scholarly journals Characteristics of Fe Reduction Process of Shallow Groundwater in a Reclaimed Area, Kim-je

2013 ◽  
Vol 46 (1) ◽  
pp. 39-50 ◽  
Author(s):  
Ji-Hoon Kim ◽  
Tae-Jin Cheong ◽  
Jong-Sik Ryu ◽  
Rak-Hyeon Kim
Keyword(s):  
Shallow Groundwater ◽  
Reduction Process ◽  
Fe Reduction

SiO2/MgO Ratio Effect on Carbothermic Reaction of Synthetic Nickelliferrous Mixtures

2015 ◽  
Vol 1112 ◽  
pp. 542-545
Author(s):  
Sri Harjanto ◽  
Reza M. Ulum
Keyword(s):  
Nickel Oxide ◽  
Carbothermic Reduction ◽  
Reduction Process ◽  
Nickel Laterite ◽  
Synthetic Compounds ◽  
Similar Composition ◽  
Ratio Effect ◽  
Nickel Recovery ◽  
Reduction Processes ◽  
Fe Reduction

The objective of this study is to understand the effect of SiO2/MgO ratio on the reducibility of Fe and Ni in the synthetic nickel laterite mixtures of similar composition to Indonesia saprolitic nickel ore. The samples were made with addition (in wt% basis ) of 12% cokes, 2 % NiO, and varied SiO2of 0 %, 10 %, 20%, 30%, and 40 % . Two types of samples were made, with and withou 14% MgO addition. Fe2O3was added to both types of samples as balance. The synthetic compounds were mixed homogenously and compacted, before subjected to carbothermic reduction process at temperature of 1250 °C for 120 minutes. The results showed that Ni was strongly influenced by MgO content after reduction processes. Higher content of MgO was more unfavorable for nickel reduction, while a higher content of SiO2was unfavorable for Fe reduction. According to the characterization results of carbothermic product, nickel oxide had been reduced to form Fe-Ni phase. Nickel recovery tends to increase with increasing of SiO2addition on sample with MgO addition.

Stable iron isotope signals as indicators for iron reduction pathways in deep methanic sediments

2020 ◽  
Author(s):  
Susann Henkel ◽  
Bo Liu ◽  
Michael Staubwasser ◽  
Simone Kasemann ◽  
Anette Meixner ◽  
...  
Keyword(s):  
Pore Water ◽  
Marine Sediments ◽  
Iron Reduction ◽  
Reduction Process ◽  
Geochemical Data ◽  
Anaerobic Oxidation Of Methane ◽  
Iron Release ◽  
Microbial Utilization ◽  
Fe Reduction ◽  
Mud Area

<p>A number of studies have shown that iron reduction in marine sediments is not confined to sulfate- or sulfide-containing depths but may also affect deep methanic intervals. In particular dynamic depositional settings often show the release of dissolved iron below the sulphate-methane transition (SMT). The specific process behind this deep iron release is not well understood. It has been suggested that anaerobic oxidation of methane (AOM) mediated by Fe oxide reduction plays an important role. So there might be a close, so far unaccounted link between the Fe and C cycles in deep marine sediments.</p><p>Here we present a compilation of inorganic geochemical data including δ<sup>56</sup>Fe values of pore water and reactive Fe fractions for sediments of the Helgoland mud area (North Sea) for which a coupling between deep iron reduction and AOM has been proposed [1]. The sediments show a shallow SMT and increasing dissolved Fe concentrations of up to 400 µM further below. High sedimentation rates led to a fast burial and preservation of reactive Fe (oxyhydr)oxides, enabling deep iron reduction as we observe it today.</p><p>Isotopic fractionation of Fe has been demonstrated for DIR in culture experiments and in shallow marine sediments. Such studies build upon the principle that microbes preferentially utilize light Fe isotopes (<sup>54</sup>Fe) causing a fractionation between solid ferric and dissolved ferrous iron. For alternative biotic Fe reduction pathways in methanic environments, there are practically no data. We hypothesized that any microbially mediated iron reduction process would result in a similar preferential release of <sup>54</sup>Fe and, thus, shift pore water δ<sup>56</sup>Fe towards negative values. Furthermore we hypothesized that the microbial utilization of a specific Fe (oxyhydr)oxide pool would result in a relative enrichment of <sup>56</sup>Fe in the residual ferric substrate.</p><p>Close to the sediment-water interface pore water δ<sup>56</sup>Fe in the mud area is generally negative and shows a downward trend towards positive values as it can be expected for in-situ dissimilatory iron reduction (DIR) [2]. The Fe isotope signal close to the sulfidic interval is ~1‰ heavier than above and below as Fe sulfide precipitation preferentially removes <sup>54</sup>Fe from pore water. A pronounced downward shift of pore-water δ<sup>56</sup>Fe to more negative values within the methanic zone is a clear indication for microbial Fe reduction coupled to organic matter degradation. However, this shift does not coincide with the main interval of Fe release for which potential for Fe-AOM had been demonstrated [1]. In this deeper interval, the released Fe has an isotopic composition that matches that of the ferric substrates. We conclude that either 1) Fe-AOM plays a subordinate role for Fe release at depth or 2) does not go along with significant Fe isotope fractionation, which might be explained by different ways of electron transfer between microbe and the iron oxide compared to DIR.</p><p>[1] Aromokeye, D. et al., 2019. Frontiers in Microbiology, doi: 10.3389/fmicb.2019.03041.</p><p>[2] Henkel, S. et al., 2016. Chemical Geology 421: 93-102.</p>

Direct Reduction of Iron from Crystal Lattice of a Complex Oxide

2019 ◽  
Vol 946 ◽  
pp. 506-511
Author(s):  
S.P. Salikhov ◽  
A.V. Roshchin
Keyword(s):  
Iron Reduction ◽  
Direct Reduction ◽  
Reduction Process ◽  
Complex Oxide ◽  
High Rate ◽  
Deep Penetration ◽  
Experimental Conditions ◽  
Direct Reduction Of Iron ◽  
Fe Reduction ◽  
Iron Manganese

This work studied a decomposition and reduction of complex carbonate (sideroplesite) siderite lump ore from the Bakal’s deposit. The decomposition caused formation of complex oxides (Fe,Mg,Mn)O and (Fe,Mg,Mn)O·Fe2O3, and it preceded the Fe reduction; the weight loss during the decomposition process reached about 32%, being followed by the formation of a large number of pores. As the pores and micro-pores provide deep penetration of the carbon monoxide in the bulk of the ore lumps, it seemed that the pores would allow reduction of this ore without difficulties. However, during reduction experiments it was discovered that the distribution of the reduction process and formation of the metal phase were not connected with the pores’ distribution. The reduction process developed via an electrochemical mechanism, and the channels of the distribution of the reduction process were oxides of metals which were difficult to reduce under the presented experimental conditions; these oxides were mostly represented by the magnesia and silica compounds. The high rate of the iron reduction from the complex iron-manganese-magnesium oxides was explained by the high rate of distribution of the negatively charged anion vacancies forming on the surface of the oxide, due to reaction with a reducing agent.

scholarly journals Arsenic(V) Reduction in Relation to Iron(III) Transformation and Molecular Characterization of the Structural and Functional Microbial Community in Sediments of a Basin-Fill Aquifer in Northern Utah

2014 ◽  
Vol 80 (10) ◽  
pp. 3198-3208 ◽  
Author(s):  
Babur S. Mirza ◽  
Subathra Muruganandam ◽  
Xianyu Meng ◽  
Darwin L. Sorensen ◽  
R. Ryan Dupont ◽  
...  
Keyword(s):  
Microbial Community ◽  
Sediment Cores ◽  
Shallow Groundwater ◽  
Content Type ◽  
Redox Transition ◽  
Cache Valley ◽  
Northern Utah ◽  
And Function ◽  
Fe Reduction ◽  
Basin Fill

ABSTRACTBasin-fill aquifers of the Southwestern United States are associated with elevated concentrations of arsenic (As) in groundwater. Many private domestic wells in the Cache Valley Basin, UT, have As concentrations in excess of the U.S. EPA drinking water limit. Thirteen sediment cores were collected from the center of the valley at the depth of the shallow groundwater and were sectioned into layers based on redoxmorphic features. Three of the layers, two from redox transition zones and one from a depletion zone, were used to establish microcosms. Microcosms were treated with groundwater (GW) or groundwater plus glucose (GW+G) to investigate the extent of As reduction in relation to iron (Fe) transformation and characterize the microbial community structure and function by sequencing 16S rRNA and arsenate dissimilatory reductase (arrA) genes. Under the carbon-limited conditions of the GW treatment, As reduction was independent of Fe reduction, despite the abundance of sequences related toGeobacterandShewanella, genera that include a variety of dissimilatory iron-reducing bacteria. The addition of glucose, an electron donor and carbon source, caused substantial shifts toward domination of the bacterial community byClostridium-related organisms, and As reduction was correlated with Fe reduction for the sediments from the redox transition zone. ThearrAgene sequencing from microcosms at day 54 of incubation showed the presence of 14 unique phylotypes, none of which were related to any previously describedarrAgene sequence, suggesting a unique community of dissimilatory arsenate-respiring bacteria in the Cache Valley Basin.

Green synthesis of mixed metallic nanoparticles using room temperature self-assembly

2017 ◽  
Vol 13 (2) ◽  
pp. 4671-4677 ◽  
Author(s):  
A. M. Abdelghany ◽  
A.H. Oraby ◽  
Awatif A Hindi ◽  
Doaa M El-Nagar ◽  
Fathia S Alhakami
Keyword(s):  
Self Assembly ◽  
Metallic Nanoparticles ◽  
Room Temperature ◽  
Bimetallic Nanoparticles ◽  
Reduction Process ◽  
Nano Particles ◽  
Nano Structure ◽  
Small Shift ◽  
Molar Ratios ◽  
Vis Spectroscopy

Bimetallic nanoparticles of silver (Ag) and gold (Au) were synthesized at room temperature using Curcumin. Reduction process of silver and gold ions with different molar ratios leads to production of different nanostructures including alloys and core-shells. Produced nanoparticles were characterized simultaneously with FTIR, UV/vis. spectroscopy, transmission electron microscopy (TEM), and Energy-dispersive X-ray (EDAX). UV/vis. optical absorption spectra of as synthesized nanoparticles reveals presence of surface palsmon resonance (SPR) of both silver at (425 nm) and gold at (540 nm) with small shift and broadness of gold band after mixing with resucing and capping agent in natural extract which suggest presence of bimetallic nano structure (Au/Ag). FTIR and EDAX data approve the presence of bimetallic nano structure combined with curcumin extract. TEM micrographs shows that silver and gold can be synthesized separately in the form of nano particles using curcumin extract. Synthesis of gold nano particles in presence of silver effectively enhance and control formation of bi-metallic structure.

Scalable Synthesis of Functionalized Ferrocenyl Azides and Amines Enabled by Flow Chemistry

2019 ◽  
Author(s):  
Merlin Kleoff ◽  
Johannes Schwan ◽  
Lisa Boeser ◽  
Bence Hartmayer ◽  
Mathias Christmann ◽  
...  
Keyword(s):  
Reaction Time ◽  
Heterogeneous Reaction ◽  
Reduction Process ◽  
Flow Chemistry ◽  
Subsequent Reaction ◽  
Scalable Synthesis ◽  
High Yields ◽  
Reactor Section

A scalable access to functionalized 1,1’- and 1,2-ferrocenyl azides has been realized in flow. By halogen‒lithium exchange of ferrocenyl halides and subsequent reaction with tosyl azide, a variety of functionalized ferrocenyl azides was obtained in high yields. To allow a scalable preparation of these potentially explosive compounds, an efficient flow protocol was developed accelerating the reaction time to minutes and circumventing accumulation of potentially hazardous intermediates. Switching from homogeneous to triphasic flow amidst process was key for handling a heterogeneous reaction mixture formed after a heated reactor section. The corresponding and synthetically versatile ferrocenyl amines were then prepared by a reliable reduction process.

Green synthesis of iron nanoparticles using flower extract of Piliostigma thonningii and their antibacterial activity evaluation

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Antibacterial Activity ◽  
Environmental Remediation ◽  
Iron Nanoparticles ◽  
Reduction Process ◽  
Xrd Analysis ◽  
Visible Range ◽  
Magnetic Storage ◽  
Ferrous Chloride ◽  
Flower Extract ◽  
Piliostigma Thonningii

Iron nanoparticles have gained tremendous attention due to their application in magnetic storage media, ferrofluids, biosensors, catalysts, separation processes, environmental remediation and antibacterial activity. In the present paper, iron nanoparticles were synthesized using aqueous flower extract of Piliostigma thonningii, a natural nontoxic herbal infusion. Iron nanoparticles were generated by reaction of ferrous chloride solution with the flower extract. The reductants present in the flower extract acted as reducing and stabilizing agents. UV-vis analysis of the iron nanoparticles showed continuous absorption in the visible range suggesting the iron nanoparticles were amorphous. This was confirmed by X-ray diffraction (XRD) analysis which did not have distinct diffraction peaks. Scanning electron microscopy (SEM) analysis revealed that the synthesized iron nanoparticles were aggregated as irregular clusters with rough surfaces. FT-IR studies showed the functional groups that participated in the bio-reduction process to include a C-H stretch (due to alkane CH3, CH2 or CH), C=O stretch (due to aldehydes), O-H bend (due to tert-alcohol or phenol), C-O stretch (due to aldehydes or phenols) and C-O stretch (due to alcohols) corresponding to absorptions at 2929.00, 1721.53, 1405.19, 1266.31 and 1030.02 cm-1 respectively. The iron nanoparticles showed significant antibacterial activity against Escharichia coli and Staphylococcus aureus suggesting potential antibacterial application.

Sign in / Sign up

Export Citation Format

Share Document