• Proceedings of the Membrane Society of Korea Conference
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• 한국막학회 2004년도 Proceedings of the second conference of aseanian membrane society
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• pp.86-89
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• 2004

The present study reports the preparation of a compact ZSM-5 membrane showing high thermal stability and high separation factors, especially n-/i-butane isomers at high temperatures. ZSM-5 membrane was prepared on a porous $\alpha$-Al$_2$O$_3$ tube (an average pore diameter, ca. 100 nm) at 18$0^{\circ}C$ by the seed-assisted crystallization method. The XRD and SEM results showed that a thin zeolite layer (ca. 1 ${\mu}{\textrm}{m}$) was formed on the support surface. The single gas permeances of $N_2$, H$_2$, SF$_{6}$, n-butane, and i-butane were taken at 27$0^{\circ}C$. i-Butane permeance hardly changed after repeated thermal treatments up to 40$0^{\circ}C$, indicating the membrane is thermally stable. On the other hand, other single gas permeances increased when the membrane was further dried at 40$0^{\circ}C$, indicating thermal pretreatment at 27$0^{\circ}C$ could not remove all the adsorbed species in the membrane. i-Butane and SF$_{6}$ permeances were significantly lower than the permeances of smaller molecules, indicating that the membrane has a low concentration of defects. The ideal selectivities at 27$0^{\circ}C$ were 61 for $H_2$/i-butane and 47 for $H_2$/SF$_{6}$. The temperature dependency of n/i-butane ideal selectivities and separation factors for an equimolar n/i-butane mixture was studied. The ideal selectivity showed a maximum of 36 at 30$0^{\circ}C$. The separation factors increased with temperature and reached around 12 at 300-40$0^{\circ}C$, which were much higher than those reported in the literature.ature.

• Membrane and Water Treatment
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• 제2권3호
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• pp.137-145
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• 2011

Membrane processes are major breakthrough for the removal of organic pollutants in water remediation. The separations of solutes depend on nature of the membranes and solutes. The separation performance depends on the nature of the solutes (i.e., molecular volume, polarity, and hydrophobicity) for the same membrane. As 4-chlorophenol is of more dipolemoment compared to 2-chlorophenol, the orientation of the molecule enables it pass through the pores of the membrane, which is of negatively charged and thus separation order follows: 2-chlorophenol > 4-chlorophenol. Hydrophobicity factor also supports the order. Addition of sodium dodecyl sulfate (SDS) to chlorophenol solution shows remarkable increase in separation performance of the membrane. The improvement in separation is 1.8 and 1.5 times for 4- and 2- chlorophenol consecutively in case of 0.0082 M SDS (1cmc = 0.0082 M) in the solution. 4-chlorophenol has better attachment tendency with SDS because of its relatively more hydrophobic nature and thus reflects in performance i.e. the separation performance of 4-chlorophenol with SDS through the membrane is better compared to 2-chlorophenol.

• Resources Recycling
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• 제12권1호
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• pp.25-32
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• 2003

A study on the separation of heavy metals such as iron, copper, zinc and nickel from electroplating waste water has been investigated. The results showed that the PC-88A was more effective extractant for the extraction of zinc and the efficiency of zinc was to be about 100% at pH 2.5. And copper and nickel were extracted about 100% at pH 2 and more than 90% at pH 4～5 with LIX 84, respectively. On the other hand, in the case of solvent extraction of electroplating waste water(Acid-Alkali type) containing heavy metals, the ferric ion was first extracted at pH 2∼2.5 with 20% Naphthenic acid or 10% Versatic acid-10. And then, copper and zinc were extracted at pH 2 with 3% LIX 84 and at pH 2.5∼3 with 20% PC-88A respectively, remaining nickel in the raffinate. In this manner, the heavy metals in electroplating waste water could be effectively separated with solvent extraction method.

• Journal of the Korean Chemical Society
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• 제43권5호
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• pp.522-526
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• 1999

2-Hydroxybenzaldehyde-5-nitro-pyridylhydrazone (2HB-5NPH) was synthesized and its application to the spectrophotometric determination of iron was studied. The reagent reacts with iron in the pH range 6.0-7.5 to form a yellow coIored 1:2 chelate which is very stable in methanol solution. Beer's law is obeyed in the concentration range 0.05∼2.0 ${\mu}gmL^{-1}$ iron and separation procedure using a short column filled with Amberlite XAD-7 nonionic chelating resin is proposed for the spectrophotometric determination of traces of iron. The influence of several ions as interference was discussed. The separation of Fe(III) ion from the mix-ture solution were carried out with the buffer solution (pH 5.0) and 0.25M HCl as eluents.

• Membrane and Water Treatment
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• 제8권5호
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• pp.437-448
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• 2017

A high quality Na-X zeolite membrane was synthesized on a seeded ${\alpha}-alumina$ disc by the secondary growth method. Structural characterization was done by X-ray spectroscopy, FT-IR spectroscopy, SEM and AFM imaging. The performance evaluation of the membrane was firstly tested in separation of glucose/water solutions by pervaporation process. There was obtained a separation factor $182.7{\pm}8.8$, while the flux through the membrane was $3.6{\pm}0.3kg\;m^{-2}\;h^{-1}$. The zeolite membrane was then used for desalination of aqueous solutions consisting of $Na^+$, $Ca^{2+}$, $Cs^+$ and $Sr^{2+}$ because of the importance of these ions in water and wastewater treatments. The effects of some parameters such as temperature and solution concentration on the desalination process were studied for investigating of diffusion/adsorption mechanism in membrane separation. Finally, high water fluxes ranged from 2 up to $9kg\;m^{-2}\;h^{-1}$ were obtained and the rejection factors were resulted more than 95% for $Na^+$ and $Ca^{2+}$ and near to 99% for $Cs^+$ and $Sr^{2+}$. Based on the results, fluxes were significantly improved due to convenient passage of water molecules from large pores of NaX, while the fouling was declining dramatically. Based on the results, NaX zeolite can efficiently use for the removal of different cations from wastewaters.

• Korean Journal of Food Science and Technology
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• 제19권3호
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• pp.225-230
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• 1987

The foam separation of bovine serum proteins was investigated and the protein fractionation by foam separation was analyzed by PAG electrophoresis. The protein concentration for the surface excess formation of bovine serum was in the range of $20-800\;{\mu}g/ml$. At pH 5, the foamate volume was maximum, but the enrichment ratio minimum. As the temperature was elevated, the foamate volume decreased and the enrichment ratio increase. As the gas flow rate increased from 25 to 100 ml/min, the foamate volume decreased and the enrichment ratio increased. The enrichment ration became maximum when the added ionic strength of serum solution was in the range of 1-3 by the addition of different types of salts, and this was related to the reduction of surface tension of the solution. In general, BSA, ${\alpha}_1$, and ${\alpha}_2-globulins$, which have relatively small molecular weight and high hydrophobicity, moved easily to the foam, and the separation of protein fractions in the serum varied with the changes in pH, temperature, gas flow rate and ionic strength of the solution.

• Applied Chemistry for Engineering
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• 제22권3호
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• pp.272-276
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• 2011

The separation of metallic and semiconducting single-wall carbon nanobubes (SWCNTs) by agarose gel method was carried out in this study. The effect of concentration of agarose, SDS (sodium dodecyl sulfate), and pH in the solution on separation behavior was investigated. With increasing the concentration of agarose in the solution, it showed that the ratio of metallic SWCNTs, which was analyzed from UV-vis-NIR spectroscopy, was increased in the solution phase, while the overall concentration of SWCNTs was decreased. With increasing the concentration of SDS, we could observe that the ratio of metallic SWCNTs was increased due to more affinity between SDS molecules and metallic SWCNT. The highest metallic SWCNTs ratio was reached up to 58.4% when the pH of solution was 8.2.

• Korean Chemical Engineering Research
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• 제53권1호
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• pp.31-38
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• 2015

At present, carbon dioxide ($CO_2$) emission, which causes global warming, is a major issue all over the world. To reduce $CO_2$ emission directly, commercial deployment of $CO_2$ separation processes has been attempted in industrial plants, such as power plant, oil refinery and steelmaking plant. Besides, several studies have been done on indirect reduction of $CO_2$ emission from recycle of reducing gas (carbon monoxide or hydrogen containing gas) in the plants. Unlike many competing gas separation technologies, pressure swing adsorption (PSA) and membrane filtration are commercially used together or individually to separate a single component from the gas mixture. However, there are few studies on operation of sequential separation process of multi-component gas which has more than two target gas products. In this paper, process simulation model is first developed for two available configurations: $CO_2$ PSA-CO PSA-$H_2$ PSA and $CO_2$ PSA-CO PSA-$H_2$ membrane. Operation optimization and economic evaluation of the processes are also performed. As a result, feed gas contains about 14% of $H_2$ should be used as fuel than separating $H_2$, and $CO_2$ separation should be separated earlier than CO separation when feed gas contains about 30% of $CO_2$ and CO. The simulation results can help us to find an optimal process configuration and operation condition for separation of multicomponent gas with $CO_2$, CO, $H_2$ and other gases.

• Journal of the Korean Chemical Society
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• 제23권5호
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• pp.277-285
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• 1979

CNDO/2 calculations on $XC_6H_4CH_2Cl,\;where\;X = H,\;p-CH_3,\;p-NH_2\;and\;p-NO_2$, and on benzyl radicals, cations and anions have been carried out in order to investigate nonlinear Hammett behavior. Main conclusions reached are: 1. Benzyl chloride exhibits borderline behavior due to ${\sigma}-{\pi}$ conjugation between C-Cl bond and the ring-system. 2. The extent of mutual conjugation can be judged by $\pi$-charge and bond alternation and interfrontier level separation narrowing effects. 3.The electron donating para substituent reduces the HOMO AO coefficient of the benzylic carbon, while the electron withdrawing para substituent reduces the LUMO AO coefficient of the benzylic carbon.

• Applied Chemistry for Engineering
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• 제16권6호
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• pp.848-852
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• 2005

The two important problems to solve before the industrialization of the iodine-sulfur (IS) process are (i) methods to separate $H_2SO_4$ and HI and (ii) to maintain constant components. However undesired reaction was occurred and $H_2S$ and S were formed during the Bunsen reaction. It is necessary to forbid the undesired reaction between $H_2SO_4$ and HI by separating the two acids into two different layers. The experimental conditions for the present study was chosen in such a way that to achieve the separation between the two acids and minimize the side reaction. $H_2S$ formation was reduced and the separations of the two liquids were occurred at $H_2O$ molar fraction from 0.86 to 0.909. But the separations between the two liquids were not occurred at $H_2O$ molar fraction more than 0.92.