• Journal of the Society of Cosmetic Scientists of Korea
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• v.23 no.2
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• pp.48-62
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• 1997

Chitosan oligosaccharides having aldehyde group at reducing end were prepared by oxidative-deamination reaction of chitosan by using sodium nitrite, and the resulting aldehyde group was reduced to 2, 5-anhydro-D-mannitol group. The obtained chitosan oligosaccharides showed an average degree of polymerization 2~3 by gel permeation chromatography analysis. It was highly soluble in hydrophilic solvents and thermally stable. N, N-diacyl, O-acyl chitosan oligosaccharides were obtained from the reaction between chitosan oligosaccharides and acyl chloried under dimethylaminopyridine. From differential scanning calorimetric measurement, N, N-dilauroyl, O-lauroyl chitosan oligosaccharides showed mesophase region, which was confirmed by polarized microscope as a thermotropic liquid crystalline state. X-ray diffraction pattern revealed that N, N-dilauroyl, O-lauroyl chitosan oligosaccharedes were highly crystalline, whereas chitosan oligosaccharides were not.

• Resources Recycling
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• v.9 no.2
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• pp.11-17
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• 2000

Consumption of nickel is continuously increasing and the wastes of secondary battery, ferrite and catalyst containing Ni are also generated periodically. Among those wastes, the aim of this research is the recovery of nickel from used Ni-Cd recharge battery. Battery consisted of Ni 24 wt%, Fe 30 wt% and Cd 18.5 wt%. Metal was recovered by solvent extraction after leaching. Cadmium was leached completely in 1N-HCl and Ni was recovered above 70%. 30 vol% MSP-8 separated Cd and Ni completely from acidic leaching solution. In addition $NH_4NO_3$ as one of ammonium salt type leachants showed an excellent leaching selectivity to Ni and Cd. Ni in leached solution was recovered completely by LIX-extractant and more than 70% of Cd in raffinate was by D2EHPA.

• Journal of Korean Society on Water Environment
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• v.20 no.6
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• pp.571-576
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• 2004

Since anaerobic/anoxic/oxic process, which is a typical mainstream biological nitrogen and phosphorus removal process, utilizes influent organic matter as an external carbon source for phosphorus release in anaerobic or anoxic stage, influent COD/T-P ratio gives a strong influence on performance of phosphorus removal process. In this study, a bench scale experiment was carried out for SBR process to investigate nitrogen and phosphorus removal at various influent COD/T-P ratio and nitrate loadings of 23~73 and 1.6~14.3g $NO_3{^-}-N/kg$ MLSS, respectively. The phosphorus release and excess uptake in anoxic condition were very active at influent COD/T-P ratios of 44 and 73. However, its release and uptake was not obviously observed at COD/T-P ratio of 23. Consequently, phosphorus removal efficiency was decreased. In addition, the phosphorus release and uptake rate in anoxic condition increased as the nitrate loading decreased. Specific denitrification rate had significantly high correlation with organic materials and nitrate loadings of the anoxic phase too. The rate of phosphorus release and uptake in the anoxic condition were $0.08{\sim}0.94kg\;S-P/kg\;MLSS{\cdot}d$ and $0.012{\sim}0.1kg\;S-P/kg\;MLSS{\cdot}d$, respectively.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.51-51
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• 2018

산업의 발달 및 인구 증가에 따라 발생되는 폐수의 종류는 다양해지고 있으며, 폐수의 처리를 위해서는 주로 생물학적 처리를 먼저 검토하게 된다. 하지만 최근 폐수의 성분은 생물학적으로 처리하기 어려운 난분해성 요인(고농도의 염분, 독성 유기용매, 중금속 등)이 존재 할 뿐 아니라, 생물학적 처리 후 존재하는 잔류 유기물은 환경부에서 제시하는 방류수 기준을 만족시키기에 어려움이 있다. 이러한 난분해성 요인을 제거하기 위해서 전기 화학적 처리의 필요성이 대두되고 있으며, 다양한 고도산화기술들이 제시되고 있다. 그 중 처리시간의 단축으로 인한 처리비용 절감과 산화제 발생에 따른 높은 처리 효율로 인해 전기화학적 폐수산화처리에 대한 연구가 활발히 진행되고 있는 실정이다. 본 연구에서는 기존에 사용되어 지고 있는 전기화학적 폐수산화처리를 위한 불용성 전극을 BDD 전극으로 대체하여 다양한 폐수에 전기분해 처리 적용 가능성을 검토하고자 기존 BDD 전극의 기판 모재로 이용되던 Si, Nb 대신에 Ti 기판 위에 BDD 형성시켜 전극을 제작하였고, 폐수의 전기분해 적용 가능성을 확인하기 위하여 축산폐수, 해양폐수, 질산염폐수 등 실제 폐수를 채수하여 폐수 내 유기물의 전기분해 처리 효율을 분석하였다. 이에 Ti 모재 기판에 증착된 BDD 전극을 이용하여 폐수 내 유기물의 전기분해 처리효율을 분석 한 결과, 축산폐수의 경우 처리시간 150분에 95% 이상 처리효율을 나타냈으며, 해양폐수의 경우 처리시간 60분에 98% 이상의 유기물 제거 효결과가 나타남에 따라 축산폐수와 선박 평형수, 양식장폐수 등 다양한 폐수에 적용이 가능할 것으로 판단되며, 기존에 적용되어 지고 있는 고도산화처리 기술을 BDD 전극을 이용한 전기화학적 처리로 대체 할 수 있을 것으로 기대할 수 있다.

• Korean Chemical Engineering Research
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• v.49 no.6
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• pp.720-725
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• 2011

Gold catalysts supported on metal-oxides were prepared by co-precipitation using the various metal nitrates and chloroauric acid as precursors, and effect of water addition on the catalytic activity in CO oxidation was investigated. Among the various supported gold catalysts, Au/$Co_{3}O_{4}$ and Au/ZnO catalysts showed the excellent activity for CO oxidation. Water in the reactant gas had a negative effect on the oxidation activity over Au/$Co_{3}O_{4}$ catalysts and a positive effect on that over Au/ZnO, which means the activity depends strongly on the nature of support. It was also confirmed that no significant change in the particle size of gold was observed after reaction both in dry and wet conditions. This fact suggested that the deactivated catalyst due to a carbonate species could be regenerated by water addition in the reactant gas.

• Journal of the Korean Society for Marine Environment & Energy
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• v.6 no.2
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• pp.28-37
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• 2003

We investigated water quality, salinity, nutrients, SS, COD and Chlorophyll-a concentrations in the seawater of the Mokpo costal area, southwestern coast of Korea. Seawater samples at 25 stations were collected in July 20, 25 and September 3, 2002 after a strong rain event. The distributions nutrients in seawater were analyzed using an method of sea water analysis presented by the ministry of Maritime Affairs and Fisheries of Korea. The sampling sites were categorized into the inner and outer harbour based on salinity distribution and difference of nutrients distributions was evidence between these two zones. Nutrients and SS inflow and distributed in the inner harbour by the discharged freshwater from Youngsan river during strong rainfall whereas they were distributed in seawater of outer harbour by natural processes in general coastal area.

• Resources Recycling
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• v.11 no.3
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• pp.10-16
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• 2002

In the leaching of $LiCoO_2$with a strong acid such as sulfuric and nitric acid, an additional step was needed to recover cobalt and lithium separately from spent lithium ion batteries (LIBs). The leaching of $LiCoO_2$in an oxalic acid solution was investigated to recover cobalt selectively using a low solubility of cobalt oxalate at low pH. Leaching efficiency of 95% of lithium and less than 1% of cobalt were obtained when pure $LiCoO_2$powder was leached in 3M oxalic acid at $80^{\circ}C$ and 50 g/L pulpdensity. Under the above leaching conditions, complete dissolution of lithium was accomplished with mere 0.25% of cobalt in the solution when the cathodic active material collected from spent LIBs was employed. The lithium in the leaching solution can be recovered as a form of carbonate or hydroxide depending on the addition of $Na_2$$CO_3$or LiOH.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.8
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• pp.554-560
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• 2014

To investigate the applicability of montmorillonite to capping material for the remediation of contaminated marine sediment, adsorption characteristics of $PO{_4}{^{3-}}$ onto montmorillonite were studied in a batch system with respect to changes in contact time, initial concentration, pH, adsorbent dose amount, competing anions, adsorbent mixture, and seawater. Sorption equilibrium reached in 1 h at 50 mg/L but 3 h was required to reach sorption equilibrium at 300 mg/L. Freundlich model was more suitable to describe equilibrium sorption data than Langmuir model. The $PO{_4}{^{3-}}$ adsorption decreased as pH increased, due to the $PO{_4}{^{3-}}$ competition for favorable adsorption site with OH- at higher pH. The presence of anions such as nitrate, sulfate, and bicarbonate had no significant effect on the $PO{_4}{^{3-}}$ adsorption onto the montmorillonite. The use of the montmorillonite alone was more effective for the removal of the $PO{_4}{^{3-}}$ than mixing the montmorillonite with red mud and steel slag. The $PO{_4}{^{3-}}$ adsorption capacity of the montmorillonite was higher in seawater than deionized water, resulting from the presence of calcium ion in seawater. The water tank elution experiments showed that montmorillonite capping blocked well the elution of $PO{_4}{^{3-}}$, which was not measured up to 14 days. It was concluded that the montmirillonite has a potential capping material for the removal of the $PO{_4}{^{3-}}$ from the aqueous solutions.

• Journal of the Korean Professional Engineers Association
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• v.29 no.2
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• pp.80-90
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• 1996

This research aimed at investigating the changes of volatile basic nitrogen, amino nitrogen and lipids during the fermentation of 6 month Anchovy cured under room temperature with various treatments(20, 30 and 40% salted) and examing the optimum condition of Anchovy sauce. The results are summerized as the V.B.N which increased with the curing period of anchovy from 14 mg% to 90～107mg% in 180 days curing at 20% salt level. Amino nitrogen in minced anchovy was higher than in whole anchovy during fermentation and the content of Extractive Nitrogen in the curing anchovy containing 20% of salt, kept the highest amount in 60 curing days. As a rule, minced anchovy showed more rapidly increased than whole anchovy. The lipid in curing anchovy containing 20% and 30% of salt has already been oxidized in 30 days while the lipid of anchovy cured with 40% salt prolonged the initial stage to 45 days. During fermentation, peroxide value and acid value showed constant increasing, while thiobarbituric acid began to decrease after 120 days curing. Among the non-polar lipids, linolenic acid, linoleic acid and erucic acid was decomposed by 24.5%, 22.2%, and 20.0%, respectively. It was noticed that the decomposition of polar lipid was retarded by higher salt content.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.12
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• pp.1102-1110
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• 2010

Tidal mudflat is a reservoir for diverse microbial resources. Microbial diversity in tidal mudflat sediment can be easily influenced by various human activities. It is necessary to take representative samples to monitor microbial diversity in tidal mudflat sediments. In this study, we analyzed the microbial diversity and chemical characteristics of vegetation and non-vegetation tidal mudflat regions in the Kangwha tidal mudflat using geo-statistics and data-mining. According to the geo-statistical analysis, most correlation range values for the vegetation region were smaller than those for the non-vegetation region, which suggested that the shorter number and interval of sampling are required for the vegetation tidal mudflat environment due to its higher degree of chemical and biological complexity and heterogeneity. The data-mining analysis suggested that the organic content and nitrate were the major environmental factors influencing microbial diversity in the vegetation region while pH and sulfate were the major influencing factors in the non-vegetation region. Using the geo-statistical and data-mining integration approach, we proposed a guideline for determining the sampling interval and number to monitor microbial diversity in tidal mudflat.