• Applied Chemistry for Engineering
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• v.4 no.1
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• pp.41-45
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• 1993

Rescently we are interested in the biosurfactant. Biosurfactant have a low toxcity and easily biodegradable compound. Pseudomonas sp. 13 was isolated from soil. This microorganism produced biosurfactant that consists of glycolipid R-1 and R-2. A time course study of fermentation indicated that the appearance of glycolipid in the fermentation broth the commencement of the stationary phase with the respect to biomass. The effect of variation of the media components such as amount of glucose, nitrogen, phosphate and metal ions has been investigated. The following values found to be optimum for biosurfactant production (glucose, $20g/{\ell}$; carbon to nitrogen ratio, 40; carbon to phosphate, 18; $FeSO_4{\cdot}7H_2O\;20mg/{\ell}$).

• Journal of Environmental Science International
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• v.18 no.1
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• pp.61-72
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• 2009

Fabrication and oxidants production of 3 or 4 components metal oxide electrode, which is known to be so effective to destruct non-biodegradable organics in wastewater, were studied. Five electrode materials (Ru as main component and Pt, Sn, Sb and Gd as minor components) were used for the 3 or 4 components electrode. The metal oxide electrode was prepared by coating the electrode material on the surface of the titanium mesh and then thermal oxidation at $500^{\circ}C$ for 1h. The removed RhB per 2 min and unit W of 3 components electrode was in the order: Ru:Sn:Sb=9:1:1 > Ru:Pt:Gd=5:5:1 > Ru:Sn=9:1 > Ru:Sn:Gd=9:1:1 > Ru:Sb:Gd=9:1:1. Although RhB decolorization of Ru:Sn:Sb:Gd electrode was the highest among the 4 components electrode, the RhB decolorization and oxidants formation of the Ru:Sn:Sb=9:1:1 electrode was higher than that of the 3 and 4 components electrode. Electrogenerated oxidants (free Cl and $ClO_2$) of chlorine type in 3 and 4 components electrode were higher than other oxidants such as $H_2O_2\;and\;O_3$. It was assumed that electrode with high RhB decolorization showed high oxidant generation and COD removal efficiency. OH radical which is electrogenerated by the direct electrolysis was not generated the entire 3 and 4 components electrode, therefore main mechanism of RhB degradation by metal oxide electrode based Ru was considered indirect electrolysis using electrogenerated oxidants.

• Journal of Chitin and Chitosan
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• v.23 no.4
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• pp.256-261
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• 2018

Recently, the number of cardiovascular disease-related deaths worldwide has increased. Therefore, the importance of percutaneous cardiovascular intervention and drug-eluting stents (DES) has been highlighted. Despite the great clinical success of DES, the re-endothelialization at the site of stent implantation is retarded owing to the anti-proliferative effect from the coated drug, resulting in late thrombosis or very late restenosis. In order to solve this problem, studies have been actively carried out to excavate new drugs that promote rapid re-endothelialization. In this study, we introduced hydrophilic drug, tauroursodeoxycholate (TUDCA), that improves the proliferation of endothelial progenitor cells and promotes apoptosis of vascular smooth muscle cells. In addition, we utilized shellac, which is a natural resin from lac bug to coat TUDCA on the surface of the metal. When using conventional coating method including biodegradable polymers and organic solvents, phase separation between polymer and drug occurred in the coating layer that caused incomplete incorporation of drug into the polymer layer. However, when using shellac as a coating polymer, no phase separation was observed and drug was fully covered with the polymer matrix. In addition, by adjusting the composition of coating solution and modifying the hydrophilicity of the metal surface using oxygen plasma, the surface roughness decreased due to the increased affinity between coating solution and metal surface. This result provides a method of depositing a hydrophilic drug layer on the stent.

• Applied Chemistry for Engineering
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• v.20 no.3
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• pp.301-306
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• 2009

This research was carried out to establish the effective treatment condition and characteristic of wastewater from the electroplating plant of cold rolling mill by using microorganism. Alkaline wastewater and acidic heavy metal wastewater accounted for 64%, 30%, respectively, of the total wastewater. Highly concentrated thiocyanate was 53890 mg/L as COD and it was 53% of total COD, even though it was 0.03% of wastewater from the electroplating plant. When treating mixed wastewater with microorganism, it was easy to remove when SCN concentrations of mixed wastewater was 200 mg/L or less. While the treatment effect of COD-causing materials was low at the concentration of 400 mg/L or less, it implies that highly concentrated thiocyanate contains a large amount of slowly biodegradable organics. When treating with mixed wastewater, pH was 7.33 at the beginning, but after 8 hours it increased to 7.99. This is caused by ammonia which is generated when SCN of highly concentrated thiocyanate was degraded by microorganism.

• Journal of Wetlands Research
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• v.10 no.3
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• pp.27-35
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• 2008

Sediment cores were obtained from Upo and Mokpo in Upo Wetland and core samples were divided by depth into 20 ~ 21 subsamples. The heavy metal concentrations of Fe, Mn, Zn, AS, Cu, Cd, Ni, Pb, and Cr in the sediments of each depth were determined by ICP-MS. The texture of sediemnts from Upo Wetland appeared to be clayey silt with average grain size of $7.52{\sim}11.15{\mu}m$ for physical properties. It was found to have a clear tendency of depth profile with respect to TOC and ignition loss. Organics were stabilized in the range of 0.5 ~ 0.7 % TOC and 8 ~ 9 % ignition loss in 30 years, whereas, the surficial sediments have the highest concentrations of about 3.0 % of TOC and 13 ~ 15 % ignition loss. Those are much higher than the values of the main stream, the Nakdong River, which reflects the deposit of biodegradable organics from plants and other lifes. The vertical distribution of heavy metals in two sediment cores was investigated to elucidate historical trends of heavy metals deposited into Upo wetland. The depth profile concentrations of each heavy metal were compared and discussed with the Concensus-Based Sediment Quality Guidelines for freshwater ecosystems. All the Cd data for the vertical distribution in the sediments were detected above PEC value for Cd, which predict harmful effects on sediment-dwelling organisms expected to occur frequently. The concentrations of Zn, Cu, and Cr in all sediment samples for depth profile were detected below the TEC values, which provided a basis predicting the absence of toxicity by Zn, Cu, and Cr.

• Toxicological Research
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• v.27 no.3
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• pp.143-147
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• 2011

Cadmium is considered one of the most toxic, non biodegradable heavy metal for the human and animals. The purpose of the present study was to investigate the changes in biochemical parameters of blood and accumulation of cadmium in various tissue caused by various levels of dietary cadmium chloride ($CdCl_2$) in broiler chicks. $CdCl_2$ was administered through drinking water to broiler chicks. In spectral analysis, $CdCl_2$ treatment caused a significant increase in Glutamate pyruvate transaminase (GPT), creatinine and uric acid levels in all treated groups. Intriguingly, the GPT, creatinine, and uric acid levels were significantly higher at 75 mg/kg as compared to the groups treated with high doses (100, 125 and 150 mg/kg) of $CdCl_2$. Atomic Absorption Spectrophotometer (AAS) was used for the determination of Cd accumulation in kidney, liver and Breast muscles. AAS analysis revealed that Cd accumulation is increased in breast muscles as compared to liver and kidney at higher doses of Cd than 75 mg/kg.

• Journal of Environmental Health Sciences
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• v.28 no.2
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• pp.99-108
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• 2002

This study was carried out to evaluate the Physicochemical characteristics of mined waste(separated waste and soil) and to predict environmental effect of an old landfill site located at north of Seoul. Municipal solid waster(MSW) had been disposed of at the old landfill site used in this study for about 2 years(1990-1992). The old landfill site selected for this study had accepted mainly municipal solid waste. The landfill-mined waste contained separated waste (40.9%) and soil(59.1%) by wet weight basis. The separated waste consisted of combustible(91.0%) and non-combustible(9.0%). The combustible waste was mainly non-biodegradable plastics. The low heating value of the separated combustible waste, which is calculated by Dulong's equation, was as high as 3,470kcal/kg. According to the Korean Extraction Procedure, separated waste and soil were proved to be not hazardous. The total content of heavy metal in the separated waste and soil met standard of California State, USA. Therefore the separated waste may be relandfilled at a sanitary landfill site and/or burned up at an incinerator, and the separated old soil may be used ad landfill cover-soil at a sanitary landfill site. Water quality of two streams was grade IV, of which water could be used as industrial and agricultural water. The streams near the landfill site might not be contaminated by leachate from the old landfill site. It was estimated that organic matter in the old landfill site would not be actively biodegraded within a short period of time.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.128-131
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• 2003

It is well known that the membrane separation process combined with surfactant micelle (micellar-enhanced ultrafiltration) or polyelectrolyte (polyelectrolyte-enhanced ultrafiltration) can remove heavy metals effectively. However, the environmental hazard of surfactant or polyelectrolyte remained in effluent is a serious disadvantage of these methods. In this study, humic substances (HS) were used as complexing agents for metal removal instead of synthetic chemicals. The HS are a sort of natural organic matters which are biodegradable and abundant in natural environment. And the functional groups such as carboxyl groups and phenols in HS can bind with the cationic radionuclides and form complexes. Therefore separation process using them will be more environmental-friendly. The effects of concentration of HS and pH on the removal of cobalt were investigated. The ultrafiltration process was applied to the separation of the cobalt - HS complexes from the aqueous stream. At the concentration of > 3 g/L of HS and pH of 6, over 95 % of cobalt was removed by regenerated cellulose membrane of molecular weight cut-off (MWCO) 3,000. As the concentration of HS increased, the removal of cobalt also was improved because of increase in biding sites (functional groups). The cobalt removal increased from 72.5 % to 97.5 % when pH increased from 4 to 8 at the concentration of 3 g/L HS because of increase in HS solubility and cobalt hydroxide precipitation. In the presence of NaCl, the removal efficiency of cobalt decreased.

• Korean Chemical Engineering Research
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• v.49 no.4
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• pp.475-479
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• 2011

Chitosan is a natural polymer that has many physicochemical(polycationic, reactive OH and $NH_2$ groups) and biological(bioactive, biocompatible, and biodegradable) properties. In this study, chitosan nanoparticles were prepared using poly-${\gamma}$-glutamic acid(${\gamma}$-PGA) as gelling agent. Nanoparticles were formed by ionic interaction between carboxylic groups in ${\gamma}$-PGA and amino groups in chitosan. Chitosan(0.1~1 g) was dissolved in 100 ml of acetic acid (1% v/v) at room temperature and stirred overnight to ensure a complete solubility. An amount of 0.1 g of ${\gamma}$-PGA was dissolved in 90 ml of distilled water at room temperature. Chitosan solution was dropped through needle into beaker containing ${\gamma}$-PGA solution under gentle stirring at room temperature. The average particle sizes were in the range of 80~300 nm. The prepared chitosan/${\gamma}$-PGA nanoparticles were used to examine their removal of several heavy metal ions($Cd^{2+}$, $Pb^{2+}$, $Zn^{2+}$, $Cu^{2+}$, and $Ni^{2+}$) as adsorbents in aqueous solution. The heavy metal removal capacity of the nanoparticles was in the order of $Cu^{2+}$ > $Pb^{2+}$ > $Cd^{2+}$ > $Ni^{2+}$ > $Zn^{2+}$.

• Microbiology and Biotechnology Letters
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• v.24 no.1
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• pp.92-100
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• 1996

For the production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate)(P(3HB-co-3HV)) from butyric acid and valeric acid, 10 strains of bacteria capable of producing P(3HB-co-3HV) were isolated from soil. Among them, the strain HJ-067 showed the best ability of producing P(3HB-co-3HV), and was indentified as a Azotobacter sp. For the production of P(3HB-co-3HV), the optimum concentrations of butyric and valeric acid were 3.0g/l, respectively. The most effective nitrogen source was $(NH_4)_{2}SO_4$ at an optimum concentration of 0.75g/l, which was equivalent to 21.36 in C/N ratio. Deficiency of the cationic metal ions ($Zn^{2+},\;Co^{2+},\;Mn^{2+}$) in the proguction medium had stimulating effect on P(3HB-co-3HV) accumulation, especially in the manganese. deficient medium. The optimum temperature for P(3HB-co-3HV) production was 27$^{\circ}C$ and the optimum initial pH was 7.0. Under the optimum conditions, 1.82g/l of P(3HB-co-3HV) and 3.00g/l of dry biomass were produced after 36 hour cultivation, and the P(3HB-co-3HV) yield and HV% were 60.60% (w/w), 15.92%, respectively.