Catalytic oxidation removal of manganese from groundwater by iron-manganese co-oxide filter films under anaerobic conditions

Although dissolved oxygen (DO) is a key factor for the removal of manganese (Mn) from aqueous solutions, this study presents an efficient method for Mn removal without any DO consumption. We demonstrate the feasibility of using an iron (Fe) Mn co oxide filter film to continuously remove Mn from groundwater under anaerobic conditions. A pilot-scale filter equipped with Fe-Mn co-oxide filter media ( 120 cm high) was adapted to explore the Mn removal performance under three DO levels (6-7 mg/L, 1 2 mg/L, and 0 02 mg/L). The Fe-Mn co-oxide filter exhibited a higher Mn removal performance under anaerobic conditions (no DO consumption) than under the other two DO conditions. The morphology, structure, and Mn valence changes of the Fe-Mn co-oxide filter film were studied using scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Brunauer Emmett Teller (BET) theory, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The Fe-Mn co-oxide filter film under anaerobic conditions had a large contact surface area and large pore volume, and thus possessed more adsorption sites and reaction channels for Mn removal. By considering all of the characterization and reaction data reported in this study, we conclude that H2O ligands, hydrogen bonding (OH), and vacant sites affect the transformation of Mn, thus play important roles in the continuous removal of Mn under anaerobic conditions. This discovery presents a new and effective approach for Mn removal during groundwater treatment. (C) 2020 Elsevier B.V. All rights reserved.