A new eco-material (Bio-MnOx-C) was produced by carbonizing biogenic Mn oxides.
Bio-MnOx-C contained C, O and Mn composed of Mn (IV) and Mn (III).
IC removal by Bio-MnOx-C included a rapid oxidation reaction and slow adsorption.
IC removal by Bio-MnOx-C followed second-order kinetic equation.
Bio-MnOx-C can efficiently remove indigo carmine from waste water.