• Journal of Korean Society of Environmental Engineers
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• v.35 no.2
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• pp.144-150
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• 2013

Hybrid ceramic membrane (HCM) processes that combined ozonation with a ceramic membrane (CM) or a reactive ceramic membrane (RM), an iron oxide nanoparticles (IONs) incorporated-CM were investigated for membrane fouling control. Alumina disc type microfiltration and ultrafiltration membranes doped with IONs by sintering method were tested under varying mass fraction of IONs. Scanning electron microscope (SEM) images showed that IONs were well-doped on the CM surface and doped IONs were approximately 50 nm in size. Change in the pure water permeability of RM was negligible compared to that of CM. These results indicate that IONs incorporation onto CM had little effect on CM performance in terms of the flux. Natural organic matter (NOM) fouling and fouling recovery patterns during HCM processes confirmed that the RM-ozonation process enhanced the destruction of NOM and reduced the extent of fouling more than the CM-ozonation process by hydroxyl radical formation in the presence of IONs on RM. In addition, analyses of NOM in the feed water and the permeate showed that the efficiency of membrane fouling control results from the NOM degradation during HCM processes; leading to removal and transformation of relatively high contents of aromatic, high molecular weight and hydrophobic NOM fractions.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2000.04b
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• pp.357-364
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• 2000

The three main processes involved in the design of stressed membrane surface are surface form-finding, stress analysis and cutting pattern generation. The last process, cutting pattern generation, is considered as a very important procedure in the aspect of the practical design for the fabric membrane surface. In this paper, The cutting pattern generation technique using the geodesic line algorithms is first introduced. And the numerical examples resulting from this technique are presented. Cable elements are used for the approximating membrane surface and two kinds of model, square line and central line model, are used in pattern generation. Finally, a number of different cutting pattern generation for the same membrane surface is carried out and the numerical results are compared each

• Journal of the Korean Ceramic Society
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• v.32 no.3
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• pp.349-358
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• 1995

The ceramic composite membrane was synthesized by thermal oxidation after evaporation of Al on the support prepared by slip casting process. Oxidation was performed at $700^{\circ}C$ and 80$0^{\circ}C$ under dry oxygen atmosphere. It was considered as optimum oxidation condition that the membrane showed a knudsen behaviro. A further oxidation resulted in an increase of gas permeability because top layer became densified. Then, a multi-layered composite membrane was synthesized through a sol-gel method, evaporation and thermal oxidation of Al coating processes. While the membrane was thermally stable up to 80$0^{\circ}C$, gas permeability was rapidly decreased even at a slight amount of deposition of Al.

• Membrane and Water Treatment
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• v.5 no.1
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• pp.41-56
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• 2014

A series of microporous PVDF membranes were prepared by isothermal immersionprecipitation of PVDF/TEP casting dopes in both soft and harsh coagulation baths. Morphologies of the membranes' top surfaces were found to depend strongly on the bath strength, which could be controlled by the TEP content in the bath. By changing the bath gradually from pure water to 70% TEP, the top surface evolved from a dense skin-like (asymmetric) to a totally open porous morphology (symmetric). The latter structure could similarly be obtained by precipitation of the same dope in an alcoholic bath, e.g., 1-butanol. Membrane distillation processes to desalt sodium chloride aqueous solutions were conducted using various prepared membranes and two commercial microporous membranes, PTFE (Toyo, Japan, code: J020A330R) and PVDF (GE, USA, code: YMJWSP3001). The permeation fluxes were compared and correlated with the morphologies of the tested membranes.

• Membrane and Water Treatment
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• v.7 no.2
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• pp.143-154
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• 2016

Acetic acid can be removed from wastewater by esterification in a membrane reactor. Pervaporation membrane reactor (PVMR) is an alternative process to conventional separation processes. It is an environmentally friendly process. The main advantages of the PVMR are simultaneous water removal and production of an ester economically. In this study, the synthetic wastewater has been used. Esterification reaction of acetic acid with isopropanol has been studied in the presence of tungstosilicic acid hydrate as a catalyst in a batch reactor and in a PVMR. The effects of important operating parameters such as reaction temperature, initial molar ratio of isopropanol to acetic acid and catalyst concentration has been examined. Removal of acetic acid (conversion of acetic acid) was obtained as 85% using a PVMR by removal of water from the reaction mixture.

• Membrane and Water Treatment
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• v.7 no.5
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• pp.433-449
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• 2016

The successful application of cleaning protocols is vital for optimized filtration processes. A series of experiments with an ultrafiltration ceramic tubular membrane were carried out for the foulants dextran and carboxymethyl cellulose. Firstly, the impact on fouling of concentration changes was investigated with the increase in resistance being used as the key parameter. In the second phase, removal of reversible fouling was also investigated by employing intermittent rinsing consisting of a cold water rinse followed by a hot one. A comparative analysis for both foulants is reported. Across a range of concentrations and for both foulants, the reduction in resistance due to rinsing was found to depend upon concentration (C); it changed as $C^n$ where n was found to be 0.3. A plausible semi-theoretical explanation is given. Thirdly, for both foulants, the application of a combination of strong alkaline solutions with oxidizing agent (mainly sodium hypochlorite) followed by acid was found to be appropriate for cleaning of the ceramic membrane. The effect of increased temperature for cleaning agents followed by a warm water rinse contributed positively to the cleaning capability.

• Proceedings of the Membrane Society of Korea Conference
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• 1995.09a
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• pp.21-22
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• 1995

Gas separation science and technology is among the most rapidly growing areas involving membrane-based processes. Nitrogen enrichment of air, hydrogen recovery from a broad array of stream types, and removal of acid gases from natural gases are typical of the applications in this field. Great progress has been made in the discovery of guidelines optimization of polymer structures with simultaneously high permeabilities and selectivities for these important gas pairs. The development of thin-skinned asymmetric hollow fibers have also provided structures with extremely high permeation fluxes. Especially in the case of O$_{2}$/N$_{2}$ separations, the rate of improvements in new polymeric materials for gas separations appears to be slowing to a halt. Evidence will be presented, however, that the practical tradeoff between membrane permeability and selectivity has not been reached.

• Proceedings of the Membrane Society of Korea Conference
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• 1995.10a
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• pp.94-100
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• 1995

In recent years it has become necessary to design water management system to minimize water consumption as well as satisfy more stringent environmental requirements. This is mainly due to the seasonal water shortage and environmental problems on water pollution that have taken place at many industrialized regions in Korea. Accordingly, membrane technology in Korea is finding increasing application in the water industry because it has been found to be effective and economic treatment method compared with conventional technology. The membrane processes with the greatest potential for water and wastewater treatment are microfiltration(MF), ultrafiltration(UF), nanofiltration(NF) and reverse osmosis (RO), which utilize pressure differentials.

• Membrane Journal
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• v.2 no.1
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• pp.49-58
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• 1992

Functionalized organic polymers have been used as supports for heterogenized homogeneous catalytic process[1]. Sprcific advantages of using these resins as support reagents have been reviewed[2-4]. These include: -ease of by-product separation from the main reaction product usuallyby simple filtration. -prevention of intermolecular reaction of reactive species or functional groups by simulating high dilution conditions[5]. -utility of the "fish-hook" principle in which a minor component in fished out of a large excess substrate by the insoluble polymer[6]. -the possibility of reusing recovered reagents as well as eliminating the use of volatile or noxious substances[7]. Catalysis by ion-exchange membranes is perhaps one of the latest examples of the use of a polymer-supported species. Conceptually, catalysts on membrane supports offer several possible advantages over traditional powder type systems. They are: (1) Membranes immobilize the catalyst, preventing agglomeration. (2) Filtration is unnecessary for the catalyst separation and so complete catalyst recovery is facilitated. (3) Catalytyic and separation processes can be combined, allowing membrane supported catalysts for the continous flow reactors. reactors.

• Proceedings of the Membrane Society of Korea Conference
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• 1995.06a
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• pp.27-38
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• 1995

Based on innovative membrane module concepts reverse osmosis and nanofiltration are going to become important instruments in environmental engineering. One example is the Disc-Tube-module and its application for the purification of landfill leachate. Currently over 45 different landfills are using this ROCHEM DT-module, in some cases combined with the high pressure reverse osmosis versions of this module, operating at up to 120 bar and 200 bar. This state of the art membrane technology and the DTF-module for nanofiltration, developed by ROCHEM on the basis of the DT-module and RO-systems for the purification of landfill leachate, make possible in hybrid processes permeate recovery rates of more than 97 % with concentration factors up to 40.