Characterization of Circle Cliffs tar sands: 2. Application of the e.p.r. technique to paramagnetic metal ions

Abstract

In the second of a two-part investigation, the results of an e.p.r. study of the paramagnetic metal ions in the bitumen and mineral components of Circle Cliffs tar sand are reported. Analysis of a spectrum observed at g ≈ 2 in the bitumen component and assigned to V 4+ shows that vanadium originates in the vanadyl etioporphyrin complex. A computer simulation of a complex exhibiting characteristics of the Mn 2+ ion, which is observed in the mineral component at g ≈ 2, is shown to arise from manganese in dolomite. A broad feature at g ≈ 4 in the mineral spectrum is identified as Fe 3+ located at sites in kaolinite clay. Finally, a very broad band underlying the manganese spectrum at g ≈ 2 is tentatively identified as originating with amorphous iron oxides coating clay particles. The results demonstrate the utility of e.p.r. in not only identifying important metallic ions but also establishing the organic or inorganic complexes in which they occur.