• Applied Chemistry for Engineering
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• v.21 no.4
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• pp.435-439
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• 2010

Pt-$MoO_3$ electrodes were fabricated on ITO-coated glass by electrodeposition method using 20 mM hydrogen hexachloroplatinate ($H_2PtCl_6$) and 10 mM Mo-peroxo electrolyte. Deposition order was varied, and catalytic activities of synthesized electrodes were compared with that of pure Pt electrode. Scanning Electron Microscopy (SEM) was utilized to examine surface morphology. The crystallinity of synthesized films was analyzed by X-ray Diffraction (XRD), and the oxidation state of both the platinum and molybdenum were determined by X-ray Photoelectron Spectroscopy (XPS) analyses. The catalytic activity and stability for methanol oxidation were measured using cyclic voltammetry (CV) and chronoamperometry (CA) in a mixture of 0.5 M $H_2SO_4$ and 0.5 M $CH_3OH$ aqueous solution. $MoO_3$ electrodeposited on the surface of Pt showed much higher catalytic acitivity and stability than pure Pt electrode due to the good contact between Pt and $MoO_3$.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.7
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• pp.729-734
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• 2008

The higher valence state of iron i.e., Fe(VI) was employed for the treatment of Cu(II)-EDTA in the aqueous/waste waters. The ferrate(VI) was prepared through wet oxidation of Fe(III) by sodium hypochlorite. The purity of prepared Fe(VI) was above 93%. The stability of Fe(VI) solution decreased as solution pH decreased through self decomposition. The reduction of Fe(VI) was obtained by using the UV-Visible measurements. The dissociation of Cu(II)-EDTA complex through oxidation of EDTA using Fe(VI) and subsequent treatment of organic matter and metal ions by Fe(III) reduced from Fe(VI) in bench-scale of continuous flow reactor were studied. The removal efficiencies of copper were 69% and 79% in pH control basin and reactor, respectively, at 120 minutes as retention time. In addition, Cu(II)-EDTA in the reactor was decomplexated more than 80% after 120 minutes as retention time. From this work, a continuous treatment process for the wastewater containing metal and EDTA by employing Fe(VI) as muluti-functional agent was developed.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.3
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• pp.392-400
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• 2004

This research uses the $TiO_2$/UV process to verify the most suitable condition and possibility to dispose dyeing wastewater that contains pigment and a large amount of pollutants. For this, this research has enforced experiments that compare photo adsorption, photolysis, and photo catalyst oxidation reaction, and also evaluated and analyzed the change of pH and $TiO_2$ dosage, irradiation rates of ultraviolet rays and the dosage change and injection method of $H_2O_2$. According to the results of the dyeing wastewater experiment of storehouse catalyst that uses the new form of $TiO_2$, the photo catalyst oxidation reaction proved to be more effective than photo adsorption and photolysis; 35%, 21% in the case of $TCOD_{cr}$ and 39%, 28% in the case of chromaticity. Taking into consideration the reaction time, amount of photo catalyst reaction and irradiation amount of ultraviolet rays, the decomposition efficiency of pH change proved to be most effective at pH 4. On the whole, the acidity area proved to be effective in dyeing water exclusion than neutral and alkalinity areas. Having evaluated the influence of $TiO_2$ dosage, not only does the decomposition efficiency continuously improve as the $TiO_2$ dosage increases but the shielding effect does not occur also when the $TiO_2$ is at a fixed state. The influence of ultraviolet irradiation amount concluded in the result that as the ultraviolet irradiation amount increases the decomposition efficiency continually increased, but in the case of chromaticity when the irradiation amount was higher than 37.8mW/cm2 the removal efficiency is slowed remarkably. The influence of $H_2O_2$ dosage evaluation reached the results that although the decomposition efficiency increases with the increase of $H_2O_2$ dosage, when above 150mg (total dosage: 1200mg) $H_2O_2$ consumes OH radical itself and reduces the decomposition efficiency. Also in the case of the $H_2O_2$ injection method rather than injecting in the whole amount of $H_2O_2$ (1200mg) needed at the beginning all at once, injecting divided quantities of $H_2O_2$ whenever the electric current density falls below 10mgfl reduces the wases of OH radical due to an excess of $H_2O_2$ and in tum heightens the decomposition efficiency.

• Applied Chemistry for Engineering
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• v.17 no.5
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• pp.451-457
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• 2006

We synthesized phase pure CrN having surface areas up to $47m^2/g$ starting from $CrCl_{3}$ with $NH_{3}$. Thermal Gravimetric Analysis coupled with X-ray diffraction was carried out to identify solid state transition temperatures and the phase after each transition. In addition, the BET surface areas, pore size distributions, and crystalline diameters for the synthesized materials were analyzed. Space velocity influenced a little to the surface areas of the prepared materials, while heating rate did not. We believe it is due to the fast removal of reaction by-products from the system. Temperature programmed reduction results revealed that the CrN was hardly passivated by 1% $O_{2}$. Molecular nitrogen was detected from CrN at 700 and $950^{\circ}C$, which may be from lattice nitrogen. In temperature programmed oxidation with heating rate of 10 K/min in flowing air, oxidation started at or higher than $300^{\circ}C$ and resulting $Cr_{2}O_{3}$ phase was observed with XRD at around $800^{\circ}C$. However the oxidation was not completed even at $900^{\circ}C$. CrN catalysts were highly active for n-butane dehydrogenation reaction. Their activity is even higher than that of a commercial $Pt-Sn/Al_{2}O_{3}$ dehydrogenation catalyst in terms of volumetric reaction rate. However, CrN was not active in pyridine hydrodenitrogenation.

• Journal of the Korean Ceramic Society
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• v.39 no.7
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• pp.657-662
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• 2002

The reduced ferrites, reduced NiF $e_2$ $O_4$ and CuF $e_2$ $O_4$, by C $H_4$ were applied to $CO_2$ decomposition to avoid the greenhouse effects. At the reduction reaction above $700^{\circ}C$, $H_2$ and CO were generated by partial oxidation of C $H_4$ After the reduction reaction up to 80$0^{\circ}C$, the spinel structure ferrites changed to mixture of the oxygen deficient iron oxide (Fe $O_{(1-{\delta})}$(0$\leq$$\delta$$\leq$1)) and the metallic Ni or Cu. The rate and quantity of $CO_2$ decomposition with reduced CuF $e_2$ $O_4$ were larger than those with reduced NiFe $O_4$. The $CO_2$ gas was decomposed by oxidation of the oxygen deficient iron oxide. The metallic Cu and Ni were not oxidized and remained in a metallic state up to 80$0^{\circ}C$. The $CO_2$ decomposition reaction with the reduced ferrite by C $H_4$ gas is excellent process preparing useful gas such as $H_2$and CO and decomposing $CO_2$ gas.

• Journal of the Mineralogical Society of Korea
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• v.30 no.1
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• pp.21-29
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• 2017

Surface soils on Barton Peninsula, King George Island, West Antarctica were investigated to acquire the mineralogical and geochemical data of soil in Antarctica. Multiline of techniques for example, X-ray diffraction (XRD), transmission electron microscopy (TEM)-electron energy loss spectroscopy (EELS), and wet chemistry analysis were performed to measure the composition of clay minerals, Fe-oxidation states, cation exchange capacity, and total cation concentration. Various minerals in sediments such as smectite, illite, chlorite, kaolinite, quartz and plagioclase were identified by XRD. Fe-oxidation states of bulk soils showed 20-40% of Fe(II) which would be ascribed to the reduction of Fe in clays as well as Fe-bearing minerals. Moreover, redox states of Fe in smectite structure was a ~57% of Fe(III) consistent to the values for the bulk soils. The cation exchange capacity of bulk soils ranged from 100 to 300 meq/kg and differences were not significantly measured for the sampling locations. Total cations (Mg, K, Na, Al, Fe) of bulk soils varies, contrast to the heavy metals (Co, Ni, Cu, Zn, Mn). These results suggested that composition of bed rocks influenced the distribution of elements in soil environments and soils containing clay compositions may went through the bio/geochemical alteration.

• Korean Chemical Engineering Research
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• v.54 no.2
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• pp.248-254
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• 2016

Efficacious wastewater treatment is essential for increasing sewage sludge volume and implementing strict environmental regulations. The operation cost of sludge treatment amounts up to 50% of the total costs for wastewater treatment plants, therefore, an economical sludge destruction method is crucially needed. Amid several destruction methods, wet air oxidation (WAO) can efficiently treat wastewater containing organic pollutants. It can be used not only for sludge destruction but also for useful by-product production. Volatile fatty acids (VFAs), one of many byproducts, is considered to be an important precursor of biofuel and chemical materials. Its high reaction condition has instituted the study of gravity pressure reactor (GPR) for an economical process of WAO to reduce operation cost. Simulation of subcritical condition was conducted using Aspen Plus with predictive Soave-Redlich-Kwong (PSRK) equation of state. Conjointly, simulation analysis for GPR depth, oxidizer type, sludge flow rate and oxidizer injection position was carried out. At GPR depth of 1000m and flow rate of 2 ton/h, the conversion and yield of VFAs were 92.02% and 0.17g/g, respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.91-91
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• 2013

Imagine a world where we could biomanufacture hybrid nanomaterials having atomic-scale resolution over functionality and architecture. Toward this vision, a fundamental challenge in materials science is how to design and synthesize protein-like material that can be fully self-assembled and exhibit information-specific process. In an ongoing effort to extend the fundamental understanding of protein structure to non-natural systems, we have designed a class of short peptides to fold like proteins and assemble into defined nanostructures. In this talk, I will talk about new strategies to drive the self-assembled structures designing sequence of peptide. I will also discuss about the specific interaction between proteins and inorganics that can be used for the development of new hybrid solar energy devices. Splitting water into hydrogen and oxygen is one of the promising pathways for solar to energy convertsion and storage system. The oxygen evolution reaction (OER) has been regarded as a major bottleneck in the overall water splitting process due to the slow transfer rate of four electrons and the high activation energy barrier for O-O bond formation. In nature, there is a water oxidation complex (WOC) in photosystem II (PSII) comprised of the earthabundant elements Mn and Ca. The WOC in photosystem II, in the form of a cubical CaMn4O5 cluster, efficiently catalyzes water oxidation under neutral conditions with extremely low overpotential (~160 mV) and a high TOF number. The cluster is stabilized by a surrounding redox-active peptide ligand, and undergo successive changes in oxidation state by PCET (proton-coupled electron transfer) reaction with the peptide ligand. It is fundamental challenge to achieve a level of structural complexity and functionality that rivals that seen in the cubane Mn4CaO5 cluster and surrounding peptide in nature. In this presentation, I will present a new strategy to mimic the natural photosystem. The approach is based on the atomically defined assembly based on the short redox-active peptide sequences. Additionally, I will show a newly identified manganese based compound that is very close to manganese clusters in photosystem II.

• Applied Chemistry for Engineering
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• v.30 no.5
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• pp.620-626
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• 2019

In this study, the effects of the structural properties of the catalyst on CO oxidation reaction by controlling the $Cu/CeO_2$ catalyst amount and calcination temperature were studied, and also the CO conversion rate of the catalyst at the temperature range of $100{\sim}300^{\circ}C$ was evaluated. XRD, Raman, BET, $H_2-TPR$, and XPS analyses were performed to confirm the effect of changes in the structural properties on the chemical properties of the catalyst. The result confirmed that a substitution bond between Cu and Ce was formed and a lot of Cu and Ce bonds were formed when the catalyst carrying 5 wt.%. Of Cu was calcined at $400^{\circ}C$. The Cu-Ce binding was confirmed by peak shifts in Raman analysis and also peaks appeared in $H_2-TPR$. In addition, the balance state analysis demonstrated that a lot of surface labile oxygen molecules are formed, which can be more easily contributed to the reaction with $Ce^{3+}$ species known to form a substitution bond easily. It was found that CO conversion rate of the catalyst used in this study was close to 100% at $150^{\circ}C$.

• Journal of Practical Agriculture & Fisheries Research
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• v.18 no.1
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• pp.71-78
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• 2016

The present study was performed to examine the high temperature adaptability with CO₂ treatment for tomato under the condition of greenhouse cultivation during summer season. The plants with the CO₂ concentration of 1000 ppm recorded higher scores in Fm/Fo and Fv/Fm but lower score in Fo than others through the measurement of chlorophyll fluorescence, which implicated that the plants with the CO₂ concentration of 1000 ppm had more adaptability to high temperature than the others. At the condition of the same air temperature as 30℃ and 40℃, the photosynthetic rate was increased with the increase of CO₂ concentration. When in the high air temperature state of 40℃, although the photosynthic rate was low in comparison with 30℃, its value was about 18.5umolm^-2s^-1 in case of 1000ppm. The higher concentration of CO₂ made the more activated anti-oxidation enzyme (superoxide dismutase and peroxidase) for the both cultivars as 'momotaro' and 'minichal'. The cultivar of 'minichal' performed the high temperature limit as 41℃ at the CO₂ condition of 500 ppm and 43℃ at the CO₂ condition of 1000 ppm through the estimation on the variation of chlorophyll fluorescence Fo by CO₂ concentrations.