• Membrane Journal
• /
• v.32 no.4
• /
• pp.209-217
• /
• 2022

Ion exchange membrane (IEM) is an important class of membrane applied in batteries, fuel cells, chloride-alkali processes, etc to separate various mono and multivalent ions. The membrane process is based on the electrically driven force, green separation method, which is an emerging area in desalination of seawater and water treatment. Electrodialysis (ED) is a technique in which cations and anions move selectively along the IEM. Anion exchange membrane (AEM) is one of the important components of the ED process which is critical to enhancing the process efficiency. The introduction of cross-linking in the IEM improves the ion-selective separation performance due to the reduction of free volume. During the desalination of seawater by reverse osmosis (RO) process, there is a lot of dissolved salt present in the concentrate of RO. So, the ED process consisting of a monovalent cation-selective membrane reduces fouling and improves membrane flux. This review is divided into three sections such as electrodialysis (ED), anion exchange membrane (AEM), and cation exchange membrane (CEM).

• Proceedings of the Korean Society of Toxicology Conference
• /
• 2001.05a
• /
• pp.22-40
• /
• 2001

Apoptosis is characterized by DNA fragmentation, chromatin condensation and plasma membrane blebbing. These apoptotic processes have been mainly associated with genetic mechanisms. Recently, these processes have been also associated with mitochondrial events that include the release of cytochrome c and Diablo/SMAC by modulation of mitochondrial membrane permeability.(omitted)

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.11a
• /
• pp.42-45
• /
• 2003

Inorganic polymer based hybrid membranes consisting of zirconium oxide and polydimethylsiloxane (PDMS) have been synthesized by sol-gel processes. The hybrid membranes showed thermal stability and flexibility up to $300^{\circ}C$. The membrane becomes proton conducting polymer electrolyte when added with 12-phosphotungstic acid (PWA). The conductivity of the membranes was measured in the temperature range from room temperature to $150^{\circ}C$ under saturated humidity and a maximum conductivity of $5{\times}10^{-5}\;Sm^{-1}$ was obtained at $150^{\circ}C$.

• Membrane Journal
• /
• v.27 no.6
• /
• pp.519-527
• /
• 2017

Membrane fouling is the main issue hindering the expansion of low pressure membrane processes for surface water treatment. Therefore, applying periodic hydraulic cleaning for fouling control should be well optimized. Better understanding of membrane fouling associated with periodic hydraulic cleaning would be useful to optimize membrane cleaning strategies. By comparing experimental permeability data with the classical Hermia blocking laws, this study aims at analyzing membrane fouling and understanding dominant fouling mechanisms occurring when filtering a synthetic surface water solution with a pressurized membrane process during six filtration cycles of 30 min each, separated with cyclic cleaning of 1 min by backwashing and forward flushing separately and combined. When applying single cleaning technique, membrane fouling during the first cycles was controlled by complete blocking mechanism while the last cycles were dominated by cake formation. Nevertheless, when combining cleaning technique better membrane regeneration was obtained and fouling was mainly due to cake formation.

• KSBB Journal
• /
• v.28 no.1
• /
• pp.24-30
• /
• 2013

Dissolved oxygen, pH and cell concentration have been online monitored in cultivation processes with Escherichia coli by using a $MABOOMS^{TM}$ (microplate-based bioreactor with optical online monitoring systems). Fluorescent sensing membranes containing Ru ${(dpp)_3}^{2+}$ or HPTS were prepared with GA sol-gel matrix and coated into a well of a 24-well microplate. Fluorescence intensity was measured and correlated to the dissolved oxygen or pH. Cell concentrations were also online monitored by measuring optical reflectance at 650 nm. A well of a 24-well microplate could also be divided into 4 parts, each of which was coated with fluorescent sensing membranes for the detection of dissolved oxygen or pH. The 24-well microplate coated with fluorescent sensing membranes or a 4-divided sensing membrane. was used to online monitor the dissolved oxygen, pH and cell concentration during E. coli cultivations. The online monitoring results showed the characteristics of cell growth in cultivation processes very well.

• Membrane and Water Treatment
• /
• v.3 no.4
• /
• pp.253-266
• /
• 2012

In this work, the effect of hybrid salts precipitation-nanofiltration (SP-NF) process on the scale deposits in thermal and membrane desalination processes has been studied. The analysis was carried out to study the scale formation from the Arabian Gulf seawater in MSF and RO reference processes by changing the percentage of pretreatment from 0 to 100%. Four different SP-NF configurations were suggested. A targeted Top Brine Temperature (TBT) of $130^{\circ}C$ may be achieved if 30% portion is pretreated by SP and/or NF processes. As a rule of thumb, each 1% pretreatment portion increases the reference TBT of $115^{\circ}C$ by $0.6^{\circ}C$. For both MSF and RO, parallel pretreatment of certain percentage of the feed by SP and the rest by NF, showed the lowest scale values. The case showed the best values for sulfate scale prevention and the highest values of increasing the monovalent ions relative to the divalent scale forming ions. Sulfate scale is significant in MSF process while carbonate scale is significant in RO. Salt precipitation was suggested because it is less costly than nanofiltration, but nanofiltration was used here because it is efficient in sulfate ions removal.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.22 no.3
• /
• pp.493-503
• /
• 1998

The sectional forming analysis considering bending effects from the geometrically deformed shape of two linear membrane finite elements(called super element) was performed under plane strain assumption for analyzing forming processes of an arbitrarily shaped draw-die. For the evaluation of bending effects, the bending equivalent forces are calculated from the bending moment computed using the changes in the interior angle at the middle node of super element, and are agumented to the membrane stretch forces. In order to verify the validity of the bending formulation, the simulation results for the stretch, draw, and bend sections were compared with membrane analysis results and measurements.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.14 no.5
• /
• pp.126-133
• /
• 2015

Recently, there has been demand for polymeric porous membranes in various fields, such as environmental engineering, pharmaceutics, tissue engineering, drug delivery, biology, and fuel cells. In this study, it is proposed that a polymer particle-based porous membrane can be fabricated using electrospraying and sintering processes. Electrospraying can fabricate polymeric particles with diameters ranging from several micrometers to tens of nanometers without the cumbersome particle aggregation problem. Additionally, the particles can be sintered through thermo-compression under the glass transition temperature. In this study, a polymethyl methacrylate particle-based porous membrane with an average pore size of less than 500 nm is fabricated using the proposed method.

• Proceedings of the Membrane Society of Korea Conference
• /
• 1994.10a
• /
• pp.21-23
• /
• 1994

무방류폐수처리 시스템 개발에 막분리공정이 핵심적인 기술로 자리잡고 있다. 그러나 막분리기술의 경제성을 높히고 적용범위를 확대하기 위해서는 새로운 막의 개발과 폐수처리에서 항상 문제가 되는 fouling의 원인규명 및 막세척방법의 개발이 절실히 요구되고 있다. 본 연구에서는 염료폐수처리 및 재활용을 위한 pilot 실험에의 막의 fouling 현상과 세척효과를 역삼투막인 BW-30(2540)과 Nanofiltration막인 NF-40(2540) 모듈을 사용하여 조사하였다. RO 투과수에 의한 물리적 세척법인 flushing과 화학적세척을 실시하여 투과율 회복능력을 조사하였다.

• Korean Membrane Journal
• /
• v.1 no.1
• /
• pp.50-58
• /
• 1999

Symmetric asymmetric and composite perfluoropolymer membranes made with HYFLON AD have been prepared and evaluated. Porous and non porous symmetric membranes have been prepared by solvent evaporation with various processing conditions. Non-contact atomic force microscopy (AFM) was used to investigate the membrane morphology in air. Analysis of the images gave quantitative imformation on the surface pore strcture in particular on the pore size distributin. Possible useful uses of porous membranes are envisaged in the field of gas-liquid separations such as membrane contactors (MSc) Molecular Dynamics(MD) simulations structure of HYFLON AD 60X copolymer supporting these results are also reported. Amorphous perfluoropolymer membranes appears to be ideal other than in MCs when separation processes have to be performed in hostile environments i.e. high temperatures and aggressive non-aqueous media such as chemicals and solvents. In these cases HYFLON AD mem-branes can exploit the outstanding resistance of perfluoropolymers.