The Controlled Synthesis of Birnessite Nanoflowers HO Reducing KMnO For Efficient Adsorption and Photooxidation Activity.

Birnessite nanoflowers composed of layers have been proven to be the strongest adsorbent and oxidant in the surface environment. However, the current synthesis methods of birnessite nanoflowers are suffering from long reaction time and high reaction temperature. Based on these, this paper explores a new method for the rapid and controlled synthesis of layered manganese oxides. The method relies on the molar ratios of KMnO and HO redox reacting species to drive the production of birnessite nanoflowers under acidic conditions. The molar ratios of KMnO and HO are the key to the crystal structure of the as-prepared. It was found that when the molar ratios of KMnO and HO is from 1:1.25 to 1:1.90, the sample is birnessite nanoflowers, and when the ratio is increased to 1:2.0, the sample is a mixture of birnessite nanoflowers and feitknechtite nanoplates. Among the as-prepared samples, BF-1.85 (molar ratios of KMnO and HO is 1:1.85) shows the highest capacity for Pb adsorption (2,955 mmol/kg) and greatest degradation efficiency of phenol and TOC. The method proposed herein is economical and controllable, and it yields products with high efficiency for the elimination of inorganic and organic pollutants.