Mechanism of charging of the pyrite/aqueous interface as deduced from the surface potential measurements

摘要

Surface potential of pyrite in an aqueous environment was measured by means of a single crystal pyrite electrode. The effect of the activity of S~(2-) and Fe~(2+) ions as well as of pH, was examined. The results show that S~(2-) and Fe~(2+) ions are the dominant potential determining ions. These ions are bound to surface sites with the extent depending on their activity in the bulk of the solution. Adsorption affinity of S~(2-) ions is significantly higher than that of Fe~(2+) ions so that in most cases the pyrite surface is negatively charged. The results were explained on the basis of the surface complexation model. It was found that the surface potential depends also on pH.