title: Hierarchical MnO₂ nanostructures: synthesis and their application in water treatment.
abstract: Hierarchical MnO₂ nanostructures were prepared through the reaction between KMnO₄ and oleic acid at room temperature in the surfactant-free microemulsion system. The obtained samples were characterized by powder X-ray diffraction, N₂ adsorption, scanning electron microscopy, and transmission electron microscopy. The results indicated that the flowerlike nanospheres were three-dimensional (3D) porous microstructures consisting of nanoplates. The surface area of the sample was 171.5 m(2)/g and the distribution of pore diameter lay within the range of 5-15 nm. The prepared hierarchically structured MnO₂ showed excellent adsorption capacity and rapid adsorption rate for methylene blue ions in water. The maximum adsorption capacity of methylene blue was as high as 273.9 mg/g and 97.5% of the dye was removed within initial 5 min of contact time. Compared with other adsorbents, the synthesized hierarchical MnO₂ nanostructures displayed a faster adsorption rate and higher adsorption capacity, which implied potential application for removing dye pollutants from waste water.
authors.affiliation: School of Chemical Engineering, Zhengzhou University, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Zhai
authors.forename: Yazhen
authors.initials: Y
authors.lastname: Wan
authors.forename: Lin
authors.initials: L
authors.lastname: Liu
authors.forename: Xiang
authors.initials: X
authors.lastname: Zhang
authors.forename: Weiqiang
authors.initials: W
authors.lastname: Wang
authors.forename: Jindun
authors.initials: J
authors.lastname: Liu
authors.forename: Bing
authors.initials: B
authors.lastname: Zhang
mesh_terms: D006863:Hydrogen-Ion Concentration; D017895:Manganese Compounds / Q000737:chemistry*; D008751:Methylene Blue; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D049329:Nanostructures / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D014865:Waste Disposal, Fluid / Q000379:methods*; D014867:Water / Q000737:chemistry; D018508:Water Purification / Q000379:methods*
chemical_list: D017895:Manganese Compounds; D010087:Oxides; D014867:Water; D008751:Methylene Blue; C016552:manganese dioxide