• Membrane Journal
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• v.17 no.3
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• pp.269-275
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• 2007

Sodium type faujasite(FAU) zeolite membranes with a thickness of 5${\mu}m$ and a Si/Al molar ratio of 1.5 were prepared by the secondary growth process. The $CO_2/N_2$ separation in the vacuum mode was investigated at $30^{\circ}C$ for an equimolar $CO_2-N_2$ mixed gas before and after embedding 13X zeolite beads in the permeate side. The embedded 13X zeolite beads improved both $CO_2$ permeance and $CO_2/N_2$ separation factor, simultaneously. The phenomenon was explained by an increment in the $CO_2$ desorption rate at the FAU zeolite/$\alpha-Al_2O_3$ phase boundary due to an enhanced $CO_2$ escaping through the pore channels of the $\alpha-Al_2O_3$ support layer. In the present paper, it will be emphasized that a hybridization of a membrane with an adsorbent can provide a key to break through the trade-off between permeance and separation factor, generally shown in a membrane separation.

• Korean Membrane Journal
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• v.6 no.1
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• pp.16-23
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• 2004

The silica containing carbon (C-SiO$_2$) membranes were fabricated using poly(imide siloxane) (PIS) having -CO- swivel group. The characteristics of porous C-SiO$_2$ structures prepared by the pyrolysis of poly(imide siloxane) were related with the micro-phase separation between the imide block and the siloxane block. Furthermore, the nitrogen adsorption isotherms of the CMS and the C-SiO$_2$ membranes were investigated to define the characteristics of porous structures. The C-SiO$_2$ membranes derived from PIS showed the type IV isotherm and possessed the hysteresis loop, which was associated with the mesoporous carbon structures, while the CMS membranes derived from PI showed the type I isotherm. For the molecular sieving probe, the C-SiO$_2$ membranes pyrolyzed at 550, 600, and 700$^{\circ}C$ showed the O$_2$ permeability of 924, 1076, and 367 Barrer (1 ${\times}$ 10$\^$-10/㎤(STP)cm/$\textrm{cm}^2$$.$s$.$cmHg) and O$_2$/N$_2$ selectivity of 9, 8, and 12.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.6 no.1
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• pp.25-33
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• 2008

A selective separation of Actirlide(III) by a nPr-BTP/nitrobezene extraction system was studied. The nPr-BTP (2.6-Bis-(5.6-n-propyl-1.2.4-triazin-3-yl)-pyridine) of a environmentally -friendly CHN type was self-synthesized and its compatability with diluent and stability with nitric acid were investigated. At the 0.1M nPr-BTP/nitrobenzene-1M $HNO_3$ and O/A=2, extraction yields of Am used as a representative of Actinide(III) and Eu were about 85% and 8%, respectively, and the other RE elements such as Nd, Ce and Y were extracted less than 3% (separation factor of Am and Eu was about 60). Thus, there was no problems in the selective extraction of Actinide(III) from RE. The stripping yield of Am with 0.05M $HNO_3$ at O/A= 1, however, was about 43% and the maximum stripping yield was 65% at O/A=0.3. It is necessary to develop the stripping system including the stripping agent instead of nitric acid solution.

• Nuclear Engineering and Technology
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• v.16 no.2
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• pp.58-63
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• 1984

Paper electrophoretic separation of octahedrally bonded (Ruc $l_{6}$ )$^{3-}$ has been carried out by using the specially designed migration apparatus. The supporting electrolyte solutions are as follows: 0.1M-HCl $O_4$, 0.05 M-HCl+0.09M-KCl, 0.1M-HCl, 5$\times$10$^{-3}$ M-NTA, 0.01M-HCl, 0.01M-HCl $O_4$, 0.01M-citric acid, 0.01M-K $H_2$P $O_4$+0.01M-N $a_2$HP $O_4$, 0.05M-borax, 0.025M-N $a_2$C $O_3$+0.025M-NaHC $O_3$, 0.01M-N $a_3$P $O_4$, 0.01M-NaOH and 0.1 M-NaOH. The (Ruc $l_{6}$ )$^{3-}$ appears in 2 to 4 peaks and is found in several chemical species such as (RuCl ($H_2O$)$_{5}$ )$^{2+}$, cis and trans (RuC $l_2$($H_2O$)$_4$)$^{1+}$, (RuC $l_3$($H_2O$)$_3$)$^{0}$ , (RuC $l_4$($H_2O$)$_2$)$^{1-}$, (RuC $l_{5}$ ($H_2O$))$^{2-}$ and (RuC $l_{6}$ )$^{3-}$. The retention value has been found to be highest in the 0.025M-N $a_2$C $O_3$+0.025M-NaHC $O_3$ electrolyte solution.n.

• Analytical Science and Technology
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• v.12 no.5
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• pp.370-374
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• 1999

Extraction chromatography was used to scarch optimum separation conditions of terbium. Stationary phase was 2-ethylhexyl-2-ethylhexyl phosphonic acid(HEH[EHP])levextrel (-100~+150 mesh), column size was ${\Phi}20{\times}530mm$ and kept constantly temperature at $50^{\circ}C$, adsorption flow rate of $0.2mL/cm^2{\cdot}min$, elution flow rate of $1.0mL/cm^2{\cdot}min$, column diameter to packing height of 1:15. But to search optimum separation conditions of terbium, it changed the eluent acidity, the loading weight of sample. the composition of sample. In conclusion, acidity was 0.6 N HCl, loading weight of sample was about 5% and composition of sample was $Gd_2O_3(20%)+Tb_4O_7(60%)+Dy_2O_3(20%)$. Moreover purity of separated terbium by ICP-AES analysis was 99.98% in yield of 99.99%.

• KEPCO Journal on Electric Power and Energy
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• v.5 no.3
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• pp.173-179
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• 2019

Cryogenic air separation unit produces various gases such as $N_2$, $O_2$, and Ar by liquefying air. The process also varies with diverse production conditions. The one for SNG production among them has lower efficiency compared to other air separation unit because it requires ultrapure $O_2$ with purity not lower than 99.5%. Among factors that reduce the efficiency of air separation unit, power consumption due to compress air and heat duty of double column were representatives. In this study, simulation of the air separation unit for SNG production was carry out by using ASEPN PLUS. In the results of the simulation, 18.21 kg/s of at least 99.5% pure $O_2$ was produced and 33.26 MW of power was consumed. To improve the energy efficiency of air separation unit for SNG production, the sensitivity analysis for power consumption, purities and flow rate of $N_2$, $O_2$ production in the air separation unit was performed by change of air boosting ratios. The simulated model has three types of air with different pressure levels and two air boosting ratio. The air boosting ratio means flow rate ratio of air by recompressing in the process. As increasing the first air boosting ratio, $N_2$ flow rate which has purity of 99.9 mol% over increase and $O_2$ flow rate and purity decrease. As increasing the second air boosting ratio, $N_2$ flow rate which has purity of 99.9 mol% over decreases and $O_2$ flow rate increases but the purity of $O_2$ decreases. In addition, power consumption of compressing to increase in the two cases but results of heat duty in double column were different. The heat duty in double column decreases as increasing the first air boosting ratio but increases as increasing the second air boosting ratio. According to the results of the sensitivity analysis, the optimum air boosting ratios were 0.48 and 0.50 respectively and after adjusting the air boosting ratios, power consumption decreased by approximately 7% from $0.51kWh/O_2kg$ to $0.47kWh/O_2kg$.

• Membrane Journal
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• v.16 no.2
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• pp.123-132
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• 2006

The PTMSP-silica-PEI composite membranes were synthesized from tetraethoxysilane (TEOS) and poly (1-trimethylsilyl-1-propyne) (PTMSP) by sol-gel process. The PTMSP-silica nanocomposite membranes were characterized by $^1H-NMR$, FT-IR, TGA, XPS, SEM, GPC and gas permeation measurements were accomplished with $H_2,\;O_2,\;N_2,\;CO_2,\;CH_4$. The gases permeability increased with increasing TEOS content. Both the permeability and selectivity of $H_2,\;CH_4$ increased to 15 wt% TEOS. While the permeability of $O_2,\;CO_2$ increased without decrease of selectivity.

• Membrane Journal
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• v.28 no.6
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• pp.424-431
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• 2018

The gas separation performance of a mixed membrane structure based on a mixture of polyethersulfone (PES) and cobalt tetraphenylporphyrin-benzylimidazole (CoTpp-BIm) as an oxygen carrier was investigated. The CoTpp-BIm mixed PES membrane had an asymmetric structure with a mixture of finger structure and sponge-like structure, and the upper surface was dense. The gas separation performance test was carried out using $94%\;N_2$ gas and $6%\;O_2$ mixed gas. Oxygen and nitrogen permeability coefficients were measured at ${\Delta}P$ ranging from 15 to 228 cmHg and the permeate side of the PES membrane was maintained at vacuum level. The oxygen permeability coefficient of CoTpp-BIm mixed PES membranes increased as supplied pressure was decreased. When the supply pressure was 15 cmHg, the gas permeability ($P_{O_2}$) was 6676 Barrer, the $O_2/N_2$ selectivity (${\alpha}$) was 6.1, and the promoting factor (F) was 2.39. Based on these results, it was confirmed that the addition of CoTpp-BIm to the PES film improved the oxygen separation characteristics.

• Korean Membrane Journal
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• v.1 no.1
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• pp.65-72
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• 1999

The surface of polypropylene membrane was modified by plasma treatment using Ar,$N_{2}$, $NH_{2}$ and $O_{2}$ Permeabilities for $CO_{2}$, $N_{2}$ and separation factor for $CO_{2}$ relative to $N_{2}$ were measured. The permeation experiments were performed by a variable volume method at $25^{\circ}C$ and 0.303MPa. The effects of the plasma conditions such as treatement time power input gas flow rate and pressure in the reactor on the transport properties of modified membrane were investigated. The surface of the plasma treated membrane was analyzed by means of FTIR-ATR XPS and AFM. The surface structure of the plasma treated membrane was fairly different from that of the untreated membrane. Although the permeation rates for both $CO_{2}$ and $N_{2}$ decreased with increasing plasma treatement time the separation factor was found to be improved by the plasma treatement. The operating conditions of plasma treatement imposed on membranes had notable effect on the permeability and separation factor.

• Elastomers and Composites
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• v.33 no.1
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• pp.37-43
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• 1998

The permeation of gas through polymer membrane at temperatures above its glass transition, generally occurs by a solution-diffusion mechanism. This mechanism is performed by the affinity difference between polymeric materials and gas molecules, and various technologies, such as copolymerization, impregnation and so on, have been researched to improve the affinity of polymeric material for the gases. In this study, permeability and selectivity for some gases were obtained from steady-state rates of gas permeation through silicone rubber membrane which is prepared by supercritical fluid extraction method. The permeability was measured by the volumetric method proposed by Barrer. Permeability was increased generally with temperature and permeation pressure. Silicone rubber membrane shows a higher permeability to $CO_2$ than to $O_2$, $N_2$. This results probably reflect the relatively high solubility of CO_2 in silicone rubber membrane, which is due to the affinity of $CO_2$ molecules. Since separation powers of $CO_2/N_2$, $CO_2/O_2$ were more than 200, and 100, respectively, it is able to separate $CO_2$ from the air, and the optimum temperature and pres-sure was 328.15 K, 60 cmHg respectively. In future, it is possible that the silicone rubber membrane can be used for separation or concentration of $CO_2$ through experiment for mixed gas separation.