• Title/Summary/Keyword: Fe-P

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The Relationship Between pH and the Activity of Ferrous Iron In the Reduced Soil Under Water-logging (담수조건(湛水條件)에서 환원(還元)된 토양용액(土壤溶液)중 pH와 Fe++ 이온의 활동도(活動度)와의 관계(關係))

  • Hong, Chong-Woon
    • Korean Journal of Soil Science and Fertilizer
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    • v.26 no.4
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    • pp.294-298
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    • 1993
  • The relationship between pH and the activity of ferrous iron in the reduced soil under water-logging was investigated theoretically and experimentally. The results of this study revealed, contrary to hitherto assumed, that the $pH-Fe^{+{+}}$ relationship in the commonly occurring rice soils under reduced condition is close to that in $FeCO_3-CO_2-H_2O$ system, being remote from that in $Fe_3(OH)_8-H_2O$ system and $Fe(OH)_2-H_2O$ system. This indicates that the activity of ferrous iron in the reduced rice soils under water-logging is likely to be governed by $FeCO_3$, neither by $Fe_3(OH)_8$, nor by $Fe(OH)_2$.

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Mechanistic Study of FeS Reacted with Arsenate under Various pH Conditions (FeS 수용액 내 pH에 따른 5가비소의 반응 메커니즘 연구)

  • Han, Young-Soo;Lee, Mu Yeol;Seong, Hye Jin
    • Journal of Soil and Groundwater Environment
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    • v.27 no.1
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    • pp.25-30
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    • 2022
  • Mackinawite (FeS), as a ubiquitous reduced iron mineral, is known as a key controller of redox reactions in anaerobic subsurface environment. The reaction of FeS with redox-sensitive toxic element such as arsenic is substantially affected by pH conditions of the given environments. In this study, the interaction of As(V) with FeS was studied under strict anaerobic conditions with various pH conditions. The pH-dependent arsenic removal tests were conducted under wide ranges of pH conditions and X-ray absorption spectroscopy (XAS) was applied to investigate the reaction mechanisms under pH 5, 7, and 9. The removal efficiency of FeS for As(V) showed the higher removal of As(V) under low pH conditions and its removal efficiency decreased with increasing pH, and no As(V) reduction was observed in 1 g/L FeS solution. However, XAS analysis indicated the reduction of As(V) to As(III) occurred during reaction between FeS and As(V). The reduced form of As(III) was particularly identified as an arsenic sulfide mineral (As2S3) in all pH conditions (pH 5, 7, and 9). As2S3 precipitation was more pronounced in pH 5 where the solubility of FeS is higher than in other pH conditions. The linear combination fitting results of XAS demonstrated that As(V) removal mechanism is concerted processes of As2S3 precipitation and surface complexation of both arsenic species.

Optimum Conditions for Removal of Hydrogen Sulfide Using Fe-EDTA Complex (Fe-EDTA 착물을 이용한 황화수소 제거의 최적 반응 조건)

  • Jin, Sang-Gi;Cha, Jin-Myeong;Lee, In-Wha;Yoon, Suk-Jin;Kim, Si-Wouk
    • Applied Chemistry for Engineering
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    • v.7 no.1
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    • pp.177-185
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    • 1996
  • The optimum conditions for the removal of hydrogen sulfide by Fe-EDTA complex in the bubble column reactor were investigated. As the concentrations of the complex increased, the conversion rate of hydrogen sulfide increased, while Fe concentration and pH were stably decreased and the amount of elemental sulfur produced was also increased. Hydrogen sulfide was removed efficiently when the concentration of Fe-EDTA complex was maintained more than 0.05M. pH acts as an important factor for the stability of complex in the oxidation of hydrogen sulfide and optimum pH range was 8.5~9.5. As the molar ratio of EDTA : Fe was increased, the conversion rate of hydrogen sulfide became stable. However, the rate was decreased due to the precipitation of FeS when the concentration of EDTA was decreased. As the concentration of EDTA increased, the conversion rate of hydrogen sulfide increased due to the high stability of Fe-EDTA complex.

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The Effects of Si or Sn on the Sintered Properties of Fe-(Mo,Mn)-P Lean alloy (Fe-(Mo,Mn)-P계 Lean alloy의 소결특성에 미치는 Si와 Sn의 영향)

  • Jung, Woo-Young;Ok, Jin-Uk;Park, Dong-Kyu;Ahn, In-Shup
    • Journal of Powder Materials
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    • v.25 no.4
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    • pp.302-308
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    • 2018
  • A lean alloy is defined as a low alloy steel that minimizes the content of the alloying elements, while maintaining the characteristics of the sintered alloy. The purpose of this study is to determine the change in microstructure and mechanical properties due to the addition of silicon or tin in Fe-Mo-P, Fe-Mn-P, and Fe-Mo-Mn-P alloys. Silicon- or tin-added F-Mo-P, Fe-Mn-P, and Fe-Mo-Mn-P master alloys were compacted at 700 MPa and subsequently sintered under a $H_2-N_2$ atmosphere at $1120^{\circ}C$. The sintered density of three alloy systems decreases under the same compacting pressure due to dimensional expansion with increasing Si content. As the diffusion rate in the Fe-P-Mo system is higher than that in the Fe-P-Mn system, the decrease in the sintered density is the largest in the Fe-P-Mn system. The sintered density of Sn added alloys does not change with the increasing Sn content due to the effect of non-dimensional changes. However, the effect of Si addition on the transverse rupture strengthening enhancement is stronger than that of Sn addition in these lean alloys.

Synthesis of MnFeP1-xAsx Nanocrystalline Powders by High-Energy Ball Milling (고에너지볼밀링을 이용한 MnFeP1-xAsx 나노분말의 합성)

  • 조영환
    • Journal of Powder Materials
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    • v.10 no.2
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    • pp.129-135
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    • 2003
  • Nanocrystalline powders of $MnFeP_{1-x}As_x$(x=0.45-0.6) have been synthesized by mechanochemical reaction at room temperature using high-energy ball milling from mixtures of Mn, Fe, P, and As Powders. It has been found that a mechanically induced self-propagating reaction (MSR) occurs within 2 hours of milling and it produces very fine polycrystalline powder having a hexagonal $Fe_2P$ structure. Further milling up to 24 hours did not change the crystalline and average particle sizes or the phase composition of the milling product. When x is 0.65, no reaction among the reactants has been observed even after 24 hours of milling. As the P content decreases in $MnFeP_{1-x}As_x$, the incubation time for the MSR has increased and the lattice constants in both a and c axes have changed.

Preparation and Maghemite Using Waste Pickling Acid (산세폐액을 이용한 Maghemite의 제조)

  • 변태봉;이재영;김대영;손진군;권순주
    • Journal of the Korean Ceramic Society
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    • v.28 no.12
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    • pp.996-1004
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    • 1991
  • In this study, we tried to synthesis iron hydroxide suitable for longitudinal magnetic recording media from waste acid, which is a by-product of an iron works factory. Effects of initial pH of reactants, reaction temperature, reaction time for the synthesis of acicular iron hydroxide were studied in relation to particle properties of iron hydroxide and magnetic properties of maghemite powders. As the pH in reactant solution increased, $\beta$-FeOOH(pH=4.5), mixture of $\beta$-FeOOH and $\alpha$-FeOOH(4.5$\alpha$-FeOOH and Fe3O4(6.4$\alpha$-FeOOH (pH>13) was found to from in order. Especially, $\alpha$-FeOOH formed above pH 13 was single phase with superior acicularity. The temperature range over which the single-phase goethite can be formed increased as the initial pH of reactants increased (pH 13:10~5$0^{\circ}C$, pH 13.2:10~7$0^{\circ}C$, pH 13.5:0~8$0^{\circ}C$). The goethite formed between 40~6$0^{\circ}C$ has superior characteristics because the acicularity increased with increasing temperature but at high temperature (>6$0^{\circ}C$) Fe3O4 (pH=13) was found to start to form. Generally, single phase of goethite was found to form after one hour when an optimized condition. The particle size of goethite did not change as the reaction time increased over one hour. Accordingly, the magnetic properties of ${\gamma}$-Fe2O3 produced from goethite were not altered.

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Poly(D-glutamic acid)-Fe(II) Complex Formation and Its Stability Constant (Poly(D-glutamic acid)-Fe(II) 복합물의 형성과 안정도 상수에 관하여)

  • Chong-Su Cho;Seon-Ung Kim
    • Journal of the Korean Chemical Society
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    • v.31 no.5
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    • pp.471-475
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    • 1987
  • Fe(II)-poly(D-glutamic acid) (PGA) complex in aqueous solution has been investigated as functions of pH and concentration of Fe(II) by using absorption and circular dichroism spectroscopies. The helix-breaking interaction occurred at pH 4.3 while the helix-directing one occurred at pH 5.7 after forming complex between PGA and Fe(II). The relationship between conformation change of PGA by forming complex with Fe(II) and complex constants for the above system was studied. As a result, stability constants in random coil structure of PGA are larger than those in ${\alpha}$-helix structure. This result indicates that the random coil structure of PGA-Fe(II) complex shows more stable complex than ${\alpha}$-helix one.

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pH Dependence on the Degradation of Rhodamine B by Fe-ACF/$TiO_2$ Composites and Effect of Different Fe Precursors (Fe-ACF/$TiO_2$ 복합체에 의한 로다민 B 용액의 분해에 있어서 pH 의존성 및 여러 가지 Fe 전구체의 효과)

  • Zhang, Kan;Oh, Won-Chun
    • Elastomers and Composites
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    • v.44 no.4
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    • pp.408-415
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    • 2009
  • Iron-loaded activated carbon fibers (Fe-ACF) supported titanium dioxide ($TiO_2$) photocatalyst (Fe-ACF/$TiO_2$) was synthesized using a sol-gel method. Three different types of Fe-ACF/$TiO_2$ were obtained by treatment with different precursor of Fe, and characterized using BET, SEM, XRD and EDX analysis. The photocatalytic activity of Fe-ACF/$TiO_2$ was investigated by the degradation of Rhodamine B (Rh.B) solution under UV irradiation. From the experimental results, it was revealed that Fe-ACF/$TiO_2$ composites show considerable photocatalytic ability for the removal of Rh.B by comparing non-treated ACF/$TiO_2$ composites. And photo-Fenton reaction with Fe element was incoordinately influenced due to different precursor of Fe. It clearly indicates that Fe-ACF/$TiO_2$ composites prepared using $FeCl_3$ provided the highest photo-Fenton activity, then, which was affected by pH changes on the degradation of Rh.B.

Evaluation of the Stability of Fe(III)-Impregnated Activated Carbon and Copper Adsorption (3가철 첨착 활성탄의 안정성 및 구리 흡착특성 평가)

  • Yu, Mok-Ryun;Yang, Jae-Kyu;Lee, Seung-Mok;Kim, Keun-Han
    • Journal of Korean Society on Water Environment
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    • v.22 no.2
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    • pp.328-332
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    • 2006
  • Fe(III)-impregnated activated carbon (Fe-AC) was applied in the treatment of synthetic wastewater containing Cu(II). To investigate the stability of Fe-AC at acidic condition, dissolution of Fe was studied with a variation of solution pH ranging from 2 to 4. Fe-AC was unstable at pH 2, showing a gradual increase of the dissoluted Fe as reaction time increased, while negligible amount of Fe was dissoluted above pH 3. This stability test suggests the applicability of Fe-AC in the treatment of wastewater above pH 3. Adsorption capacity of Cu(II) onto activated carbon (AC) and Fe-AC was investigated in a batch and a column test. In the adsorption kinetics, rapid adsorption of Cu(II) onto AC and Fe-AC was noted at initial reaction time and then reached a near complete equilibrium after 6 hrs. Adsorption trends of Cu(II) onto AC and Fe-AC were similar, showing an increased Cu(II) adsorption at higher pH. Compared with AC, Fe-AC showed a greater Cu(II) adsorption over the entire pH range studied in this research. From the adsorption isotherm obtained with variation of the concentration of Cu(II), the maximum adsorption capacity was identified as 61,700 mg/kg.

Dielectric Properties of P(VDF/TrFE) Thin Films Prepared by Vapor Deposition Method (진공증착법으로 제조된 P(VDF/TrFE) 박막의 유전특성)

  • Jeong, Mu-Yeong;Yun, Jong-Hyeon;Lee, Seon-U;Park, Su-Hong;Yu, Do-Hyeon;Lee, Deok-Chul
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.50 no.1
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    • pp.1-5
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    • 2001
  • P(VDF/TrFE) copolymer thin films with 70/30 and 80/20 mol% VDF (polyvinylidene fluoride) and TrFE (trifluoroethylene) rates were prepared by using a vapor deposition method, During thin films were prepared, the substrate temperatures were maintained at 30 $^{\circ}C$ and 120 $^{\circ}C$, and the heating source temperature was fixed at 350 $^{\circ}C$. Contary to PVDF homopolymer, P(VDF/TrFE) copolymers showed the Curie point(Tc) below the melting point. The Curie point (Tc) and the melting point of the P(VDF/TrFE) copolymers were changed as a function of substrate temperature and the VDF mol%. The Curie point and the melting point of P(VDF/TreFE) thin films decreased and increased with increasing substrate temperature, respectively. Also with increasing VDF mol%, the melting point decreased slightly, however the Curie point increased.

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