• Membrane Journal
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• v.28 no.3
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• pp.143-156
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• 2018

In this review article, hybrid water/wastewater treatment processes of membrane and photocatalyst were summarized from papers published in various journals. It included (1) membrane photoreactor (MPR), (2) fouling control of a membrane coupled photocatalytic process, (3) photocatalytic membrane reactors for degradation of organic pollutants, (4) integration of photocatalysis with membrane processes for purification of water, (5) hybrid photocatalysis and ceramic membrane filtration process for humic acid degradation, (6) effect of $TiO_2$ nanoparticles on fouling mitigation of ultrafiltration membranes for activated sludge filtration, (7) hybrid photocatalysis/submerged microfiltration membrane system for drinking water treatment, (8) purification of bilge water by hybrid ultrafiltration and photocatalytic processes, and (9) Hybrid water treatment process of membrane and photocatalyst-coated polypropylene bead.

• Membrane Journal
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• v.2 no.2
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• pp.91-103
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• 1992

Synthetic membrane processes are being increasingly integrated into existing reaction, isolation, and recovery schemes for the production of valuable biological molecules. In many cases they are replacing traditional unit processes. The properties of membrane systems which are most often exploited for both upstream and downstream processing and their permselectivity, high surface area per unit volume, are their potential for controlling the level of contact and/or mixing between two separate phases. Advances in both membrane materials and module design and operation have led to better control of concentration polarization and membrane fouling. After presenting some recent advances in membrane materials and fluid mechanics, we demonstrate how membranes have been integrated into cellular and enzymatic reaction schemes. This is followed by a review of established and emerging synergism between biological processes and synthetic membranes.

• Membrane Journal
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• v.17 no.3
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• pp.161-173
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• 2007

Membrane filtration processes are increasingly popular for drinking water treatment that requires high quality of water. Low pressure membrane(LPM) processes such as microfiltration(MF) and ultrafiltration(UF), however, are ineffective in the removal of dissolved organic matter and also membrane fouling is still an important issue to be resolved. High pressure membranes(HPMs) may guarantee better water quality, but at the high energy consumption. Thus, various approaches to combine LPM processes with other physicochemical methods have been recently made to achieve their efficiency to the level comparable to that of HPM processes. In this work, therefore, hybrid processes that coupled MF/UF with coagulation, adsorption, chemical reactions(e.g., chelation and oxidation) are reviewed regarding system design and performance and also membrane surface modifications conducted by grafting and polyelectrolyte multilayer formation were assessed.

• Proceedings of the Membrane Society of Korea Conference
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• 1993.04a
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• pp.25-27
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• 1993

Multiphase equilibrium-based processes for separation and purification generally utilize dispersed systems in which one phase is dispersed in the other as bubbles or drops or thin films. Using microporous membranes, novel techniques have been developed such that multiphase processes can now be carried out in a nondispersive fashion for gas-liquid (Sirkar, 1992) and liquid-liquid (Prasad and Sirkar, 1992) contacting processes. Among such processes, only nondispersive solvent extraction of pollutants using microporous membranes will be of concern here. These processes employ immobilized immiscible phase interfaces at the pore mouths in a microporous membrane. Through such interfaces, solutes are extracted into the solvent as two immiscible phases flow on two sides of a microporous membrane. Many advantages of such a technique over conventional dispersion-based extractors have been summarized (Prasad and Sirkar, 1992).

• Journal of Korean Society of Water and Wastewater
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• v.32 no.4
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• pp.301-307
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• 2018

Membrane distillation (MD) is a thermally driven desalination process with a hydrophobic membrane. MD process has been known to have a lower fouling potential compared to other pressure-based membrane desalination process (NF, RO). However, membrane fouling also occurs in MD process. In this study, the membrane fouling was observed in MD process according to the pre-treatment processes. The filtration and precipitation processes were applied as the pre-treatment to prevent the membrane fouling. The pore sizes of roughing filters were 0.4, 5, 10, 30, and $60{\mu}m$. The concentration of the coagulant was 1.2 mg/L as $FeCl_3$. The membrane fouling on MD membrane was successfully removed with both pre-treatment processes.

• Membrane Journal
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• v.1 no.1
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• pp.93-93
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• 1991

• Membrane and Water Treatment
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• v.13 no.6
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• pp.291-301
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• 2022

In this study, cement/PVDF hollow-fiber hybrid membranes were prepared via a mixed process of diffusion-induced phase separation and hydration. The presence of X-ray diffraction peaks of Ca(OH)₂, an AFt phase, an AFm phase, and C-S-H phase confirmed the hydration reaction. Good hydrophilicity was obtained. The cross-sectional and surface morphologies of the hybrid membranes showed that an asymmetric pore structure was formed. Hydration products comprising parallel plates of Ca(OH)₂, fibrous ettringite AFt, and granulated particles AFm were obtained gradually. For the hybrid membranes cured for different time, the pore-size distribution was similar but the porosity decreased because of blocking of the hydration products. In addition, the water flux decreased with hydration time, and carbon retention was 90% after 5 h of rejection treatment. Almost all the Zn²⁺ ions were adsorbed by the hybrid membrane. The above results proved that the obtained membrane could be alternative as basement membrane for separation application.

• Proceedings of the Membrane Society of Korea Conference
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• 1991.10a
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• pp.47-48
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• 1991

The pressure in RO leads to a concentration difference across the membrane, while the concentration difference in PVAP across the membrane is achieved by applying a vacuum to the downstream compartment. Therefore, it could be possible to compare this two processes using the solution-diffusion mechanism.

• Membrane Journal
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• v.31 no.3
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• pp.170-183
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• 2021

Fouling has continued to be a problem that hinders the effectiveness of membrane properties. To solve this problem of reducing fouling effects on membrane surface properties, different and innovative types of membrane patterning has been proposed. This article reviews on the progress of patterned membranes and their separation process concerning the fouling effects of membranes. The types of separation processes that utilize the maximum effectiveness of the patterned membranes include nanofiltration (NF), reverse osmosis (RO), microfiltration (MF), ultrafiltration (UF), and pervaporation (PV). Using these separation processes have shown and prove to have a major effect on reducing fouling effects, and in addition, they also add beneficial properties to the patterned membranes. Each patterned membrane and their separation processes gave notable results in threshold towards flux, salt rejections, hydrophilicity and much more, but there are also some unsolved cases to be pointed out. In this review, the effects of patterned membrane for separation processes will be discussed.

• Journal of Electrochemical Science and Technology
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• v.14 no.2
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• pp.152-161
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• 2023

Vanadium redox flow batteries (VRFBs) have been considered one of promising power sources for large scale energy storage systems (ESS) because of their excellent cycle performance and good safety. However, VRFBs still have a few challenging issues, such as poor Coulombic efficiency due to vanadium crossover between catholyte and anolyte, although recent efforts have shown promise in electrochemical performance. Herein, the vanadium complexes with various glyme ligands have been examined as active materials to suppress vanadium crossover between catholyte and anolyte, thus improving the Coulombic efficiency of VRFBs. The conventional Nafion membrane has a channel size of ca. 10 Å, whereas vanadium cation species are small compared to the Nafion membrane channel. For this reason, vanadium cations can permeate through the Nafion membrane, resulting in significant vanadium crossover during cycling, although the Nafion membrane is a kind of ion-selective membrane. In this regard, various glyme additives, such as 1,2-dimethoxyethane (monoglyme), diethylene glycol dimethyl ether (diglyme), and tetraethylene glycol dimethyl ether (tetraglyme) have been examined as complexing agents for vanadium cations to increase the size of vanadium-ligand complexes in electrolytes. Since the size of vanadium-glyme complexes is proportional to the chain length of glymes, the vanadium permeability of the Nafion membrane decreases with increasing the chain length of glymes. As a result, the vanadium complexes with tetraglyme shows the excellent electrochemical performance of VRFBs, such as stable capacity retention (90.4% after 100 cycles) and high Coulombic efficiency (98.2% over 100 cycles).