نتایج جستجو برای: Todorokite

تعداد نتایج: 59  

2015
Huaiyan Zhao Xinran Liang Hui Yin Fan Liu Wenfeng Tan Guohong Qiu Xionghan Feng

BACKGROUND Todorokite, a 3 × 3 tectomanganate, is one of three main manganese oxide minerals in marine nodules and can be used as an active MnO6 octahedral molecular sieve. The formation of todorokite is closely associated with the poorly crystalline phyllomanganates in nature. However, the effect of the preparative parameters on the transformation of "c-disordered" H(+)-birnessites, analogue t...

Journal: :Science 1983
M D Siegel S Turner

Platy intergrowths of crystalline todorokite are associated with biogenic debris in the cores of manganese nodules from a site in the Pacific Ocean. Analyses by electron diffraction and transmission electron microscopy demonstrate that this material is composed of tunnels of chains of linked MnO(6) octahedra. The chemical composition, morphology, and stability of the todorokite differ from thos...

2008
Haojie Cui Xionghan Feng Wenfeng Tan Jizheng He Ronggui Hu Fan Liu

1387-1811/$ see front matter 2008 Elsevier Inc. A doi:10.1016/j.micromeso.2008.06.006 * Corresponding author. E-mail address: [email protected] (F. Liu). A todorokite-type manganese oxide molecular sieve material was successfully synthesized at atmospheric pressure by refluxing treatment of Cu exchanged Na-buserite (named as Cu-OMS-1). TEM (transmission electron microscope) and HRTEM (hig...

Journal: :The Journal of the Japanese Association of Mineralogists, Petrologists and Economic Geologists 1964

Journal: :Environmental pollution 2009
You-Ting Meng Yuan-Ming Zheng Li-Mei Zhang Ji-Zheng He

Biogenic Mn oxides exert important controls on trace metal cycling in aquatic and soil environments. A Mn-oxidizing bacterium Bacillus sp. WH4 was isolated from Fe-Mn nodules of an agrudalf in central China. The biogenic Mn oxides formed by mediation of this Mn oxidizing microorganism were identified as short-ranged and nano-sized Mn oxides. Cd adsorption isotherms, pH effect on adsorption and ...

Journal: :Chemical communications 2010
Hui Huang Chun-Hu Chen Linping Xu Homer Genuino Javier Garcia-Martinez Hector F Garces Lei Jin Cecil King'ondu Kithongo Steven L Suib

A facile single-step method was developed for synthesizing todorokite-type manganese oxide octahedral molecular seieves (OMS-1) and 2 x 4 tunnel structured manganese oxide (OMS-5) materials. Selection of starting materials and initial pH conditions in the syntheses are crucial.

Journal: :Proceedings of the National Academy of Sciences of the United States of America 1999
J E Post

Manganese oxide minerals have been used for thousands of years-by the ancients for pigments and to clarify glass, and today as ores of Mn metal, catalysts, and battery material. More than 30 Mn oxide minerals occur in a wide variety of geological settings. They are major components of Mn nodules that pave huge areas of the ocean floor and bottoms of many fresh-water lakes. Mn oxide minerals are...

2006
ROBERT B. FINKELMAN HOWARD T. EVANS JOHN J. MATZKO

Seven manganese minerals have been observed in geodes from Chihuahua, Mexico. Ramsdellite occurs in a number of different habits, but the morphology and precession X-ray patterns suggest that it is pseudomorphous after groutite. Pyrolusite is found only in association with ramsdellite and is believed to be an alteration product of that mineral. Todorokite generally occurs as a late-stage fibrou...

Journal: :ACS nano 2009
V Petkov Y Ren I Saratovsky P Pastén S J Gurr M A Hayward K R Poeppelmeier J-F Gaillard

Biogenic materials are produced by microorganisms and are typically found in a nanophase state. As such, they are difficult to characterize structurally. In this report, we demonstrate how high-energy X-ray diffraction and atomic pair distribution function analysis can be used to determine the atomic-scale structures of MnO(x) produced by bacteria and fungi. These structures are well-defined, p...

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