• Analytical Science and Technology
• /
• v.12 no.1
• /
• pp.68-74
• /
• 1999

The Concentrations of PCDDs/PCDFs and their precusors(chlorophenols, chlorobenzenes, PCB) were analyzed from the dioxin control device such as EP and SCR to know the emission patterns of these compounds and find the dioxin index compounds. The dioxin concentration increased 7 times in outlet part than inlet part of EP and the concentration of CBs, CPs and PCBs also were increased through this control device. These phenomia may be related to the operating temperature of Electroprecipitator(EP), which the operating temperature is near the $300^{\circ}C$, the method of the decreasing the operating temperature need to consider to prevent the formation of these compounds. In the selected catalytic reactor with wet scrubber(SCR+WS), these compounds were removed after passing the device over 90% for CPs, 30~40% for CBs and 60% for PCBs. But, the systematic study have to perform to reduce the formation of PCDDs/PCDFs and precusors.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.22 no.2
• /
• pp.220-227
• /
• 2016

In this paper, polychlorinated biphenyls (PCBs) were measured in surface sediments collected three times (June, October, December, 2013), inside Jeju Harbor as major harbors of Jeju Island. The concentration of PCBs inside Jeju Harbor was in the range of 1.62~4.45 (mean) ng/g on a dry weight basis and the levels were very low. In the analysis of PCBS homologue patterns, high-chlorinated PCB congeners were dominant in surface sediments inside Jeju Harbor, indicating that their sources were originated from shipping activity. In the relationships between PCBs concentrations and particle size (mud, sand and gravel) in surface sediments, PCBs concentrations were higher in the sediments with higher mud content, indicating that higher PCBs were distributed with increasing sediments of fine gradules. The PCBs concentrations in surface sediments in this study were very low, compared with ER-L (effect range-low) and TEL (threshold effects level) among sediment quality guideleines (SQGs) applied in foreign countries, such as USA, Canada, and Australia, etc), indicating that their biological effects on the bottom organisms in marine environment were expected to be very low.

• Applied Biological Chemistry
• /
• v.23 no.3
• /
• pp.184-188
• /
• 1980

A survey of pesticide and copper residues of the citrus orchard soil was conducted during October 1979-June 1980 in Jeju, Seogwipo county. The citrus orchards were classified into five groups according to different cultivated period; 5 year orchard, 10 year orchard, 15 year orchard, 20 year orchard, and 30 year orchard. Each of the above samples was divided again to three layers of soil depth; the surface layer$(0{\sim}10cm)$, the middle layer $(10{\sim}20cm)$, and the bottom layer $(20{\sim}40cm)$. In this experiments, Kelthane and Akar, as well as copper residues were detected in all soil samples. Residue levels of above chemicals were increased in soils of orchard with longer cultivation periods, and at the same time, decreased with soil depth. The residues of those ranged as follows; a) from trace to 1.359ppm in Kelthane, b) from trace to 0.925ppm in Akar, and c) from trace to 40.734ppm in copper. It is noted that the average residues of Kelthane was 0.251ppm, Akar, 0.120ppm, and that of copper was 2.168ppm, respectively.

• Korean Journal of Soil Science and Fertilizer
• /
• v.21 no.4
• /
• pp.409-415
• /
• 1988

This study was carried out to investigate the effects of barley straw application on the eluviation of components in submerged paddy soil percolated. The chemical components of soil, percolated water and humus fraction were as follows. $NH{^+}_4$-N in percolated water and soil, $NO{^-}_3$- N in soil were not detected after prime tillering stage by absorption of rice plant. Phosphate was not affected by the application but a little amount was eluviated through a whole period. Eluviation phase of $Ca^{{+}{+}}$ was similar to $Mg^{{+}{+}}$ and the changes of $K^+$, $Na^+$ and $Cl^-$ were almost same patterns, whereas the amount of these eluviated elements in plot applied was higher than non-applied. In the plot applied, eluviation of $SO{^{-2}}_4$ was low during the tillering stage but high after heading stage, whereas the whole amount of eluviation was high during the tillering stage. Eluviation of iron in the plot applied was increased rapidly. Humus type was almost same as type B in the plot applied or not after harvest, and contents of humic acid was about 60 percent.

• Journal of Soil and Groundwater Environment
• /
• v.7 no.2
• /
• pp.73-81
• /
• 2002

In normal Fenton's reagent, the reductive mechanism of carbon tetrachloride (CT) with superoxide radical (${O_2}^-$.) was observed and the rate of ${O_2}^-$. production was investigated as a function of $H_2O$$_2$ concentration and pH. As pH was increased, the rate of 1-hexanol degradation was rapidly decreased from 90% (at pH 3) to 5% (at pH 11). On the other hand, more degradation of carbon tetrachloride was observed at higher pH regimes indicating Fenton's reaction is an oxidant-reductant co-existing system at neutral pHs. The rate of $O_2^{-}$ . production was observed at different $H_2$$O_2$ concentrations and at different pHs. The rate increased from (45.3$\pm$7.8) x $10^{-6}$ M/s to (151.0$\pm$26.2) x $10^{-6}$ M/s ($294mM H_2$$O_2$) at pH 11: the rate 3150 increased from (22.1$\pm$3.8) x $10^{-6}$ M/s at pH 7 to (151.0$\pm$26.2) x $^10{-6}$ M/s at pH 11 with 294mM $H_2$$O_2$, These results showed that Fenton's reagent could be applied at wide pH regimes. Especially, carbon tetrachloride, which can not be easily adsorbed to soils and then can be dissolved into groundwater causing a cancer, could be efficiently treated by Fenton's reagent.reagent.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
• /
• v.20 no.1
• /
• pp.17-24
• /
• 2014

The purpose of this study was to review the brief physiological characteristics and some factors of the quality decay of strawberry harvested in Korea. Strawberries are highly perishable with soft surface. Surface injury and fungus growth are common as a result of handling and distribution. Many growers and distributers are considered to protect the physical impact and inhibit the fungus growth for prolonging the shelf life in the distribution and market channels. Post-harvest treatments of precooling, carbon dioxide, chlorine dioxide, ozone, and ultrasound are practiced on strawberry in order to extend shelf-life and preserve the quality. Modified atmosphere packaging, edible coating, and oxygen absorbent application can be used as supplemental treatments to extend postharvest-life of strawberry. The packaging types for current domestic and export strawberry in Korea were summarized. The findings from this study can be lead to a better understanding of strawberry packaging development associated with the proper handling and distribution of strawberry. This could be useful for the strawberry growers, distributors, and buyers.

• Applied Chemistry for Engineering
• /
• v.24 no.5
• /
• pp.544-550
• /
• 2013

This work investigated the environmental application of an underwater dielectric barrier discharge plasma reactor consisting of a porous hydrophobic ceramic tube to the decolorization of an azo dyeing wastewater. The reactive species generated by the plasma are mostly short-lived, which also need to be transferred to the wastewater right after the formation. Moreover, the gas-liquid interfacial area should be as large as possible to increase the decolorization rate. The arrangement of the present wastewater treatment system capable of immediately dispersing the plasmatic gas as tiny bubbles makes it possible to effectively decolorize the dyeing wastewater alongside consuming less amount of electrical energy. The effect of discharge power, gas flow rate, dissolved anion and initial dye concentration on the decolorization was examined with dry air for the creation of plasma and amaranth as an azo dye. At a gas flow rate of $1.5Lmin^{-1}$, the good contact between the plasmatic gas and the wastewater was achieved, resulting in rapid decolorization. For an initial dye concentration of $40.2{\mu}molL^{-1}$ (volume : 0.8 L; discharge power : 3.37 W), it took about 25 min to attain a decolorization efficiency of above 99%. Besides, the decolorization rate increased with decreasing the initial dye concentration or increasing the discharge power. The presence of chlorine anion appeared to slightly enhance the decolorization rate, whereas the effect of dissolved nitrate anion was negligible.

• The Korean Journal of Food And Nutrition
• /
• v.29 no.4
• /
• pp.499-505
• /
• 2016

To improve the shelf-life of mushrooms, Lentinula edodes GNA01 mushrooms were treated with gel packs containing slow-released chlorine dioxide ($ClO_2$) gas at 5~10 ppm for 5 days at $20^{\circ}C$ and the weight loss rate as well as the changes in pH, color and texture properties of the treated samples were investigated. The weight of the control and $ClO_2$ gas treated samples were decreased slightly, and there were no differences during the storage period. However, the weight of the control changed faster than those of the $ClO_2$ gas treated samples during storage period. The pH in the control and in the $ClO_2$ gas treated samples were decreased during storage period, but the samples treated with 5 and 7 ppm $ClO_2$ gas were the least changed. On the other hand, the samples treated with 10 ppm $ClO_2$ gas showed no difference from the other treatments during 4 days, but the pH was lower than that of the control on the fifth day. The lightness of inside and outside in mushroom were decreased whereas redness and yellowness were increased during storage period. However, color changes in the $ClO_2$ gas treated samples were lower than those of the control. Especially, the samples treated with 5 and 7 ppm $ClO_2$ gas were the least changed. The texture of the mushroom were decreased consistently during storage period. The texture of the control changed faster than those of the $ClO_2$ gas treatments during 5 days. Especially, the samples treated 5 ppm $ClO_2$ gas were the least changed.

• The Korean Journal of Food And Nutrition
• /
• v.30 no.3
• /
• pp.591-598
• /
• 2017

To prolong the shelf-life of strawberry, samples were treated with gel packs containing slow-released chlorine dioxide($ClO_2$) gas at 3~7 ppm for 6 days at room temperature. The weight loss and decay ratio as well as changes in pH, color and texture properties of the treated samples were investigated. The weight of the control and $ClO_2$ gas treated samples decreased slightly, but the weight of the control changed faster than those of the $ClO_2$ gas treated samples during the storage period. The decay ratio of control was higher than those of the $ClO_2$ gas treatments since 4 days of storage. The pH and acidity in the control and in the $ClO_2$ gas treated samples were no differences during storage period. The lightness of strawberry decreased during storage, but there was no difference in lightness among the treatments even when storage time was extended. The redness and yellowness of the control showed higher change than those of the $ClO_2$ gas treatments during 6 days. The firmness of the control changed more rapidly than those of the $ClO_2$ gas treatments during 6 days. Especially, the samples treated 3 and 5 ppm $ClO_2$ gas were the least changed. And the scores for appearance, firmness and overall acceptance control and 7 ppm $ClO_2$ gas treatment decreased more rapidly than those of 3 and 5 ppm treatment.

• Applied Chemistry for Engineering
• /
• v.20 no.1
• /
• pp.87-93
• /
• 2009

Pd/activated carbon (Pd/AC) and Pd/alumina (Pd/AO) catalysts were prepared by the impregnation of palladium into activated carbon and alumina. The catalytic characteristics according to the kinds of support materials were compared. The decomposition efficiencies of ozone according to kinds of support materials are about the same when these were compared by adding 10 g of catalysts into the water saturated with ozone. The decomposition efficiencies and the oxidation characteristics (TOC, $COD_{Cr}$) of dichloroacetic acid were compared with the ozone only process and the catalytic ozonations using Pd/activated carbon and Pd/alumina catalysts. The decomposition efficiencies of dichloroacetic acid by catalytic ozonations were better than the one by ozone only process, but there was slight difference of the one between Pd/activated carbon and Pd/alumina catalyst. The decomposition efficiency of dichloroacetic acid was increased with increasing ozone dose at a constant concentration of dichloroacetic acid, but the one was little increased with increasing ozone dose at more than 1.0 L/min of ozone dose. It was seemed that the bicarbonate and the chloric ion formed throughout the decomposition of dichloroacetic acid acted as the scavenger of hydroxyl radical.