• Proceedings of the Membrane Society of Korea Conference
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• 2003.07a
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• pp.95-97
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• 2003

The main purpose of this work is to investigate the performance of membranes for treatment of dyeing wastewater. The microfiltration (MF) membranes (titania-blended polysulfone & alumina) were prepared. The nanofiltration (NF) and reverse osmosis (RO) membranes were kindly supplied by the Sae-Han. In order to reuse the wastewater for dyeing, the effluents were treated by the high flux RO and the fouling resistant RO (FRM) membranes. Also, the NF membrane was used for water reuse in rinsing.

• Membrane Journal
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• v.20 no.2
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• pp.97-105
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• 2010

This study was to evaluate the performance of the Double stage Pore controllable fiber (DP) filter system as the pre-treatment of the RO membrane. The evaluation for the pre-treatment filter was performed through the indirect method, SDI (Silt Density Index) measurement of the filtrate. This study was done during Jan. 3 of 2009 to Dec. 3 of 2009 at OO Water Treatment Plant that was suppling industrial water to plants, and the raw water was contaminated lake water and it was fed to the system after clarification with coagulation. The average turbidity of the feed water and that of the filtrate was 0.79 NTU (0.28~4.01 NTU), and 0.16 NTU (0.04~0.50) respectively. And so the average turbidity removal efficiency was 77%. The filtrate flow rate and the backwash water flow rate was about 230 $m^3$/day and about 8.7 $m^3$/day respectively, and so the backwash rate was 3.8%. The data for some samples were obtained after a few days storage, and it caused the higher turbidity and SDI15 as the storage time was increased. But average SDI value of the filtrate was 3.6 (2.26~5.00) which was lower than minimum value required by the RO membrane manufacturer as the RO feed water to guarantee the life time of the RO membrane. So, the DP filter system was enough for the application as the pre-treatment of the RO membrane.

• Proceedings of the Membrane Society of Korea Conference
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• 1998.10a
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• pp.11-14
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• 1998

1. Introduction : Research progresses in Chemistry and Chemical Engineering have been made during the last decades with important contributions to the industrial development and to the quality of our life. An interesting case is related to the membrane science and technology continuous impact to innovative processes and products, particularly appropriate for a sustainable industrial growth. Membrane operations have been familiar for many years to biologists and chemists working in their laboratorier or studying biological phenomena. Only recently engineers started to operate in' this area. The preparation of asymmetric CA membranes at University of California, Los Angeles in the early 60s is generally recognized as a crucial moment for membranology (1). Loeb and Sourirajan with their discovery of how to increase significantly the permeability of polymeric membranes without significant changes in their selectivity, made realistic the possibility of their use in large scale operations for desalting brackish and sea water by reverse osmosis and for various other molecular separations in different industrial areas. Reverse osmosis is today a well recognized basic unit operations, togheter with ultrafiltration, crossflow microfiltration,. nanofiltration, all pressure driven membrane processes. Already in 1992 more than 4 milIions m$^3$/day were the total capacity of RO desalination plants and in 1995 more than 180.000 m$^2$ of ultrafiltration membranes were installed for the treatment of wheys and milk (2) (3).

• Journal of Korean Society of Water and Wastewater
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• v.35 no.1
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• pp.39-52
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• 2021

The global water shortage is getting more attention by global climate change. And water demand rapidly increases due to industrialization and population growth. Desalination technology is being expected as an alternative water supply method. Desalination technology requires low energy or maintenance costs, making it a competible next generation technology, with examples such as forward osmosis (FO), membrane distillation (MD), capacitive deionization (CDI), and electrodialysis (ED) to compete with reverse osmosis (RO). In order to identify recent research trends in desalination technologies (FO, MD, RO, CDI, and ED) between 2000-2020, a bibliometric analysis was conducted in the current study. The number of published papers in desalination technology have increased in Desalination and Journal of Membrane Science mainly. Moreover, it was found that FO, MD, RO, CDI, and ED technologies have been applied in various research areas including electrochemical, food processing and carbon-based material synthesis. Recent research topics according to the desalination technologies were also identified.

• Environmental Engineering Research
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• v.23 no.4
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• pp.474-484
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• 2018

The cleaning efficiency of reverse osmosis (RO) membranes inevitably fouled by organic foulants depends upon both chemical (type of cleaning agent, concentration of cleaning solution) and physical (cleaning time, flowrate, temperature) parameters. In attempting to determine the optimal procedures for chemical cleaning organic-fouled RO membranes, the design of experiments concept was employed to evaluate key factors and to predict the flux recovery rate (FRR) after chemical cleaning. From experimental results and based on the predicted FRR of cleaning obtained using the Central Composite Design of Minitab 17, a modified regression model equation was established to explain the chemical cleaning efficiency; the resultant regression coefficient ($R^2$) and adjusted $R^2$ were 83.95% and 76.82%, respectively. Then, using the optimized conditions of chemical cleaning derived from the response optimizer tool (cleaning with 0.68 wt% disodium ethylenediaminetetraacetic acid for 20 min at $20^{\circ}C$ with a flowrate of 409 mL/min), a flux recovery of 86.6% was expected. Overall, the results obtained by these experiments confirmed that the equation was adequate for predicting the chemical cleaning efficiency with regards to organic membrane fouling.

• Membrane and Water Treatment
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• v.8 no.6
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• pp.613-623
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• 2017

We report the novel thin film composite RO membrane modified by graphene oxide. The thin film composite RO membrane was exposed to 2000 mg/l sodium hypochloride; thereafter it was subjected to different graphene oxide concentration ranging from 50 mg/l to 1000 mg/l in water. The resultant membrane was crosslinked with 5000 mg/l N-hydroxysuccinimide. The performance of different membranes were analysed by solute rejection and water-flux measurement. It was found that 100 mg/l graphene oxide exposure followed by 5000 mg/l N-hydroxysuccinimide treatment resulted in the membrane with the highest solute rejection of 97.78% and water-flux of 4.64 Liter per sqm per hour per bar g. The membranes were characterized by contact angle for hydrophilicity, scanning electron micrographs for surface morphology, energy dispersive X-Ray for chemical composition of the surface, Atomic force microscope for surface roughness, ATR-FTIR for chemical structure identification. It was found that the graphene oxide modified membrane increases the salt rejection performance after exposure to high-fouling water containing albumin. Highly hydrophilic, antifouling surface formation with the nanomaterial led to the improved membrane performance. Moreover, the protocol of incorporating nanomaterial by this post-treatment is simple and can be applied to any RO membrane after it is manufactured.

• Membrane and Water Treatment
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• v.11 no.5
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• pp.323-331
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• 2020

With the increasing demand on reverse osmosis (RO) membranes for water purification worldwide, the number of disposed membrane elements is expected to increase accordingly. Thus, recycling and reuse of end-of-life RO membranes should be a global environmental action. In this work, we aim to reuse the spent RO membrane for nanofiltration (NF) and ultrafiltration (UF) process by subjecting the spent membrane to solvent and oxidizing solution treatment, respectively. Our results showed that solvent-treated RO membrane could perform as good as commercial NF membrane by achieving similar separation efficiencies, but with reduced water permeability due to membrane surface fouling. By degrading the polyamide layer of RO membrane, the transformed membrane could achieve high water permeability (85.6 L/㎡.h.bar) and excellent rejection against macromolecules (at least 87.4%), suggesting its reuse potential as UF membrane. More importantly, our findings showed that in-situ transformation on the spent RO membrane using solvent and oxidizing solution could be safely conducted as the properties of the entire spiral wound element did not show significant changes upon prolonged exposure of these two solutions. Our findings are important to open up new possibilities for the discarded RO membranes for reuse in NF and UF process, prolonging the lifespan of spent membranes and promoting the sustainability of the membrane process.

• Membrane and Water Treatment
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• v.8 no.4
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• pp.323-336
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• 2017

The main challenge in many applications of acetic acid is acid dehydration and its recovery from wastewater streams. Therefore, the performance of polyamide thin film composite is evaluated to separate acetic acid from water. To reach this goal, the formation of polyamide layer on polysulfone support membrane was investigated via interfacial polymerization (IP) of meta-phenylenediamine (MPD) in water with trimesoyl chloride (TMC) in hexane. Also, the effect of synthesis conditions, such as concentration of monomers and curing temperature on separation of acetic acid from water were investigated by reverse osmosis process. Moreover, the separation mechanism was discussed. The solute permeation was carried out under applied pressure of 5 bar at $25^{\circ}C$. Surface properties of TFC membrane were characterized by ATR-FTIR, SEM and AFM. The performance test indicated that 3.5 wt% of MPD, 0.35 wt% of TMC and curing temperature of $75^{\circ}C$ are the optimum conditions. Moreover, the permeate flux was $4.3{\frac{L}{m^2\;h}}$ and acetic acid rejection was about 43% at these conditions.

• Proceedings of the Membrane Society of Korea Conference
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• 1998.04a
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• pp.124-126
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• 1998

1. INTRODUCTION : With good physical and chemical properties as a membrane material, poly(vinyl alcohol) (PVA) has been widely used for the preparation of several kinds of membranes for different applications. Considering such good physical chemical properties, some people have tried to use it for the formation of reverse osmosis (RO) membranes with a good chemical stability as well as high flux and high rejection rate. However, unfortunately, the performance of the RO membranes based on PVA has not been satisfactory yet. The PVA RO membranes thermally crosslinked have shown very low flux and relatively low salt rejection. In this experiment, ionic polymers such as sodium alginate and chitosan were used together with PVA to increase the nanofiltration performance of the PVA membranes.

• Membrane Journal
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• v.22 no.4
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• pp.235-242
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• 2012

Ammonium perchlorate (AP) is primarily derived from the process of liquid incineration treatment when dismantling a solid rocket propellant. A series of batch dead-end nanofiltration (NF) and reverse osmosis (RO) membrane experiments were conducted to explore the retention mechanisms of AP under various hydrodynamic and solution conditions. Low levels of silicate type of siloxane had been detected through the GC/MS and FTIR analysis of liquid solutions extracted from solid ammonium perchlorate composite propellant (APCP). It is indicated that NF/RO membranes fouling in the presence of APCP was mainly attributed to the AP interactions because the concentration of silicate type of siloxane was negligible compared to that of AP. The osmotic pressure of AP was presumably resulted in the flux declines ranging from 13 to 17% in the case of the application of low-pressure (551 and 896 kPa for NF and RO) compared to those in application of high-pressure. The retention of AP by NF/RO membranes significantly varied from approximately 10 to 70% for NF and 26 to 87% for RO, depending on the operating and solution water chemistry conditions. The results suggested that retention efficiency of AP was fairly increased by reducing concentration polarization (i.e. application of low-pressure and stirring speed of 600 rpm) and increasing the pH of a solution. The result of this study was also consistent with the previous modeling of 'solute mass transfer of NF/RO membranes' and demonstrated that hydrodynamic and solution water chemistry conditions are to be a key factor in the retention of AP by NF/RO membranes.