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Substructure and superstructure of four-layer Ca-exchanged birnessite
Substructure superstructure four-layer Ca-exchanged birnessite
2012/3/30
Synthetic Ca-exchanged birnessite (CaBi) was studied by X-ray and selected-area elec-tron diffraction (XRD, SAED). The substructure of CaBi may be described with a four-layer monoclinic subcell with a...
Structure of monoclinic Na-rich birnessite and hexagonal birnessite: I. Results from X-ray diffraction and selected-area electron diffraction
Structure monoclinic Na-rich birnessite hexagonal birnessite X-ray diffraction selected-area electron diffraction
2012/4/6
Onthebasisoftheseexperimentalobervations,structuralmodelsforNaBiandHBiareproposed.NaBiconsistsofalmostvacancy-freeMnoctahedrallayers.Thedeparturefrom
thehexagonalsymmetryoflayersiscausedbytheJahn-Tel...
Structure of synthetic monoclinic Na-rich birnessite and hexagonal birnessite: II. Results from chemical studies and EXAFS spectroscopy
synthetic monoclinic Na-rich birnessite hexagonal birnessite II. Results chemical studies EXAFS spectroscopy
2012/4/6
SolutionchemicaltechniqueswereusedtostudytheconversionofsyntheticNa-richbuserite(NaBu)tohexagonal(H-exchanged)birnessite(HBi)atlowpH.Thelow-pH
reactionisbroadlycharacterizedbytheexchangeofstructuralN...
Crystal Structure Modeling of a Highly Disordered Potassium Birnessite
Birnessite Crystal Structure Modeling Turbostratic Stacking
2011/12/27
The structure of a highly disordered synthetic birnessite was studied by comparing powder X-ray diffraction (XRD) data with calculated patterns generated by BIRNDIF and WILDFIRE© in an attempt to...
Transformations of Synthetic Birnessite as Affected by pH and Manganese Concentration
Birnessite Manganese oxides Mn2+ concentration pH Structural conversion TEM XRD
2011/12/29
The amount of Mn2+ adsorbed or removed from solution by birnessite is several times greater than its reported cation exchange capacity. Extractability of the sorbed Mn2+ decreases with aging. It is un...
Reaction Scheme for the Oxidation of As(III) to As(V) by Birnessite
Arsenic Birnessite Oxidation Potassium Solution
2012/1/5
The oxidation of As(III) to As(V) by K-birnessite was examined at different temperatures, pHs, and birnessite/As(III) ratios. Experiments ranged in duration from 5 to 64 hr, and solution and solid pro...
Oxidation of 1,2- and 1,4-Dihydroxybenzene by Birnessite in Acidic Aqueous Suspension
Birnessite Dihydroxybenzene Electron spin resonance Manganese Oxidation Phenol Ultraviolet-visible spectroscopy
2012/1/6
The rate and extent of oxidation of dihydroxybenzenes (DHB) to quinones in acetate-buffered suspensions of synthetic birnessite were studied using Mn dissolution to monitor reaction progress. Concentr...
Oxidation of Dihydroxybenzenes in Aerated Aqueous Suspensions of Birnessite
Birnessite Dihydroxybenzene Electron spin resonance Manganese Oxidation
2012/1/5
The oxidation of 1,2- and 1,4-dihydroxybenzenes (1,2-DHB and 1,4-DHB) by unbuffered aerated suspensions of synthetic birnessite was studied by continuously monitoring the H+, Mn2+ dissolved O2, and or...
Transformation of Hausmannite into Birnessite in Alkaline Media
Alkaline solution Birnessite Dissolution Hausmannite Manganese Synthesis
2012/1/9
The transformation of hausmannite (Mn3O4) into a K-bearing, 7-A phyllomanganate (K-birnessite) in KOH was followed using X-ray powder diffraction and transmission electron microscopy. The transformati...
Transformation of Birnessite to Buserite, Todorokite, and Manganite under Mild Hydrothermal Treatment
Birnessite Buserite High-resolution transmission electron microscopy Hydrothermal Manganite Todorokite
2012/1/11
Investigations were conducted to determine the hydrothermal transformations of synthetic birnessite exchanged with different metal ions. Autoclaving in a Teflon-lined stainless steel pressure vessel a...
Transformation of Synthetic Birnessite to Cryptomelane: An Electron Microscopic Study
Birnessite Cryptomelane Selected area diffraction Structural disorder Synthesis Thermal treatment Transmission electron diffraction
2012/1/12
Na-saturated birnessite was synthesized by oxidizing an alkaline MnCl2 solution with gaseous O2. Transmission electron microscopy (TEM) showed no morphological change upon K-saturation of the birnessi...
Ion Exchange, Thermal Transformations, and Oxidizing Properties of Birnessite
Birnessite Bixbyite Buserite Cation exchange Cryptomelane Hausmannite Hollandite Oxidation Thermal treatment
2012/1/12
Synthetic sodium birnessite, having a cation-exchange capacity (CEC) of 240 meq/100 g (cmol/kg) was transformed into Li, K, Mg, Ca, Sr, Ni, and Mn2+ cationic forms by ion exchange in an aqueous medium...