Structural and magnetic studies on heavy-metal-adsorbing iron sulphide nanoparticles produced by sulphate-reducing bacteria

The structure of weakly magnetic and strongly magnetic iron sulphide material produced by sulphate-reducing bacteria (SRB) with a view to increasing the understanding of its adsorbent and the magnetic properties is examined using high-resolution imaging and electron diffraction in a transmission electron microscope (TEM), the measurements of magnetization versus field and temperature, extended X-ray absorption fine-structure (EXAFS) spectroscopy, X-ray absorption near-edge structure (XANES) spectroscopy and neutron diffraction. The strongly magnetic iron sulphide is composed of some greigite (Fe₃S₄) and mackinawite (Fe_1+xS). The weakly magnetic and strongly magnetic iron sulphide are good adsorbents for heavy metals and halogenated hydrocarbons.