scholarly journals Sequestration and Oxidation of Cr(III) by Fungal Mn Oxides with Mn(II) Oxidizing Activity

Catalysts ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 44 ◽  
Author(s):  
Ryohei Suzuki ◽  
Yukinori Tani ◽  
Hirotaka Naitou ◽  
Naoyuki Miyata ◽  
Kazuya Tanaka
Keyword(s):  
Manganese Oxides ◽  
Surface Passivation ◽  
Early Stage ◽  
Contaminated Sites ◽  
Repeated Treatment ◽  
Environmental Application ◽  
Acremonium Strictum ◽  
Rapid Production ◽  
Significant Release ◽  
Mn Oxides

Biogenic manganese oxides (BMOs) have gained increasing attention for environmental application because of their sequestration and oxidizing abilities for various elements. Oxidation and sequestration of Cr(III) by BMOs, however, still remain unknown. We prepared BMOs in liquid cultures of Acremonium strictum strain KR21-2, and subsequently conducted single or repeated treatment experiments in Cr(NO3)3 at pH 6.0. Under aerobic conditions, newly formed BMOs exhibited a rapid production of Cr(VI) without a significant release of Mn(II), demonstrating that newly formed BMO mediates a catalytic oxidation of Cr(III) with a self-regeneration step of reduced Mn. In anaerobic solution, newly formed BMOs showed a cessation of Cr(III) oxidation in the early stage of the reaction, and subsequently had a much smaller Cr(VI) production with significant release of reduced Mn(II). Extraordinary sequestration of Cr(III) was observed during the repeated treatments under anaerobic conditions. Anaerobically sequestered Cr(III) was readily converted to Cr(VI) when the conditions became aerobic, which suggests that the surface passivation is responsible for the anaerobic cessation of Cr(III) oxidation. The results presented herein increase our understanding of the roles of BMO in Cr(III) oxidation and sequestration processes in potential application of BMOs towards the remediation of Cr(III)/Cr(VI) in contaminated sites.

Chromium(iii) oxidation by biogenic manganese oxides with varying structural ripening

2014 ◽  
Vol 16 (9) ◽  
pp. 2127-2136 ◽  
Author(s):  
Yuanzhi Tang ◽  
Samuel M. Webb ◽  
Emily R. Estes ◽  
Colleen M. Hansel
Keyword(s):  
Environmental Conditions ◽  
Manganese Oxides ◽  
Natural Systems ◽  
Mn Oxides

Manganese (Mn) oxides, which are generally considered biogenic in origin within natural systems, are the only oxidants of Cr(iii) under typical environmental conditions.

scholarly journals A Date Palm Disease (Bunch Blight) Caused by Acremonium strictum (Cephalosporium) in Saudi Arabia

2018 ◽  
Vol 7 (1) ◽  
pp. 01-06
Author(s):  
Mohammad F. Rashed
Keyword(s):  
Saudi Arabia ◽  
Dna Sequence ◽  
Date Palm ◽  
Early Stage ◽  
Causal Agent ◽  
Acremonium Strictum ◽  
Pathogenicity Tests

Acrimonium strictum is reported as a new causal agent of a disease it names (bunch blight) in date palm (phoenix dactylefera) in Saudi Arabia. Symptoms and necrosis caused by A. strictum in susceptible cultivars showed small brown necrosis streak at midrib of fruit stalk in an early stage. There was an increase in number and size as the disease progresses; then extended to the bases of fruit strands due to death of bases and strands wilt, the infection of fruit strand caused drying the fruits and their fall. A. strictum attacks the bunches and move quickly inside and out the tissues causing brown necrosis and death of the tissues. A. strictum was isolated and pathogenicity tests were repeated more than once during two seasons and the identifications was caried several ways to confirm The confirmation of results by Biolog technique and DNA sequence were done. The proper temperature for infection was between 20-30 °C and the optimum 25 °C. When testing the susceptibility of varieties of infection, more varieties like Medjool, Saqae and Kholas were susceptible to infection and the most resistant to infection were Barhy and Khidri. The best results in the control of the fungus in vitro were due to use of Karpendazem followed Topsen M70, at the same time, the worst results were seen with the use of Abredion followed Karant (Cupper hydroxide).

Li/Fe substitution in Li-rich Ni, Co, Mn oxides for enhanced electrochemical performance as cathode materials

2019 ◽  
Vol 7 (25) ◽  
pp. 15215-15224 ◽  
Author(s):  
Juliette Billaud ◽  
Denis Sheptyakov ◽  
Sébastien Sallard ◽  
Daniela Leanza ◽  
Michael Talianker ◽  
...  
Keyword(s):  
Electrochemical Performance ◽  
Manganese Oxides ◽  
Rate Capability ◽  
Potential Drop ◽  
Specific Charge ◽  
Nickel Cobalt ◽  
Charge Potential ◽  
Enhanced Electrochemical Performance ◽  
Fe Substitution ◽  
Mn Oxides

The addition of Fe in Li-rich nickel cobalt manganese oxides allows for higher specific charge, potential drop mitigation and enhanced rate capability.

scholarly journals Insights into the structure–property–activity relationship in molybdenum-doped octahedral molecular sieve manganese oxides for catalytic oxidation

2018 ◽  
Vol 8 (24) ◽  
pp. 6493-6502 ◽  
Author(s):  
Homer C. Genuino ◽  
Diego Valencia ◽  
Steven L. Suib
Keyword(s):  
Co Oxidation ◽  
Catalytic Oxidation ◽  
Molecular Sieve ◽  
Manganese Oxides ◽  
Activity Relationship ◽  
Computational Studies ◽  
Structure Property ◽  
Catalytic Activities ◽  
Mn Oxides

Experimental and computational studies on the properties of Mo-substituted octahedral molecular sieve Mn oxides provide insights into their excellent catalytic activities and stability for CO oxidation.

Influence of Inhibition Layer on Adhesion of a Galvanized High Al Dual Phase Steel

2011 ◽  
Vol 295-297 ◽  
pp. 1669-1674
Author(s):  
Zhao Jun Deng ◽  
Jing Liu ◽  
Zhi Hong Lu ◽  
Hui Wang ◽  
Cheng Jiang Lin
Keyword(s):  
Electron Microscopy ◽  
Manganese Oxides ◽  
Dual Phase Steel ◽  
Steel Substrate ◽  
Dual Phase ◽  
Inhibition Layer ◽  
Good Adhesion ◽  
Transmission Electron ◽  
Mn Oxides ◽  
Scanning Electron

The morphology of inhibition layer and adhesion of Zn coating about a 600MPa grade high Al dual phase steel were studied by grow discharge spectrometry (GDS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that the inhibition layer is mainly composed of Fe2Al5-xZnx particles with a size of 0.5~1μm, and the adhesion is directly related to the density of the inhibition layer, the denser the inhibition layer, the better the adhesion. It is found: for the samples with good adhesion that besides the Fe2Al5-xZnx particles, there are also some small spherical Al-Mn oxides particles in sizes from 30 to 100nm uniformly distributed in the inhibition layer; for the samples with bad adhesion, the steel substrate is not fully covered by Fe2Al5-xZnx particles and large amount manganese oxides are detected at the non-covered positions.

scholarly journals Electrochemical characterization of manganese oxides as a water oxidation catalyst in proton exchange membrane electrolysers

2019 ◽  
Vol 6 (5) ◽  
pp. 190122 ◽  
Author(s):  
Toru Hayashi ◽  
Nadège Bonnet-Mercier ◽  
Akira Yamaguchi ◽  
Kazumasa Suetsugu ◽  
Ryuhei Nakamura
Keyword(s):  
Water Oxidation ◽  
Manganese Oxides ◽  
Proton Exchange Membrane ◽  
Water Electrolysis ◽  
Electrode System ◽  
Proton Exchange ◽  
Oxidation Catalyst ◽  
Carbon Supports ◽  
Exchange Membrane ◽  
Mn Oxides

The performance of four polymorphs of manganese (Mn) dioxides as the catalyst for the oxygen evolution reaction (OER) in proton exchange membrane (PEM) electrolysers was examined. The comparison of the activity between Mn oxides/carbon (Mn/C), iridium oxide/carbon (Ir/C) and platinum/carbon (Pt/C) under the same condition in PEM electrolysers showed that the γ-MnO 2 /C exhibited a voltage efficiency for water electrolysis comparable to the case with Pt/C, while lower than the case with the benchmark Ir/C OER catalyst. The rapid decrease in the voltage efficiency was observed for a PEM electrolyser with the Mn/C, as indicated by the voltage shift from 1.7 to 1.9 V under the galvanostatic condition. The rapid deactivation was also observed when Pt/C was used, indicating that the instability of PEM electrolysis with Mn/C is probably due to the oxidative decomposition of carbon supports. The OER activity of the four types of Mn oxides was also evaluated at acidic pH in a three-electrode system. It was found that the OER activity trends of the Mn oxides evaluated in an acidic aqueous electrolyte were distinct from those in PEM electrolysers, demonstrating the importance of the evaluation of OER catalysts in a real device condition for future development of noble-metal-free PEM electrolysers.

Microstructural Characterization of Oxide Scale Formed by Early Stage of Oxidation of 17%Cr-Mn-Ni Austenitic Stainless Steel

2007 ◽  
Vol 561-565 ◽  
pp. 99-102
Author(s):  
Takayuki Oshima ◽  
Yutaka Yamaguchi ◽  
Kotaro Kuroda
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Oxide Scale ◽  
Spinel Structure ◽  
Early Stage ◽  
Microstructural Characterization ◽  
The Third ◽  
Cold Rolled ◽  
Mn Oxides

The microstructure of oxide scale formed in the early stage of oxidation of cold-rolled sheets of 17%Cr-Mn-Ni austenitic stainless steel was examined using SEM and TEM. Samples were oxidized at 973 to1373K for 1 to 15min. Nodules were observed on the surfaces of specimens oxidized at 1173K. The nodules were composed of two layers, which comprised Fe oxides and Cr-rich Fe-Cr-Mn oxides, respectively. The other scale was composed of two layers of Fe-Cr-Mn oxides with different compositions. Nodules were not observed on the surfaces of the specimens oxidized at 973 and 1373K. After oxidation at 1373K for 1min, the scale was composed of three layers. The first layer consisted of Fe-Mn oxides with a spinel structure, the second consisted mainly of Cr oxides, and the third consisted of Cr-Mn oxides containing a small amount of Fe.

scholarly journals Exceptional Tl-bearing manganese oxides from Zalas, Krakow area, southern Poland

Mineralogia ◽  
2015 ◽  
Vol 46 (1-2) ◽  
pp. 3-17 ◽  
Author(s):  
Bożena Gołębiowska ◽  
Grzegorz Rzepa ◽  
Adam Pieczka
Keyword(s):  
Manganese Oxides ◽  
Early Paleozoic ◽  
Groundwater System ◽  
Southern Poland ◽  
Small Fault ◽  
Sandy Limestone ◽  
Polymetallic Mineralization ◽  
Native Bismuth ◽  
Mn Oxides ◽  
Fault Breccia

AbstractIn the Permian rhyodacite quarry at Zalas near Krakow, southern Poland, thallium-bearing Mn oxides occur in a small fault zone cutting Middle Jurassic sandy limestone poorly encrusted by an oxidized polymetallic mineralization. The encrustation comprises sulphides (pyrite, chalcopyrite, chalcocite, covellite, galena, marcasite), native bismuth, hematite, goethite, cuprite, mottramite, iodargyrite, unrecognized Cu sulphates and Bi oxychlorides as supergene minerals, barite and rare tiny grains of gold. It is most likely connected with rejuvenation of Early-Paleozoic faults during the Alpine orogeny on the Oligocene–Miocene boundary. Rare Tlbearing Mn oxides occur in an outside zone of the encrustations, filling small fractures and voids in limestone forming the fault breccia. Tl contents, reaching 20.82wt% as Tl2O, exceed by more than two orders of magnitude those reported in similar minerals before, making the oxides unique on a world scale. The Tl-bearing Mn oxides from Zalas reflect intensive weathering of an older Tl-bearing sulphide mineralization in an arid climate, involving saline fluids delivered to the groundwater system as the nappe structure of the Carpathians was developing during the Sava tectonic phase Oligocene/Miocene boundary.

scholarly journals Preferential Elimination of Ba2+ through Irreversible Biogenic Manganese Oxide Sequestration

Minerals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 53
Author(s):  
Yukinori Tani ◽  
Satomi Kakinuma ◽  
Jianing Chang ◽  
Kazuya Tanaka ◽  
Naoyuki Miyata
Keyword(s):  
Manganese Oxides ◽  
Toxic Elements ◽  
X Ray Diffraction ◽  
Oxidation Activity ◽  
Acremonium Strictum ◽  
X Ray ◽  
Mn Oxide ◽  
Sequestration Potential ◽  
Oxide Phases ◽  
X Ray Absorption

Biogenic manganese oxides (BMOs) formed in a culture of the Mn(II)-oxidizing fungus Acremonium strictum strain KR21-2 are known to retain enzymatic Mn(II) oxidation activity. Consequently, these are increasingly attracting attention as a substrate for eliminating toxic elements from contaminated wastewaters. In this study, we examined the Ba2+ sequestration potential of enzymatically active BMOs with and without exogenous Mn2+. The BMOs readily oxidized exogenous Mn2+ to produce another BMO phase, and subsequently sequestered Ba2+ at a pH of 7.0, with irreversible Ba2+ sequestration as the dominant pathway. Extended X-ray absorption fine structure spectroscopy and X-ray diffraction analyses demonstrated alteration from turbostratic to tightly stacked birnessite through possible Ba2+ incorporation into the interlayer. The irreversible sequestration of Sr2+, Ca2+, and Mg2+ was insignificant, and the turbostratic birnessite structure was preserved. Results from competitive sequestration experiments revealed that the BMOs favored Ba2+ over Sr2+, Ca2+, and Mg2+. These results explain the preferential accumulation of Ba2+ in natural Mn oxide phases produced by microbes under circumneutral environmental conditions. These findings highlight the potential for applying enzymatically active BMOs for eliminating Ba2+ from contaminated wastewaters.

scholarly journals Light-driven formation of manganese oxide by today’s photosystem II supports evolutionarily ancient manganese-oxidizing photosynthesis

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Petko Chernev ◽  
Sophie Fischer ◽  
Jutta Hoffmann ◽  
Nicholas Oliver ◽  
Ricardo Assunção ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Manganese Oxide ◽  
Water Oxidation ◽  
Manganese Oxides ◽  
Early Stage ◽  
Oxygenic Photosynthesis ◽  
Oxide Nanoparticles ◽  
Manganese Ions ◽  
Oxide Particles ◽  
Photosynthetic Water Oxidation

AbstractWater oxidation and concomitant dioxygen formation by the manganese-calcium cluster of oxygenic photosynthesis has shaped the biosphere, atmosphere, and geosphere. It has been hypothesized that at an early stage of evolution, before photosynthetic water oxidation became prominent, light-driven formation of manganese oxides from dissolved Mn(2+) ions may have played a key role in bioenergetics and possibly facilitated early geological manganese deposits. Here we report the biochemical evidence for the ability of photosystems to form extended manganese oxide particles. The photochemical redox processes in spinach photosystem-II particles devoid of the manganese-calcium cluster are tracked by visible-light and X-ray spectroscopy. Oxidation of dissolved manganese ions results in high-valent Mn(III,IV)-oxide nanoparticles of the birnessite type bound to photosystem II, with 50-100 manganese ions per photosystem. Having shown that even today’s photosystem II can form birnessite-type oxide particles efficiently, we propose an evolutionary scenario, which involves manganese-oxide production by ancestral photosystems, later followed by down-sizing of protein-bound manganese-oxide nanoparticles to finally yield today’s catalyst of photosynthetic water oxidation.

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