X-RAY PHOTOELECTRON SPECTROSCOPIC STUDY OF CHROMIUM SORBED ON MONTMORILLONITE

Chromium, a potentially toxic element, sorbs on clays like montmorillo nite and can also form Cr-hydroxy polymers in the interlayer of this e xpansible clay. Therefore, Cr may be at least partially immobilized in systems that contain montmorillonite, provided Cr is present as Cr(II I). The oxidation state of Cr sorbed on montmorillonite from aqueous s olutions containing Cr(III) was examined by X-ray plotoelectron spectr oscopy. The data show that no detectable amounts of Cr(III) sorbed on montmorillonite are oxidized by O-2 or by components present in the cl ay such as Mn-bearing minerals. This result supports the contention th at expanding clays like montmorillonite may serve as effective sinks f or Cr in some contaminated environments.