• Journal of Environmental Science International
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• v.22 no.7
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• pp.863-871
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• 2013

Dielectric discharges are an emerging technique in environmental pollutant degradation, which that are characterized by the production of hydroxyl radicals as the primary degradation species. For practical application of the plasma reactor, reactor that can handle large amounts of water are needed. Plasma research to date has focused on small-scale water treatment. This study was carried out basic study for scale-up of a single DBD (dielectric barrier discharge) plasma reactor. The degradation of N, N-Dimethyl-4-nitrosoaniline (RNO, indicator of the generation of OH radical) was used as a performance indicator of multi-plasma reactor. The experiments is divided into two parts: design parameters [effect of distance of single plasma module (1~14 cm), arrangement of ground electrode (single and multi), rector number (1~5) and power number (1~5)]; operation parameter [effect of applied voltage (60~220 V), air flow rate (1~5 L/min), electric conductivity of solution ($1.4{\mu}S/cm$, deionized water)~18.8 mS/cm (addition of NaCl 10 g/L) and pH (5~9)]. Considering the electric stability of the plasma reactor, optimum spacing between the single plasma module was 2 cm. Multi discharge electrodes - single ground electrode array was selected. Combination of power 3-plasma module 5 was the optimal combination for maximum RNO degradation. The optimum 1st voltage and air flow rate for RNO degradation were 180 V and 4 L/min, respectively. The pH and conductivity of the solution was not influencing the RNO degradation.

• Journal of Adhesion and Interface
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• v.7 no.2
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• pp.19-25
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• 2006

Since the enzymatic degradation of microbial poly(hydroxylalkanoate)s (PHAs), such as poly[(R)-3-hydroxybutyrate] and poly[(R)-3-hydroxybutyrate-co-3-hydroxyvalerate] initially occurs by a surface erosion process, their degradation behaviors can be controlled by the change of surface property. In order to control the rate of enzymatic degradation, plasma modification technique was applied to change the surface property of microbial PHAs. The surface hydrophobic and hydrophilic properties of PHA films were introduced by $CF_3H$ and $O_2$ plasma exposures, respectively. The enzymatic degradation was carried out at $37^{\circ}C$ in 0.1 M potassium phosphate buffer (pH 7.4) in the presence of an extracellular PHB depolymerase purified from Alcaligenes facalis T1. The results showed that the significant retardation of initial enzymatic erosion of $CF_3H$ plasma-treated PHAs was observed due to the hydrophobicity and the enzyme inactivity of the fluorinated surface layers while the erosion rate of $O_2$ plasma-treated PHAs was not accelerated.

• Journal of Environmental Health Sciences
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• v.37 no.3
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• pp.218-225
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• 2011

Objectives: In this paper, a dielectric barrier discharge (DBD) plasma reactor was investigated for degrading the dye Rhodamine B (RhB) in aqueous solutions. Methods: The DBD plasma reactor system in this study consisted of a plasma component [titanium discharge (inner), ground (outer) electrode and quartz dielectric tube], power source, and gas supply. The effects of various parameters such as first voltage (input power), gas flow rate, second voltage (output power), conductivity and pH were investigated. Results: Experimental results showed that a 99% aqueous solution of 20 mg/l Rhodamine B is decolorized following an eleven minute plasma treatment. When comparing the performance of electrolysis and plasma treatment, the RhB degradation of the plasma process was higher that of the electrolysis. The optimum first voltage and air flow rate were 160 V (voltage of trans is 15 kV) and 3 l/min, respectively. With increased second voltage (4 kV to 15 kV), RhB degradation was increased. The higher the pH and the lower conductivity, the more Rhodamine B degradation was observed. Conclusions: OH radical generation of dielectric plasma process was identified by degradation of N, N-dimethyl-4-nitrosoaniline (RNO, indicator of OH radical generation). It was observed that the effect of UV light, which was generated as streamer discharge, on Rhodamine B degradation was not high. Rhodamine B removal was influenced by real second voltage regardless of initial first and second voltage. The effects of pH and conductivity were not high on the Rhodamine B degradation.

• Applied Biological Chemistry
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• v.38 no.3
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• pp.263-268
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• 1995

A study was undertaken to compare degradation patterns of carbofuran in soils between submerged and upland moisture conditions [$3-^{14}C$]Carbofuran was treated in each soils at the rate of 1.0 mg/kg (87.8 kBq $^{14}C/50g$ soil) and the time-course analysis for distribution of radioactivity and degradation products were conducted. Differences in the pathway and rate of carbofuran degradation in soils were observed between submerged and upland moisture conditiona major degradation being hydrolysis at 7-C position and oxidation at 3-C position, respectively. Carbofuran showed less persistence in soils of higher moisture contents A significant portion, $24{\sim}39%$ of the total radioactivity, resided in soils as nonextractable residues at 60 days after treatment The nonextractable radioactivity was mainly located in soil organic matter, fulvic acid, humic acid and humin factions Gel filtration chromatography confirmed the incorporation of carbofuran and its degradation products into the organic matter.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.3
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• pp.389-393
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• 2003

Present study investigate the effect of enzyme supplementation, methods (applied to rumen or enzyme treated diet) compared with no enzyme diet, on rumen fermentation and apparent nutrient digestibility in a $3{\times}3$ Latin square design with three rumen cannulated Korean Native goats. In situ rumen degradation kinetics was studied in three rumen cannulated Holstein steers. Three diets were, no enzyme, 1% enzyme in rumen and 1% enzyme in diet. The enzyme was sprayed onto forage, and the forage: concentrate ratio was 30:70. Degradation kinetics was studied with three enzyme levels (0, 1 and 2%, w/w) and four pre-treatment times (0, 1, 12 and 24 h). Results suggested that enzyme application method did not affect rumen fermentation, ruminal enzyme activity and total tract apparent digestibility. Nutrient degradation rate and effective degradability of DM, NDF and ADF increased with increasing enzyme level and pre-treatment times. Degradation of nutrients was affected by enzymes levels or pre-treatment times. Therefore, it is probable that the improved degradation may be due to the supplemented exogenous hydrolytic enzymes under a certain condition.

• Journal of the Korean Solar Energy Society
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• v.22 no.3
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• pp.57-65
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• 2002

The photocatalytic degradation of TCE using solar energy in POFR was studied. The use of solar energy was investigated in plastic optica fiber photocatalytic reactor (POFR). In POFR, the main parameters of photocatalytic degradation of TCE were lihgt intensity, thickness of $TiO_2$-coated film on plastic fiber core, the same of total $TiO_2$-coated surface area with changed length. We studied the apparent photonic efficiency and photocatalytic degradation rate of TCE in POFR. The apparent photonic efficiency of various light intensities was decreased by an incresed intensities. The photocatalytic activities of $TiO_2$-coated optical fiber reactor system depended on the coating thickness, and total clad-stripped surface area of POF. Photocatalytic degradation of trichloroethylene ($C_2HCl_3$, TCE) in the gas-phase was elucidated by using $TiO_2$-coated plastic optical fiber reactor. In TCE degradation, in-situ FTIR measurement resulted in mineralization into $CO_2$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.3
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• pp.208-214
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• 2011

In this thesis, the partial discharge according to applied voltage and variations of cross-sectional area and length of the conductor related to general condition for using cable was measured in order to study degradation diagnosis for 2-Core cable of the PVC insulator used in industrial fields for other safety installations. Also the thermal degradation conditions under various installation circumstances of cables were studied by assuming degradation conditions with each different degradation rate (50%, 67%, 100%) such as variation in degradated temperature, thermal exposure time, normal state, partially degradated state and overall degradated state for thermal degradation diagnosis. The quantity of electric discharge (V-Q) according to applied voltage was measured for measurement of inception voltage and extinction voltage. The quantity of electric discharge and the number of electric discharge (Q-N) were measured with applied voltage kept constantly. In addition, pictures were taken using SEM (scanning electron microscope) to compare the surface of external insulator to degradated state of internal insulator according to thermal degradation temperature and also compare the surface of external insulator to degradated surface state of internal insulator according exposure time of cables to thermal stress.

• Journal of Applied Biological Chemistry
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• v.61 no.4
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• pp.383-389
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• 2018

Degradation of the insecticide O,O-diethyl O-3,5,6-trichloro-2-pyridyl phosphorothioate (chlorpyrifos) in aqueous solution was investigated using iron salts and potassium persulfate during ZVI treatment through a series of batch experiments. The degradation rate of chlorpyrifos increased with increases in the concentrations of iron salts and potassium persulfate in the aqueous system. Ferric chloride was found to be the most effective iron salt for the ZVI-mediated degradation of chlorpyrifos in aqueous solution. Further, the iron salts tested could be arranged in the following order in terms of their effectiveness: $FeCl_3$> $Fe_2(SO_4)_3$> $Fe(NO_3)_3$. The persulfate-ZVI system could significantly degrade chlorpyrifos present in the aqueous medium. This revealed that chlorpyrifos degradation by treatment with $Fe^0$ was promoted on adding ferric chloride and potassium persulfate. The kinetics of the degradation of chlorpyrifos by persulfate-amended $Fe^0$ was higher than that for iron-salt-amended $Fe^0$. This suggests that using a sequential $Fe^0$ reduction-ferric chloride or $Fe^0$ reduction-persulfate process may be an effective strategy to enhance the removal of chlorpyrifos in contaminated water.

• Membrane and Water Treatment
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• v.13 no.2
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• pp.97-104
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• 2022

With a small particle size, specific surface area and chemical nature, Pd/Cu-Fe nanocomposites can efficiently remove the organic compounds. In order to understand the applicability for in situ remediation of contaminated groundwater, the degradation of p-nitrophenol by Pd/Cu-Fe nanoparticles was investigated. The degradation results demonstrated that these nanoparticles could effectively degrade p-nitrophenol and near 90% of degradation efficiency was achieved by Pd/Cu-Fe nanocomposites for 120 min treatment. The efficiency of degradation increased significantly when the Pd content increased from 0.05 wt.% and 0.10 wt.% to 0.20 wt.%. Meanwhile, the removal percentage of p-nitrophenol increased from 75.4% and 81.7% to 89.2% within 120 min. Studies on the kinetics of p-nitrophenol that reacts with Pd/Cu-Fe nanocomposites implied that their behaviors followed the pseudo-first-order kinetics. Furthermore, the batch experiment data suggested that some factors, including Pd/Cu-Fe availability, temperature, pH, different ions (SO42-, PO43-, NO3-) and humic acid content in water, also have significant impacts on p-nitrophenol degradation efficiency. The recyclability of the material was evaluated. The results showed that the Pd/Cu-Fe nanoparticles have good recycle performance, and after three cycles, the removal rate of p-nitrophenol is still more than 83%.

• Journal of Pharmaceutical Investigation
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• v.25 no.2
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• pp.109-116
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• 1995

For the administration of narcotic antagonist with short half-life and low patient compliance, the sustained release system using biodegradable matrix is effective. Polyphosphazenes are of considerable interest as biodegradable matrix systems for controlled release of drugs. In this study, biodegradable polyphosphazenes available for the sustained release implantable device were synthesized, and their application was examined. Poly[dichlorophosphazene] was synthesized by solution polymerization method and confirmed with IR spectrum. Poly[bis(ethyl glycinate) phosphazene] and poly[ (diethyl glutamate)-co-(ethyl glycinate)phosphazene] were then produced by substitution of amino acid alkyl esters for chloride side groups. Using these polymers, the implantable devices of 1 mm thickness and $10{\times}10\;mm$ size containing naloxone hydrochloride were prepared and their release and degradation profiles were measured. In the case of poly[bis(ethyl glycinate)phosphazene] with swelling characteristics, degradation rate was slower than the release rate, showing that the release rate is partly dependent on the swelling rate. In contrast, the degradation rate of polyl[(diethyl glutamate)-co-(ethyl glycinate)phosphazene] matrix was identical with release rate of naloxone hydrochloride. On the basis of these results, it is expected that these polymers can be applied to sustained release implantable systems delivering narcotic antagonist.