• Journal of the Korean Electrochemical Society
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• v.2 no.2
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• pp.70-74
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• 1999

The electrode kinetic parameters at the Pd/0.5 M LiOH electrolyte interface have been qualitatively studied using the phase-shift method. The phase shift $(\phi)$ depends on both the cathode potential (E>0) and frequency (f), and $\theta$ is inversely proportional to the fractional surface coverage $\theta$. At an intermediate frequency (10 Hz), the phase-shift profile $(\phi\;vs.\;E)$ can be related to the fractional surface coverage $(\theta\;vs.\;E)$. The phase-shift method can be used to estimate or plot the Frumkin adsorption isotherm. The rate (r) of change of the free energy of adsorption with $({\theta})$ is 22.3 kJ/mol. The equilibrium constant (K) for adsorption and the standard free energy $({\Delta}G_{\theta})$ of the adsorbed hydrogen atom $(H_{ads})$ are $3.7\times10^{-3}{\Delta}G_{\theta}>-8.4kJ/mol$, respectively. For 1$0.38>\theta>0$, the energy liberation or the exothermic reaction for hydrogen adsorption at the Pd cathode can be occurred. The electrode kinetic parameters $(r,\;K,\;{\Delta}G_{\theta}$ depend on the fractional surface coverage $({\theta})$ or the phase shift $(\phi)$.

• Journal of the Korean institute of surface engineering
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• v.50 no.2
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• pp.98-107
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• 2017

Pd-based membranes have been widely used in hydrogen purification and separation due to their high hydrogen diffusivity and infinite selectivity. However, it has been difficult to fabricate thin and dense Pd-based membranes on a porous stainless steel(PSS) support. In case of a conventional PSS support having the large size of surface pores, it was required to use complex surface treatment and thick Pd coating more than $6{\mu}m$ on the PSS was required in order to form pore free surface. In this study, we could fabricate thin and dense Pd membrane with only $3{\mu}m$ Pd layer on a new PSS support manufactured by metal injection molding(MIM). The PSS support had low surface roughness and mean pore size of $5{\mu}m$. Pd membrane were prepared by advanced Pd sputter deposition on the modified PSS support using fine polishing and YSZ vacuum filling surface treatment. At temperature $400^{\circ}C$ and transmembrane pressure difference of 1 bar, hydrogen flux and selectivity of $H_2/N_2$ were $11.22ml\;cm^{-2}min^{-1}$ and infinity, respectively. Comparing with $6{\mu}m$ Pd membrane, $3{\mu}m$ Pd membrane showed 2.5 times higher hydrogen flux which could be due to the decreased Pd layer thickness from $6{\mu}m$ to $3{\mu}m$ and an increased porosity. It was also found that pressure exponent was changed from 0.5 on $6{\mu}m$ Pd membrane to 0.8 on $3{\mu}m$ Pd membrane.

• Resources Recycling
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• v.18 no.1
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• pp.30-37
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• 2009

Distribution diagram of Pt(IV), Pd(II), and Rh(III) in HCl solution was obtained as a function of HCl concentration from 0.001 to 10 M by considering complex formation reaction together with mass balance. When HCl concentration was higher than 0.1 M, most of Pt and Pd in HCl solution exist as $PtCl_6^{2-}$ and $PtCl_4^{2-}$. The concentration of HCl had a feat effect on the speciation of Rh(III). As HCl concentration increases from 0.1 to 10 M, the pedominant species changes from $PhCl_5^{2-}$ to $PhCl_6^{3-}$. Interaction parameters of $PtCl_6^{2-}$ and $PdCl_4^{2-}$ with hydrogen ion were evaluated from the solvent extraction data of Pt and Pd reported in the literature.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.8
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• pp.1201-1207
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• 2007

This study compared the recovery rate of intrajugular-administered allantoin in the urine and saliva between swamp buffaloes and zebu cattle to examine whether it could explain the lower excretion rate of urinary purine derivatives (PD) in the buffaloes. Three male swamp buffalo yearlings, with an average body weight of $349{\pm}40.35$ kg, and three Thai native cattle ($154{\pm}3.26$ kg) of similar age and sex were used in the study. Animals were kept in individual pens and fed at a maintenance energy level with a diet containing 65% monk bean husk (Vigna radiata) as roughage and 35% concentrates. Allantoin solution was infused into the jugular vein in four incremental rates equivalent to 0, 5, 10 and 15 mmol/d and urine was collected daily in acidified form. Daily PD excretion was linearly correlated with intrajugular allantoin infusion in both species. The relationship between daily urinary PD excretion (Y, mmol/d) and intrajugular allantoin infused (X, mmol/d) was $Y=0.75{\pm}0.318X+22.45{\pm}2.98$ ($r^2$ = 0.36, n = 12, MSE = 38.02, CV = 21.9, p<0.01) for swamp buffaloes and $Y=0.96{\pm}0.10X+15.93{\pm}0.92$ ($r^2$ = 0.91, n = 12, MSE = 3.60, CV = 8.27, p<0.01) for zebu cattle. The salivary PD concentration was not correlated with intrajugular allantoin infusion in both species, with values for buffaloes numerically lower than those for cattle. The present study reconfirmed previous studies that buffaloes have a lower plasma PD excretion rate via the renal route and a significant proportion (22%) of the plasma PD loss is via the saliva. However, results of our present and previous studies suggest that differences in purine base (PB) metabolism between buffaloes and zebu cattle occur before the purine compounds reach the plasma pool.

• Journal of the Korean Magnetics Society
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• v.14 no.4
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• pp.127-130
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• 2004

Magnetic properties and thermal stability by exchange biased perpendicular magnetic anisotropy in (Pd/Co)$_{N}$FeMn multilayer deposited by do magnetron sputtering system are investigated. We measured the perpendicular magnetization curves of (Pd(0.8nm)/Co(0.8nm)$_{5}$FeMn multilayer as function of FeMn thickness and annealing temperature. As FeMn thickness increases from 0 to 21nm, the perpendicular exchange bias(Hex) obtained 127 Oe at FeMn thickness 15nm. As the annealing temperature increases to 24$0^{\circ}C$, the E$_{ex}$ increased from 115 Oe to 190 Oe and disappeared exchange biased perpendicular magnetic anisotropy effect at 33$0^{\circ}C$.

• Journal of the Korean Magnetics Society
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• v.26 no.1
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• pp.1-6
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• 2016

Pd has the highest magnetic susceptibility among single element metals and often shows ferromagnetism under some special environments. In this paper, we report magnetism of 5- and 9-monolayers (ML) calculated by using full-potential linearized augmented plane wave method. Exchange-correlation interaction is taken into account in local density approximation (LDA) and generalized gradient approximation (GGA) and calculational results in LDA and GGA are compared with each other. It is found that calculations by LDA are more reliable compared to those by GGA because LDA prediction of paramagnetism of bulk Pd is consistent with experiments, whereas GGA predicts wrongly ferromagnetim of bulk Pd. Calculational results in LDA on a 5-ML Pd(111) thin film shows a ferromagnetic ground state unlike a paramagnetic ground state of bulk Pd. The center Pd layer of the 5-ML Pd(111) thin film has the largest magnetic moment ($0.273{\mu}_B$) among the layers and |m| = 1 orbital states play a dominant role in stabilizing the ferromagnetism of the 5-ML Pd(111) thin film. A 9-ML Pd(111) thin film in a ferromagnetic state has almost the same total energy as in a paramagnetic state. Since the magnetization of the 9-ML Pd(111) thin film is stable, the ferromagnetic state may be meta-stable.

• Journal of the Korean Chemical Society
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• v.27 no.4
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• pp.268-272
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• 1983

Polyurethane foam impregnated with ${\beta}$-diphenylglyoxime has been applied to the extraction of palladium(II) from platinum(IV) and nickel(II) in aqueous solution. Palladium(II) is quantitatively extracted from $0.01{sim}0.05M$ HCl. On the other hand, platinum(Ⅳ) was slightly extracted and nickel(II) was not found to be extraction in the same experimental condition. Based on the results obtained, the selective separation, removal and recovery of Pd(II) from Pt(IV) or Ni(II) was possible by batch or elution method.

• Journal of Electrochemical Science and Technology
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• v.12 no.1
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• pp.38-57
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• 2021

The different weight ratios of Pd to Pt, i.e., 16:4, 10:10, 4:16 in Pd-Pt/C and Pd (20 wt. %) /C electrocatalysts with low metal loading were synthesized for glycerol electrooxidation in an air breathing microfluidic fuel cell (MFC). The cell performance on Pd-Pt (16:4)/C anode electrocatalyst was found best among all the electrocatalysts tested. The single cell when tested at a temperature of 35℃ using Pd-Pt (16:4)/C, showed maximum open circuit voltage (OCV) of 0.70 V and maximum power density of 2.77 mW/㎠ at a current density of 7.71 mA/㎠. The power density increased 1.45 times when cell temperature was raised from 35℃ to 75℃. The maximum OCV of 0.78 V and the maximum power density of 4.03 mW/㎠ at a current density of 10.47 mA/㎠ were observed at the temperature of 75℃. The results of CV substantiate the single cell performance for various operating parameters.

• Bulletin of the Korean Chemical Society
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• v.16 no.3
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• pp.211-214
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• 1995

The catalytic activities of palladium(0,Ⅰ,Ⅱ)-diphosphine complexes were investigated in styrene oxidation using H2O2 as terminal oxidant. The rates showed a dependence on the chelate ring patterns of complexes (PdCl2L); 5-membered ring (L=dppe: 1,2-bis(diphenylphosphino)ethane) < 6-membered ring (L=dppp: 1,3-bis(diphenylphosphino)propane) < 4-membered ring (L= dppm: bis(diphenylphosphino)methane). This sequence correlates with the ligand field strength and interactions between metal and phosphine ligands. Pd(Ⅱ,Ⅰ)-diphosphine complexes which are capable of making 4-membered chelate ring showed an enhancement of catalytic activities for styrene oxidation. The catalytic activities of Pd(0,Ⅰ,Ⅱ)-diphosphine complexes are described in terms of electronic and steric factors.

• Korean Chemical Engineering Research
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• v.47 no.6
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• pp.768-774
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• 2009

To improve the productivity of 1,3-propanediol(1,3-PD) with K. pneumoniae DSM4799 using pure glycerol and crude glycerol derived from the biodiesel process, optimizing fermentation conditions was performed by changing environmental factors such as anaerobic/aerobic condition, temperature, glycerol concentration, and pH. When anaerobic conditions were maintained, there was an improved 1,3-PD production compared with that from aerobic/anaerobic 2-stage fermentation. From the results with temperature $26{\sim}37^{\circ}C$, the higher 1,3-PD production yield was observed at $30{\sim}33^{\circ}C$. For an initial glycerol concentration higher than 60 g/L, cell growth and 1,3-PD production were inhibited. When crude glycerol was used, the initial 1,3-PD production appeared to be inhibited. After 48 hr of incubation, however, 1,3-PD production with crude glycerol was even higher than that with pure glycerol, demonstrating the feasibility of 1,3-PD production using crude glycerol as a substrate. Fed-batch fermentation was applied for the high concentration of 1,3-PD without substrate inhibition. By regulating pH at 7 during the fed-batch with glycerol lower than 40 g/L, the yield of 1,3-PD was 25% higher than that without pH regulation(0.56 g/g vs. 0.45 g/g). In conclusion, based on our results, anaerobic conditions, temperature at $30^{\circ}C$, pure or crude glycerol lower than 40 g/L, and pH regulation at 7 were the optimized conditions for 1,3-PD production using K. pneumoniae DSM4799, making it more feasible to produce 1,3-PD at higher concentration and a lower price.