• Membrane and Water Treatment
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• v.10 no.4
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• pp.259-264
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• 2019

Cost effective clay adsorptive microfiltration membranes were synthesized to remove Cr (III) from high polluted water. Raw and calcined bentonite were mixed in order to decrease the shrinkage and also increase the porosity; then, 20 wt% of carbonate was added and the samples, named B (without carbonate) and B-Ca20 (with 20 wt% calcium carbonate) were uniaxially pressed and after sufficient drying, fired at $1100^{\circ}C$ for 3 hours. Then, physical and mechanical properties of the samples, their phase analyses and microstructure and also their ability for Cr(III) removal from high polluted water (including 1000 ppm Cr (III) ions) were studied. Results showed that the addition of calcium carbonate lead the porosity to increase to 33.5% while contrary to organic pore formers like starch, due to the formation of wollastonite, the mechanical strength not only didn't collapse but also improved to 36.77 MPa. Besides, sample B-Ca20, due to the presence of wollastonite and anorthite, could remove 99.97% of Cr (III) ions. Hence, a very economic and cost effective combination of membrane filtration and adsorption technology was achieved for water treatment which made microfiltration membranes act even better than nanofiltration ones without using any adsorptive nano particles.

• Membrane Journal
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• v.28 no.4
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• pp.286-295
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• 2018

A novel multi-valent salt based on polyethyleneimine having molecular weight of 800 (PEI 800) has been synthesized and characterized as forward osmosis draws solute. A reaction intermediate was synthesized by the neutralization reaction of polyethyleneimine and methyl acrylate, and was hydrolyzed with potassium hydroxide to synthesize a water soluble carboxylic acid (potassium salt) polyethyleneimine. NMR spectrometry, viscometry measurements and osmometry measurements was performed to characterize the draw solute. Forward osmosis experiments were done to know whether the solute could be used as a draw solute or not. The result shows comparable water flux and lower reverse salt flux compared with NaCl as a draw solute. We have also demonstrated recycling of the draw solute in the FO-NF integrated process.

• Proceedings of the Membrane Society of Korea Conference
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• 1994.04a
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• pp.23-23
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• 1994

환경에 대한 관심이 높아지는 가운데 용존무기염을 효과적으로 분리하기 위한 많은 기술이 연구되고 개발되었다. 이중 막분리를 이용한 무기염의 제거 방법(역삼투법)은 상변화를 수반하지 않는다는 점에서 많은 주목을 받아왔다. 최근들어서는 2가 이상의 염에 대한 선택적 분리 능력을 가지고 있고, 작동압력이 낮아 에너지 소모가 적은 나노여과법(Nanofiltration)이 폐수나 정수처리에 도입되고 있다. 본 연구는 이러한 나노여과법을 이용하여 무기 염을 제거하는 방법에 관한 것이다. 실험에 사용한 분리 막은 Filmtec사의 NF-40, NF-45 두 가지이고 사용한 모듈은 평탄형과 나관형의 두 가지이다. 대상이 되는 폐수는 소석회 처리 단계를 거친 산 폐수로 주로 $Ca^{2+},So_4^{2-}$등의 2가 이온과 Na, Cl등의 1가 이온으로 구성되어 있다. 여기서 $CaSO_4$는 스케일을 형성할 가능성이 크므로 1가 이온에 비해 제거할 필요성이 크지만, 비교적 용해도가 높고 과포화 되는 성질이 커서 처리에 어려움이 있다. 이러한 폐수를 나노여과하였을 때 NF-45 평판평 막의 경우 농축 인자 2.6 부근에서, NF-40 나관평 막의 경우 농축 인자 3 부근에서 막 투과 유속의 급격한 감소가 관찰되었다. 이 때 용액 내 전도도와 용액 내 입자의 분포 변화를 종합하여, 평판형 모듈과 나관형 모듈의 막 오염 현상에 대한 메커니즘을 제시하였다.

• Membrane Journal
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• v.28 no.1
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• pp.1-20
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• 2018

Fresh water is an important resource for humans, and pressure-driven membrane technology has been widely known as an energy-efficient method to obtain water resource. However, membrane fouling phenomenon, which is one of the major issue during operation, deteriorates membrane permeability. These fouling is usually affected by interaction between surface of membrane and various foulants, therefore, modification of membrane's surface is one of the methods to improve fouling-resistance. This review focuses on the method to modify surface of pressure-driven membranes such as microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO). Specifically, there are two different surface modification methods: (1) adsorption and coating as the physical modification methods, (2) cross-linker, free radical polymerization (FRP), atom transfer radical polymerization (ATRP), plasma/UV-induced polymerization as the chemical modification methods. This review introduces the physico - chemical surface modification methods reported in recent papers and suggests research directions for membrane separation which can increase membrane fouling resistance.

• Proceedings of the Korean Fiber Society Conference
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• 1998.04a
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• pp.354-359
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• 1998

본 연구에서는 분획분자량이 RO막과 UF막 사이에 있는 NF막(Nanofiltration Membrane) 의 특성을 이용하여 앞서의 기초연구$^{1)}$ 를 바탕으로 현장적용을 위한 소현장규모의 실험을 수회 진행하여 실제로 NF막 공정기술의 현장실용화를 위해 검토되어야 할 사항 및 운전시간에 따른 막투과량 거동의 변화 및 온도의존성 등을 검토하였고, 이와 병행하여 염색공장, 염색공단조합, 폐알칼리 수거회사와의 면담을 통하여 머어서 공정 및 머어서 폐수 관련 현황을 조사하여 이를 토대로 분리막 공정의 경제성에 주요 역할을 하는 고농도 가성소다 폐수 수집을 위한 수세방법을 소개하였고 본 기술의 국내 실용화를 위한 문제점 파악 및 현 상황에서의 실용화 최적 방안을 제안하여 보았다.(중략)

• Journal of Korean Society of Water and Wastewater
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• v.29 no.1
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• pp.1-9
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• 2015

A combined treatment system using multiple source water is becoming important as an alternative to conventional water supply for small-scale water systems. In this research, combined water treatment systems were investigated for simultaneous use of multi-source water including rainwater, ground water, river water, and reclaimed wastewater. A laboratory-scale system was developed to systematically compare various combinations of water treatment processes, including sand filtration, microfiltration (MF), granular activated carbon (GAC), and nanofiltration (NF). Results showed that the efficiency of combined water treatment systems was affected by the quality of feed waters. In addition, a simply approach based on the concept of linear combination was suggested to support a decision-making for the optimum water treatment systems with the consideration of final water quality.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.15-20
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• 2003

During operation process of SIES(Selective ion exchange system) at Kori Unit 2, it was impossible to remove radionuclides such as ion form and Ag-110m, etc., because activated carbon and ion exchange resin of this system are fouled easily by suspended solids and oils in liquid radwaste that was flowed in this system. In this study, an experiment to improve quality of water which was flowed in SIES was performed. and design data of Scale-up pretreatment process were secured. Also, each module design for Microfiltration and Nanofiltration unit of the pretreatment process for SIES was performed.

• Proceedings of the KAIS Fall Conference
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• 2005.05a
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• pp.272-273
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• 2005

분리막 기술은 탁월한 처리효율뿐 아니라 안정적으로 용수를 생산할 수 있는 장점이 있기 때문에 용수의 생산을 전통적인 수처리 (Conventional water treatment) 공정에서 역삼투 공정(Reverse Osmosis) 및 나노여과 (Nanofiltration)와 같은 분리막 기술을 활용하는 공정으로 변환하는 추세에 있다. 그러나 분리막 공정은 항상 막오염 현상이 문제점으로 지목되고 있기 때문에 막오염 제어 기술의 확보가 시급한 실정이다. 따라서 본 연구에서는 화학물질의 사용에 따른 2차 환경오염 문제가 발생하는 화학약품이나 물리적인 세정이 아닌 고전압 임펄스 (HVI, High Voltage Impulse) 장치를 이용하여 막오염의 근본적인 문제를 제어하려 한다.

• Membrane Journal
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• v.32 no.5
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• pp.314-324
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• 2022

This study is aimed to design a membrane process that systematically removes contaminants including microplastics in sun-dried salt using a separation membrane. In this study, we selected the separation membrane material, pore size, and module suitable for the sun-dried salt fields, and proceeded with the experiments under the salt fields and laboratory conditions. A pilot plant was constructed and tested in our lab and in the actual saltern with the selected 200 kDa, 4 kDa ultrafiltration membranes, and 3 kDa nanofiltration membranes. Most of the impurities in the sea salt were 0.1 ㎛ in size, and more than 7 types of various microplastics were detected in the impurities. After that, as a result of checking the filtered water through the separation membrane process, no impurities were detected. As a result of comparing the existing sea salt component and the sea salt component prepared with separation membrane filtrate, impurities were effectively removed without change in the sea salt component.

• Membrane Journal
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• v.28 no.3
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• pp.180-186
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• 2018

The nano-composite membranes were prepared onto the polyvinylidene fluoride (PVDF) hollow fiber membranes through twice dip-coating known layer-by-layer method. For the first coating, poly(vinylsulfonic acid, sodium salt)(PVSA) and Poly(styrene sulfonic acid)(PSSA) were used with varying the concentration and ionic strength (IS) and the poly(ethyleneimine)(PEI) as the second coating material was fixed at 10,000 ppm and IS = 0.3. To characterize the prepared nano-composite membranes, the permeabilities and rejection ratio were measured for each 100 ppm NaCl, $CaSO_4$, $MgCl_2$, and 25 ppm MO aqueous solution. The rejections were increased as the concentrations of coating materials increased. And it was confirmed that the salt rejections for PSSA as the coating material were higher than for PVSA. Typically, the permeability, 1.848 LMH and the rejection for MO 76.3% were obtained at the coating conditions of PSSA 30,000 ppm and I.S = 1.0.