Controlled Synthesis of Manganese Dioxide Nanostructures via a Facile Hydrothermal Route

Manganese dioxide nanostructures with controllable morphological structures and crystalline phases were synthesized via a facile hydrothermal route at low temperatures without using any templates or surfactants. Both the aging duration and aging temperatures were the main synthesis parameters used to influence and control the rate of morphological and structural evolution of MnO2 nanostructures. MnO2 nanostructures comprise of spherical nanoparticulate agglomerates and highly amorphous in nature were formed at lower temperature and/or short aging duration. In contrast, MnO2 nanostructures of sea-urchin-like and nanorods-like morphologies and nanocrystalline in nature were prepared at the combined higher aging temperatures and longer aging durations. These nanostructures underwent notable phase transformation from δ-MnO2 to α-MnO2 upon prolonged hydrothermal aging duration and exhibited accelerated rate of phase transformation at higher aging temperature

Controlled Synthesis of Manganese Dioxide Nanostructures via a Facile Hydrothermal Route

Manganese dioxide nanostructures with controllable morphological structures and crystalline phases were synthesized via a facile hydrothermal route at low temperatures without using any templates or surfactants. Both the aging duration and aging temperatures were the main synthesis parameters used to influence and control the rate of morphological and structural evolution of MnO2 nanostructures. MnO2 nanostructures comprise of spherical nanoparticulate agglomerates and highly amorphous in nature were formed at lower temperature and/or short aging duration. In contrast, MnO2 nanostructures of sea-urchin-like and nanorods-like morphologies and nanocrystalline in nature were prepared at the combined higher aging temperatures and longer aging durations. These nanostructures underwent notable phase transformation from δ-MnO2 to α-MnO2 upon prolonged hydrothermal aging duration and exhibited accelerated rate of phase transformation at higher aging temperature

Synthesis and characterization of self-assembled manganese dioxide nanostructures and thin-film materials

Manganese dioxide (MnO2) nanostructures in the forms of thin film and powder had been prepared by two different preparative approaches. There were sol-gel and hydrothermal approaches. In the sol-gel synthesis approach, stable colloidal suspensions of MnO2 were pepared by chemical reduction of permanganate salt. Nanostructured MnO2 thin films were prepared by a self-assembly horizontal submersion process which involved spontaneous assembly of MnO2 nanoparticles in stable colloidal suspension. The films were subsequently deposited directly onto the supporting substrate (stainless steel foils or Ni-coated PET films) under controlled conditions

Heavy metal ions removal by lignocellulosics materials derived from Sago Bark and leaves

Lignocellulosics materials derived from sago bark and leaves are available in abundance and cheaply. In this study, sago leaflet, leaf stalk, and bark were characterized chemically and physically and used in the removal of lead(ll), copper(lI), and nickel(lI) ions from aqueous solutions. Two types of experimental apparatus were being used, equilibrium and column experiments. All the adsorbent samples varied considerably in their adsorption capacities. The metal adsorption capacity of all the adsorbent samples for different metals in both types of experiments were found to be in the order: Pb>Cu>Ni. The effects of solution pH, particle size of adsorbent and initial metal concentrations on the adsorption of heavy metal ions from aqueous solutions were also studied. Heavy metal ions adsorption capacities of all adsorbent samples were observed to be affected by these factors. The adsorption equilibrium data were observed to fit the Fruendlich model better than the Langmuir model. Kinetic studies showed that the sorption rates could be described well by the pseudo second-order kinetic equation

Preparation and Characterization of Self-Assembled Manganese Dioxide Thin Films

Thin films of manganese dioxide (MnO2) were prepared by self-assembly of MnO2 nanoparticles directly unto nickel-coated poly(ethylene terephthalate) flexible films using the newly developed horizontal submersion process. The thickness of deposited thin films was controllable by the deposition duration. This horizontal submersion deposition process for thin-film deposition is relatively easy, simple, and cost effective. Effects of deposition duration and calcination temperatures on the microstructure and electrochemical properties of self-assembled MnO2 thin films were investigated. Optimized MnO2 thin films exhibited high charge capacity, good cycling reversibility, and stability in a mild aqueous electrolyte and are thus promising electrode materials for the fabrication of thin-film electrochemical capacitors