• Membrane Journal
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• v.19 no.4
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• pp.333-340
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• 2009

This paper is designed with the purpose of improving the efficiency of the sulfonic acid ion exchange membranes by radiation induced graft polymerization. It has been shown that the porous hollow fiber membranes could cause permeability blocking between pores and ion exchanged graft chains. Addition of crosslinker such as N-ethylene glycol dimethacrylate will permit to increase the permeation flux. In this research, the ethylene glycol dimethacrylate (EDMA) and diethylene glycol dimethacrylate (DDMA) with different length are used as crosslinkers. The ion exchanged cross-linked membrane (EDMA, DDMA) containing sulfonic acid group by radiation induced grafted polymerization are sn died for adsorb metal ions (Pb). It has been shown that adsorbed metal ions ($Pb^{2+}$) for the EDMA and DDMA membranes with the density of sulfonic acid groups, 1.40 mmol/g and 2.14 mmol/g, respectively are 13.82 mg/g, 17.37 mg/g, accordingly.

• Applied Chemistry for Engineering
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• v.10 no.1
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• pp.12-18
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• 1999

This research was undertaken to do the technical and economical feasibility study of membrane water treatment system. For the technical feasibility study, batch water treatment system using UF(ultrafiltration) was set up and several experiments were carried out. The performance of the UF membrane was tested in terms of turbidity. The experimental results showed that the UF membrane process produced less than 1 NTU water regardless of input water turbidity. For the economical feasibility study, the cost model was analyzed and programmed for simulation. Also costs of the membrane water treatment and the conventional treatment were evaluated. The simulation results showed that the unit production cost increased when design flow or permeate flow decreased. The production cost of membrane water treatment system was lower than that of the conventional system. Both technical and economical feasibility study showed that the UF membrane water purification system was a very competitive water purification process.

• Membrane Journal
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• v.33 no.6
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• pp.439-446
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• 2023

Ceramic membranes are generally used for various industrial processes operating under extreme conditions because of its high thermal and chemical stability. However, due to the trade-off phenomenon of permeability and mechanical strength, preparation of high permeability-high strength membrane is necessary. In this study, the change in characteristics and performances of ceramic membranes was analyzed depending on the type of polymer binder and its mixing ratio. Because the solubility between solvent and polymer binder was higher in PSf (polysulfone) than in PES (polyethersulfone), the viscosity and discharge pressure of the PSf-based dope solution were higher than those of PES-based dope solution. When PSf was used as a polymer binder, ceramic membrane showed high mechanical strength and low water permeability due to the dense structure. On the other hand, in case of PES, the mechanical strength was slightly reduced and the water permeability was increased. It was confirmed that the optimum mixing ratio of the PSf and PES with high water permeability and mechanical strength was 9:1.

• Membrane Journal
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• v.21 no.1
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• pp.46-54
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• 2011

In this study, combined effect of airflow rate, $TiO_2$ concentration, solution pH and $Ca^{+2}$ addition on HA (humic acid) fouling in submerged, photocatalytic hollow-fiber microfiltraiton was investigated systematically. Results showed that UV irradiation alone without $TiO_2$ nanoparticles could reduce HA fouling by 40% higher than the fouling obtained without UV irradiation. Compared to the HA fouling without UV irradiation and $TiO_2$ nanoparticles, the HA fouling reduction was about 25% higher only after the addition of $TiO_2$ nanoparticles. Both adsorptive and hydrophilic properties of $TiO_2$ nanoparticles for the HA can be involved in mitigating membrane fouling. It was also found that the aeration itself had lowest effect on fouling mitigation while the HA fouling was affected significantly by solution pH. Transient behavior of zeta potential at different solution pHs suggested that electrostatic interactions between HA and $TiO_2$ nanoparticles should improve photocatalytic efficiency on HA fouling. $TiO_2$ concentration was observed to be more important factor than airflow rate to reduce HA fouling, implying that surface reactivity on $TiO_2$ naoparticles should be important fouling mitigation mechanisms in submerged, photocatalyic microfiltraiton. This was further supported by investigating the effect of $Ca^{+2}$ addition on fouling mitigation. At higher pH (= 10), addition of $Ca^{+2}$ can play an important role in bridging between HA and $TiO_2$ nanoparticles and increasing surface reactivity on nanoparticles, thereby reducing membrane fouling.

• Journal of Chest Surgery
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• v.27 no.9
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• pp.723-731
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• 1994

We have modified the isolated perfused working rabbit lung model [IPWL] by perfusing the isolated lung with a hollow fiber membrane deoxygenator.For assessment the stored lung was ventilated with FIO2 0.4 and perfused with 37$^{\circ}$C deoxygenated circulating blood at a rate 5ml/kg/min for several hours until lung failure.We chose to compare our developing solution which contained low potassium and pentastarch with the modified Euro-Collins solution .Experiments were divided into four groups[n=6] based on the type of flushing preservation solution and preservation time.The flushed lungs were then preserved into same solution at 8~10$^{\circ}$C with 100% O2 inflated condition for 1 or 20 hours.These following results were obtained.The IPWL model requires only one animal per experiment and allows for the continuous assessment of aerodynamic performance. This should therefore be used as screening test in lung preservation.One hour preservation groups, there were no significant difference in recovery rates of PaO2, PAP and Paw. Survival time in the one hour preservation groups were very significant long in the Group II[LPPS, p<0.01]. Twenty hours preservation groups, there were no significant difference in the recovery rates of PAP and Paw between Group III[m-ECS] and Group IV[NS], but PaO2 was significantly worse at onset of reperfusion in Group III when compared with Group IV [p<0.05]. And also survival time in the 20 hours preservation groups were significant long in the Group IV [p<0.05].

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.10
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• pp.1347-1353
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• 2014

It's possible for a human to breathe under water, if dissolved oxygen is effectively used. Fish can stay under water using the gill which extracts dissolved oxygen from water. Water includes small amounts of oxygen, so a human needs larger amounts of water to acquire oxygen enough for underwater breathing. The exhalation gas from a human is another method to get higher amounts of oxygen under water. It mainly composes of oxygen, nitrogen and carbon dioxide. So, if only carbon dioxide is decreased, the exhalation gas has good characteristics for breathing of a human under water. In this paper, composition of the exhalation gas from a human was analyzed using GC. Based on these results, the synthesized gas was prepared and mixed into water which was used for experimental devices to analyze separation characteristics of dissolved gases from water. Experimental devices included a water pump, a hollow fiber membrane module and a vacuum pump. The effects of pressure and water flow on separation characteristics of synthesized gas were investigated. The compositions of gases separated from water using synthesized gas were investigated using GC. These results expect to be applied to the development of underwater breathing technology for a human.

• Food Science and Preservation
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• v.6 no.4
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• pp.424-428
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• 1999

The performance of a 30K polysulfone membrane for clarification of depectinized peach juice was studied Ultrafiltration of peach juice could minimize to loss of flavor and many compounds and was expected to effectively remove precipitation and suspended solid. The results showed that permeate flux increased with the increase of operating pressure and temperature. The permeate flux declined continuously as the process time increased. The values of soluble solid and titratable acidity of permeate were decreased or were at the same level, the turbidity was largely decreased. Total resistance decreased with lower temperature and lower pressure.

• Membrane Journal
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• v.25 no.3
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• pp.223-230
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• 2015

We synthesized novel polyimides with high gas permeability and selectivity for application of gas separation membrane. 2,2-bis(3,4-carboxylphenyl) hexafluoropropane dianhydride (6FDA) and two kinds of amines with high permeability and solubility were used to prepare the novel polymide. 2,4,6-Trimethyl-1,3-phenylenediamine (DAM) was used to improve gas permeability and 4,4-Methylenedianiline was used to improve the gas selectivity respectively. The polyimide copolymers were synthesized by commercial chemical imidization method using Triethylamine and Acetic anhydride and their average molecular weights were over 100,000 g/mol. The glass temperature (Tg) and the thermal degradation temperature were characterized using differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA). The synthesized copolymers showed high Tg over $300^{\circ}C$ and high thermal degradation temperature over $500^{\circ}C$. The gas permeation properties were measured by time-lag equipment. Although general polyimides showed very low gas permeability, synthesized polyimide copolymer showed high $O_2$ permeability of 10.1 barrer with high $O_2/N_2$ selectivity around 5.3. From this result, we confirm that these membranes have possibility to apply to gas separation membrane.

• Applied Chemistry for Engineering
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• v.17 no.5
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• pp.521-526
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• 2006

A membrane bioreactor (MBR) is an effective tool for wastewater treatment with recycling. MBR process has several advantages over conventional activated sludge process (ASP); reliability, compactness, and quality of treated water. The resulting high-quality and disinfected effluents suggest that MBR process can be suitable for the reused and recycling of wastewater. An anoxic/oxic (A/O) type MBR was applied to simultaneous removal of organics and nutrients in sewage. At first, the efficiency of submerged MBR process was investigated using a hollow fiber microfiltration membrane with a constant flux of $10.2L/m^2{\cdot}h$ at each solids retention time (SRT). Results showed that protein/carbohydrate (P/C) ratio increased and total extracellular polymeric substances (EPS) remained constant with SRT increased. Secondly, A/O type MBR with a reverse osmosis (RO) membrane was employed to treat the municipal wastewater. The performance of A/O type MBR-RO process is better for the treatment of organics and nutrients than ASP-MF-RO process in terms of consistent effluents quality.

• Membrane Journal
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• v.32 no.6
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• pp.456-464
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• 2022

Hydrogen permeation performance was analyzed by manufacturing Pd and Pd-Cu membranes through electroless plating. As a support for the Pd and Pd-Cu membranes, α-Al₂O₃ ceramic hollow fiber were used. Pd-Cu membrane was manufactured through sequential electroless plating, and then annealing was performed at 500°C, for 18 h in a hydrogen atmosphere to make Pd and Cu alloy. After annealing, the Pd-Cu membrane confirmed that the alloy was formed through EDS (Energy Dispersive X-ray Spectroscopy) and XRD (X-ray Diffraction) analysis. In addition, the thickness of the Pd and Pd-Cu plating layers were measured to be about 3.21 and 3.72 µm, respectively, through SEM (Scanning Electron Microscope) analysis. Hydrogen permeation performance was tested for hydrogen permeation in the range of 350~450°C and 1~4 bar in hydrogen single gas and mixed gas (H₂, N₂). In a single hydrogen gas, Pd and Pd-Cu membranes have flux of up to 54.42 and 67.17 ml/cm²⋅ min at 450 °C and 4 bar. In the mixed gas, it was confirmed that the separation factors of 1308 and 453 were obtained under the conditions of 450 °C and 4 bar.