Enhancing the Adsorption Capacity of Hematite by Manganese Doping: Facile Synthesis and its Application in the Removal of Congo Red

This work aims to provide a facile method for the preparation of Mn-doped hematite microrods and reveals the relationship between Mn doping and the enhanced adsorption properties. The adsorption performance of hematite could be greatly enhanced by Mn doping. The maximal adsorption capacity of the Mn-doped alpha-Fe2O3 is calculated to be 84.54mg/g, which exhibits obviously enhanced adsorption capacity as compared to the un-doped alpha-Fe2O3 (33.02mg/g). To further understand the adsorption process, the adsorption kinetic as well as thermodynamic behaviors are carefully investigated. The results suggest that the adsorption process of CR onto the adsorbents follows the pseudo-second-order kinetic model. Meanwhile, the adsorption process can be designated to be a Langmuir process. The adsorption capacities of CR vary as a function of Mn contents, which are regarded as the synergistic effect between surface areas and pore sizes.