title: Iron dissolution of dust source materials during simulated acidic processing: the effect of sulfuric, acetic, and oxalic acids.
abstract: Atmospheric organic acids potentially display different capacities in iron (Fe) mobilization from atmospheric dust compared with inorganic acids, but few measurements have been made on this comparison. We report here a laboratory investigation of Fe mobilization of coal fly ash, a representative Fe-containing anthropogenic aerosol, and Arizona test dust, a reference source material for mineral dust, in pH 2 sulfuric acid, acetic acid, and oxalic acid, respectively. The effects of pH and solar radiation on Fe dissolution have also been explored. The relative capacities of these three acids in Fe dissolution are in the order of oxalic acid > sulfuric acid > acetic acid. Oxalate forms mononuclear bidentate ligand with surface Fe and promotes Fe dissolution to the greatest extent. Photolysis of Fe-oxalate complexes further enhances Fe dissolution with the concomitant degradation of oxalate. These results suggest that ligand-promoted dissolution of Fe may play a more significant role in mobilizing Fe from atmospheric dust compared with proton-assisted processing. The role of atmospheric organic acids should be taken into account in global-biogeochemical modeling to better access dissolved atmospheric Fe deposition flux at the ocean surface.
authors.affiliation: Departments of †Chemical and Biochemical Engineering and ‡Chemistry, University of Iowa , Iowa City, Iowa 52242, United States.
authors.forename: Haihan
authors.initials: H
authors.lastname: Chen
authors.forename: Vicki H
authors.initials: VH
authors.lastname: Grassian
mesh_terms: D019342:Acetic Acid / Q000737:chemistry*; D000327:Adsorption; D000393:Air Pollutants / Q000737:chemistry; D060729:Coal Ash / Q000737:chemistry*; D004391:Dust; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000737:chemistry*; D019815:Oxalic Acid / Q000737:chemistry*; D010782:Photolysis; D012995:Solubility; D013464:Sulfuric Acids / Q000737:chemistry*; D013472:Sunlight
chemical_list: D000393:Air Pollutants; D060729:Coal Ash; D004391:Dust; D013464:Sulfuric Acids; D019815:Oxalic Acid; D007501:Iron; C033158:sulfuric acid; D019342:Acetic Acid