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We report the use of a novel and efficient method to remove aqueous boron by using electrospun, water-resistant poly(vinyl alcohol) (PVA) mats stabilized in methanol. The removal of the primary aqueous boron species as (B(OH)3), was accomplished by chemical adsorption in reactions with −OH (hydroxyl) groups on the PVA mat surface. The chemical adsorption of B(OH)3 was qualitatively confirmed by the analysis of IR and Raman spectra. The bands, corresponding to the molecular vibration modes of chemically bonded boron in PVA, were identified by using the frequency calculation from the computational chemistry for the first time. The adsorption capacities of PVA mats for aqueous boron were then quantitated at a low boron concentration (range: 0.0010 to 0.0025 g of aqueous boron per g of PVA mats) by the Carmine method. The PVA mats were prepared by a well-established electrospinning technique, which make these substrates promising potential candidates for use as boron-selective sorbent media in applications su...

Mineral salt components (Na+, Ca2+, K+, Mg2+, etc.) are naturally excluded during the gas hydrate in which water molecules form cavities by hydrogen bonding and guest gas molecules are encapsulated into the cavities to stabilize the overall gas hydrate structure. However, when using refrigerant hydrofluorocarbon-134a (HFC-134a) for guest gas, it resided in resulting brackish water after the desalination process because of its high solubility in water. Jet loop reactors (JLRs) are frequently employed in many commercial applications because of their high mass transfer capabilities. In this study, a semi-batch type JLR was introduced to improve the degassing of HFC-134a from brackish water. The effect of parameters, such as the initial HFC-134a concentration (200&ndash, 772 mg/L), liquid circulation (40&ndash, 80 L/min) rate, and air flow rate (10&ndash, 30 L/min), were studied in this JLR. The removal efficiency and overall volumetric transfer were calculated and it was determined that increasing the air flow rate has a high effect on KLa.

For any conceivable desalination process using the gas hydrate formation, the kinetics has to be one of the most important parameters from the economic point of view. We thus were to improve the kinetics of the R-134a (also known as HFC- 134a) gas hydrate formation by using promoters and three different kinds of edible surfactants were selected for the desalination process targeted to produce potable water; κ-carrageenan, lecithin, and polysorbate 80 among anionic, amphoteric, and nonionic surfactants, respectively. Then, the kinetics change of the R-134a hydrate formation was monitored by varying the surfactant concentration. Experimental results demonstrated that the rate of R-134a hydrate formation increases with the addition of edible surfactants in general and the effect as a promotor has an order of polysorbate 80 > κ-carrageenan > lecithin. As a supportive measure, the atomic charges of each surfactant were calculated by using a DFT (density functional theory)-based molecular modeling and the results showed a positive relationship between the promotor effect of each surfactant and the number of oxygens available for hydrogen bonding and the negativity of their atomic charge values.

Gas hydrates are crystalline solids in which gas molecules (guests) are trapped in water cavities (hosts) that are composed of hydrogen-bonded water molecules. During the formation of gas hydrates in seawater, the equilibria and kinetics are then affected by salinity. In this study, the effects of salinity on the equilibria of CO2 and R134-a gas hydrates has been investigated by tracing the changes of operating temperature and pressure. Increasing the salinity by 1.75% led to a drop in the equilibrium temperature of about 2 oC for CO2 gas hydrate and 0.38 oC for R-134a gas hydrate at constant equilibrium pressure; in other words, there were rises in the equilibrium pressure of about 1 bar and 0.25 bar at constant equilibrium temperature, respectively. The kinetics of gas hydrate formation have also been investigated by time-resolved in-situ Raman spectroscopy; the results demonstrate that the increase of salinity delayed the formation of both CO2 and R134-a gas hydrates. Therefore, various ions in seawater can play roles of inhibitors for gas hydrate formation in terms of both equilibrium and kinetics.

Textile industry is considered as one of the most polluting sectors in terms of effluent composition and volume of discharge. It is well known that the effluents from textile dying industry contain not only chromatic substances but also large amounts of organic compounds and insolubles. The azo dyes generate huge amount of pollutions among many types of pigments. In general, the electrochemical treatments, separating colors and organic materials by oxidation and reduction on electrode surfaces, are regarded as simpler and faster processes for removal of pollutants compared to other wastewater treatments. In this paper the electrochemical degradation characteristics of dye wastewater containing CI Direct Blue 15 were analyzed. The experiments were performed with various anode materials, such as RuO2/Ti, PtO2/Ti, IrO2/Ti and graphite, with stainless steel for cathode. The optimal anode material was located by changing operating conditions like electrolyte concentration, current density, reaction temperature and initial pH. The degradation efficiency of dye wastewater increased in proportion to the electrolyte concentration and the current density for all anode materials, while the temperature effect was dependent on the kind. The performance orders of anode materials were RuO2/Ti > PtO2/Ti > IrO2/Ti > graphite in acid condition and RuO2/Ti > IrO2/Ti > PtO2/Ti > graphite in neutral and basic conditions. As a result, RuO2/Ti demonstrated the best performance as an anode material for the electrochemical treatment of dye wastewater.

This paper investigates the feasibility of applying the jet loop reactor for the neutralization of alkaline wastewater using carbon dioxide (). In this study, pH changes and removal characteristics were examined by changing influent flow rate of alkaline wastewater (initial pH

Boron is difficult to be removed from seawater by simple RO (reverse osmosis) membrane process, because the size of boric acid (), the major form of aqueous boron, is as small as the nominal pore size of RO membrane. Thus, the complexation of boric acid with polyols was suggested as an alternative way to increase the size of aqueous boron compounds and the complexation behavior was investigated with Raman spectroscopy. As a reference, the Raman peak for symmetric B-O stretching vibrational mode both in boric acid and borate ion () was selected. A Raman peak shift () was observed to confirm that boric acid in water is converted to borate ion as the pH increases, which is also correctly predicted by frequency calculation. Meanwhile, the Raman peak of borate ion () did not appear as the pH increased when polyols were applied into aqueous solution of boric acid, suggesting that the boric acid forms complexing compounds by combining with polyols.

A semi-batch jet loop fluidized bed reactor (JLFBR) was used as a crystallization reactor to remove nitrogen and phosphorus from synthetic wastewater through struvite crystallization. The reactor performance obtained in the JLFBR was compared with that in a same-size jet loop reactor (JLR). The time required to increase the initial pH of the synthetic wastewater from 7.3 to 8.0 by aeration in the JLFBR was shorter than in the JLR. Moreover, the removal rates of ammonium nitrogen (NH4-N) and total phosphorus (T-P) were faster in the JLFBR. This may be due to the enhanced turbulent intensity that promoted struvite formation, as well by the fluidized particles in the JLFBR.

The complexation of boric acid (B(OH)3), the primary form of aqueous boron at moderate pH, with polyols is proposed and mechanistically studied as an efficient way to improve membrane processes such as reverse osmosis (RO) for removing boron in seawater by increasing the size of aqueous boron compounds. Computational chemistry based on the density functional theory (DFT) was used to manifest the reaction pathways of the complexation of B(OH)3 with various polyols such as glycerol, xylitol, and mannitol. The reaction energies were calculated as −80.6, −98.1, and −87.2 kcal/mol for glycerol, xylitol, and mannitol, respectively, indicating that xylitol is the most thermodynamically favorable for the complexation with B(OH)3. Moreover, the 1: 2 molar ratio of B(OH)3 to polyol was found to be more favorable than the ratio of 1: 1 for the complexation. Meanwhile, latest lab-scale actual RO experiments successfully supported our computational prediction that 2 moles of xylitol are the most effective as the complexing agent for 1 mole of B(OH)3 in aqueous solution.

Gas hydrate (GH) desalination process is based on a liquid (salty water) to solid (GH) phase change coupled with a physical process to separate the GHs from the remaining salty water. However, GH process exhibits less than 90% of salt rejection, so reverse osmosis (RO) process is needed to finally meet the desalinated product water quality. In order to increase the total recovery of the GH and RO hybrid system, the concentrate of the RO process should return to the feed stream of the GH process. In this work, RO simulation was carried out to find an optimal RO recovery with which the energy consumption of RO was minimized. The optimal RO recovery values for GH processes with salt rejection of 78, 84, and 90% were 0.6, 0.8, and 0.8, respectively. The minimal total energy consumption appears at higher RO recovery rates than the optimal values to minimize the RO energy consumption because the portion of the GH energy consumption is inversely proportional to the RO recovery. The simulation also reveal...

The removal of boron is a very important issue in desalination using seawater reverse osmosis (SWRO). A novel approach using polyol compounds to remove boron is introduced in this study. Polyols are compounds possessing multiple hydroxyl groups and they can combine with uncharged boric acid by generating anionic complexes. As a result, a large molecule is formed and it can be easily rejected by SWRO membrane at seawater pH. Lab-scale SWRO tests were performed to investigate the effect of polyol on the boron removal using different types of polyol (xylitol, glycerol, and D-mannitol). The polyol–boron reaction occurs in seawater condition with low boron concentration and various ion compounds, which leads to two important findings that boron-polyol reaction occurs with low boron and polyol concentrations, and there are no significant inhibitors for the reaction in seawater. The boron-polyol reaction rate is so fast that it can be easily applied to full-scale SWRO processes. The boron removal rate in...

We have introduced switching poles in the conventional electrolysis for the removal of ammonia in aquaculture wastewater to prevent the fouling on the electrode surface by the deposition of insoluble metallic compounds. We have also tried to locate the optimal period of switching poles considering the effect of the current loss during switching poles on the free chlorine generation. First, we have observed the decrease of free chlorine generation with the decrease of the period of switching poles due to the expected current loss, and this would lead to the decrease of ammonia removal efficiency. Meanwhile, the measurement of calcium and magnesium concentration in wastewater vs. the period of switching poles have demonstrated that a properly low level of fouling on the electrode surface could be retained with a period of switching poles of less than 60 sec by the decomposition of metallic compounds during switching poles. In a summary, we have optimized the period of switching poles to gain a high level of free chlorine generation and a high level of fouling prevention on the electrode at the same time.

To investigate the performance of a jet loop reactor with the two-fluid swirl nozzle (TSN), CO2 absorption experiments in an alkaline solution were performed. The experimental results obtained in the reactor were compared with those in a jet loop reactor with the two-fluid conventional nozzle (TCN). The neutralization time of alkaline solution and the CO2 removal efficiency were used as the indices for a comparison of the reactor performance. Due to the swirling flow, the neutralization times of alkaline solutions by CO2 in the reactor with the TSN were shortened compared with those in the reactor with the TCN. Also, the instantaneous and/or overall CO2 removal efficiencies in the reactor with the TSN were higher than those in the reactor with the TCN at the same liquid circulation flow rate.

The growth behavior of CH4 and SF6 mixture gas hydrate has been investigated by a combined approach of Raman spectroscopy and molecular modeling. Raman spectroscopy results presented that when CH4 is used only, CH4 guest molecule is inserted first into the large cavity of the host structure built by H2O molecules and then into the small cavity to stabilize the whole gas hydrate structure. In the other hand, when SF6 is mixed together, SF6 is favored over (or competing with) CH4 in being inserted into the large cavity and the small cavity still prefers CH4 insertion. The calculations of binding energies clearly supported this. While SF6 has a binding energy of -26.9 kcal/mol a little lower than -24.2 kcal/mol of CH4 in the large cavity, SF6 and CH4 has 1.2 kcal/mol and -22.0 kcal/mol, respectively, in the small cavity. It indicates that the sizable SF6 is not preferred in the small cavity but has a relative energetic advantage over CH4 in the large cavity.

The purpose of this study was to remove sediments obtained from breeding ground using supersonics and micro-air flotation method. Sediments from Tongyong breeding grounds showed no contaminations of heavy metals but had great amount of organics. Thus, efficient removal of sediments was required to preserve water quality near breeding ground. Supersonics treatment for sediments was determined to be essential because higher removal efficiency of sediments was obtained when supersonics treatment was used. In addition, application of coagulants increased removal efficiency because its usage increased particle size of sediments, which enabled easy trapping of sediments particle into micro-air bubbles. Removal efficiency of sediments slightly decreased from 95.8% (1 g/L) to 83.9% (8 g/L) at the tests for different amount of sediments, but most of tiny particles were removed from water where sand size particles were left in the bottom of reactors.

This paper presents the results of the electrochemical treatment of chemical oxygen demand(COD) and total nitrogen(T-N) compounds in the wastewater generated from flue gas desulfurization process by using a lab-scale electrolyzer. With the increase in the applied current from 0.6 Ah/L to 1.2 Ah/L, the COD removal efficiency rapidly increases from 74.5% to 96%, and the T-N removal efficiency slightly increases from 37.2% to 44.9%. Therefore, it is expected that an electrochemical treatment technique will be able to decrease the amount of chemicals used for reducing the COD and T-N in wastewater of the desulfurization process compared to the conventional chemical treatment technique.

The purpose of this study was to determine the optimum conditions for the cultivation of Chlorella sp. FC-21 under light-emitting diodes (LEDs). Specific growth rates and Chlorella cell concentrations were measured when they were grown under different LED wavelengths (red, blue, white, and mixed). The red LEDs were the most effective light source as determined by increases in specific growth rates and cell concentrations. Cell concentrations increased as light intensity was increased; however, the specific growth rate decreased as the initial cell concentration rose due to the shading effect of cells in the reactor. To determine if aeration is beneficial during cell cultivation, micro-air bubbles were aerated at 0.70 vvm in the reactor under red LED illumination. Aeration led to two- and ten-times greater specific growth rates. Our findings show that red LEDs with aeration are optimal for cultivation of Chlorella sp. FC-21.

Acid-labile high surface mesoporous ZnO/Zn(OH)2 composite material is used as a novel hard template for the preparation of mesoporous amorphous TiO2. The template-free amorphous TiO2 material is then thermally crystallized at suitable temperature to control the relative ratio of anatase and rutile phases in a particle. Four different anatase/rutile (AR) mixed-phase TiO2 nanoparticles (AR-3, AR-15, AR-20, and AR-23 denoted for the samples of 3%, 15%, 20%, and 23% rutile phase, respectively) are prepared and characterized by powder X-ray diffraction (PXRD) and transmission electron microscopy (TEM). The coexistence of anatase and rutile phases in a TiO2 nanoparticle is visually confirmed by HRTEM analysis. These mixed-phase TiO2 nanoparticles are examined as candidates for photoelectrodes of dye-sensitized solar cells (DSSCs). The J-V curves and IPCE spectra for the DSSCs prepared from the mixed-phase TiO2 nanoparticles are obtained, and their photovoltaic properties are investigated. The photo-conversion efficiency (eta) indicates the highest value of 5.07% for AR-20. The synergistic effect of coexisting anatase and rutile phases with an optimal ratio in a TiO2 nanoparticle of AR-20 for an efficient interfacial transfer of photo-generated electrons is likely to lead to the highest efficiency among the AR-n samples.

An organic dye ( PH-1 ), in which bis-dimethylfluoreneaniline (BDFA) acts as a single electron donor and dithiophene groups as double electron acceptors, has been synthesized for use in dye sensitized solar cells (DSSCs). The other dye ( PH-2 ) carrying one donor with one acceptor on meta- position has also been synthesized for comparison and the effect of the donor position of the dye has been investigated. The geometries and electronic structures of the dyes are elucidated by density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations. The PH-1 and PH-2 dyes show their power conversion efficiencies of 3.04 and 4.06%, short circuit current densities of 6.2 and 7.8 mA cm −2 , open circuit voltage of 644 and 689 mV, and fill factors of 76 and 75%, respectively. The TD-DFT computational study demonstrates that the excited states and localized electronic structures of the dyes renders the electron injection from dyes to TiO 2 conduction band inefficient, compared to the well-known dye ( JK-2 ) carrying one donor with one acceptor on para- position.

The purpose of this study was to determine optimum conditions for the cultivation of Chlorella sp. FC-21 using light emitting diodes (LEDs). Specific growth rate and cell concentration were measured for the reactors at the illuminations of different wavelengths of LEDs. Among various types of LEDs, red LEDs were the most effective light source, and also greatest increases of specific growth rate and cell concentrations were obtained when light intensity of red LEDs increased. The specific growth rate decreased when initial cell concentration increased due to the shading effect of each cell in the reactor. To determine beneficial effect of aeration to cell cultivation, micro-air bubbles were aerated at 0.35 vvm in the reactor at the illumination of red LEDs. Two and ten times greater specific growth rate and cell concentration were obtained when aeration was applied. From this study, we found that red LEDs with aeration were the most appropriate light source for the cultivation of Chlorella sp. FC-21.

A Ni 3 Al intermetallic compound was added to the cathode to decrease the solubility of Ni in a Li/K eutectic molten salt. The solubility of Ni/Ni 3 Al used as a cathode was examined by measuring the concentrations of Ni and Al ions in alkali metal carbonate. The electrolyte consisted of a mixture of lithium carbonate and potassium carbonate (62Li 2 CO 3 –38K 2 CO 3 ) at 650 °C. A significant decrease in Ni precipitation was observed over a long term operation using a Ni/(4%, 7%, 10%) Ni 3 Al stabilized cathode. Al is easily oxidized and forms an Al 2 O 3 film on the surface. This Al 2 O 3 film can inhibit corrosion of the electrode. The solubility of the Ni–Al oxidized electrodes containing Ni 3 Al and NiO decreased with increasing amounts of Ni 3 Al added and with increasing sintering temperature. The solubility decreased to 1.57 ppm, which is 1/10 that of the pure NiO cathode.

This study examined the characteristics of continuous operation in a continuous flow planar electrode reactor, such as Faradaic efficiency, selectivity, and products ratio of carbon dioxide. A silver electrode was found to be useful for the selective formation of carbon monoxide by the electrochemical reduction of carbon dioxide in aqueous electrolytes. The products (CO, H2) were analyzed by gas chromatography, which was equipped with a thermal conductivity detector (TCD), and the Faradaic efficiency and selectivity were calculated from the data. The yield of monoxide carbon increased with decreasing temperature but the hydrogen yield decreased. The carbon monoxide yield was higher at the lower range of electrolyte concentrations. A graph of the yield as a function of the electrode potential showed a negative parabolic curve. The maximum value is shown at −1.8 V vs. SCE. The optimized carbon monoxide to hydrogen ratio was obtained under the following conditions using a silver electrode: a 0.1 M KHCO3 electrolyte, 20 °C and a potential of −1.8 V vs. SCE.

The contact angles of pure Ni, Ni/7wt%Ni3Al, Ni/5wt%Ni3Al/ 5wt%Cr and Ni/10wt%Cr anodes for the MCFC were measured by means of the capillary rise method in 62mol%Li2CO3+ 38mol%K2CO3 and 52mol%Li2CO3+ 48mol% Na2CO3 electrolyte and at different atmosphere. Also surface fractal dimension (Ds), which could characterize pore structure of the anodes, was calculated from experimental data obtained by mercury porosimetry and nitrogen adsorption method. The surface fractal dimensions of the anode were in range from 2.75 to 2.81, because porosities of the anodes for MCFC were controlled regularly to about 62% during sintering. It was investigated from wetting-in experiment by capillary-rise method that the contact angles between the anodes and the carbonate electrolytes were relatively decreased at CO2 atmosphere rather than air atmosphere and the angles were also decreased in the 62mol%Li2CO3+38mol%K2CO3 electrolyte rather than that measured and in the 52mol%Li2CO3+48mol% Na2CO3 electrolyte.

The recycling of magnesium chloride brines via a multi-step chemical reaction and precipitation process has been studied in waste bittern from a salt purification plant. In this study, the rates of particle (magnesium hydroxide) growth, the effects of initial concentration of reactants and optimum condition of reaction to make high purity magnesium hydroxide were investigated. Produced magnesium hydroxide was separated and washed using carboxy methyl cellulose as sedimentation agent, and used sodium stearate to prevent particle from aggregating. The mean particle size of obtained high quality magnesium hydroxide are 5 μm and concentration is 99.5%.

This study investigated the production behavior of amino acids from polypeptone under various operation parameters and reactor modes (batch and continuous). In the batch experiments, the effect of heating time on amino acid production was studied using different type of reactor materials (Hastelloy (HAS) and SUS). The results showed that the production behavior of amino acids such as Gly, Ala, and Leu was quite similar regardless of reactor materials. To further investigate the relationship of reaction time on the amino acids production, experiments were conducted in batch and continuous reaction at the same conditions (T=523 K and P=30 MPa). The results showed that it is possible to get the same result at the same reaction time using a batch and continuous reaction mode if the reaction time is started after heating time in a batch reaction mode. From the study of reaction pressure, it was observed that the production of amino acids is not favored at reaction pressure between 4 and 30 MPa at 523 K.

Creep tests were conducted to measure the creep rates of pure Ni, Ni/7wt%Ni3Al, and Ni/5wt%Ni3Al/5wt%Cr anodes for MCFCs. The resulting creep rates were well modeled by a creep rate equation. During the initial stage of sintering, the creep mechanism was affected by the microstructure, and geometry referred to the macroscopic shapes of the porous anodes. For the Ni/7wt%Ni3Al and Ni/5wt%Ni3Al/5wt%Cr anodes, the creep rate varied nonlinearly with time, obeying a power law with an exponent of n < 1, in contrast to the behavior of high-density materials, which exhibit linear Nabarro-Herring or Coble creep when subjected to an applied load. Compared to the pure Ni anode, the anodes containing Ni3Al showed considerably increased creep resistance due to the impeding of mass transport of nickel particles in the anode when it was subjected to a compressive load. Collectively, the present results suggest that Ni/7wt%Ni3Al and Ni/5wt%Ni3Al/5wt%Cr anodes simultaneously have high creep resistance, and thus may represent a viable alternative porous anode for use in MCFC. © 2005 American Institute of Chemical Engineers AIChE J, 2006

The biomass of nonliving, dried marine brown algaeU. pinnatifida, H. fusiformis, andS. fulvellum harvested in the sea near Cheju Island, Korea were studied for their sorption ability of copper, zinc, and lead. The metal uptakes by biosorbent materials increased with increasing initial metal concentration and pH in the range of Ci 0.0510 mM. The higher metal uptakes were obtained in the range of pHs 4.0–5.3, 4.0–6.0, and 3.0–6.0 for copper, lead, and zinc, respectively. The metal uptakes by biosorbent materials decreased in the following sequence:U. pinnatifida> H. fusiformis> S. fulvellum. The maximum metal uptake values ofU. pinnatifida for Cu2+, Pb2+, and Zn2+ in the single metal solution are 2.58, 2.6, and 2.08 meq/g in the range of pHs 5.3–4.4, respectively. The metal uptakes by biosorbent materials in the mixed metal solution decreased greatly in comparison to each metal uptake in the single metal solution.

A study was undertaken to examine the possibility of combining a batch-recirculated photoreactor with a ceramic membrane filter for heterogeneous photocatalysis applications. D-cargo red GS (GS) was used as the test substrate and titanium dioxide was used as photocatalyst for this study. The dark adsorption of GS on the TiO2 particle surface was also analyzed. The adsorption trends of GS at various initial concentrations followed the Langmuir isotherm trend. The GS were decolorized from 20% to 70% by the dark adsorption with various concentrations. The photodegradation of GS after the dark adsorption showed the behavior of Langmuir-Hinshelwood model. The variation of recirculation flow rate did not much influence photocatalysis. Variation tendencies of GS concentration were almost similar after about 90 minutes illumination in spite of the flow rate change. The values ofk (apparent first order rate constant) also varied with increase of the recirculation flow rate, but there were no observable significant differences between them.

Experiments on the electrochemical oxidation of ammonia in artificial seawater are carried out in a lab-scale electrochemical apparatus. The operating parameters are current density (16–66 A/m2) and hydraulic residence time in a reactor (30–90 sec). The ammonia concentration in the effluent of the reactor exponentially decreases with increasing the current density and the hydraulic residence time, while the concentration of chlorine residuals increases. Most of the chlorine residuals are free available chlorine and the remainder is dichloramine. A strong disinfection characteristic can be seen during electrochemical treatment of ammonia.

Grain growth of high-density material, such as metal, during sintering was generally retarded by the pinning effect of the second phase particles which were included between the matrix metal grains. Grain size of the high-density material was inversely proportional to the 0.31-1.0th order with respect to the volume fraction of the second phase particles, and the grain was maintained at a relatively smaller size than that sintered without the second phase particles. It was investigated that the nickel grain size in the porous Ni/Ni3Al anode material for MCFC sintered for 1 hr at 900°C was inversely proportional to the 0.7th order with respect to the volume fraction of the Ni3Al intermetallics, and that the pore network in the anode was more stable than that in the pure Ni anode material by controlling the subsequent sintering process.

Microstructural changes in pure Ni, Ni/(4–10 wt%)Ni3Al and Ni/5 wt%Ni3Al/5 wt%Cr anodes for molten carbonate fuel cell were investigated by sintering experiment. Submicron-sized Ni3Al intermetallic particles were dispersed in nickel powders to improve mechanical strength by dispersion strengthening and to control both densification and pore structure of these anodes during sintering. The mechanical strengths of Ni/7 wt%Ni3Al and Ni/5 wt%Ni3Al/ 5 wt%Cr anodes were considerably higher than that of the pure Ni anode by strong bonding between small nickel grains. Pore volume in the anodes which included Ni3Al was considerably high by impeding nickel grain growth, because the retarding force exerted by the Ni3Al inclusion obstructed the nickel grain boundary movement. Pore structure in the anodes was maintained in a relatively stable open network in contrast with that in the pure Ni anode.

The effect of Ni3Al on nickel grain growth inhibition is investigated during the sintering process of a Ni-based porous molten carbonate fuel cell (MCFC) anode including 4 to 10 wt% fine Ni3Al intermetallic particles. Nickel grain growth is retarded and the grains are kept the proper size due to the pinning effect of Ni3Al intermetallics that control nickel grain boundary movement, and due to the dominant surface diffusion in the vicinity of necks formed between nickel powders. It is found that the nickel grain growth rate of the anode including Ni3Al intermetallics follows the kinetics law; Gm – Gom = Kt with m = 4.5, in which the grain size exponent is higher than that of porous pure nickel anode. A pore size distribution in the anode ranges from 3 to 6 μm, which is compatible with the electrochemical reaction of the MCFC.

A porous Ni-Al alloy anode for the molten carbonate fuel cell has been developed to enhance the creep resistance of the anode as well as to minimize the electrolyte loss A dual-porosity filmed agglomerate model for the Ni-Al alloy anode has been investigated to predict the cell performance The major physicochemical phenomena being modeled include mass transfer ohmic losses and reaction kinetics at the electrode-electrolyte interface The predicted polarization curves are compared with the experimental results obtained from a half cell test The model predicted very well the steady-state cell performance at the given conditions that characterize the state of the electrode