• Membrane Journal
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• v.31 no.2
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• pp.120-132
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• 2021

Microbial fuel cell (MFC) is a bio-electrochemical device that generates electricity by utilizing bacterial catalytic activity that degrades wastewater. Proton exchange membrane (PEM) is the core component of MFC that decides its performance, and Nafion membrane is the most widely used PEM. In spite of the excellent performance of Nafion, it has drawbacks such as high cost, biofouling issue, and non-biodegradable property. Recent studies in MFC attempted to synthetize the alternative membrane for Nafion by incorporating various polymers, sulfonating, fluorinating, and doping other chemicals. This review summarizes characteristics and performances of different composite membrane based MFCs, mostly focusing on PEM.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.58-59
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• 2006

Less than a decade ago, most alternate membrane materials for fuel cells relied upon a post-sulfonation process to generate ionic groups capable of transporting protons from the anode to the cathode. These random post sulfonations showed some promise, but in general they produced materials that were not sufficiently stable or protonically conductive at ion exchange capacities where aqueous swelling could be restricted. Our group began to synthesize disulfonated monomers that could be used to incorporate into random copolymer proton exchange membranes. The expected limitation was that the aromatic polymers might not be stable enough to withstand fuel cell conditions. However, this was mostly based upon an accelerated test known was the Fenton's Reagent Test, which did not seem to this author as being a reliable predictor of performance. A much better approach has been to evaluate the open circuit voltage (OCV) for alternate membranes, as well as the benchmark perfluorosulfonic acid systems. When this is done, the aromatic ionomers of this study, primarily based upon disulfonated polyarylene ether sulfones, show up quite well. Real time 3000 hours DMFC results have also been generated. Obtaining conductive materials at low humidities is another major issue where alternate membranes have not been particularly successful. In order to address this problem, multiblock copolymers with relatively high water diffusion coefficients have been designed, which show promise for conductivity at lowered humidity.

• Membrane and Water Treatment
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• v.7 no.1
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• pp.39-53
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• 2016

In this study, polysufone (PSf) was used as a base polymer to synthesize sulfonated polysulfone (SPSf) and aminated polysulfone (APSf) as cation and anion exchange polymers, respectively. Then the ion exchange polymers were coated onto the surface of commercial carbon electrodes. To compare the capacitive deionization (CDI) and membrane capacitive deionization (MCDI) processes, the pristine carbon electrodes and ionic polymer coated electrodes were tested under various operating conditions such as feed flow rate, adsorption time at fixed desorption time, and feed concentration, etc., in terms of effluent concentration and salt removal efficiency. The MCDI was confirmed to be superior to the CDI process. The performance of MCDI was 2-3 times higher than that of CDI. In particular, the reverse desorption potential was a lot better than zero potential. Typically, the salt removal efficiency 100% for 100 mg/L NaCl was obtained for MCDI at feed flow rate of 15 ml/min and adsorption/desorption time of 3 min/1 min and applied voltages 1.0 V for adsorption and -0.3 V for desorption process, and for 500 mg/L, the salt removal efficiency 91% was observed.

• Membrane and Water Treatment
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• v.7 no.1
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• pp.23-38
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• 2016

Batch adsorption of methyl orange (MO) from aqueous solution using three kinds of anion exchange membranes BI, BIII and DF-120B having different ion exchange capacities (IECs) and water uptakes ($W_R$) was investigated at room temperature. The FTIR spectra of anion exchange membranes was analysed before and after the adsorption of MO dye to investigate the intractions between dye molecules and anion exchange membranes. The effect of various parameters such as contact time, initial dye concentration and molarity of NaCl on the adsorption capacity was studied. The adsorption capacity found to be increased with contact time and initial dye concentration but decreased with ionic strength. The adsorption of MO on BI, BIII and DF-120B followed pseudo-first-order kinetics and the nonlinear forms of Freundlich and Langmuir were used to predict the isotherm parameters. This study demonstrates that anion exchange membranes could be used as useful adsorbents for removal of MO dye from wastewater.

• Membrane Journal
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• v.32 no.6
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• pp.486-495
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• 2022

This study presents the improved recovery efficiency of rare metal ions through the modified separation membrane wettability and hydrogen ion permeation in the anion exchange membrane (AEM) under the recovery process of combined electrodialysis and solvent extraction. Specifically, the wettability of the separator was enhanced by hydrophilic modification on one separator surface through polydopamine (PDA) and lipophilic modification on the other surface through SiO₂ or graphene oxide (GO). In addition, the modified surface of AEM with polyethyleneimine (PEI), PDA, poly(vinylidene fluoride) (PVDF), etc. reduces the water uptake and modify the pore structure for proton ions generation. The suppressed transport resulted in the reduced hydrogen ion permeation. In the characterization, the surface morphology, chemical properties and composition of membrane or AEM were analyzed with Scanning Electron Microscopy (SEM) and Fourier Transform-Infrared Spectroscopy (FT-IR). Based on the analyses, improved extraction and stripping and hydrogen ion transport inhibition were demonstrated for the copper ion recovery system.

• YAKHAK HOEJI
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• v.59 no.3
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• pp.113-119
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• 2015

Protein phosphorylation is one of most important post-translational modifications (PTMs) and plays an important role in regulation of protein function. Here we develop a method for a global identification of phosphopeptides and phosphorylation sites using nano-LC MS/MS. We compared two separation methods, C4 and strong cation ion exchange (SCX). Before phosphopeptides enrichment with $TiO_2$, total proteins from Rat 1 cells have been separated using C4 column or tryptic peptides of proteins from the cells have been separated using SCX column. Finally, we have detected 52 phosphorylation sites on 41 proteins from SCX method and 375 phosphorylation sites on 252 proteins from C4 method, and determined the function and localization of identified phosphoproteins using DAVID software. In particular, we showed new phosphorylation sites from membrane proteins related to various cell signaling mechanisms. This method may contribute to study global signal networks induced by various signals including ligands and drugs.

• Resources Recycling
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• v.25 no.4
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• pp.3-10
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• 2016

A lot of researches have been carried out on the recovery of resources from the seawater all over the world. The boron concentration in seawater is low about at 4.5ppm, but considering the volume of seawater, the total weight of dissolved boron amounts to about 5.4 trillion tons. The boron is an essential resource in about 300 kinds of industries. Korea has imported all of the boron and spent more than 700 billion won each year. In this article, we introduce the domestic and international research trends and technologies for removing or recovering the boron from wastewater and seawater. Most of the researches have been conducted to remove the boron from the desalination process, and to recover the boron mainly from wastewater and brine. The technique for the recovery of the dissolved boron includes the ion exchange, which is the most representative, the adsorption membrane filtration (AMF), solvent extraction, and so on.

• Journal of Hydrogen and New Energy
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• v.18 no.4
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• pp.391-398
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• 2007

The covalently cross-linked sulfonated polyetheretherketone (CL-SPEEK) membrane was prepared by four-step synthesis of sulfonation-sulfochlorination, partial reduction, lithiation, and cross-linking, and its electrochemical and mechanical properties were investigated for water electrolysis application. The prepared ion exchange membranes showed good electrochemical and mechanical properties; proton conductivity of 0.116 S/cm at $80^{\circ}C$, water uptake of 44.6%, ion exchange capacity of 1.75 meq/g-dry-memb., tensile strength of 64.25 MPa and elongation of 61.11%. The membrane electrode assembly (MEA) with homemade membranes were prepared by non-equilibrium impregnation-reduction (I-R) method. Especially, the electrochemical surface area (ESA) and roughness factor of CL-SPEEK electrolyte by cyclic voltammetry method were 23.46 $m^2/g$ and 307.3 $cm^2-Pt/cm^2$, respectively. The prepared MEA was used in the unit cell of water electrolysis and the cell voltage was 1.81 V at 1 A/$cm^2$ and $80^{\circ}C$, with platinum loadings of 1.31 mg/$cm^2$.

• Korean Chemical Engineering Research
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• v.55 no.3
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• pp.302-306
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• 2017

Humidity affect performance and durability of proton exchange membrane fuel cell (PEMFC). High humidity of gases generally enhance the performance, but high humidity have the danger of flooding. I-V performance, linear sweep voltammetry, cyclo voltammetry, and impedance of micro-channel cell measured with change of relative humidity (RH). Flooding phenomena started at RH 70%. Ion conductivity of membrane reached maximum value at RH 80%. Maximum current density of $1,700mA/cm^2$ (at 0.6 V) was obtained at RH 80%. Therefore the effect of ion conductivity increasement was higher than that of mass transfer decrease by flooding at RH 80%.

• Journal of Korean Society on Water Environment
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• v.33 no.3
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• pp.334-340
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• 2017

A pilot-scale electrodialysis system was designed and constructed to treat groundwater polluted with arsenic and manganese. Synthetic groundwater, in which some amount of arsenic and manganese was added to make 500 mg/L of Mn and $50{\mu}g/L$ of As, was used as a feed for the ED system. The limiting current density, linear water velocity, applied voltage, and membrane surface area were investigated to obtain efficient and economic operation of the ED system. The linear water velocity was increased 0.74 cm/s to 11 cm/s based on evaluation of limiting current density. The water quality of diluate for 85 minutes of operation was satisfied with water quality criteria for drinking water using the ED system with 14 pairs of ion exchange membranes. The increased membrane pairs to 21 and 42 pairs were very effective to reduce conductivities of the diluate. The operation cost of the ED system was assessed using specific energy consumption, which was $1.065{\sim}1.2kWh/m^3$. Considering low salt concentrations of the groundwater, improvement of the ED system are required to increase current utilization and to apply low voltage while the ED system was applicable to produce drinking water.