO by distillation-extraction combination and the crystal recovered by MC used as raw materials of MC and SC, respectively. The solvent of SC used was a mixture of methanol and acetone (60 : 40 wt%). The crystal of 2,6-DMN with a high-purity of 99.5% was recovered by MC-SC combination. We confirmed that the MC-SC combination was one of the very useful combinations for the high-purity purification of 2,6-DMN contained in the enriched DMN isomer mixtures.

• Analytical Science and Technology
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• v.24 no.2
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• pp.127-134
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• 2011

Quantitative HPLC analysis for the determination of in herbal liquid preparations was improved from the general test method besides the Korean Pharmacopeia. Good chromatographic separation of samples containing parabens, interferences, and other pharmaceutical excipients was effectively achieved by using acetonitrile water (containing 1% glacial acetic acid) mixture (30:70 v/v) as mobile phase. To monitor preservatives (benzoic acid, parabens, sorbic acid, dehydroacetic acid, and their salts) in herbal liquid preparations, a group of 47 samples was divided into two different group: preservative labeled group and unlabeled group. From the results, the contents of preservatives in 31 samples of preservative labeled group fell under KFDA regulations, and the contents of dehydroacetic acid in 6 samples of preservative labeled group were not followed by KFDA regulations. Preservatives were detected in 3 samples out of 10 samples in preservative unlabeled group.

• Applied Chemistry for Engineering
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• v.17 no.5
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• pp.458-464
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• 2006

The Pd-Ni-Ag alloy composite membrane using modified porous stainless steel (PSS) as a substrate was prepared by a electroless plating technique. In this work, we have introduced the intermediate layer between Pd-based alloy and a metal substrate. As an intermediate layer, the mixtures of nickel powder and inorganic sol such as $SiO_{2}$ sol, $Al_{2}O_{3}$ sol, and $TiO_{2}$ sol were used. The intermediate layers were coated onto a PSS substrate according to various membrane preparation conditions and then $N_{2}$ fluxes through the membranes with different intermediate layers were measured. The surface morphology of the intermediate layer in the mixture of nickel powder and inorganic sol was analyzed using scanning electron microscope (SEM). Finally, the Pd-Ni-Ag alloy composite membrane using the support coated with the mixture of nickel powder and silica as an intermediate layer was fabricated and then the gas permeances for $H_{2}$ and $N_{2}$ through the Pd-based membrane were investigated. The selectivity of $H_2/N_2$ was infinite and the $H_{2}$ flux was $1.39{\times}10^{-2}mol/m^2{\cdot}s$ at the temperature of $500^{\circ}C$ and trans-membrane pressure difference of 1 bar.