Synthesis of mono-dispersed mesoporous Mn2O3 powders with micro-nanostructure for removing Congo red dye from aqueous solution.

• Uniformly dispersed MnCO 3 particles has been synthesized. • CO 2 gas was employed as the sole carburizer. • Mesoporous Mn 2 O 3 microparticles has the similar shape with MnCO 3 precursor. • High adsorption capacity is attributed to electrostatic interaction. Taking the importance and significance of wastewater treatment into consideration, mono-dispersed Mn 2 O 3 powders with sphere-like morphology and mesopore features has been firstly synthesized from the thermal decomposition of MnCO 3 which is prepared via a modified carbonization method using CO 2 gas as the sole carbonate source. The measured isoelectric point, the pH value at which the ζ-potential is zero, of uniformly dispersed Mn 2 O 3 particles is 9.13. Benefiting from the surface electrostatic interaction, as-prepared Mn 2 O 3 microparticles has high adsorption capacity up to 135.5 mg/g toward Congo red dye in aqueous solution. Accordingly, the adsorption process of Congo red by Mn 2 O 3 microspheres could be explained by Langmuir isotherm model and the pseudo-second-order kinetic model. Especially, it is necessary to point out that the removal efficiency of Mn 2 O 3 toward Congo red dye still be well maintained at about 90.78% even after five cycles. Therefore, as-prepared Mn 2 O 3 powders has potential application in large-scale wastewater treatment. [ABSTRACT FROM AUTHOR]