A VIBRATIONAL SPECTROSCOPIC STUDY OF THE OXIDATION OF PYRITE BY MOLECULAR OXYGEN

Abstract

In situ flow-through attenuated total reflectance (ATR) Fourier transform infrared (FTIR) spectroscopy has been used to investigate the formation, and step-wise oxidation, of sulfoxyanions at the pyrite surface during oxidation by molecular oxygen. The surface was studied under two different pH regimes (pH 2.5 and pH 5.6) and under two light conditions (dark and ultraviolet light). It was experimentally observed that multiple sulfoxyanions were present at the pyrite surface during oxidation by molecular oxygen, spectroscopically illustrating the concept of sulfur step-wise oxidation. The results from photochemical experiments were complex and suggest a dependence on both pH and surface speciation.