Chemical processes on active carbon surface: A new example of nitrogen fixation

The behavior of activated carbon fibers (ACF) and activated carbon (AC) in water and aqueous solutions of H₂O₂, NaOH, NaCN and KI₃ in the presence of atmospheric air is studied by physicochemical methods: X-ray photoelectron spectroscopy (XPS), ESR, and attenuated total reflectance IR (ATR-IR) and Fourier Transform IR (FT-IR) spectroscopy. The superoxide radical anion O ₂ ^?· is shown to exist on the ACF surface in aqueous solutions, whose formation is explained by reaction of molecular oxygen with radical active centers of surface defects. It is found that in aqueous solutions of inorganic compounds, both possessing (H₂O₂, KI₃) and not possessing (NaOH, NaCN) pronounced oxidative properties, the ACF surface is oxidized more rapidly than on aging in air. Evidence for fixation of atmospheric nitrogen on contact of ACF and AC with H₂O or aqueous solutions of NaOH, NaCN, and KI₃ is obtained. Possible conjugate redox reactions resulting in fixation of N₂ molecules and oxidation of the surface of carbon materials are discussed.