• Membrane Journal
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• v.32 no.2
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• pp.83-90
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• 2022

Wastewater from refineries and petroleum plant lead to severe environmental pollution. There are various existing processes applied for oily water treatment, but membrane-based technology is one of the most efficient methods. Polymeric membranes prepared from organic materials for the separation of oil in water often face chronic problem of membrane fouling. Inorganic membranes are considered to be more efficient due to longer lifetime than organic membranes. Zeolite membranes have better chemical stability and long-term recyclability. The presence of hydrophilicity enhances the water flux of membrane. Ceramic membranes prepared from zeolites are another efficient class of inorganic membranes applied for oil water separation. This review is focused on oily wastewater separation based on zeolite membrane which classified into two categories, i) neat zeolite and ii) zeolite composites with other materials.

• Membrane Journal
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• v.22 no.1
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• pp.72-76
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• 2012

$SF_6$ has an extremely high global worming potential (GWP). Therefore, there has been an effort to reduce the use of $SF_6$ and its emission into atmosphere. One possible solution for minimizing the use of $SF_6$ in electrical equipments is utilization of gas mixtures such as $SF_6/N_2$. The $SF_6$ concentration in the gas mixture varies from 10 to 60%. However, when the apparatus is repaired or dismantled, we have to recover $SF_6$ from the gas mixture. Since the boiling point of $SF_6$is low (${\sim}-60^{\circ}C$), the liquefaction method is difficult to apply. One possible alternative is the membrane separation technology. In this study, we investigated the $SF_6$ and $N_2$ permeation properties of 5 polymeric membranes. For example, permeability of $N_2$ in BOPP membrane at $25^{\circ}C$was 0.19 barrer, whereas that of $SF_6$ was only 0.0012 barrer, resulting in the selectivity of 158. An upper bound for $SF_6/N_2$ gas pair was suggested for the first time with n = -1.33 and k = 160 (barrer).

• Membrane Journal
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• v.27 no.2
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• pp.189-198
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• 2017

In this study, we used thermally induced phase separation (TIPS) to produce water treatment membrane and poly(vinylidene fluoride) (PVDF), silica with excellent mechanical properties and chemical resistance to evaluate characterization of the membrane. The diluents used for the characterization were dioctyl phthalate (DOP) and dibutyl phthalate (DBP). We observed the crystallization temperature, cloud point and SEM images to see the manufacture conditions according to the ratio of PVDF and silica. The crystallization temperature and cloud point increased with the contents of silica. Through the phase diagram drawn from these results, the conditions for the preparation of the membrane confirmed.

• Journal of Microbiology and Biotechnology
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• v.24 no.1
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• pp.97-105
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• 2014

Quorum quenching (QQ) with a microbial vessel has recently been reported as an economically feasible biofouling control platform in a membrane bioreactor (MBR) for wastewater treatment. In this study, a quorum quenching MBR with a ceramic microbial vessel (CMV) was designed to overcome the extremely low F/M ratio inside a microbial vessel. The CMV was prepared with a monolithic ceramic microporous membrane and AHL-degrading QQ bacteria, Pseudomonas sp. 1A1. The "inner flow feeding mode" was introduced, under which fresh feed was supplied to the MBR only through the center lumen in the CMV. The inner flow feeding mode facilitated nutrient transport to QQ bacteria in the CMV and thus enabled relatively long-term maintenance of cell viability. The quorum quenching effect of the CMV on controlling membrane biofouling in the MBR was more pronounced with the inner flow feeding mode, which was identified by the slower increase in the transmembrane pressure as well as by the visual observation of a biocake that formed on the used membrane surface. In the QQ MBR with the CMV, the concentrations of extracellular polymeric substances were substantially decreased in the biocake on the membrane surface compared with those in the conventional MBR. The CMV also showed its potential with effective biofouling control over long-term operation of the QQ MBR.

• Membrane Journal
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• v.32 no.2
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• pp.100-108
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• 2022

Among various industries, the textile industry uses the largest amount of water for coloring textiles which leads to a large amount of wastewater containing various kinds of dye. There are various methods for the removal of dye such as flocculation, ozone treatment, adsorption, etc. But these processes are not much successful due to the issue of recycling which enhances the cost. Alternatively, the membrane separation process for the treatment of dye in wastewater is already documented as the best available technique. Polymeric membrane and ceramic membrane are two separate groups of separation membranes. Advantages of ceramic membranes include the ease of cleaning, long lifetime, good chemical and thermal resistance, and mechanical stability. Ceramic membranes can be prepared from various sources and natural materials like clay, zeolite, and fly ash are very cheap and easily available. In this review separation of wastewater is classified into mainly three groups: ultrafiltration (UF), microfiltration (MF), and nanofiltration (NF) process.

• Journal of Environmental Science International
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• v.9 no.4
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• pp.331-337
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• 2000

The variation of microorganisms (activated slude, Saccharomyces cerevisiae, Aureobasidium pullulans) caused by the biosorption of $Pb^{2+}$ was observed by TEM and microscope. By the TEM observation of S. cerevisiae, the plasmolysis and lysis of cell wall or cell membrane were occurred by the penetration of $Pb^{2+}$ into the inner cellular region. However, in the case of A. pullulans, the plasmolysis and lysis of cell wall or cell membrane were not occurred because of the prevention of $Pb^{2+}$ penetration by the extracelluar polymeric substances (EPS). A flocculation of microorganisms, in the case of A. pullulans, was observed by the $Pb^{2+}$ accumulation after 3~4 h and the color was changed from white to black after 1 day. The flocculation of activated sludge was improved by the accumulation $Pb^{2+}$ after 1 h, however, the floc was broken up and the settling efficiency decreased after 1 day.

• Macromolecular Research
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• v.17 no.4
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• pp.227-231
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• 2009

New polyelectrolytes derived from poly(amide-sulfone)s and 1,5-dibromopentane were simultaneously fabricated on the electrode by the crosslinking reaction. The substrate was pretreated with a bromoalkyl-containing, silane-coupling agent to anchor the humidity-sensitive membrane to the substrate through the covalent bond. When the resistance dependence on the relative humidity of the crosslinked poly(amide-sulfone)s was measured, the resistance varied by three orders of magnitude between 20%RH and 90%RH, which was the required RH range for a humidity sensor operating at ambient humidity. Their water durability, long-term stabilities under various environments, hysteresis and response and recovery times were measured and evaluated as a humidity-sensing membrane.

• Proceedings of the Membrane Society of Korea Conference
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• 1997.10a
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• pp.27-30
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• 1997

1. Introduction : Molecular diffusion of small molecules in polymers plays an important role in many areas where polymers are acting as barriers, and in separation processes, such as selective diffusion. Different applications of polymers have different requirements on their transport properties. Therefore, reliable predictions of diffusion coefficients for small molecules in polymeric materials could be a useful tool to design appropriate materials. For many years, the theories based on free-volume concepts have been widely used to correlate and predict diffusion behavior in polymer/solvent systems. In the theory derived by Vrentas and Duda, the empty space between molecules that is available for molecular transport, referred to as hole free-volume, is being redistributed. Molecular transport will occur only when a free-volume of sufficient size appears adjacent to a molecule and the molecule has enough energy to jump into this void. The diffusive jump is considered complete when the void left behind is closed before the molecule returns to its original position. In this paper, the Vrentas-Duda free-volume theory is presented and the methods to estimate free-volume parameters for predicting polymer/ solvent diffusion coefficients are described in detail.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.2
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• pp.21-27
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• 2014

Recently, various biochip environments have been presented. In this study, a novel transparent film with porous membrane windows, which is an essential component in a co-cultured biochip environment, is fabricated using spin-coating, 3D printing, and electrospinning processes. In detail, a transparent polystyrene film was fabricated by means of the spin-coating process followed bywindow cutting, after which apolycaprolactone-chloroform solution was deposited along the window edge to introduce an adhesion layer between the PS film and the PCL nanofibers. Nanofibers were electrospun into the window region using a direct-write electrospinning method. Consequently, it was demonstrated that the fabricated window film could be used in a co-culture biochip environment.

• Proceedings of the Membrane Society of Korea Conference
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• 1995.10a
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• pp.43-44
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• 1995

The diffusion behavior of liquid into polymer has been described by Fick's law, but the departure from Fickian diffusion is frequently found. In this study, 'noble' expressions for the rates of relaxation and sorption are introduced to eliminate these limitations. The ralaxation-sorption coupled mechanism model are based on the possibility of contacting liquid molecule and the active site which has the numerical concept of free volume. The concept has an analogy of reaction rate expressed by the possibility of collision with molecules and used in adsorption and reactive extraction etc. The new model simulated by Rungc-Kutta method for initial-value problem and Fickian diffusion is caompared with experimental data. The results show that the ralaxation-sorption coupled mechanism is able to account well for Fickian and non-Fickian sorption behavior including sigmoid and two-stage. In addition, this model has a chance of expansion to multi-component sorption with ease.