• Title/Summary/Keyword: Iron oxides

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Oxalic Acid-based Remediation of Arsenic-contaminated Soil (옥살산 기반의 비소오염토양 정화 연구)

  • Lee, Myeong Eun;Jeon, Eun-Ki;Kim, Jong-Gook;Baek, Kitae
    • Journal of Soil and Groundwater Environment
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    • v.23 no.1
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    • pp.85-91
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    • 2018
  • Arsenic (As) usually is bound to amorphous iron oxides in the soils, and it can be removed via dissolution of iron oxides. Inorganic acid and chelating agent are widely used to extract As in the soil washing. However, the overall performance is highly dependent on the state of As fractionation. In this study, oxalic acid and inorganic acids (HCl, $H_2SO_4$, and $H_3PO_4$) were applied to enhance the dissolution of iron oxides for remediation of As-contaminated soils. Oxalic acid was most effective to extract As from soils and removal of As was two times greater than other inorganic acids. Additionally, 75% of As bound to amorphous iron oxides was removed by 0.2 M oxalic acid. Arsenic removal by oxalic acid was directly proportional to the sum of labile fractions of As instead of the total concentration of As. Therefore, the oxalic acid could extract most As bound to amorphous iron oxides.

The Effect of Different Iron Oxides Produced from Steel Plants in the Magnetic Properties of Cabined Sr-ferrite Powders. (염산폐액 정제방법에 따른 산화철이 Sr-ferrite의 히소특성에 미치는 영향)

  • 김효준;조태식;양충진;남효덕
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.124-127
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    • 1997
  • The magnetic properties of calcined Sr-ferrites, related to the iron oxides, produced from three different process in steel plants, have been investigated. The powder f.characteristics of iron oxides are much affected on the magnetic properties of calcined Sr-ferrite Powders. It was possible to improve the magnetic property of calcined Sr-ferrites with the iron oxide powders of small size and narrow size distribution. The maximum magnetic properties of calcined Sr-ferrites, showing 69 emu/g of saturation magnetization and 4020 Oe of intrinsic coercivity, are achieved at the following conditions; the iron oxides from the chemirite process(EP), mole ratio of 5.8, and calcination condition of 120$0^{\circ}C$/1hr.

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Effect of the Powder Characteristics of Iron Oxides on the Magnetic Properties of Sr-ferrite (산화철의 분체특성이 Sr-ferrite의 자기특성에 미치는 영향)

  • 조태식;김효준;최승덕;남효덕;염충진
    • Resources Recycling
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    • v.7 no.4
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    • pp.43-49
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    • 1998
  • We investigated the effects of the powder characteristics of various domestic iron oxides (${\alpha}Fe_2O_3$) on the magnetic properties of Sr-ferrites The particle size and the distribution of iron oxides were classified hy three different rerinning methods, and greatly a affected on the magn$\xi$tic prope$\pi$ies and the mmphology of Sr-ferntes. The agglomeration of Ruthner iron oxides and the large particles of Chemirite (CY) above $0.80{\mu}\textrm{m}$ were degraded the prope며es of Sr-fcrrites. The optimal magnetic prope$\pi$ies of Srt territes, showing 68.2 emu/g of saturation magnetization and 4300 Oe of intrinsic coerClvity, were achieved at the following c conditions; Chemirite (P2EP) iron oxides of $0.14{\mu}\textrm{m}$ molar ratio of 5.8. and calcination of $1150^{\circ}C$/1 hr.

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The Effect of Iron Oxides $(Fe_2O_3,\;Fe_3O_4)$ on Tribological Characteristics of Automotive Friction Materials (자동차용 마찰재에서 철산화물이 마찰특성에 미치는 영향에 관한 연구)

  • Cho KeunHyung;Jang Ho
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • pp.289-295
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    • 2004
  • The relationship between friction characteristics and iron oxides at the sliding interface was investigated. Three friction materials containing iron, magnetite $(Fe_3O_4)$ or hematite $(Fe_2O_3)$ were manufactured and friction tests were performed on gray cast iron disks to evaluate the friction coefficient as a function of sliding speed $\mu-\nu$. In-situ noise spectrum analyzer was employed to compare noise propensity during friction tests. Results show that the specimens with magnetite are more sensitive to velocity than those with iron or hematite. The specimens containing magnetite and hematite generated noise with different peaks in the spectrum. The difference in the peak frequency seems attributed to the different surface aggressiveness of iron oxides and intermittent changes of real contact area at the sliding interface during sliding. Surface morphology and roughness of the counter disc after the tests are also consistent with the aggressiveness of iron oxides.

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Characteristics of Copper and Cadmium Partitioning in Aquatic Sediment (수계내 저질에 대한 구리 및 카드뮴의 분배 특성)

  • 이군자;박청길
    • Journal of Environmental Science International
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    • v.1 no.2
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    • pp.71-79
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    • 1992
  • Selective extraction procedure has been used to quantify copper and cadmium In association with the various phases of aquatic sediment such as exchangeable/adsorbed, carbonate, manganese oxides, organic matter and iron oxides. Changes of pH influenced on the partitioning of copper in carbonate and exchangeable/ad- sorbed phases and of cadmium in carbonate phase of aquatic sediment. Addition of NTA and EDTA, copper and cadmium associated with carbonate phase were released from sediment to water. Total partitioning coefficient was 8.361 for copper and 0.497 for cadmium. The relative binding strengths of copper and cadmium to each solid phase can be ranked by using the partitioning coefficints. For copper it was observed that carbonate > organic matter > exchangeable/adsorbed > manganese oxides > iron oxides and for cadmiunm it was observed that exchangeable/adsorbed > carbonate > manganese oxides > organic matter > iron oxides.

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Effect of Orientation on Magnetic Tape Properties (도포형 자기기록 매체의 자성층에서 자성체의 배향거동과 배향상태에 따른 Tape 특성의 변화)

  • 김상문;김태옥;신학기;여운성
    • Journal of the Korean Magnetics Society
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    • v.7 no.6
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    • pp.314-320
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    • 1997
  • We have observed the orientation behavior of acicular iron oxides in magnetic layer of the particular magnetic tape after magnetic paint was coated on polyester film. As results of the static orientation, orientation of iron oxides come to the maximum at the front and the back of orientation magnets, but it was a litter lower at the back than at the front, and it slowly decreases and come to the constant level after passing through the orientation magnets. In case of edge portion to be futher away from center in the coated film, the orientation of iron oxides in magnetic layer come to worse than that of the center. We think it is owing to the shape and the magnetic magnitude of orientation magnets. The results of the dynamic orientation are as follows. As the orientation of iron oxides in the particulated magnetic tape is higher, the output properties of tape come to better than ever. And the orientation of iron oxides can be changed by drying condition, as result, the output properties of tape can be also. Therefore we think the considrations of the design of orientation magnets and the control of drying condition are needed to improve output properties of the particulated magnetic tape.

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Purification of Iron Oxides and Application to Magnetic Hard Ferrite

  • Kim, Jeong-Seog;Chou, Kyoung-Ho;Kim, Jai-Young
    • The Korean Journal of Ceramics
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    • v.2 no.3
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    • pp.125-130
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    • 1996
  • Hematite iron ore and waste iron oxide sludge containing about 3-5 wt% $SiO_2$ were purified by three types of method developed on the basis of the Bayer process which is known as the purification process of bauxite ore. The basic principle of the developed methods lies in the fact that the impurities contained in the iron oxides, such as $SiO_2$ and $Al_2O_3$ are soluble in the alkaline reagents. Reaction of the raw materials with KOH was done in pressure vessel, at atmospheric pressure, and by both of these two. By the pressure vessel method $SiO_2$ content was reduced to below 0.5 wt% in the waste iron oxide sludge, while, in iron ore, $SiO_2$ remained at 2-3 wt%. The atmospheric pressure reaction rendered the waste iron oxide sludge $SiO_2$ content below 0.5wt% when the reaction temperature increased to above 90$0^{\circ}C$. The combined method of two previous methods was the most effective process and rendered the refined iron oxide about 300-400ppm of $SiO_2$. Using some refined iron oxides, Ba-ferrite was produced and magnetic properties were measured. The highest quality of magnetic properties obtained in this study were Br=2.09 G, bHc=1.99 KOe, iHc=4.54 KOe, $(BH)_{max}$=1.06 MGOe. Effect of sintering condition and chemical composition will be discussed.

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Preparation and properties of multiferroic bismuth iron oxides

  • Nam, Joong-Hee;Joo, Yong-Hui;Cho, Jeong-Ho;Chun, Myoung-Pyo;Kim, Byung-Ik
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.19 no.2
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    • pp.66-69
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    • 2009
  • The compositional dependence of bismuth iron oxides and effect of La-substitutions in the structure of $BiFeO_3$ compounds were investigated, which compounds were synthesized by conventional ceramic processing. It is shown that some of bismuth iron oxides including $BiFeO_3$ show the narrow single phase region. The effect of La-doping in $BiFeO_3$ was presented as disappearance of many impurity phases of Bi-Fe-O compounds. The lower electrical resistivity was obtained as those compositions of Fe deficient region and La-doped $BiFeO_3$. The saturation magnetization of La-doped $BiFeO_3$ was increased with La content. The dielectric dispersion was also observed for those Bi-Fe-O compounds with Fe deficient and La-doped $BiFeO_3$ at low frequencies under 1 kHz.

Synthesis of Iron Oxide Using Ferrous Sulfate and Ammonia Water (황산제일철과 암모니아수를 이용한 산화철 합성)

  • Kim, Sam-Joong;Eom, Tae-Hyoung;Wang, Wei;Suhr, Dong-Soo
    • Korean Journal of Materials Research
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    • v.18 no.4
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    • pp.218-221
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    • 2008
  • A $Fe(OH)_2$ suspension was prepared by mixing iron sulfate and a weak alkali ammonia solution. Following this, iron oxides were synthesized by passing pure oxygen through the suspension (oxidation). The effects of different reaction temperatures ($30^{\circ}C$, $50^{\circ}C$, $70^{\circ}C$) and equivalent ratios ($0.1{\sim}10.0$) on the formation of iron oxides were investigated. An equilibrium phase diagram was established by quantitative phase analysis of the iron oxides using the Rietveld method. The equilibrium phase diagram showed a large difference from the equilibrium phase diagram of Kiyama when the equivalent ratio was above 1, and single $Fe_3O_4$ phase only formed above an equivalent ratio 2 at all reaction temperatures. Kiyama synthesized iron oxide using iron sulfate and a strong alkali NaOH solution.