• Food Science of Animal Resources
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• v.23 no.4
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• pp.356-360
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• 2003

The purpose of this paper was to determine the quantity of selenium in milk by inductively coupled plasma optical emission spectrometry. The sample was digested in teflon vessel containing nitric-hydrogen peroxide acid mixture. After digestion, the sample is treated with additional hydrochloric acid. Total selenium was reduced with sodium borohydride and concentrated hydrochloric acid in a simplified hydride generation(HG) manifold. The optimum conditions of HG are 2 M for HCl, 1.5％ for NaBH$_4$, 1.2 mL/mim for sample flow. Recovery rates by the standard addition method were 88.0％ at 10 ppb and 92.2％ at 10 ppm. The relative standard deviations were 4.8 and 3.2％, respectively. This method showed a good accuracy and precision. And so it was highly suitable for determination of small quantity of selenium in milk.

• Resources Recycling
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• v.33 no.1
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• pp.15-21
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• 2024

The demand for electric vehicles powered by lithium-ion batteries is continuously increasing. Recovery of valuable metals from waste lithium-ion batteries will be necessary in the future. This research investigated the effect of reaction temperature on the lithium recovery ratio from hydrogen reduction followed by water leaching from lithium-ion battery NCM-based cathode materials. As the reaction temperature increased, the weight loss ratio observed after initiation increased rapidly owing to hydrogen reduction of NiO and CoO; at the same time, the H₂O amount generated increased. Above 602 ℃, the anode materials Ni and Co were reduced and existed in the metallic phases. As the hydrogen reduction temperature was increased, the Li recovery ratio also increased; at 704 ℃ and above, the Li recovery ratio reached a maximum of approximately 92%. Therefore, it is expected that Li can be selectively recovered by hydrogen reduction as a waste lithium-ion battery pretreatment, and the residue can be reprocessed to efficiently separate and recover valuable metals.

• Proceedings of the Materials Research Society of Korea Conference
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• 1997.05a
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• pp.68-68
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• 1997

• Proceedings of the Materials Research Society of Korea Conference
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• 1997.05a
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• pp.66-66
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• 1997

• Journal of Korean Society of Environmental Engineers
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• v.28 no.4
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• pp.362-367
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• 2006

Waste activated sludge(WAS) collected from domestic wastewater treatment plant is biomass that contains large quantities of organic matter. However, relevant literature show that the bio-hydrogen yield using WAS was too low. In this study, the effect of pretreatment of WAS on hydrogen yield was investigated. Pretreatment includes acid and alkali treatments, grinding, heating, ozone and ultrasound methods. After pretreatment organic matters of WAS were solubilized and soluble chemical oxygen demand(SCOD) was increased by 14.6 times. Batch experiments were conducted to investigate the effects of pre-treatment methods and buffer solution, hydrogen partial pressure, and sodium ion on hydrogen production from WAS by using heated anaerobic mixed cultures. Experimental results showed that addition of buffer solution, efficient pre-treatment method with alkali solution, and gas sparging condition markedly increased the hydrogen yield to 0.52 mmol $H_2/g$-DS.

• Journal of Hydrogen and New Energy
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• v.20 no.5
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• pp.439-446
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• 2009

This paper investigates the dehydration and RDF (Refuse Derived Fuel) production of organic wastes, livestock manure and sewerage sludge with pressurized hydrothermal treatment process. The renewable technology for the organic wastes must involve short treatment time required, reusable energy source, anti-odor and viruses, low cost for the treatment, and well-fertilization. The pressurized hydrothermal treatment process promotes to evaporate moisture in the waste after being shortly treated in a reactor, which uses steam and heat supplied by an external boiler. By the pressurized steam, the cell walls of the waste break and effectively release the internal moisture. Then, the dried waste can be mixed with waste vinyls to produce RDF with a higher heating value as high as 6,700 kcal/kg.

• Journal of Soil and Groundwater Environment
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• v.6 no.1
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• pp.3-12
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• 2001

During ozonation process, the hydroxyl radical generation rates were measured under different experimental conditions (ozone feed rate, nitrobenzene concentration, hydroxyl radical scavenger, pH, HO$_2$O$_2$/O$_3$ etc.) Nitrobenzene could be decomposed by hydroxyl radical rather than ozone only and nitrobenzene decomposition rate was expressed with functions of ozone and nitrobenzene concentration. The rate was decreased as the hydroxyl radical scavenger concentration was increased, and all results were followed pseudo first-order reaction. Using a competitive method, hydroxyl radical generation rate was measured with probe compound and scavenger. It was proportional to ozone concentration, and 0.24mo1 of hydroxyl radical was produced with 1mol of ozone. Under different pH conditions, hydroxyl radical generation rates were measured (pH 10.2 (0.91Ms$^{-1}$ ) > pH 7.3 (0.72Ms$^{-1}$ ) > pH 5.6 (0.67Ms$^{-1}$ ) > pH 3.4 (0.63Ms$^{-1}$ )) showing higher generation rate at high pH values. Addition of hydrogen peroxide promoted the generation rate of hydroxyl radical. Considering the results of pH experiments and addition of hydrogen peroxide experiments, the hydroxyl radical generation rate was 1.6 times higher in hydrogen peroxide solution than in high pH solution, indicating addition of hydrogen peroxide is better promoter to produce the hydroxyl radical in ozonation. These results could be applied to AOPs to remediate the contaminated wastewater and groundwater.

• The Magazine for Energy Service Companies
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• s.46
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• pp.64-65
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• 2007

고등기술연구원 플랜트엔지니어링센터에서는 10년이상 축적된 기반기술과 연구 설비를 환경 및 에너지 분야의 다양한 플랜트에 적용하고 있으며, 고부가가치 창출물 목표로 대기업 및 중소기업을 지원하고 있다. 석탄과 중질잔사유 등 다양한 원료의 가스화와 액화기술 개발 및 열분해/가스화 용융기술의 광범위한 적용을 통하여 생활/산업 폐기물을 환경에 적합하게 처리할 수 있는 공정기술 개발을 하고 있다. 또한 플랜트의 설계/건설/시운전까지 종합한 turn-key서비스를 제공하고 있다. 뿐만 아니라 차세대에너지원인 수소제조를 위한 고온 수전해 전극개발 및 지구온난화 가스를 저감하는 촉매와 공정기술계발, 환경에너지 분야에 대한중소기업 기술지원에도 중점을 두고 있다. 고온고압의 석탄가스화 연구로부터 축적된 가스화용융에 대한 기반기술을 하수슬러지 및 생활폐기물 처리에 성공적으로 적용하여,2003년 1뭘과 12월에 환경부 신기술을 각각 지정 받은 바 있다.

• Journal of Hydrogen and New Energy
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• v.6 no.2
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• pp.85-90
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• 1995

Activation behavior, hydriding rate and disintegration were tested for hydrogen storage alloy particles fixed in an adhesive after treating with inorganic solution. Commertial adhesive as a binder was used. Chemical-treated particles showed the best characteristics for activation and a little effect of prevention the break down of the powders themselves after several repeated operations. Furthermore activation characteristics were found to show a similar trend to chemical-treated powders even in the fixed one with an adhesive, except for a slight decrease in reaction velocity.

• Journal of the Korean Vacuum Society
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• v.5 no.1
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• pp.73-76
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• 1996

We have prepared hydrogenated amophous silicon (a-si : H) films with superlattice structure by hydrogen radical anneling(HRA) technique. We have studied the preparation of a-Si :H films by HRA and the optical & electronic characteristics. Optical band gap and the hydrogen contents in the a Si : H film is decreased as HRA time increased. We first report a -Si : H film prepared by periodicdeposition of a-Si : H layer and HRA have the superlattice structure using TEM . After 1 hour light soaking on the a-Si :H film prepared by HRA, there are no difference in the temperatre dependence of dark conductivity and the conductivity activation energy. An excellent stability for light in a-Si :H films by HRA can be explained using the long-range structural relaxation of the amorphous network and the propertiesof light -induced defects(LID) proposed by Fritzsche.