• Journal of Korean Society on Water Environment
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• v.21 no.6
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• pp.624-629
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• 2005

The purpose of this study is to investigate the performance of nitrogen removal using autotrophic microorganism in the Membrane-Attached Biofilm Reactor (MABR). The treatment system consists of an aerobic MABR (R1) for nitrification and an anaerobic MABR (R2) for hydrogenotrophic denitrification. Oxygen and hydrogen were supplied through the lumen of hollow-fiber membranes as electron acceptor and donor, respectively. In phase Ι, simultaneous organic carbon removal and nitrification were carried out successfully in R1. In phase II, to develop the biofilm on the hollow-fiber membrane surface and to acclimate the microbial community to autotrophic condition, R1 and R2 were operated independently. The MABRs, R1 and R2 were connected in series continuously in phase III and operated at HRT of 8 hr or 4 hr with $NH_4{^+}-N$ concentration of influent, from 150 to 200 mgN/L. The total nitrogen removal efficiency reached the maximum value of 99% at the volumetric nitrogen loading rate of $1.20kgN/m^3{\cdot}d$ in the combined MABR system with R1 and R2. The results in this study demonstrated that the combined MABR system could operate effectively for the removal of nitrogen in wastewater not containing organic materials and can be used stably as a high rate nitrogen removal technology.

• Biomedical Science Letters
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• v.7 no.4
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• pp.161-166
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• 2001

Most mammalian cells take up glucose by passive transport proteins in the plasma membranes. The best known of these proteins is the human erythrocyte glucose transporter, GLUT1. High levels of heterologous expression far the transporter are necessary for the investigation of its three-dimensional structure by crystallization. To achieve this, the baculovirus expression system has become popular choice. However, Spodoptera frugiperda Clone 9 (Sf9) cells, which are commonly employed as the host permissive cell line to support baculovirus replication and protein synthesis, grow well on TC-100 medium that contains 0.1% D-glucose as the major carbon source, suggesting the presence of endogenous glucose transporters. Furthermore, very little is known of the endogenous transporters properties of Sf9 cells. Therefore, human GLUT1 antibodies would play an important role for characterization of the GLUT1 expressed in insect cell. However, the successful use of such antibodies for characterization of GLUT1 expression m insect cells relies upon their specificity for the human protein and lack of cross-reaction with endogenous transporters. It is therefore important to determine the potential cross-reactivity of the antibodies with the endogenous insect cell glucose transporters. In the present study, the potential cross-reactivity of the human GLUT1 antibodies with the endogenous insect cell glucose transporters was examined by Western blotting. Neither the antibodies against intact GLUT1 nor those against the C-terminus labelled any band migrating in the region expected fur a protein of M$_r$ comparable to GLUT1, whereas these antibodies specifically recognized the human GLUT1. Specificity of the human GLUT1 antibodies tested was also shown by cross-reaction with the GLUT1 expressed in insect cells. In addition, the insect cell glucose transporter was found to have very low affinity for cytochalasin B, a potent inhibitor of human erythrocyte glucose transporter.

• Clean Technology
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• v.21 no.1
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• pp.12-21
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• 2015

Development of novel conducting polymers (CPs) is expected to facilitate the advancement of functional materials used for energy, environmental, and nanotechnology. Recent research efforts are focused on doping CPs with functional dopants to enhance their performance or add additional functions that are not inherent in CPs. This review surveys literatures about the doped CPs focusing on the roles of functional dopants, unlike other reviews focusing on the development of new conducting polymer backbones. The functional dopants presented in this review include redox active molecules, carbon nanomaterials, biopolymers, and chelating molecules. Depending on the dopants and their physicochemical properties, the doped CPs can be used for a variety of applications such as polymer batteries, membranes for waste water treatment, and chemical sensors. A major challenge of the CPs is presented and the ways to overcome the challenge is also suggested for the future development of stable, high performance CPs.

• Membrane and Water Treatment
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• v.6 no.3
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• pp.237-249
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• 2015

In this study we investigate a laboratory scale vacuum membrane distillation system to produce pure water from model oil in water emulsion. Experimental determination of liquid entry pressure (LEP) of a commercial Durapore$^{TM}$ GVPH flat sheet membrane using model emulsions in various oil concentrations has been carried out. Two different methods of liquid entry pressure determination - a frequently used, so-called static and a novel dynamic method - have been investigated. In case of static method, LEP value was found to be 2.3 bar. No significant effect of oil content on LEP was detected up to 3200 ppm. In contrast, LEP values determined with dynamic method showed strong dependence on the oil concentration of the feed and decreased from 2.0 bar to a spontaneous wetting at 0.2 bar in the range 0-250 ppm, respectively. Vacuum membrane distillation tests were also performed. The separation performance is evaluated in terms of flux behavior, total organic carbon removal and droplet size distribution of the feed and final retentate. No significant effect of oil content on the flux was found ($5.05{\pm}0.31kgm^{-2}h^{-1}$) up to 250 ppm, where a spontaneous wetting occurred. High separation performance was achieved along with the increasing oil concentration between 93.4-97.0%.

• Membrane Journal
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• v.8 no.4
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• pp.228-234
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• 1998

Among various water contaminents, organic compounds like phenol are difficult to be removed or destroyed by conventional methods under the unusual discharge conditions. The separation of phenol from aqueous solution has been carried out by several methods recently: absorption by an activated carbon, solvent extraction and liquid membrane technology. The liquid membrane based on water-oil emulsification has been tested as an alternative technology of the conventional technology. In this work, tri-n-butyl phosphate(TBP) and liquid polymers were examined as a liquid membrane in the supported liquid membrane(SLM). The feed concentration of phenol was varied and various types of liquid membranes were used to examine their effects on separation of phenol. It was found that TBP, polypropylene glycol 4000(PPG 4000) and polybutytene glycol 500(PBG 500) were proper carriers because mass transfer rates through them were much higher than or similar to that through methyl isobutyl ketone(MIBK) which was used as a conventional solvent in a solvent extraction process.

• Membrane Journal
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• v.22 no.1
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• pp.1-7
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• 2012

We make a studyof the hydrogen permeability and chemical stability of $Nb_{56}Ti_{23}Ni_{21}$ metal alloy membrane. For this purpose, we produced the $Nb_{56}Ti_{23}Ni_{21}$ membrane which has 10 mm diameter and 0.5 mm thick, and experiment the hydrogen transport properties under two kinds of feed gas ($H_2$ 100%; $H_2$ 60% + $CO_2$ 40%) at $450^{\circ}C$C with variation of absolute pressure.The maximum hydrogen permeation flux was $5.58mL/min/cm^2$ in the absolute pressure 3 bar under pure hydrogen. And each case of feed gases about gas composition, the permeation fluxes were satisfied with Sievert's law, and the hydrogen permeation flux decreased with decrease of hydrogen partial pressure irrespective of temperature and pressure. After permeation test, we experiment the stability and durability of $Nb_{56}Ti_{23}Ni_{21}$ alloy membrane for carbon dioxide by XRD analysis.

• Journal of Adhesion and Interface
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• v.20 no.3
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• pp.110-115
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• 2019

Graphene oxide has been gathering interests as a way to exfoliate graphene. Since the oxidation group of graphene oxide can hydrogen bond with various functional groups, tremendous efforts have been actively conducted to apply various applications. However, graphene oxide alone cannot substantially possess the mechanical properties required for the practical application. Therefore, in this study, polydopamine, which is a bio-mimetic mussel protein-inspired material, was combined with graphene oxide to form a large-area composite membrane at the liquid-gas interface. In addition, the morphology of the polydopamine-graphene oxide composite thin film was also controlled to obtain a composite membrane having a nano-wrinkle structure. It can be expected to be used in the next generation seawater desalination membranes or carbon composites because it can form mechanically superior and sophisticated nanostructures.

• Membrane Journal
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• v.29 no.1
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• pp.1-10
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• 2019

Poly(ether block amide) (PEBA) is one of the commercially important class of block copolymer very much suitable specifically for $CO_2$ separation. Gas separation membrane need to have good mechanical strength as well as high gas permeability. The crystalline polyamide (PA) block provides the mechanical strength while the rubbery polyether (PE) group being $CO_2$-philic facilitate $CO_2$ permeation though the membrane. Composition of thermoplastic and rubbery phase in the polymer are changed to fit into suitable gas separation application. Although PEBA has good permeability, the selectivity of the membrane can be enhanced by incorporating molecular sieve without affection much the gas permeability. Mixed matrix membrane (MMM), a class of composite membrane combine the advantage of polymer matrix with the inorganic fillers. However, there are some disadvantages based on the compatibility of the inorganic fillers and polymeric phase. This review covers both the advantage and limitations of PEBA block copolymer based composite membrane.

• Membrane Journal
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• v.32 no.1
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• pp.13-22
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• 2022

Ever increasing global energy demand gives rise to uncontrollable environmental pollution. Demand on fossil fuel and consequent carbon emission leads to global warming and climate change. Nuclear energy is an alternative source to generate clean energy but mining of nuclear fuel is associated with harmful chemicals. Mining of valuable minerals from sea water by membrane separation process is a cost effective along with environmental friendly process. Separation and adsorption based mining of valuable minerals from sea water are another efficient process. Recovery of actinides from rare earth elements are very challenging and expensive process. Pressure driven membrane separation process is economically more viable along with environmental process. In this review membrane separation process are based on polyether sulfone, polyamide, polyimide, polyamidoxine and hybrid membranes. In case of adsorption process, mainly amidoxime kind of adsorbent are discussed.

• Korean Chemical Engineering Research
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• v.54 no.5
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• pp.653-658
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• 2016

Poly(ether-block-amide)(PEBAX$_{(R)}$) resin is a thermoplastic elastomer combining linear chains of hard-rigid polyamide block interspaced soft-flexible polyether block. It was believed that the hard polyamide block provides the mechanical strength and permselectivity, whereas gas transport occurs primarily through the soft polyether block. The objective of this work was to investigate the gas permeation properties of carbon dioxide and methane for PEBAX$^{(R)}$-1657 membrane, and compare with those obtained for other grade of pure PEBAX$^{(R)}$, PEBAX$^{(R)}$-2533 and PEBAX$^{(R)}$ based hybrid membranes. The hybrid membranes based PEBAX$^{(R)}$ were obtained by a sol-gel process using GPTMS ((3-glycidoxypropyl) trimethoxysilane) as the only inorganic precursor. Molecular structure and morphology of membrane were analyzed by $^{29}Si$-NMR, DSC and SEM. PEBAX$_{(R)}$-2533 membrane exhibited higher gas permeability coefficients than PEBAX$^{(R)}$-1657 membrane. This was explained by the increase of chain mobility. In contrast, ideal separation factor of $CO_2/CH_4$ for PEBAX$^{(R)}$-1657 membrane was higher than PEBAX$^{(R)}$-2533 membrane. It was explained by the decrease of diffusion selectivity caused by increase of chain mobility. For PEBAX$^{(R)}$/GPTMS hybrid membrane, gas permeability coefficients were decreased with reaction time. Gas permeability coefficient of $CH_4$ was more significantly decreased than $CO_2$. It can be explained by the reduction of chain mobility caused by the sol-gel process, and strong affinity of PEO segment with $CO_2$. Comparing with pure PEBAX$^{(R)}$-1657 membrane, ideal separation factor of $CO_2/CH_4$ for PEBAX$^{(R)}$/GPTMS hybrid membrane has decreased to 4.5%, and gas permeability coefficient of $CO_2$ has increased 3.5 times.