• Polymer(Korea)
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• v.36 no.5
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• pp.573-578
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• 2012

In general, most physical properties of wood/polyvinyl chloride (PVC) composites are lower than those of corresponding neat PVC resin because of poor interfacial adhesion between the hydrophilic wood flour and hydrophobic PVC. Therefore, in this study, we treated wood flour with three aminosilanes to improve wood/PVC interfacial adhesion strength, and eco-friendly wood/PVC/nanoclay composites were prepared by melt blending the aminosilane-treated wood flour, a heavy metal free PVC compound, and a type of nanoclay. The effects of treating wood flour with the aminosilanes and adding the nanoclay on the mechanical properties of the composites were investigated. Mechanical properties of the composites were investigated by universal testing machine (UTM), izod impact tester, dynamic mechanical analyzer (DMA), and thermomechanical analyzer (TMA). The tensile properties of the composites with the aminosilane-treated wood flour were considerably higher than those of the composites with neat wood flour. Furthermore, a small amount of the nanoclay improved mechanical properties of the composites. The performance of the wood/PVC composites was considerably improved by using the aminosilane-treated wood flour and the nanoclay.

• Clean Technology
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• v.24 no.3
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• pp.255-266
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• 2018

In this paper, the effects of large national industrial complexes on the generation of local hazardous substances were analyzed based on their size, industrial characteristics. In Seoul, the proportion of hazardous substances, which adversely affect the atmosphere of the entire city, was much less than that of other regional industrial complexes, centered on knowledge-based industries. On the other hand, other national industrial complexes based on manufacturing industries, such as machinery, metal, electricity, and electronics, were found to have a combination of industry characteristics and logistics and regional characteristics. Overall, it was found that the increase in productivity in large national industrial complexes was not proportional to the increase in hazardous substances throughout the region. In addition, it was also found that in North Gyeongsang Province, which is based on the heavy chemical industry, the percentage of hazardous substances is different from other regions due to the characteristics of the industry.

• Environmental Engineering Research
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• v.21 no.1
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• pp.15-21
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• 2016

Magnesium potassium phosphate cement (MKPC) is an effective agent for solidification/stabilization (S/S) technology. To further explore the mechanism of the S/S by MKPC, two kinds of Cd including $Cd(NO_3)_2$ solution (L-Cd) and municipal solid waste incineration fly ash (MSWI FA) adsorbed Cd (S-Cd), were used to compare the effects of the form of heavy metal on S/S. The results showed that all the MKPC pastes had a high unconfined compressive strength (UCS) above 11 MPa. For L-Cd pastes, Cd leaching concentration increased with the increase of Cd content, and decreased with the increase of curing time. With the percentage of MSWI FA below 20%, S-Cd pastes exhibited similar Cd leaching concentrations as those of L-Cd pastes, while when the content of MSWI FA come up to 30%, the Cd leaching concentration increased significantly. To meet the standard GB5085.3-2007, the highest addition of S-Cd was 30% MSWI FA (6% Cd contained), with the Cd leaching concentration of 0.817 mg/L. The S/S of L-Cd is mainly due to chemical fixation, and the hydration compound of Cd was $NaCdPO_4$, while the S/S of S-Cd is due to physical encapsulation, which is dependent on the pore/crack size and porosity of the MKPC pastes.

• Journal of Environmental Health Sciences
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• v.36 no.3
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• pp.236-246
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• 2010

In preparative anti-corrosive coating experiments, polyaniline was obtained by reacting an oxidizing agent with the monomer aniline. Further, the primer coating was prepared using a variety of widely-used materials such as urethane resin. For the top coating, epoxy resin and acrylic urethane resin were used. Characteristics of the coatings were assessed according to KS and ASTM specifications, and the structure of the polyaniline was characterized using FT-IR and TGA. For analysis of anti-corrosive properties in salt-spray experiments, measurements of the oxidation state of iron and surface atomic analysis were conducted using XPS and SEM-EDX. Unlike general anti-corrosive coatings which exhibit anti-corrosive effects only as a primer coating, the anti-corrosive coatings using polyaniline as the anti-corrosive pigment showed a marked synergistic effect with the top coatings. In other words, the top coatings not only produce a fine view effect, but also increase, through interaction with the primer coatings, the resistance to diffusion of corrosive factors from the external environment. It was also found that, unlike the heavy metal oxide-forming layer of the passive barrier alone, the polyaniline anti-corrosive pigment oxidized iron at the interface with the iron substrate to form a passive barrier in the oxidic layer, and itself formed a potential barrier layer with anti-corrosive factors from the external environment. Although the passive layer was damaged, the damaged area did not become completely oxidized iron; on the contrary, it showed a tendency to reduction. This can be interpreted such that a passive layer is formed again on the damaged area, and that at the same time there is a tendency to self-healing.

• Journal of Environmental Science International
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• v.7 no.2
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• pp.141-148
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• 1998

Effects of alumlnlum(AA), soil pH and calcium(Cal on growth response and heavy metal accumulation and regulation of nitrogen fixation In Melilotus suaveolens seedlings, a biennial legume plant dominating in the disturbed area, were quantitatively analyzed during the growing periods. Accumulation of metals In each organ of M. suaveojens was Increased UC the lowering of pH. Al contents In leaf and root treat- ed with 30ppm Al at pH 4.2 on the 28th day after treatment were 8 and 11 folds higher than those of control, while the contents with 100ppm AA were 21 and 24 folds as compared to control. The significent inhibition in Al contents was induced by 100ppm AA and Ca at pH 6.5. Increased metals inhibited higher at pH 4.2 and the growth inhibition due to Al was reversed by the addition of Ca, suggesting that growth correlates to the pH value. Chlorophyll contents in leaves increased during growth stave were inhibited by Al treatments. The biomass was decreased UD the lowering of pH and the increase of concentrations. 100ppm Ca treatment resulted in 5.1-5.9% increase of the biomass as compared to that of 100ppm Al. Specific nitrogen fuation activities In nodules In the 100ppm Al at pH 4.2 and pH 6.5 were reduced to 35. 2% and 52.2% of control, on the 28th day after treatment, while the combination of Al and Ca induced reduced by 10% as compared to control with the treatment of 100ppm AA at pH 4.2 due to the inhibition bination of 100ppm Al and Ca and lowering of pH.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.6
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• pp.1983-1993
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• 1996

For selected (pure and compound) metallic species effects of saturation ratio, temperature, particle size and number density on condensation mechanisms are first reviewed. The tendencies for vaporization and condensation differ between metallic species because of the significant differences in their saturation pressures. Then particle pressure of a metal vapor species at incineration temperature is calculated by simplifying waste as a compound of methane, chlorine and small amounts of metals and assuming a thermodynamic equilibrium state. Next the condition is assessed for which supersaturation of combustion gases by the species above the critical level for homogeneous condensation may occur, when the gases contain a large number of pre-existing particles such as entrained ashes. Regardless of the presence of chlorine in the waste, the homogeneous condensation of PbO vapors may occur, depending on number density of the pre-existing particles. However, when chlorine exists in the waste, the homogeneous condensation of PbCl$_2$vapors does not occur, which is similar to the case of Cd and Hg vapors. Thus these highly volatile species, PbCl$_2$, Cd, and Hg, may emit to atmosphere as vapor phase. In general, for reducing the emission of hazardous metallic species into the atmosphere, the number density of pre-existing particles has to be increased. For fixed particle number density, the temperature drop rate must be kept in low if the temperature at which a condensable vapor species emits from a incineration system is fixed, while the temperature drop rate must be kept in high if the residence time for which a condensable species stays in the system is fixed.

• Korean Journal of Soil Science and Fertilizer
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• v.50 no.6
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• pp.623-633
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• 2017

Food waste has been recognized as a organic sources for composting and many research was conducted to efficiently utilize or treat. This study was to evaluate a feasibility for producing food waste compost under co-composting with mixture of food and animal waste. The mixing ratio of food and animal waste was 35% as main material, which additionally mixed 30% of sawdust for co-composting. Total days of composting experiment were 84 days and each sub samples were collected at every 7 days from starting of composting. Results showed that inner temperature in composting was rapidly increased to $70{\pm}4^{\circ}C$ within 3~5 days depending on mixing animal waste of cattle, pig, and chicken base compared to sole food waste base. Expecially, the CN ratio in the mixture of food and pig water was the highest (16.2) among compost. After finishing composting experiment, maturity was evaluated with solvita and germination test. Maturity index (MI) of the mixture of food and animal waste was ranged between 6~7, but was 3 in sole food waste. Calculated germination index (GI) was at the range of about 100 irrespectively of mixing of food and animal waste. However, NaCl content and heavy metal as Cr, Cu, Ni, Pb, and Zn contents was increased in the mixture of food and animal waste. which was the highest in compost mixed the food and pig waste. Both MI and GI showed that manufactured fertilizer was suitable for fertilizer criteria while sole food waste was not adequate for composting due to composting periods. Overall, mixing the food and animal waste can be utilized for improving compost maturity, but more research should be conducted to make high quality of food waste compost with animal waste in agricultural fields.

• The Korea Journal of Herbology
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• v.36 no.1
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• pp.41-49
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• 2021

Objective : Citrus unshiu peel (Citri Unshius Pericarpium) has been prescribed to suppress coughing and phlegm in Korean medicine. In this study, the effect of ethanol extract of Citrus unshiu peel (CEE) on apoptosis was investigated using cadmium chloride (CdCl2) treated HepG2 cells. Methods : CEE was prepared by extracting 300 g of Citri Unshius Pericarpium in 3 L of ethanol for 72 h. Apoptosis was determined by the TUNEL assay. The mitochondrial membrane potential (MMP) was monitored using the membrane-permeable fluorescent dye Rh123. The expression level of each protein was monitored by Western blot analysis. Results : CEE protected HepG2 cells from apoptosis as determined by the TUNEL assay. A decrease in MMP was observed in cells exposed to cadmium, indicating that mitochondria are involved in the induction of apoptosis. However, CEE recovered the reduction in MMP caused by cadmium. In addition, decreased expression of B-cell lymphoma 2 (Bcl-2), procaspase, and poly(ADP-ribose) polymerase (PARP) by cadmium was increased by CEE. The anti-apoptotic effect of CEE was found to be associated with inhibition of JNK and p38 phosphorylation when examining the expression of phosphorylated MAPK by Western blot. Conclusion : This study showed that CEE exerted anti-apoptotic effects in cadmium-induced HepG2 cells by inhibiting the reduction of MMP and changes in the expression level of apoptotic proteins. These results suggest the potential for CEE to be used for heavy metal-induced liver damage.

• Journal of Ecology and Environment
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• v.45 no.1
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• pp.1-9
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• 2021

Background: Abandoned coal piles after the closure of mines have a potential negative influence on the environment, such as soil acidification and heavy metal contamination. Therefore, revegetation by efficient species is required. For this, we wanted to identify the role of Silene acaulis in the succession of coal piles as a pioneer and a nurse plant. S. acaulis is a well-studied cushion plant living in the Arctic and alpine environments in the northern hemisphere. It has a highly compact cushion-like form and hosts more plant species under its canopy by ameliorating stressful microhabitats. In this research, we surveyed vegetation cover on open plots and co-occurring species within S. acaulis cushions in coal piles with different slope aspects and a control site where no coal was found. The plant cover and the similarity of communities among sites were compared. Also, the interaction effects of S. acaulis were assessed by rarefaction curves. Results: S. acaulis was a dominant species with the highest cover (6.7%) on the coal piles and occurred with other well-known pioneer species. Plant communities on the coal piles were significantly different from the control site. We found that the pioneer species S. acaulis showed facilitation, neutral, and competition effect in the north-east facing slope, the south-east facing slope, and the flat ground, respectively. This result was consistent with the stress gradient hypothesis because the facilitation only occurred on the north-east facing slope, which was the most stressed condition, although all the interactions observed were not statistically significant. Conclusions: S. acaulis was a dominant pioneer plant in the succession of coal piles. The interaction effect of S. acaulis on other species depended on the slope and its direction on the coal piles. Overall, it plays an important role in the succession of coal piles in the High Arctic, Svalbard.

• Journal of Electrochemical Science and Technology
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• v.13 no.4
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• pp.424-430
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• 2022

In the study, Ni²⁺ (nickel) removal from synthetically prepared wastewater by electrocoagulation method, which is one of the electrochemical treatment processes, was investigated and parameters such as current density, pH, mixing speed, initial Ni²⁺ concentration, supporting electrolyte type and concentration were determined to determine Ni²⁺ removal efficiencies effects were studied. Experiment conditions during 30 minutes of electrolysis; the current density was determined as 0.95 mA/cm², the initial pH of the wastewater was 6, the mixing speed was 150 rpm, and the initial nickel concentration was 250 mg/L. The Ni²⁺ removal efficiency was obtained as 75.99% under the determined experimental conditions, while the energy consumption was calculated as 3.15 kW-h/m³. In the experiments, it was observed that the type and concentration of the supporting electrolyte did not have a significant effect on the Ni²⁺ removal efficiency. In the trials where the effect of the support electrolyte concentration was examined, the Ni²⁺ removal efficiency was 75.99% in the wastewater environment without the supporting electrolyte, while the Ni²⁺ removal efficiency was 81.55% when 7.5 mmol/L NaCl was used after the 30-minute reaction, and the energy consumption was 2.15 kW-h/m³ obtained as. As a result of the studies, it was concluded that the electrocoagulation process can be applied in the treatment of wastewater containing Ni²⁺.