A New Method of Synthesizing Black Birnessite Nanoparticles: From Brown to Black Birnessite with Nanostructures

Abstract

A new method for preparing black birnessite nanoparticles is introduced. The initial synthesis process resembles the classical McKenzie method of preparing brown birnessite except for slower cooling and closing the system from the ambient air. Subsequent process, including wet-aging at7∘Cfor 48 hours, overnight freezing, and lyophilization, is shown to convert the brown birnessite into black birnessite with complex nanomorphology with folded sheets and spirals. Characterization of the product is performed by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), thermogravimetric analysis (TGA), andN2adsorption (BET) techniques. Wet-aging and lyophilization times are shown to affect the architecture of the product. XRD patterns show a single phase corresponding to a semicrystalline birnessite-based manganese oxide. TEM studies suggest its fibrous and petal-like structures. The HRTEM images at 5 and 10 nm length scales reveal the fibrils in folding sheets and also show filamentary breaks. The BET surface area of this nanomaterial was found to be 10.6 m2/g. The TGA measurement demonstrated that it possessed an excellent thermal stability up to400∘C. Layer-structured black birnessite nanomaterial containing sheets, spirals, and filamentary breaks can be produced at low temperature (−49∘C) from brown birnessite without the use of cross-linking reagents.

Biogeochemistry of manganese in ferruginous Lake Matano, Indonesia

“…7. The TEM image shows aggregates of dark, fibrous minerals, similar in morphology to Mn oxides studied previously (Cheney et al, 2008). Also in the figure, EDS elemental spectra confirms that these dark fibrous particles are predominately Mn and O.…”

“…Recalculating Mn oxidation rates based only on the first two time points for 119-121 m gives higher rates of 0.36-0.72 µmol l −1 d −1 . Aggregates of dark, fibrous minerals seen in the TEM image are similar in morphology to birnessite (Cheney et al, 2008), and an EDS spectrum collected from the point indicated with red crosshairs shows predominately Mn and O present.…”

Adsorption of Cesium, Cobalt, and Lead onto a Synthetic Nano Manganese Oxide: Behavior and Mechanism

“…NMO was obtained under fume cupboard, by the reduction of KMnO 4 (200 mL, 0.02 mol L −1 ), with HCl (5 mL, 4.0 mol L −1 ) as described in the literature (Chen et al 2011;Cheney et al 2008). The process is described by the following reaction:…”

“…The activity concentration of 137 Cs was calculated for each sample using the following equation (Cheney et al 2008;IAEA 2004):…”

Fast degradation of dyes in water using manganese-oxide-coated diatomite for environmental remediation

“…MnO2 which are well known as a strong adsorbents of metal ions, is naturally found in soils, aquifers and sediment, and therefore cost-effective. In addition, MnO2 can be synthesized using oxidation of Mn(II) in basic solution [19], oxidation by MnO4 - [20], O2, K2S2O8, and H2O2 [21], or reduction of MnO4using different routes [22][23][24][25][26].…”