Synthesis and characterization of biogenic Mn oxides by a Mn-oxidizing fungus

A Picea glauca sp.-like strain of Mn-oxidizing fungus was isolated from a constructed wetland in Hokkaido, Japan. The optimal pH was investigated for the fungus. Under the neutral pH, this fungus oxidized 380 mg dm^-3 of dissolved Mn(II). The XRD patterns of the biogenic Mn oxides showed them to be poorly crystalline, much unlike that of the synthetic Mn oxide. The BET specific surface area of the biogenic Mn oxide was much larger than that of the synthetic Mn oxide. The measurement of pore size distributions of the biogenic Mn oxides showed that the biogenic Mn oxide has more nanometer-sized fine pores than the synthetic Mn oxide and that diameters of fine pores of the biogenic Mn oxide were mostly uniform around 4 nm, suggesting the biogenic Mn oxides provide the highly reactive field. As an example application of the biogenic Mn oxides to environmental remediation, Co²⁺-adsorption was investigated.