• Korean Journal of Environmental Agriculture
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• v.39 no.3
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• pp.171-177
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• 2020

BACKGROUND: Recently, biomass conversion from agricultural wastes to carbon-rich materials such as biochar has been recognized as a promising option to maintain or increase soil productivity, reduce nutrient losses, and mitigate greenhouse gas emissions from the agro-ecosystem. This experiment was conducted to select an optimum conditions for enhancing the NH₄-N adsorption capacity of rice hull activated biochar. METHODS AND RESULTS: For deciding the proper molarity of KOH for enhancing its porosity, biochars treated with different molarity of KOH (0, 1, 2, 4, 6, 8) were carbonized at 600℃ in the reactor. The maximum adsorption capacity was 1.464 mg g^-1, and an optimum molarity was selected to be 6 M KOH. For the effect of adsorption capacity to different carbonized temperatures, 6 M KOH-treated biochar was carbonized at 600℃ and 800℃ under the pyrolysis system. The result has shown that the maximum adsorption capacity was 1.76 mg g^-1 in the rice hull activated biochar treated with 6 M KOH at 600℃ of pyrolysis temperature, while its non-treated biochar was 1.17 mg g^-1. The adsorption rate in the rice hull activated biochar treated with 6 M KOH at 600℃ was increased at 62.18% compared to that of the control. Adsorption of NH₄-N in the rice hull activated biochar was well suited for the Langmuir model because it was observed that dimensionless constant (R_L) was 0.97 and 0.66 at 600℃ and 800℃ of pyrolysis temperatures, respectively. The maximum adsorption amount (q_m) and the bond strength constants (b) were 0.092 mg g^-1 and 0.001 mg L^-1, respectively, for the rice hull activated biochar treated with 6 M KOH at 600℃ of pyrolysis. CONCLUSION: Optimum condition of rice hull activated biochar was 6M KOH at 600℃ of pyrolysis temperature.

• Journal of Applied Biological Chemistry
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• v.60 no.4
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• pp.339-342
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• 2017

Residual endosulfan in an agricultural environment has been reported, although endosulfan was listed to persistent organic pollutants and banned. To produce the safe crop from endosulfan residue risk, the plant uptake potential of endosulfan from soil to crop should be studied. In here, the plant uptake potentials of endosulfan in various crops were surveyed and ranged from 0.002-4.460. And the bioconcentration factors (BCF) of total endosulfan in carrot and spinach were calculated from the pot experiment. The BCFs in carrot and spinach were 0.285 and 0.040-0.047 respectively. Endosulfan sulfate was contributed to over 42.8% of the crop residue as a major contributor among the three endosulfan congeners in both of carrot and spinach.

• Journal of Applied Biological Chemistry
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• v.63 no.1
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• pp.111-116
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• 2020

Total polyphenol contents, flavonoid contents, 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activities of ethanol extracts of 20 herbal plants (sage, turmeric, mace, bayleaf, fenugreek, oregano, blackpepper, whitepepper, clove, marjoram, cinnamon, coriander, basil, dillseed, mustard, cadamon, thyme, celery, rosemary, cumin) were analyzed for the screening of high flavonoid-containing plant resource. Thyme extract, showing the highest flavonoid content and a high degree of antioxidant activity, was selected as a bioactive cosmetic material. The total polyphenols and flavonoids contents of thyme extracts were measured as 6.90 mg chlorogenic acid equivalent (CAE)/100 g and 1.71 mg naringin equivalent (NE)/100 g, respectively, and DPPH radical scavenging activities was 90%. Among the tested organic solvents, hexane gave the highest extraction yield. Thus hexane was selected as the most suitable solvent for the extraction of thyme. Response surface method was used to obtain optimized extraction conditions for thyme: reaction temperature of 35.9 ℃, raw material to hexane ratio of 1.63:25 (w/v), and reaction time of 192 min. These predicted extraction conditions was validated by a total flavonoid extraction experiment showing a value equivalent to 96.3% of the predicted total flavonoid content. It is expected that the optimized solvent extraction conditions could be used for the production of flavonoid using thyme.

• Applied Biological Chemistry
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• v.41 no.2
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• pp.181-186
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• 1998

The effects of sewage treatment on characteristics of sludge as a composting material were investigated for a year during the initial operation at the full-scale Chunan sewage treatment plant. Due to the shortage of design capacity of belt press, a sludge dewatering unit, non-volatile solids were recirculating and concentrating in the treatment plant, resulting in an increase of MLSS and a decrease in F/M ratio at the activated sludge system. Special attention is required for long term operations since the increase of non-volatile solids in the plant would deteriorates the treatment efficiency. The sewage sludge of the Chunan sewage treatment plant showed 79.5% of water content, 11.6% of organic content, and C/N ratio of 6.1, and contained As 1.8 mg/kg, Cd 27 mg/kg, Hg <0.1 mg/kg, Pb 54 mg/kg, T-Cr 370 mg/kg, and Cu 1,100mg/kg of heavy metals. In order to be used as raw material for optimum composting, the sewage sludge requires bulking agents for moistrure/porosity control and a carbon source for adjusting C/N ratio. However, the sewage sludge is not adequate as a soil conditioner after composing due to a high content of heavy metals. If the sewage sludge has to he used as a soil conditioner after composting, it as required to identify and remove tire industrial wastewater portions in tire influent of the plant since heavy metals in the influent were mostly concentrated in dewatered sludge.

• Applied Biological Chemistry
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• v.44 no.1
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• pp.12-19
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• 2001

The major volatiles from Allium species were found to be sulfide compounds and the ratio of sulfide to volatiles was 66.1% in garlic, 66.1% in scallion, 62.3% in green onion, 39.2% in onion, and 4.2% in chive. Trace of cyclooctasulfur was found to be present among the volatiles. The most oviposition of 17.2% occurred at diallyl sulfide and the least of 0.8% at acetylthiophene whereas the most oviposition of 43.3% occurred at ethyl alcohol if concentration was 100%. Among the organic solvents used for dilution, ethyl alcohol received the highest 52.5% of oviposition and ether the lowest of 5.9%. Furfuryl mercaptan which is also one of the volatiles, received 46.9% of oviposition. For oviposition site, D. antiqua preferred sulfides at near 1%, ethyl alcohol at high, and other volatiles at various concentrations. At 100% concentration, most volatiles except dimethyl disulfide and ethyl alcohol received less oviposition than the control which was watered sand with no volatiles added.

• Korean Journal of Environmental Agriculture
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• v.5 no.1
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• pp.30-34
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• 1986

This study was carried out to determine the heavy metal contents in sluges of Keumho river and her branches. The heavy metal contents of sludge are the highest in Sincheon, Kongdancheon and Dalseocheon among the branches. The large part of heavy metal exists in $0{\sim}5cm$ from sludge surface. The sequential extraction with various reagents showed that the residual and organically bound fraction were the most abundant pool. Decomposition of organic matter caused sludge to release heavy metals. On the extraction of sludge with various solution having different pH, it was found that the lower the pH, the more heavy metal was extracted. However, considerable amount of heavy metal was not extracted even with pH 3 solution.

• Korean Journal of Environmental Agriculture
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• v.20 no.1
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• pp.8-14
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• 2001

To investigate the effects of waste sludge from antibiotic fermentation on the growth of young radish and chemical properties of soil, five levels of fertilizer, control (recommended fertilizer, $N-P_2O_5-K_2O=160-59-104$ kg/ha), AS(control + sludge 1,000 kg/ha), AC(control + conventional compost 1,000 kg/ha), SNS(control - subtracting 30% N of sludge + sludge 1,000 kg/ha) and SNC(control - subtracting 30% N of conventional compost + conventional compost 1,000 kg/ha) were applied and radish was grown twice with same treatments on May and August in 1998. Germination rate and early growth of young radish grown with AS and SNS were lower than those grown in control and with AC, SNC. This negative effects by adding the sludge in the early growth seemed to be caused by damage of ammonia gas released during degradation of the sludge in soil. However, yield of young radish showed no significant difference among all the treatments including the AS and SNS at the 1st and 2nd experiment, and these suggested that the latter half of growth of young radish was accelerated by adding the sludge. Contents of T-N in young radish and inorganic N in soil showed a tendency to increase by adding the sludge while antibiotic substance, cephalosporin-C, was not detected in plant material and soils after harvest of young radish in both experiments. Consequently, waste sludge from antibiotic fermentation, which contains high levels of organic matter and nitrogen could be used as an useful resource in agriculture.

• Applied Chemistry for Engineering
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• v.17 no.6
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• pp.591-596
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• 2006

Topology and molecular ordering of NPD(4,4'-bis-[N-(1-naphthyl)-N-phenyl-amino]biphenyl) thin films deposited under magnetic field with post-deposition annealing were investigated. NPD was deposited onto ITO glass substrates via thermal evaporation process in vacuum. It is of great importance for highly oriented organic/metal films to have improved device performances such as higher current density and luminance efficiency. AFM (Atomic Force Microscope) and XRD (X-Ray Diffraction) analyses were used to characterize the topology and structure of oriented NPD films. The multi-source meter was used to observe the current-voltage characteristics of the ITO (Indium-Tin Oxide) / NPD (4,4'bis[N-(1-napthyl)-N-phenyl-amino]-biphenyl) / Al (Aluminum) device. While NPD thin films deposited under magnetic field were not molecularly well aligned according to the XRD results, the films after post-deposition annealing at $130^{\circ}C$ were well-oriented. AFM images show that NPD thin films deposited under magnetic field had a smoother surface than those deposited without magnetic field. The current-voltage performance of NPD thin films was improved due to the enhanced electron mobility in the well-aligned NPD films.

• Applied Chemistry for Engineering
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• v.8 no.6
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• pp.1006-1013
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• 1997

This study was carried out to elucidate the chemical characteristics of mutual separation for Am and Eu, which were selected as a stand-in from minor actinide and rare earth elements, by solvent extraction with di-(2-ethylhexyl)phosphoric acid containing zirconium at batch system. As results, 92.3% of Am and 99.1% of Eu were coextracted with 1M DEHPA/n-dodecane containing zirconium (Zr $concentration=8.7g/{\ell}$) at 0.5M $HNO_3$ in the extraction step. The extraction yields of Am and Eu were proportionally increased with the concentration of Zr in Zr salt of 1M DEHPA/n-dodecane having the synergistic effect. In the lst stripping step for the selective separation of Am, 38.1% of Am and 3% of Eu were stripped with the mixed solution of 0.05M DTPA and 1M lactic acid adjusted pH of 3.0. At that time, the separation factor calculated from the distribution coefficients of Am and Eu was 14.2. In the 2nd Stipping step to remove the Eu remained the organic phase after the lst stripping step, 94.4% 0f Eu was stripped into aqueous phase with 6M $HNO_3$.

• Applied Chemistry for Engineering
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• v.19 no.5
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• pp.574-581
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• 2008

The optimum regeneration conditions for the regeneration of three way spent catalysts (TWCs), which were taken from automobiles with different driving conditions, were investigated to evaluate the suitability as alternative catalysts for removing VOCs. The spent catalysts were washed with five different acids ($HNO_3$, $H_2SO_4$, $C_2H_2O_4$, $C_6H_8O_7$, and $H_3PO_4$) to remove contaminants and examine the optimum conditions for recovering the catalytic activity. The physicochemical properties of spent and its regenerated TWCs were evaluated by using nitrogen adsorption-desorption isotherms, XRD, and ICP. The relative atomic ratios of contaminants and platinum group metals (PGMs) of the spent TWCs were greatly dependent on the placed positions. The main contaminants formed were lubricant oil additives and metallic components. Also, the regeneration treatment increased the PGMs ratio, BET surface area, and average pore diameter of TWCs. The catalytic activity results indicated that the spent TWCs have the possibility for removing VOCs. Moreover, the employed acid treatments greatly enhanced the catalytic activity of the spent TWCs. Especially, nitric and oxalic acids provided the most improvement in the catalytic behavior. The catalytic activities of the regenerated TWCs were significantly influenced by the containing platinum ratios rather than the removal ratios of contaminants and the changes in the structural properties offered by the acid treatments.