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RISS 인기검색어
- 검색키워드
- 저자 : Gilsun Yoo (검색결과 3 건)
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유길선 ( Gilsun Yoo ),안지은 ( Jieun An ),조대철 ( Daechul Cho ),권성현 ( Sung Hyun Kwon ) 한국환경과학회 2018 한국환경과학회지 Vol.27 No.9
Bioremediation in situ is heavily dependent on the oxygenic environment which would privide the dwelling microorganism with sufficient oxygen. The situation could be easily resolved with supply of an Oxygen Releasing Compound (ORC). In this paper we prepared that sort of material out of oyster shell powder (mostly calcium carbonate) that prevails every shore areas of the country. We used two different oxidizing methods in the first step of the whole manufacturing process-conventional heating in a furnace and an ultrasound generator to obtain calcium oxide. Then that calcium oxide was further oxidized into calcium peroxide which may release oxygen under a moisturized condition. The oxygen releasing experiments were run to test the performance of our products, and to determine the gas kinetics during the experiments. Interestingly, calcium peroxide derived from ultrasound treatment was much more energy-effective as ORC than that from furnace heating although the heat derived process was better than that of ultrasound in terms of oxygen content and its releasing rate. We also found that most of the data collected from the gas releasing experiments fairly supported an ordinary 1<sup>st</sup> order kinetics to oxygen concentration, which shaped a sharp discharge of oxygen at the very early moment of each test.
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재활용 패각의 산-염기치환 반응을 통한 과산화칼슘의 제조와 산소발생 특성
권성현 ( Sung Hyun Kwon ),유길선 ( Gilsun Yoo ),조대철 ( Daechul Cho ) 한국폐기물자원순환학회 2019 한국폐기물자원순환학회지 Vol.36 No.2
The Korean coastal sediment area is apt to be contaminated by prevailing aquafarming and inland eutrophic sources. Furthermore, oyster shells are being overproduced every year with little recycling. Oxygen-releasing compounds (ORCs) are paramount in bioremediation or bioaugmentation. Calcium peroxide, one of the primary ORCs, was prepared using recyclable oyster shells via acid?base reactions based on double replacement, and this was followed by oxidation with hydrogen peroxide. Hydrogen peroxide, which is known to be effective as oxidizing agent, required an optimum dose for higher content of oxygen in the final product, because the literature shows that the oxidative reaction is reversible. A variety of concentrations of HCl and NaOH were examined in stoichiometry for the breakdown of calcium carbonates (or CO<sub>2</sub> production) and formation of calcium hydroxide in the initiation reaction. Acid and base overdoses helped the oxygenation reaction to be extended further, thus leading to calcium peroxide with the highest content of oxygen at a combination of 6 N-12 N acid-base treatment. With an elevated temperature, more oxygenated calcium peroxide was likely to be formed. Carbon dioxide and free oxygen during the experiments were determined with DO probing and gas capture in a water bath.
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Effect of oyster shell powder on nitrogen releases from contaminated marine sediment
Md Akhte Khirul,Beom-Geun Kim,Daechul Cho,Gilsun Yoo,Sung-Hyun Kwon 대한환경공학회 2020 Environmental Engineering Research Vol.25 No.2
Nitrogen flux release from organically enriched sediments into overlying water, which may have significantly influence on water quality and increasing continuous eutrophication. The purpose of this study is to evaluate the remediation efficiency of oyster shell powder and its treated product into organically enriched sediment in terms of nitrogen flux, organic matter, chlorophyll-a, pH and dissolved oxygen (DO). The TOSP was mainly composed of CaO2. The application of TOSP into the sediment has increased the pH, DO and significantly decreased the concentrations of NH₄+-N and T-N compared to other basins. On the other hand, nitrate was enriched with the addition of treated oyster powder, an oxygen releasing compound on both phases. Furthermore, chlorophyll-a was found to be increasing with time in the control basin meanwhile it dropped drastically with the addition of TOSP, which implied on the repression of algal growth owing to blockage of nitrogen source migrating from the sediment. This study has shown that the TOSP was effective to improve sediment-water quality, diminish eutrophication and control harmful algae blooms in a marine environment. Therefore, it is a good reference as an effective environmental remediation agent.
ScienceON
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