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Singh, Rashmi R.,Tipre, Devayani R.,Dave, Shailesh R. Techno-Press 2014 Advances in environmental research Vol.3 No.4
Iron precipitating organisms play a significant role in the formation of ferric hydroxide precipitate, which acts as strong adsorbent for toxic metal. In this respect four different iron precipitating cultures were isolated from Hutti gold mine surface winze water sample on citrate agar medium. The best isolate was screened out for metal removal study on the basis of fast visual iron precipitation. The selected isolate was identified as Enterobacter sp. based on routine biochemical tests and Biolog GN microplate results and as Enterobacter cloacae subsp. dissolvens by 16S rRNA gene sequence analysis (GenBank accession number EU429448). Influence of medium composition, medium initial pH, the influence of inoculum size, effect of various media and ferric ammonium citrate concentration were studied on metal removal in shake flask experiments. Under the optimized conditions studied, E. cloacae showed $94{\pm}2$, $95{\pm}2$ and $70{\pm}2%$ of cadmium, copper and mercury removal from a simulated waste in shake flask studies. In lab scale column reactor more than 85% of copper and mercury removal was achieved.
Sopapan P.,Lamdab U.,Akharawutchayanon T.,Issarapanacheewin S.,Yubonmhat K.,Silpradit W.,Katekaew W.,Prasertchiewchan N. 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.2
The co-precipitation process plays a key role in the decontamination of radionuclides from low and intermediate levels of liquid waste. For that reason, the removal of Cs ions from waste solution by the coprecipitation method was carried out. A simulated liquid waste (133Cs) was prepared from a 0.1 M CsCl solution, while wastewater generated by washing steel ash served as a representative of radioactive cesium solution (137Cs). By co-precipitation, potassium ferrocyanide was applied for the adsorption of Cs ions, while nickel nitrate and iron sulfate were selected for supporting the precipitation. The amount of residual Cs ions in the CsCl solution after precipitation and filtration was determined by ICP-OES, while the radioactivity of 137Cs was measured using a gamma-ray spectrometer. After cesium removal, the amount of cesium appearing in both XRD and SEM-EDS was analyzed. The removal efficiency of 133Cs was 60.21% and 51.86% for nickel nitrate and iron sulfate, respectively. For the ash-washing solution, the removal efficiency of 137Cs was revealed to be more than 99.91% by both chemical agents. This implied that the co-precipitation process is an excellent strategy for the effective removal of radioactive cesium in waste solution treatment.
Fe을 도핑한 Li[Ni<sub>0.575</sub>Co<sub>0.1</sub>Mn<sub>0.325</sub>]O<sub>2</sub>의 구조적인 안정성 및 전기화학적 특성
양수빈,유기원,장병찬,손종태,Yang, Su-Bin,Yoo, Gi-Won,Jang, Byeong-Chan,Son, Jong-Tae 한국전기화학회 2014 한국전기화학회지 Vol.17 No.3
본 연구에서는 리튬 이차전지의 양극 재료인 $Li[Ni_{0.575}Co_{0.1}Mn_{0.325}]O_2$를 공침법(Co-precipitation)으로 전구체를 합성 하였고, 철(Fe)을 도핑 함으로써 양극 활물질을 합성하였다. 합성된 양극 활물질을 시차주사현미경 (SEM, Scanning electron microscope)과 X선-회절분석(XRD, X-ray diffraction)으로 분석하였다. X선-회절분석 결과 철(Fe)을 도핑 함으로써 a축과 c축이 증가하였고, $I_{(003)}/I_{(104)}$의 비가 증가하는 것과 $I_{(006)}+I_{(102)}/I_{(101)}$비가 작아지는 것을 통해 구조적 안정성이 증가하는 것을 확인했다. 전기화학적 특성 측정 결과 사이클 특성이 향상되었고, 임피던스 측정 결과 전하 이동 저항($R_{ct}$) 값이 낮아짐을 통해 전기화학적 분석 결과에서도 철(Fe)을 도핑 하였을 때 개선 된 특성을 나타내었다. 특히, 고온 조건에서 사이클 특성이 개선되는 것을 확인 하였는데, 이는 구조적 안정성이 사이클 특성에 기여하였기 때문이다. In this study, a positive-electrode material in a lithium secondary battery $Li[Ni_{0.575}Co_{0.1}Mn_{0.325}]O_2$ was synthesized as precursor by co-precipitation. Cathode material was synthesized by adding iron. The synthesized cathode material was analyzed by scanning electron microscope and x-ray diffraction. The analysis of x-ray diffraction showed that the a-axis and c-axis is increased by doping iron. And $I_{(003)}/I_{(104)}$ is increased and $I_{(006)}+I_{(102)}/I_{(101)}$ is decreased. Through this result, it was confirmed that the structural stability is improved. And impedance measurements show that the charge transfer resistance ($R_{ct}$) is lowered by doping iron. Consequently, electrochemical properties are improved by doping iron. In particular, the cycle characteristics are improved at a high temperature condition (328 K). Structural stabilities are contributing to the cycle properties.
Production of High-purity Magnetite Nanoparticles from a Low-grade Iron Ore via Solvent Extraction
( Yong Jae Suh ),( Thi May Do ),( Dae Sup Kil ),( Hee Dong Jang ),( Kuk Cho ) 한국화학공학회 2015 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.53 No.1
We produced magnetite nanoparticles (MNPs) and a Mg-rich solution as a nano-adsorbent and a coagulant for water treatment, respectively, using a low-grade iron ore. The ore was leached with aqueous hydrochloric acid and its impurities were removed by solvent extraction of the leachate using tri-n-butyl phosphate as an extractant. The content of Si and Mg, which inhibit the formation of MNPs, was reduced from 10.3 wt% and 15.5 wt% to 28.1 mg/L and < 1.4 mg/L, respectively. Consequently, the Fe content increased from 68.6 wt% to 99.8 wt%. The high-purity Fe3+ solution recovered was used to prepare 5-15-nm MNPs by coprecipitation. The wastewater produced contained a large amount of Mg2+ and can be used to precipitate struvite in sewage treatment. This process helps reduce the cost of both sewage and iron-orewastewater treatments, as well as in the economic production of the nano-adsorbent.
Highly selective iron-based Fischer-Tropsch catalysts activated by CO<sub>2</sub>-containing syngas
Chun, D.H.,Park, J.C.,Hong, S.Y.,Lim, J.T.,Kim, C.S.,Lee, H.T.,Yang, J.I.,Hong, S.,Jung, H. Academic Press 2014 Journal of catalysis Vol.317 No.-
Fischer-Tropsch synthesis (FTS) was carried out over precipitated iron-based catalysts activated by syngas (H<SUB>2</SUB>+CO) with different amounts of CO<SUB>2</SUB> (0%, 20%, 33%, and 50%). The activation using CO<SUB>2</SUB>-containing syngas significantly suppressed the production of undesired products, CH<SUB>4</SUB> and C<SUB>2</SUB>-C<SUB>4</SUB> hydrocarbons, but facilitated the production of valuable products, C<SUB>5+</SUB> hydrocarbons. In particular, in the case of C<SUB>19+</SUB> hydrocarbons, the target products of low-temperature FTS (≤280<SUP>o</SUP>C), both selectivity and productivity showed a great increase with an increased inlet CO<SUB>2</SUB> content during activation. We attribute the advantageous performance of the catalysts activated by CO<SUB>2</SUB>-containing syngas to the improvement in the effective performance of active iron carbides, possibly induced by an increased ratio of ε'-carbide (Fe<SUB>2.2</SUB>C) to χ-carbide (Fe<SUB>2.5</SUB>C) and a decreased fraction of inactive bulk carbons.
Investigation of Corrosion Minerals from the Remediation for TCE-Contaminated Groundwater
Moon, Ji-Won,Moon, Hi-Soo,Song, Yungoo,Kang, Jin Kyoo,Roh, Yul 한국광물학회 2003 광물과 암석 (J.Miner.Soc.Korea) Vol.16 No.1
본 연구는 0가 철(ZVI)의 설치위치와 전극의 배열에 따른 다양한 조합의 전기적 투수성 반응벽을 대상으로 트리클로로에틸렌의 탈염소화 반응에 의한 정화시 ZVI의 부식에 기인하는 광물산 침전물에 대해 알아보고, 이에 대한 조절 요소를 알아보고자 한다. 광물학적 연구 결과, 지하수 유입부의 ZVI 시료는 상대적으로 많은 레피도크로사이트, 훼리하이드라이트 혹은 철 수산화물과(phospho)siderite가 산출되면 반면, 용출부의 ZVI 시료는 아카가나이트, 자철석/마그헤마이트, 그리고 중간 산물인 green rust (GR) Ⅰ과 GR Ⅱ가 산출되었다. 이러한 광물 조합의 변화는 용존 산소 및 pH의 상승에 주로 기인한 것으로 나타났다. 또한 전기적 투수성 반응벽 내에 신출되는 광물상 침전물들의 조절 요소들은 (1) pH, (2) 용존산소, (3) 철의 부식시 중간 산물, (4) 음이온 종류 등으로 밝혀졌다. The objective of this study was to investigate mineral precipitates, which derived from the zero valent iron (ZVI) corrosion during TCE dechlorination and to find the controlling factors in mineral precipitates. A series of column experiments were conducted to evaluate the location of ZVI and the effects of electrode arrangements in electro-enhanced permeable reactive barrier (E2PRE3) systems. Based on mineralogical study, ZVI samples near the influent port had more lepidocrocite, ferrihydrite or Fe (oxy)hydroxide, and (phospho)siderite while backward samples had more akaganeite, magnetite/maghemite, and intermediate green rust (GR) Ⅰ and GR Ⅱ. A suite of mineral distribution was preferabley related to the dissolved oxygen and the increased pH. Controlling factors of mineral precipitates in an E2PRB system were found to be (1) pH, (2) dissolved oxygen, (3) the types of Fe intermediates, and (4) anionic species to form complex strongly.
영가철 충진 컬럼을 이용한 연속적인 물리화학적 수중 인 제거
정주영,안병민,김정주,박주양 대한상하수도학회 2013 상하수도학회지 Vol.27 No.4
Excessive phosphorus in aquatic systems causes algal bloom resulting in eutrophication, DO depletion, decline in recreational value of water and foul tastes. To treat wastewater containing phosphorus including effluent of wastewater treatment plant, the continuous experiments were performed by using electrochemical way. The spherical ZVI and silica sand which act as physical filter are packed at appropriate volume ratio of 1:2. Electric potential is applied externally which can be changed as per the operational requirement. The results indicate that optimum hydraulic retention time of 36 minutes (10 mL/min at 1 L reactor) was required to meet the effluent standards. Lower concentrations of phosphorus (≺10 mg/L as phosphate) were removed by precipitation by contact with iron. Thus, additional electric potential was not required. In order to remove high concentration phosphorus around 150 mg/L as phosphate, external electric potential of 600 V was applied to the reactor.
Kinetic study of CO hydrogenation over co-precipitated iron–nickel catalyst
Ali A. Mirzaei,Rouhoullah M. Kiai,Hossein Atashi,Maryam Arsalanfar,Sara Shahriari 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.4
The kinetic of the Fischer–Tropsch synthesis over a Fe–Ni/Al2O3 catalyst was investigated in a fixed bed micro reactor. Experimental conditions were varied as follow: reaction pressure 2–10 bar, H2/CO feed ratio of 2/1 and space velocity of 96–450 cm3(STP)/h/gramcatalyst at the temperature range 523–573 K. On the basis of carbide-enol mechanism and Langmuir–Hinshelwood–Hougen–Watson (LHHW) type rate equations, seventeen kinetic expressions for CO consumption were tested and interaction between adsorption HCO and dissociated adsorption hydrogen as the controlling step gave the most plausible kinetic model. The activation energy was 46.5 kJ/mole for optimal kinetic model.
Fischer-Tropsch 합성반응용 Fe계 촉매의 성능 및 물리화학적 특성에 미치는 SiO2 첨가효과
이관영 ( Kwan Young Lee ),이호태 ( Ho Tae Lee ),정헌 ( Heon Jung ),양정일 ( Jung Il Yang ),김학주 ( Hak Joo Kim ),양정훈 ( Jung Hoon Yang ),천동현 ( Dong Hyun Chun ),현순택 ( Sun Taek Hyun ) 한국화학공학회 2010 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.48 No.3