• Applied Chemistry for Engineering
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• v.8 no.2
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• pp.292-300
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• 1997

In this study PZT powders were prepared with shapes of cubic by hydrothermal synthesis with various starting materials, and the sintering characteristics of the powders were investigated. The particle shapes were cubic regardless of starting materials, but the mean size of particles formed using $Pb(NO_3)_2$, $Ti(OC_4H_9)_4$ and $Zr(OC_4H_9)_4$ was relatively smaller than that of particles prepared from other starting materials. Agitation of the feedstock during hydrothermal reaction results in decreasing the required reaction temperature for the formation of nuclei, and in increasing the size of product particles. XRD results showed that the major phase of PZT crystal powders was a tetragonal phase at the Zr to Ti ratio of 40 to 60, or a rhombohedral phase at its ratio of 60 to 40. The density of a sintered body made from the hydrothermal powders in PbO surrounding varied with sintering temperatures and with periods of sintering time. The experimental results also showed that the optimum sintering condition was at $1150^{\circ}C$ for a 2hr sintering, and that the density of a sintered body was $7.6g/cm^3$.

• Korean Journal of Environmental Agriculture
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• v.36 no.1
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• pp.22-28
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• 2017

BACKGROUND: There is very limited knowledge of the effects of biochar derived from exhausted coffee residue on metal adsorption processes. Furthermore, only limited information is available on the adsorption mechanism of copper. The aim of this study was to evaluate the absorption behaviors of copper by biochar derived from exhausted coffee residue. METHODS AND RESULTS: Biochars produced by pyrolysis of exhausted coffee residue at $300^{\circ}C$(CB300) and $600^{\circ}C$(CB600) were characterized and investigated as adsorbents for the removal of copper from aqueous solution. The results indicated that the adsorption equilibrium was achieved around 2 h and the pseudo-second-order kinetic model fit the data better than the pseudo-first-order kinetic model. The maximum Cu adsorption capacities of CB600 by Freundlich and Langmuir isotherms were higher than those of CB300. The adsorption data were well described by a Langmuir isotherm compare to Freundlich isotherm. CONCLUSION: Our results suggest that exhausted coffee residue can be used as feedstock materials to produce high quality biochar, which could be used as adsorbents to removal copper.

• Korean Journal of Environmental Agriculture
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• v.36 no.4
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• pp.249-255
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• 2017

BACKGROUND: Globally, mulberry (Morus sp.) is exploited for feeding leaf to silkworms in order to obtain silk fiber or for animal feedstock production. Also, mulberry fruit is known to a by-product that was produced from mulberry tree after harvesting leaves for silkworm rearing, as a yield and consumption of mulberry fruit was increased, it has been fixing to a newincome crop. Mulberry leaves and fruits are used for the health benefits of human beings. Mulberry contains various bioactive components, such as alkaloids and flavonoids. Mulberry flavonoids are an important part of the diet because of their effects on human nutrition. The flavonoids in mulberry leaf and fruit of 'Suhyang'(Morus alba L.) were determined. METHODS AND RESULTS: Flavonoids for mulberry leaf and fruit of 'Suhyang' were analysed using ultrahigh performance liquid chromatography coupled with diode array detection and quadrupole time-of-flight mass spectrometry (UPLC-DAD-QTOF/MS)technique. An UPLC-DAD-QTOF/MS system was used, and identification of mulberry leaves constituents was carried out on the basis of the complementary information obtained from LC spectra, MS ions, and MS/MS fragments. The mulberry leaf (16 flavonoids) and fruit (9 flavonoids) were isolated and analyzed from Suhyang using UPLC-DAD-QTOF/MS chromatogram. To the best of our knowledge, Quercetin 3-O-(6"-O-malonyl) glucoside and quercetin 3-O-rutinoside (rutin) was detected on the highest content in leaf and fruit, respectively and further research will be devoted to evaluate their biological activity. CONCLUSION: Obtaining information about the concentration of functional materials in mulberry leaves could contribute to the development and promotion of processed, functional products and offer possible industrial use of 'Suhyang', holding promises to enhance the overall profitability of sericulture.

• Microbiology and Biotechnology Letters
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• v.39 no.3
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• pp.238-244
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• 2011

Biodiesel, mono-alkyl esters of long chain fatty acids, is one of the alternative fuels derived from renewable lipid feedstock, such as vegetable oils or animal fats. For decade, various lipases have been used for the production of biodiesel. However, the production of biodiesel by enzymatic catalyst has profound restriction in industry application due to high cost. To overcome these problems, many research groups have studied extensively on the selection of cheap oil sources, the screening of suitable lipases, and development of lipase immobilization methods. In this study, we produced biodiesel from plant oil using Proteus vulgaris lipase K80 expressed in Escherichia coli cells. The recombinant lipase K80 was not only expressed in high level but also had high specific lipase activity and high stability in various organic solvents. Lipase K80 could produce biodiesel from olive oil by 3-stepwise methanol feeding method. The immobilized lipase K80 also produced biodiesel using the same 3-stepwise method. The immobilized lipase could produce biodiesel efficiently from various plant oils and waste oils.

• Korean Chemical Engineering Research
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• v.46 no.5
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• pp.977-982
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• 2008

The production of ethanol by microbial fermentation as an alternative energy source has been of interest because of increasing oil price. Saccharomyces cerevisiae and Zymomonas mobilis are two of the most widely used ethanol producers. In this study, characteristics of ethanol fermentation by Saccharomyces cerevisiae CHY1077 and Zymomonas mobilis CHZ2501 was compared. Brown rice, naked barley, and cassava were selected as representatives of the starch-based raw materials commercially available for ethanol production. The volumetric ethanol productivities by Saccharomyces cerevisiae from brown rice, naked barley and cassava were $0.68g/l{\cdot}h$, $1.03g/l{\cdot}h$ and $1.28g/l{\cdot}h$ respectively. But for the Zymomonas mobilis, $2.19g/l{\cdot}h$(brown rice), $2.60g/l{\cdot}h$(naked barley) and $3.12g/l{\cdot}h$(cassava) were obtained. Zymomonas mobilis was more efficient strain for ethanol production than S. cerevisiae.

• Advances in Energy Research
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• v.1 no.2
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• pp.147-163
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• 2013

The world faces several issues of energy crisis and environmental deterioration due to over-dependence on single source of which is fossil fuel. Though, fuel is needed as ingredients for industrial development and growth of any country, however the fossil fuel which is a major source of energy for this purpose has always been terrifying thus the need for alternative and renewable energy sources. The search for alternative energy sources resulted into the acceptance of a biofuel as a reliable alternative energy source. This work presents the study of optimization of process of transesterification of vegetable oil to biodiesel using NaOH as catalyst. A $2^4$ factorial design method was employed to investigate the influence of ratio of oil to methanol, temperature, NaOH concentration, and transesterification time on the yield of biodiesel from vegetable oil. Low and high levels of the key factors considered were 4:1 and 6:1 mole ratio, 30 and $60^{\circ}C$ temperatures, 0.5 and 1.0 wt% catalyst concentration, and 30 and 60 min reaction time. Results obtained revealed that oil to methanol molar ratio of 6:1, tranesetrification temperature of $60^{\circ}C$, catalyst concentration of 1.0wt % and reaction time of 30 min are the best operating conditions for the optimum yield of biofuel from vegetable oil, with optimum yield of 95.8%. Results obtained on the characterizzation of the produced biodiesel indicate that the specific gravity, cloud point, flash point, sulphur content, viscosity, diesel index, centane number, acid value, free glycerine, total glycerine and total recovery are 0.8899, 4, 13, 0.0087%, 4.83, 25, 54.6. 0.228mgKOH/g, 0.018, 0.23% and 96% respectively. Results also indicate that the qualities of the biodiesel tested for are in conformity with the set standard. A model equation was developed based on the results obtained using a statistical tool. Analysis of variance (ANOVA) of data shows that mole ratio of ground nut oil to methanol and transesterification time have the most pronounced effect on the biodiesel yield with contributions of 55.06% and 9.22% respectively. It can be inferred from the results various conducted that vegetable oil locally produced from groundnut oil can be utilized as a feedstock for biodiesel production.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.131-131
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• 2013

A single-layer graphene has been uniformly grown on a Cu surface at elevated temperatures by thermally processing a poly(methyl methacrylate) (PMMA) film in a rapid thermal annealing (RTA) system under vacuum. The detailed chemistry of the transition from solid-state carbon to graphene on the catalytic Cu surface was investigated by performing in-situ residual gas analysis while PMMA/Cu-foil samples being heated, in conjunction with interrupted growth studies to reconstruct ex-situ the heating process. The data clearly show that the formation of graphene occurs with hydrocarbon molecules vaporized from PMMA, such as methane and/or methyl radicals, as precursors rather than by the direct graphitization of solid-state carbon. We also found that the temperature for vaporizing hydrocarbon molecules from PMMA and the length of time the gaseous hydrocarbon atmosphere is maintained, which are dependent on both the heating temperature profile and the amount of a solid carbon feedstock are the dominant factors to determine the crystalline quality of the resulting graphene film. Under optimal growth conditions, the PMMA-derived graphene was found to have a carrier (hole) mobility as high as ~2,700 cm2V-1s-1 at room temperature, superior to common graphene converted from solid carbon.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.5
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• pp.903-915
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• 2011

Recently, anaerobic methane production of agricultural waste biomass has received increasing attention. Until now domestic BMP (Biochemical methane potential) studies concerned with agricultural waste biomass have concentrated on the several waste biomass such as livestock manure, food waste, and sewage sludge from WWTP (Waste water treatment plant). Especially, the lack of standardization study of BMP assay method has caused the confused comprehension and interpretation in the comparison of BMP results from various researchers. Germany and USA had established the standard methods, VDI 4630 and ASTM E2170-01, for the analysis of BMP and anaerobic organic degradation, respectively. In this review, BMP was defined in the aspect of organic material represented as COD (Chemical oxygen demand) and VS (Volatile solid), and the influence of several parameters on the methane potential of the feedstock was presented. In the investigation of domestic BMP case studies, BMP results of 18 biomass species generating from agriculture and agro-industry were presented. And BMP results of crop species reported from foreign case studies were presented according to the classification system of crops such as food crop, vegetables, oil seed and specialty crop, orchards, and fodder and energy crop. This review emphasizes the urgent need for characterizing the innumerable kind of biomass by their capability on methane production.

• Korean Chemical Engineering Research
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• v.57 no.2
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• pp.244-252
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• 2019

This study investigated the effect of addition of aromatics such as Toluene/LCO/resin on the coke depression and asphaltene conversion. The experiment was carried out with vacuum residue as a feedstock with Molybdenum dispersed catalysts under the slurry-phase hydrocracking condition (Temp. of $425^{\circ}C$, $H_2$ pressure of 80 bar at $80^{\circ}C$, reaction time of 4 hr, Mo-concentration of 500 ppm). As results, the coke reduction was shown to be similar irrespective of types of aromatics, while asphaltene was more converted to gas and maltene when LCO and resin with higher dipole moment were added. The addition of aromatics with change of reaction time showed no difference in terms of depression of coke formation. But the addition of LCO rather increased the coke yield after 2 hr. And it was found that asphaltene in liquid phase had the higher aromaticity index so that asphaltene is difficult to disperse in oil phase.

• Applied Chemistry for Engineering
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• v.31 no.6
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• pp.688-696
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• 2020

Petroleum coke (petcoke) is widely used, next to coal, as a gasification feedstock. In gasification processes, the viscosity of the ash and the formation of crystalline phases must be understood to ensure the continuous removal of slag. This study investigates the effect of CaO and V2O3 on petcoke slag viscosity. The viscosity of the molten slag was measured in the temperature range of 1100~1600 ℃ while varying the concentration of each component. The crystalline phases formed in a cooled slag were examined. The most slag samples tested in this study exhibited crystalline slag behavior. The increased CaO concentration resulted in a lower viscosity and a lower Tcv. The viscosity behavior changed from the glassy to crystalline slag and also showed a higher Tcv as the concentration of V2O3 increases. Most slag samples showed different crystalline phases from top to bottom. Anorthites and Ca-V phases were observed in the top and middle section, while the bottom section mainly showed V2O3 and anorthite. The vanadium in the ash forms Ca-V and V-Fe phases and also remains in molten slag. A low melting Ca-V phase can contribute to lowering the viscosity.