• Korean Chemical Engineering Research
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• v.49 no.4
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• pp.498-504
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• 2011

In this research, hollow fiber membranes were used in order to investigate to permeation and selectivity of the $CH_4$ and $N_2$. Polyimide and polyethersulfone hollow fiber membrane were prepared by the dry-wet phase inversion method and the module was manufactured by fabricating fibers after surface coating with silicone elastomer. The scanning electron microscopy (SEM) studies showed that the produced fibers typically had an asymmetric structure. The permeance of $CH_4$ and $N_2$ were increased with pressure and temperature. However, the selectivity was decreased with increasing temperature. The permeances of $CH_4$ and $N_2$ were decreased with increasing the air gap and the effect of post-treatment on membrane showed the increase in permeance up to 3.2~7.0 times.

• Membrane Journal
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• v.20 no.2
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• pp.127-134
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• 2010

This study is conducted about the system that reduces organism after fermenting food waste from a food waste disposal equipment, divides gas made when food waste is fermented into gas and water, and then sends gas to a reactor again, condenses water, and apply it to the MBR system with submerged MF hollow fiber membranes. A submerged MF hollow fiber membrane module was installed to a food waste disposal equipment and a water treatment system made by Bio Hitech Co,. Ltd. to process food waste generated from a staff cafeteria in a H institute for 90 days. For initial seeding of a food waste disposal equipment, 305 kg of rice bran, chaff, and sawdust as well as 1,648 kg of food were input during the operation, and 1,600 L of condensed wastewater occurred. Fermented by-product after finishing running a food waste disposal equipment was 386 kg and its reduction was shown to be 80%. The organism was processed by applying submerged MF hollow fiber membrane module to the MBR system of condensed wastewater, and the result shows reduction rates were BOD 99.9%, COD 97.5%, SS 98.6%, T-N 54.6% and T-P 34.7% and the total colon bacillus was perfectly eliminated.

• Membrane Journal
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• v.26 no.3
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• pp.220-228
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• 2016

Carbon molecular sieve (CMS) hollow fiber membranes were prepared by carbonizing a polyimide precursor manufactured by non-solvent induced phase separation process. Gas separation performance of CMS hollow fiber membrane was investigated on the effect of three carbonization conditions. CMS membrane with the highest gas separation performance was obtained at the pyrolysis temperature of $250-450^{\circ}C$: $N_2$, $SF_6$, and $CF_4$ permeance were 20, 0.32, 0.48 GPU, respectively, and $N_2/SF_6$ and $N_2/CF_4$ selectivities were 62 and 42, respectively. In the $SF_6/CF_4/N_2$ mixture gas test, when the stage cut was 0.2, the recovery ratio of $SF_6$ and $CF_4$ was over 99% and 98%. $SF_6$ concentration ratio was 4.5 times higher than the $SF_6$ concentration at the feed side. From the results, it was concluded that CMS membrane was one of the promising membranes for recovery Perfluorocompound gases process.

• Applied Chemistry for Engineering
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• v.25 no.3
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• pp.274-280
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• 2014

Polysulfone (PSf) hollow fiber membranes were prepared via the nonsolvent induced phase separation technique. The cosolvent of ${\gamma}$-butyrolactone (GBL) was added to the polymer solution containing a mixture of PSf and N,N-dimethylacetamide (DMAc). Water was utilized as a precipitation nonsolvent. The morphology of prepared membranes was investigated using a field emission scanning electron microscopy. The fabricated membrane showed a typical asymmetric structure such as the dense layer on the porous support layer by the addition of GBL to the polymer solution. As the concentration of GBL increased, the asymmetric porous structure was shown to be more intensified. It was thought that the added GBL played a role of enhancing the liquid-liquid phase separation of the polymer solution, since the cosolvent of GBL might change the thermodynamic solubility parameter of the doping solution. Permeation properties through the prepared hollow fiber membranes were characterized by measuring the pure water flux and the solute rejection using $0.05{\mu}m$ polystyrene latex (PSL) beads. Experimental results revealed that the use of PEG as the internal coagulant enhanced the pure water flux up to 130 times compared to the use of EG while the rejection of the PSL beads decreased only 5%.

• Membrane Journal
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• v.20 no.4
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• pp.320-325
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• 2010

This paper was carried out to study the preparation condition and the permeation flux of reinforced poly(vinylidene fluoride) (PVDF) hollow fiber microfiltration (MF) membrane with the solvent, additive, second miscible polymer, and preparation condition used poly(vinylidene fluoride) (PVDF) such as a material with the excellent chemical stability and the milder preparation condition. The performance of the reinforced MF membrane prepared obtained the average $0.3{\mu}m$ pore size, $42kg_f/cm^2$ tensile strength, and the high water flux of 600 LMH. The change of membrane performance with various additives was considerably affected on the water flux and rejection. For hydrophilic modification of hydrophobic PVDF MF membrane, the MF membrane might be prepared with a prefer water flux and rejection by addition of hydrophilic poly(methyl methacrylate) (PMMA).

• Membrane Journal
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• v.28 no.6
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• pp.395-405
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• 2018

Poly(ethylene-co-vinylalcohol) EVOH hollow fiber membranes were successfully fabricated via a thermally induced phase separation (TIPS) method. It was observed that all membranes fabricated under different spinning conditions had interconnected and bicontinuous structures through liquid-liquid phase separation. Glycerol and poly(ethylene glycol) 200 were used as diluents for the TIPS method. Glycerol was used as a mixing component in quenching bath to control pores on the outer surface of the hollow fiber membrane. Hot quenching bath with a mixing component to generate large pores on the outer surface of the hollow fiber membrane. The effects of polymer concentration, diluent and quenching bath on the morphologies, water permeabilities, and mechanical properties of the EVOH hollow fiber membranes were systematically investigated. The relationship between water permeability, mechanical properties and spinning conditions was discussed in detail.

• Polymer(Korea)
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• v.27 no.4
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• pp.307-312
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• 2003

Hollow fiber was prepared from the blend of a high density polyethylene (HDPE)/ultra high molecular weight polyethylene (UHMWPE). The changes in the morphology and mechanical property of the hollow fiber were investigated. The commercial product (Sterapore), having a high water permeability, was analyzed with viscosity measurement and FT-IR. The molecular weight of Sterapore was very high and its surface was coated with a vinyl alcohol/vinyl acetate copolymer. The content of UHMWPE in the HDPE/UHMWPE blend was limited below 10 wt%. In order to improve the dispersion of UHMWPE, a mineral oil should be introduced in the blend. The morphology and mechanical property of the hollow fiber of HDPE/UHMWPE blend were similar to those of the commercial product.

• Korean Chemical Engineering Research
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• v.48 no.5
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• pp.660-667
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• 2010

In this research polyimide, Matrimid 5218, hollow fiber membrane was used to recover sulfur hexafluoride($SF_6$) which is one of the six greenhouse gases from $N_2/SF_6$ mixture gas. Fibers were spun from using dry-wet phase inversion method. The module was manufactured by fabricating fibers after surface coating with silicone elastomer. The scanning electron microscopy(SEM) studies showed that the produced fibers typically had an asymmetric structure; a dense top layer supported by a sponge-like substructure. The developed module had a permeance of 0.78-1.36 GPU for $N_2$ with $N_2/SF_6$ selectivity of 2.44-5.08 at various pressure and temperature. For recovery of $SF_6$, a membrane module and 10 vol.% $SF_6$ from $N_2/SF_6$ mixture gas was used. The effects of various operating condition such as pressure, temperature, and retentate side flow rate were tested. When pressure and temperature were increased and retentate flow rate was decreased, the $SF_6$ purity in recovered gas was increased up to 37.5 vol.% with decreasing recovery ratio. When retentate flow rate was increased pressure and temperature was decreased, the $SF_6$ recovery ratio in retentate side was increased up to 89% with decreasing the $SF_6$ purity in retentate side.

• Membrane Journal
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• v.15 no.3
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• pp.224-232
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• 2005

The use of the lung assist device (LAD) would be well suited for acute respiratory failure (ARF) patients, combining the simplicity of mechanical ventilation with the ability of extracoporeal membrane oxygenators (ECMO) to provide temporary relief for the natural lungs. This study's specific attention was focused on the effect of membrane vibration in the LAD. Quantitative experimental measurements were performed to evaluate the performance of the device, and to identify membrane vibration dependence on blood hemolysis. We tried to decide upon excited frequency band of limit hemolysis when blood hemolysis came to through a membrane vibration action. The excited frequency of the module type 5, consisted of 675 hollow fiber membranes, showed the maximum gas transfer rate. We concluded that the maximum oxygen transfer rate seemed to be caused by the occurrence of maximum amplitude and the transfer of vibration to hollow fiber membranes. It was excited up to $25{\pm}5$ Hz at each blood flow rate of module type 5. We found that this frequency became the 2nd mode resonance riequency of the flexible in blood flow. Blood hemolysis was low at the excited frequency of $25{\pm}5$ Hz. Therefore, we decided that limit hemolysis frequency of this LAD was $25{\pm}5$ Hz.

• Membrane Journal
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• v.22 no.1
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• pp.23-34
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• 2012

In this study, we investigated the permeation property of single gases ($N_2$, $O_2$, $SF_6$, $CF_4$ through hollow fiber polymeric membrane (PSF, PC, PI) as a function of pressure and temperature to decide operating condition for $SF_6$ gas separation process. The results showed the gas permeation varied differentlydepending on the properties of gases and membrane. When permeance of each gases was represented as a function of temperature and pressure in 3 dimensional space, the surface of permeance was shown approximately flat. Thus, we established permeance models with forms of first-and second-order polynomial. These two models showed high goodness of fit. This indicates that the two polynomial models have enough applicability to predict the gas separation process.