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首页> 外文期刊>Geochimica et Cosmochimica Acta: Journal of the Geochemical Society and the Meteoritical Society >Mechanisms of Mn(II) catalytic oxidation on ferrihydrite surfaces and the formation of manganese (oxyhydr)oxides
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Mechanisms of Mn(II) catalytic oxidation on ferrihydrite surfaces and the formation of manganese (oxyhydr)oxides

机译:Mn(II)催化氧化对Ferrihydrite表面的机制及锰(氧水)氧化物的形成

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摘要

Oxidation of Mn(II) is an important process that controls the mobility and bioavailability of Mn, as well as the formation of Mn (oxyhydr) oxides in natural systems. It was found that the surfaces of minerals, such as iron (oxyhydr) oxides, can accelerate Mn(II) oxidation to a certain degree, but the underlying mechanism has not been clearly understood. This study explores the reaction pathways and mechanisms of Mn(II) oxidation on ferrihydrite surfaces at neutral pH, commonly found in natural environments, by comparisons with montmorillonite, amorphous Al(OH)(3), goethite, and magnetite using macroscopic experiments and spectroscopic analyses. Results show that when Mn(II) concentrations are below 4 mM, macroscopic Mn (II) adsorption on the three iron (oxyhydr) oxide surfaces conforms well to the Langmuir equation, with ferrihydrite showing the highest adsorption capacity. With Mn(II) concentrations ranging within 6-24 mM, the adsorbed Mn(II) is mainly oxidized into manganite (c-MnOOH) and/or feitknechtite (b-MnOOH) by dissolved O-2, and Mn(II) removal on a unit mass basis in the presence of magnetite is the highest compared with ferrihydrite and goethite. Ferrihydrite, a semiconductor material, shows stronger catalytic ability for Mn(II) oxidation on the same surface area than insulator minerals (i. e., montmorillonite and amorphous Al(OH)(3)). Additionally, the products of Mn(II) oxidation in the presence of semiconductor iron (oxyhydr) oxides (i. e., ferrihydrite, goethite, or magnetite) at the same Fe/Mn molar ratio include both manganite and a small amount of Mn(IV) minerals, and the Mn average oxidation states (Mn AOSs) of these products follow the order: magnetite > goethite > ferrihydrite. Magnetite and goethite, with relatively smaller SSAs and lower band gap energies, exhibit greater catalysis for Mn(II) oxidation than ferrihydrite at the same Fe/Mn ratio, which goes against the conventional interfacial effect and is related to the electrochemical propert
机译:Mn(II)的氧化是控制Mn的迁移率和生物利用度的重要过程,以及在天然系统中形成Mn(氧水)氧化物的形成。发现矿物质的表面,例如铁(氧水)氧化物,可以加速Mn(II)氧化在一定程度上,但潜在的机制尚未清楚地理解。本研究探讨了Mn(II)氧化在中性pH下的Mn(ii)氧化的反应途径和机制,其在天然环境中常见,通过使用宏观实验和光谱法与蒙脱石,无定形Al(OH)(3),甲酸酯和磁铁矿进行比较分析。结果表明,当Mn(II)浓度低于4mm时,三根铁(氧水)氧化物表面上的宏观Mn(II)吸附良好,与朗米尔方程吻合,其具有最高的吸附能力。使用Mn(II)浓度范围在6-24mm内,吸附的Mn(II)主要通过溶解的O-2氧化成锰铁(C-Mnooh)和/或Feitknechtite(B-Mnooh),以及除去Mn(II)在磁铁矿存在下的单位质量基础上是与Ferrihydite和Geethite相比的最高。半导体材料,半导体材料,在相同的表面积上显示出较强的Mn(II)氧化的催化能力,而不是绝缘体矿物(即,即蒙脱石和无定形Al(OH)(3))。另外,在相同的Fe / Mn摩尔比的半导体铁(InOrhydr)氧化物(即,Ferrihydrite,甲酸酯或磁铁矿)存在下Mn(II)氧化的产物包括锰铁和少量Mn(IV)这些产品的矿物质和Mn平均氧化态(Mn AOSS)遵循命令:磁铁矿>碎片> Ferrihydrite。具有相对较小的SSA和较低带隙能量的磁铁矿和粘合淀丝,与FERRIHYDITE相同的FE / MN比率表现出更高的Mn(II)氧化的催化,这与传统的界面效应相比,与电化学性能有关

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  • 作者单位

    Huazhong Agr Univ Coll Resources &

    Environm Minist Agr Key Lab Arable Land Conservat Middle &

    Lower Reac Wuhan 430070 Peoples R China;

    Huazhong Agr Univ Coll Resources &

    Environm Minist Agr Key Lab Arable Land Conservat Middle &

    Lower Reac Wuhan 430070 Peoples R China;

    Huazhong Agr Univ Coll Resources &

    Environm Minist Agr Key Lab Arable Land Conservat Middle &

    Lower Reac Wuhan 430070 Peoples R China;

    Huazhong Agr Univ Coll Resources &

    Environm Minist Agr Key Lab Arable Land Conservat Middle &

    Lower Reac Wuhan 430070 Peoples R China;

    Huazhong Agr Univ Coll Resources &

    Environm Minist Agr Key Lab Arable Land Conservat Middle &

    Lower Reac Wuhan 430070 Peoples R China;

    Huazhong Agr Univ Coll Resources &

    Environm Minist Agr Key Lab Arable Land Conservat Middle &

    Lower Reac Wuhan 430070 Peoples R China;

    Huazhong Agr Univ Coll Resources &

    Environm Minist Agr Key Lab Arable Land Conservat Middle &

    Lower Reac Wuhan 430070 Peoples R China;

    Chinese Acad Sci Inst High Energy Phys Beijing Synchrotron Radiat Facil Beijing 100039 Peoples R China;

    Huazhong Agr Univ Coll Resources &

    Environm Minist Agr Key Lab Arable Land Conservat Middle &

    Lower Reac Wuhan 430070 Peoples R China;

  • 收录信息
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 地球化学;天体化学;
  • 关键词

    Mn(II) oxidation; Ferrihydrite; Iron oxides; Manganese oxides; Interfacial catalysis; Electrochemical electron transfer;

    机译:Mn(ii)氧化;Ferrihydrite;氧化铁;锰氧化物;界面催化;电化学电子转移;

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