• Journal of Korean Society of Water and Wastewater
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• v.30 no.6
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• pp.737-744
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• 2016

The investigation of effects on fouling propensity with various viscosity of feed solutions would be better understanding for forward osmosis (FO) performance since the fouling propensity was directly influenced with solution viscosity. Therefore, this study was focused on the FO fouling with model foultants (humic acid, alginate) by altering solution viscosity with change of ionic strength (I.S) and $Ca^{2+}$ concentrations. In the comparison between humic acid and alginate, as expected, the alginate generally caused more severe fouling (almost 35.8 % of flux reduction) based on the solution characteristics (high viscosity) and fouling patterns (coil and gel layer). However, interesting point to note is that the fouling propensity of alginate was more severe even though it was applied with low viscosity of feed conditions (I.S = 20 mM, $Ca^{2+}=1mM$). This might be due to that crossed linked gel layer of alginate on the FO membrane surface could be best formed in the condition of $Ca^{2+}$ presence and higher I.S, and that is more dominant to fouling propensity than the low viscosity of feed solutions.

• Membrane Journal
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• v.25 no.2
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• pp.132-143
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• 2015

Water is an essential resource for humans, but fresh water becomes scarce due to population growth and contamination of limited resources. Membrane technology has been widely used for water treatment, and forward osmosis is a process which does not need high hydraulic pressure for the operation. However, there are needs for (1) development of novel draw solutes causing low internal concentration polarization and reverse salt flux for high water flux, and (2) development of economic recovery method of the draw solutes in the diluted draw solution. Previous researches on the draw solute include $NaHCO_3$ which can be regenerated by about $60^{\circ}C$ heating, sucrose which can make potable water without additional process, and magnetic nanoparticles which can be regenerated by external magnetic field. Using the principles of forward osmosis process, sea water desalination, wastewater treatment, refinement of proteins, energy generation using pressure retarded osmosis process, preparation of diluted fertilizer, and growing algae for biofuel can be conducted. This paper summarizes characteristics of ideal draw solutes, recovery method of the draw solutes, and various application examples.

• Journal of Korean Society of Water and Wastewater
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• v.30 no.5
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• pp.521-532
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• 2016

Seawater desalination market after global economic crisis has been stalled due to the market uncertainties and decreased demand in desalination. It is important to review the status of the market and to estimate the appropriate share of Forward osmosis-Reverse Osmosis (FO-RO) hybrid desalination technology by figuring out the outlook of the desalination market. Main part of the desalination market will still be MENA (Middle East and North Africa) in the near future due to the fast population increase and high dependency of fossil fuel in the region. The market for FO-RO hybrid technology, however, might be smaller than the conventional SWRO desalination market anyway because of aesthetic issues from using wastewater as raw water and higher costs associated with capex. Therefore, it is essential to improve FO membrane performance and system operation technologies in order to make the hybrid technology attractive compared to the conventional SWRO technology.

• 한국방재학회:학술대회논문집
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• 2010.02a
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• pp.102.1-102.1
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• 2010

대체수자원 중 막여과 기술에 대한 관심이 지속적으로 높아지고 있다. 하지만, 이러한 막여과 기술에는 fouling이 발생시 효율저감, flux저감, 소모에너지 증대 등 문제점이 발생한다. 이러한 fouling저감을 위해 막 표면특성분석을 통한 기초연구가 필요하다고 보고 이 연구를 진행하였다. AFM을 이용하여 CML입자와 막의 상호작용을 통해 초기 막오염 경향을 예측할 수 있다.

• Membrane Journal
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• v.29 no.2
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• pp.111-121
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• 2019

An organic citrate series draw solute was synthesized using diethyl malonate for forward osmosis. The structure of the final compound potassium pentane-1,3,3,5-tetracarboxylate was confirmed by $^1H-NMR$ and $^{13}C-NMR$ analysis. Osmotic pressure, solubility, water permeability and reverse salt flux were measured for the properties of the draw solute. Forward osmosis results showed that the draw solute exhibited higher water flux than other draw solutes of trisodium citrate and tripotassium citrate. Reverse salt flux of all the organic daw solutes was much lower than that of NaCl. The osmotic pressure of the synthesized draw solute was 25% lower than that of NaCl. The solubility of the draw solute was 317 g/ 100 g water, which is 8.8 times higher than that of NaCl. A commercialized nanofiltration membrane was used for the recovery of the draw solute. The draw solute could be effectively recovered at low pressure.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.4
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• pp.357-361
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• 2018

Forward osmosis (FO) process has been attracting attention for its potential applications such as industrial wastewater treatment, wastewater reclamation and seawater desalination. Particularly, in terms of fouling reversibility and operating energy consumption, the FO process is assumed to be preferable to the reverse osmosis (RO) process. Despite these advantages, there is a difficulty in the empirical step due to the lack of separation and recovery techniques of the draw solution. Therefore, rather than using FO alone, recent developments of the FO process have adapted a hybrid system without draw solution separation/recovery systems, such as the FO-RO osmotic dilution system. In this study, we investigated the performance of the hollow fiber FO module according to various operating conditions. The change of permeate flow rate according to the flow rates of the draw and feed solutions in the process operation is a factor that increases the permeate flow rate, one of the performance factors in the positive osmosis process. Our results reveal that flow rates of draw and feed solutions affect the membrane performance, such as the water flux and the reverse solute flux. Moreover, use of hydraulic pressure on the feed side was shown to yield slightly higher flux than the case without applied pressure. Thus, optimizing the operating conditions is important in the hollow fiber FO system.

• Membrane Journal
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• v.28 no.5
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• pp.368-377
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• 2018

The n-nitrilotris(methylene) phosphonic acid (NTPA) potassium salt was synthesized as a draw solute for forward osmosis. NTPA-4K, NTPA-5K and NTPA-6K were synthesized by varying the content of KOH added to NTPA and confirmed by $^1H$-NMR and $^{13}C$-NMR. The osmotic pressure, viscosity, water flux and reverse salt flux were measured to characterize the draw solute. In the forward osmosis process when distilled water was used as a feed solution and 0.5 M of NTPA-4K, NTPA-5K and NTPA-6K were used as a draw solution, the water flux was 35.8, 38.8 and 42.2 LMH, the reverse salt flux was 5.4, 6.9 and 7.4 gMH, respectively. It was confirmed that the water flux was lower than the conventional NaCl draw solution, but the reverse salt flux was much lower. In order to recover the diluted draw solution, nanofiltration was conducted. The results showed that the draw solute could be retained by above 90%.

• Membrane Journal
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• v.24 no.5
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• pp.400-408
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• 2014

This study is to evaluate the performance of draw solutions in forward osmosis desalination using fertilizer as draw solution. Considering osmotic pressure, solubility, and pH, $NH_4NO_3$, $NH_4H_2PO_4$, $(NH_4)_2HPO_4$, KCl, $KNO_3$, and $KHCO_3$ were screened from a comprehensive lists of fertilizer. Their performance were evaluated in terms of pure water permeate flux, reverse solute flux, and specific reverse solute flux for nitrogen and phosphorus. KCl showed the highest pure water permeate flux among the selected fertilizers while $(NH_4)_2HPO_4$ draw solution had the lowest flux. $NH_4H_2PO_4$ showed the lowest reverse solute flux and specific reverse solute flux for nitrogen followed by $(NH_4)_2HPO_4$, $KNO_3$, and $NH_4NO_3$. Although the pure water permeate flux of $NH_4H_2PO_4$ is lower than the other draw solutions, because it contains both nitrogen and phosphorus, and have the lowest reverse solute flux and specific reverse solute flux, it is a promising candidate as draw solution for forward osmosis desalination.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.3
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• pp.301-305
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• 2013

This study aims to design a portable desalination device and discusses the feasibility of the device for overcoming a shortage of safe drinking water. A low-energy, self-supporting, and portable desalination device is designed based on forward osmosis (FO) using an ammonium bicarbonate solution. Experiments with various concentrations of ammonium bicarbonate solution and sodium chloride solution showed that the portable desalination device's performance such as volume and flow rate of desalting water and time required satisfied drinking water standards. The device performance is controlled by varying the concentration and temperature of the solution.

• Polymer(Korea)
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• v.38 no.5
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• pp.626-631
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• 2014

Water purification requires a large amount of energy that can cause pollution problems. For this reason, forward osmosis (FO) has attracted intense interest that required a relatively low amount of energy for water purification. The forward osmosis has a serious problem that it needs drawing agents creating osmotic pressure to extract water from contaminated water. In this study, a copolymer of zwitterionic moiety and an interpenetrating polymer network (IPN) hydrogel based on thermo-responsive polymer hydrogel, poly(N-isopropylacrylamide) (PNIPAM) were prepared and attached on FO membranes, which successfully played the role of drawing agents. In the copolymer hydrogel, its swelling ratio was improved, but thermo-sensitivity was decreased. The swelling ratio and thermo-sensitivity of IPN hydrogel was lowered. We could confirm that swelling ratio is related to osmotic pressure.