Na0.5Li0.5CoO2 nanopowders: Facile synthesis, characterization and their application for the removal of methylene blue dye from aqueous solution

• Preparation of Na0.5Li0.5CoO2 nano delafossite by sol–gel method.
• Kinetic study of the adsorption properties.
• Removal of methylene blue dye by the prepared new nanocatalyst.

In this paper, delafossite-type Na0.5Li0.5CoO2 nanoparticles (NPs) with an average particle size of 50 nm were successfully synthesized by sol–gel method. Prepared NPs were characterized by differential thermal analysis, powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and scanning tunneling microscopy. The nanoparticles showed the excellent adsorption properties towards methylene blue dye (MBD) as a reactive dye. The kinetics of removal of MBD in aqueous solutions was studied in a series of experiments which were varied in the amount of NPs, contact time, pH, and temperature. The experimental data were fitted very well in the pseudo-second order kinetic model and the Freundlich adsorption isotherm model. 92% of dye was successfully removed in 10 min using 0.02 g Na0.5Li0.5CoO2 NPs in a pH = 11. Thermodynamic study indicates that the adsorption of MBD is feasible, and spontaneous in nature.

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