Bioaccumulation of nickel by microbially-enhanced chemisorption into polycrystalline hydrogen uranyl phosphate

Summary Ni²⁺ was removed quantitatively from aqueous solution into a microbially-created crystalline deposit of hydrogen uranyl phosphate (HUP). The mechanism of Ni²⁺ removal is an ion-exchange intercalation of Ni²⁺ into the interlayer space of HUP. The Ni²⁺-removing capacity of a column was proportional to the mass of HUP deposited and the Ni/HUP-loaded column was regenerated by washing with uranyl solution containing citrate/MOPS buffer and glycerol-2-phosphate, or with citrate buffer alone. Regeneration in the presence of UO₂²⁺ increased the Ni²⁺-removing capacity of the column. A new mechanism for the removal of heavy metals via microbially enhanced chemisorption is proposed.