Immobilization of mercury by pyrite (FeS2)

Elemental mercury (Hg-0) is a metal with a number of atypical properties, which has resulted in its use in myriad anthropogenic. However, these same properties have also led to sever local subsurface contamination at many places where it has been used. As such, we studied the influence of various parameters on Hg(II) sorption onto (pH, time, Hg(II) concentration), a potential subsurface reactive barrier. Batch sorption studies revealed that total Hg(II) removal increase with both pH and time. X-ray absorption spectroscopy analysis showed that a transformation in the coordination environment at low pH occurred during aging over 2 weeks, to form an ordered monolayer of monodentate Hg-Cl complex on pyrite. In column studies packed with pure quartz sand, the transport of Hg(II) was significantly retarded by the presence of a thin pyrite-sand reactive barrier, although dissolved oxygen inhibited Hg(II) sorption onto pyrite in the column. (C) 2008 Elsevier Ltd. All rights reserved.