• Journal of Korean Society of Environmental Engineers
• /
• v.32 no.1
• /
• pp.79-86
• /
• 2010

Effects of operating parameters such as applied voltage, solution conductivity, ferrous ion concentration, electrode material on phenol degradation by pulsed corona discharges were investigated in laboratory scale experiments. The increase of applied voltage enhanced the phenol degradation by generating more energetic electrons. The solution conductivity inversely affected phenol removal rate in the tested ranges because the increase of conductivity decreased the electric field strength through the liquid phase. The addition of ferrous sulfate promoted the phenol degradation through the OH radical production by the Fentonlike reactions between ferrous ion and hydrogen peroxide generated by pulsed corona discharges. Catechol and hydroquinone were detected as primary intermediates of phenol degradation and the decrease of pH and the increase of conductivity were observed probably due to the generation of organic acids. Almost all of the initial phenol was disappeared and 29% of total organic corbon (TOC) was removed in the condition of 0.5 mM of ferrous sulfate after approximately 230 kJ of discharge energy transferred to the reactor.

• Membrane Journal
• /
• v.27 no.5
• /
• pp.425-433
• /
• 2017

As the problems related to the environmental pollution such as carbon dioxide emission are emerging, the need for the renewable energy and environmentally friendly energy is getting intense. Fuel cells are eco-friendly energy generation devices that generate electrical energy and produce water as a sole by-product. Compared to the traditional proton exchange membrane fuel cell (PEMFC), anion exchange membrane alkaline fuel cell (AEMAFC) has a main advantage of possibility to use low cost metal catalysts due to its faster kinetics. The AEM, which conducts $OH^-$ ions, should possess high ion conductivity as well as high chemical stability at high pH conditions. We hereby introduce a crosslinked poly(2,6-dimethyl-1,4-phenylene oxide) having a spacer-type conducting group as novel AEM, and report a high ion conductivity ($67.9mScm^{-1}$ at $80^{\circ}C$) and mechanical properties (Young's modulus : 0.53 GPa) as well as chemical stability (6.8% IEC loss at $80^{\circ}C$ for 1,000 h,) for the developed membrane.

• Journal of the Korean Electrochemical Society
• /
• v.10 no.1
• /
• pp.25-30
• /
• 2007

Proton exchange membrane fuel cell(PEMFC) performance could be affected by various factors such as cell temperature, total pressure, partial pressure of reactants and relative humidity. Hydrogen ion is combined with water to form hydronium ion [$H_3O^+$] and pass through membrane resulting electricity generation. Cooling system is needed to remove heat and other uses on large scale fuel cell. In case that collant conductivity is increased, fuel cell performance could be decreased because produced electricity could be leaked through coolant. In this study, triple distilled water(TDW) and antifreeze solution containing ethylene glycol was used to observe resistance change. Resistance of TDW was taken 28 days to reach preset value, and effect on fuel cell operation was not observed. Resistance of antifreeze solution was not reached to preset value up to 48 days, but performance failure occurred presumably caused by bipolar plate junction resulting stoppage resistance experiment. Generally PEMFC humidification is performed near-saturated operating conditions at various temperatures and pressures, but non-humidifying condition could be applied in small scale fuel cell to improve efficiency and reduce system cost. However, it was difficult to operate large scale fuel cell without humidifying, especially higher than $50{\sim}60^{\circ}C$. In case of small flux such as 0.78 L/min, temperature difference between inlet and outlet was occurred larger than other cases resulting performance decrease. Non-humidifying performance experiments were done at various cell temperature. When both of anode and cathode humidification were removed, cell performance was strongly depended on cell operating temperature.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.9 no.6
• /
• pp.590-596
• /
• 1999

The effects of additives on the Zn electrodeposition in chloride-based electrolyte were investigated using circulation cell with three electrodes system. The cathodic polarization increased with the addition of polyethylenglycol (hereafter PEG) in electrolyte. This was attributed to the adsorption of the additives on the electrode and the inhibition of migration of metal ion. The PEG, however, did not have any noticeable effect on the properties of plating solutions at the concentration used. The effect of PEG on the electrocrystallization was related to its molecular weight. With the increase of molecular weight, the cathodic polarization increased, while the surface roughness was improved with the decrease of brightness. Especially, the PEG mixed with different molecular weights was the most effective. The orientation and the type of the deposited grains were changed and refined by PEG, which resulted in the modification of deposited surface roughness and brightness.

• 한국신재생에너지학회:학술대회논문집
• /
• 2005.06a
• /
• pp.281-283
• /
• 2005

Water management in polymer electrolyte membrane fuel cells(PEMFCs) is one of the most challenging issues. Freeze start-up in the automotive applications is also important research topic in the PEMFC field. Transportation of proton and separation of reactant gases are main roles of polymer electrolyte membranes. It has been known that water in the membrane conducts as a vehicle for the proton transportation. At sub-zero temperature, the frozen water blocks the access of reactant gases to the active sites of electrode as well as occurs the physical destruction of fuel cell structures. In this study, property changes of electrolyte membranes in the freeze conditions $(at\;-25^{\circ}C)$ were investigated. For the various amount of water contained membranes, the property changes, especially for the proton conductivity, were observed after several times of freeze/thaw$(-25\~80^{\circ}C)$ cycle.

• 한국신재생에너지학회:학술대회논문집
• /
• 2009.06a
• /
• pp.270-273
• /
• 2009

A comb-like copolymer consisting of a poly(vinylidene fluoride-co-chlorotrifluoro-ethylene) backbone and poly(hydroxy ethyl acrylate) side chains, i.e. P(VDF-co-CTFE)-g-PHEA, was synthesized through atom transfer radical polymerization (ATRP) using CTFE units as a macroinitiator. Successful synthesis and a microphase-separated structure of the copolymer were confirmed by proton nuclear magnetic resonance (1H-NMR), FT-IR spectroscopy, and transmission electron microscopy (TEM). This comb-like polymer was crosslinked with 4,5-imidazole dicarboxylic acid (IDA) via the esterification of the -OH groups of PHEA and the -COOH groups of IDA. Upon doping with phosphoric acid ($H_3PO_4$) to form imidazole-$H_3PO_4$ complexes, the proton conductivity of the membranes continuously increased with increasing $H_3PO_4$ content. A maximum proton conductivity of 0.015 S/cm was achieved at $120^{\circ}C$ under anhydrous conditions. In addition, these P(VDF-co-CTFE)-g-PHEA/IDA/$H_3PO_4$ membranes exhibited good mechanical properties (765 MPa of Young's modulus), and high thermal stability up to $250^{\circ}C$, as determined by a universal testing machine (UTM) and thermal gravimetric analysis (TGA), respectively.

• 한국신재생에너지학회:학술대회논문집
• /
• 2006.11a
• /
• pp.421-424
• /
• 2006

Nafion/Pt/Polypyrrole composite membranes were fabricated by chemical in-situ polymerization of pyrrole monomers with Pt precursors in Nafion matrix for DMFC. We demonstrated that positively charged pyrrolinum groups of polypyrrole particles were co-interacted with sulfonic groups of Nafion as verified by FT-IR results. Mutual interaction between $Nafion-SO_3^-$ (or negatively charged Pt precursors) and Polypyrrole$-NH_2^+$ influenced the physical properties of pristine Nafion. Thermal property proton conductivity, methanol permeability, and cell performance of pristine and modified Nafion were analyzed for an application of DMFC membrane. Thermal stabilities of sulfonic groups and side chains in Nafion/Pt/polypyrrole composite membranes were higher than those of Nafion due to mutual interaction between sulfonic groups of Nafion and pyrrolinum groups of polypyrrole. Methanol permeabilities of Nafion/Pt/Polypyrrole composite were reduced more proton conductivities with the increase in the content of Pt particles. As a result of that, the enhancement of cell performance by Nafion/Pt/Polypyrole O2 relative to Nafion was more pronounced under the specific experimental condition such as high temperature and more concentrated methanol solution.

• Membrane Journal
• /
• v.20 no.3
• /
• pp.173-184
• /
• 2010

Microbial fuel cell (MFC) is a promising renewable energy source that can generate electrical energy from organic wastes using microbe. This technology has been regarded as a future green alternative energy in that MFC makes use of organic-rich wastewater and also reduces waste sludges as well as produces electricity. To be practically realized, however, achieving higher power density than now is demanded, which may be possible by eliminating various negative factors to act as resistances in MFC operations. For instance, highly activated microbes, highly conductive electrode materials, and fast electron transfer between microbes and electrodes can lead to MFC with high power density. In particular, polymer electrolyte membranes are also a key component for improved MFC performance.

• Korean Chemical Engineering Research
• /
• v.45 no.4
• /
• pp.391-395
• /
• 2007

A new electrode binder mixed with sulfonated poly (ether ether ketone) (sPEEK) and Nafion is prepared and investigated as an anode binder for direct methanol fuel cell (DMFC). The mixed binder (95 wt% sPEEK/5 wt% Nafion) shows high proton conductivity and methanol transport rate as well as no dissolution and brittleness. The effect of content as an anode binder on the performance of the cell with the given cathode is investigated. The unit cell with the anode containing 10wt% mixed binder showed the highest cell performance.

• Membrane Journal
• /
• v.14 no.3
• /
• pp.240-249
• /
• 2004

Crosslinked PVA membranes were achieved by esterification between the hydroxyl groups of PVA and carboxyl group of sulfosuccinic acid (SSA). SSA containing sulfonic group was used as a chemical crosslinking agent as well as a donor of fixed anionic group ($-SO_3$H). The crosslinking density of membranes was controlled by SSA content and calculated using polar and non-polar solvent. The crosslinking density measured by using non-polar solvent such as xylene and benzene increases with SSA content. However, using the polar solvent such as water and methanol, the crosslinking density increases up to SSA content of 20 wt% and above the content decrease due to sulfonic acid groups. The crosslinked PVA membranes were studied in relation with water diffusion coefficient and mechanical property as well as proton conductivity and methanol permeability as a function of crosslinking density. These properties were all dependent on the effect of SSA content.