Selective Sorption of Co<SUP>2+</SUP> over Ni<SUP>2+</SUP> Using Biogenic Manganese Oxides

Abstract

Preferential sorption of Co 2þ ions over Ni 2þ ions was achieved using biogenic Mn oxides produced by the Mn-oxidizing fungus Paraconiothyrium sp. WL-2 strain with a maximum selectivity coefficient ( Co ) of 18. The selective sorption was based on different sorption mechanism for Co 2þ and Ni 2þ and unique properties of biogenic Mn oxides. The octahedral Co 2þ ions occupy vacancies of central metal sites and edge sites in the octahedral Mn oxide unit structures of biogenic Mn oxides, where they are immobilized by oxidation to CoOOH by Mn(III). In contrast, Ni 2þ ions are sorbed primarily on layer edges at circumneutral pHs without oxidation. Selective sorption of Co 2þ over Ni 2þ on the biogenic Mn oxides results from more vacant sites, higher Mn(III) contents, and larger specific surface areas compared to synthetic Mn oxides.

Fungal Mn oxides supporting Mn(II) oxidase activity as effective Mn(II) sequestering materials

“…[10,13] Along with Mn(II)-oxidizing bacteria, phylogenetically diverse fungi produce BMOs and are therefore important organisms controlling the geochemical cycles of various elements. [14][15][16][17] Studies have investigated the interactions of fungal BMOs with divalent transition cations, [6,18,19] lanthanides, [8,9] and actinides [20] as well as with inorganic arsenate. [4,21] Recent studies have also shown the characteristics of fungal BMOs [22][23][24][25] with respect to their physicochemical structures at atomic scales.…”