Removal of Methylene Blue from Aqueous Solution by Manganese Oxide Nano-Sheets

Abstract

MnO2 nanosheets were synthesized with tetramethylamine, H2O2, MnCl2·4H2O and its suspension were prepared for its high efficient removal of methylene blue (MB). MB removal reached as high as 95% when MB concentrations were less than 500 mg/L at pH 11. The adsorption data fitted better with Freundlich isotherm model than Langmuir model indicating the heterogeneous adsorption nature of MB on MnO2 nanosheets. The maximum adsorption capacity of MnO2 nanosheets was ~4,300 mg/g, which is the highest reported so far. The MnO2 nanosheets suspension was aggregated as precipitates after adsorption of MB. Our results demonstrated that dispersive MnO2 nanosheets have a potential application on adsorption of organics from solution with strong base and high salinity.