Preliminary Study on the Mechanism of Non-enzymatic Bioreduction of Precious Metal Ions

Abstract

Preliminary study on the mechanism of non-enzymatic bioreduction of gold, silver, platinum, palladium and rhodium ions by Bacillus megatherium D01 biomass has been carried out by means of TEM, XRD, XPS and FTIR methods. The results showed that after contacted with D01 biomass, Au3+ has been completely reduced to elemental, cell bound Au0 for 2h and about 45% Rh3+ to Rh0 for 2 d at 30°C and pH 3. 5 without biochemical or chemical cofactors; the cardinal mechanism of D01 cell accumulating metal ions was biosorption, and the primary location where biosorption occurred was the D01 cell wall; active groups such as carbonyl of amido bond and carboxyl on the cell wall may complex or chelate with the precious metal ions; and aldose and ketose, i. e., hydrolysate of part polysaccharide on the cell wall in acidic medium, served as the election donor, and reduced soluble precious metal ions to atoms.