Preferential Elimination of Ba2+ through Irreversible Biogenic Manganese Oxide Sequestration

Biogenic manganese oxides (BMOs) formed in a culture of the Mn(II)-oxidizing fungus Acremonium strictum strain KR21-2 are known to retain enzymatic Mn(II) oxidation activity. Consequently, these increasingly attracting attention as substrate for eliminating toxic elements from contaminated wastewaters. In this study, we examined Ba2+ sequestration potential enzymatically active BMOs with and without exogenous Mn2+. The readily oxidized Mn2+ produce another BMO phase, subsequently sequestered at pH 7.0, irreversible dominant pathway. Extended X-ray absorption fine structure spectroscopy diffraction analyses demonstrated alteration turbostratic tightly stacked birnessite through possible incorporation into interlayer. Sr2+, Ca2+, Mg2+ was insignificant, preserved. Results competitive experiments revealed that favored over Mg2+. These results explain preferential accumulation natural Mn oxide phases produced by microbes under circumneutral environmental conditions. findings highlight applying