Time-dependent release of iron from soot particles by acid extraction and the reduction of fe3+ by elemental carbon

Elemental carbon reduces Fe3+ to Fe2+ in aqueous solutions. This process has\npotential implications in the adverse health effects of fine particles in air pollution,\nbecause both elemental carbon and iron are major components in atmospheric\nparticulate matter. In this study we measured the time-dependent release of iron from\nlaboratory flames and standard reference soot particles that contained iron, and the\nreduction of Fe3+ to Fe2+ in an acid extraction process. The concentration of Fe3+ and\nFe2+ ions in the extraction solutions was measured by a spectrophotometric method.\nThe results showed that while Fe3+ was the dominant valence state in the dry soot\nparticles, significant fraction of iron was reduced to Fe2+ in the aqueous solution.\nFurther investigation is needed to assess the significance of this phenomenon in the\nbiological effects of particles that contain iron and elemental carbon.