ABSTRACT
Iron (Fe) is one of the most abundant elements in the environment. These Fe(III) hydroxides have large surface areas, up to several hundred square meters per gram, and may specifically adsorb organic and inorganic compounds. Studies of the wavelength dependence of the rate of the photochemical reductive dissolution of Fe(III) hydroxides have been carried out in order to identify the primary chromophore and the electronically excited state of the primary chromophore involved in this heterogeneous photoredox reaction. The surface complex formation model interprets specific adsorption in terms of the coordination chemistry at the solid-water interface, e.g., the chemical interaction of a central metal ion of the surface lattice with a ligand. The efficiency of photoredox reactions occurring at mineral surfaces is determined to a large extent by the structure, both geometrical and electronic, of surface species. Surface spectroscopic methods and molecular orbital calculations of surface species are needed in order to elucidate their electronic and geometrical properties.
