Heavy metal adsorption on bacterially produced FeS

This paper describes experiments to investigate the adsorbent properties of an iron sulphide material produced by sulphate reducing microorganisms when they are grown with a substrate containing appreciable quantities of iron. It is found that the material when compared with other adsorbents has excellent adsorptive properties with respect to specific uptake of a range of metals and the level to which the concentrations of the metal ions can be reduced when in contact with the adsorbent. The structure of the adsorbent revealed by EXAFS corresponds with no known iron sulphide and an examination of the adsorbed ions shows that many are chemisorbed. When the adsorbent is stored in the presence of air for periods of a few months a mixed oxide of iron is formed.