Assessing the Chemical Reactivity of Nano-Sized Iron Welding Fumes for Potential Beneficial Reuse as An Environmental Catalyst and Adsorbent.

Over the past decade, the manufacturing industry in the United States has sought to reduce the quantity of industrial waste produced during the manufacturing process and/or develop/identify a beneficial use for industrial waste.  Welding fumes constitute one such waste byproduct in the automobile industry.  The fume consists of low fractal nano-particles (size range) comprised of an iron metallic core that transitions to an iron oxide coating at the particle surface similar in crystallinity and chemical composition to magnetite.  The size of the material, presence of multiple iron oxidation states, and a iron oxide surface structure indicate that welding fumes may find beneficial reuse as environmental catalysts for the oxidation of contaminants and/or as a sorbent capable of sequestering contaminants.  The oxidative potential and adsorbent capabilities of the material were assessed utilizing arsenic as a probe molecule.  Batch adsorption experiments were conducted at pH 4, 7, and 10 using various concentrations (1-1000 mg/L As) of arsenate and arsenite in order to determine the reactivity of iron fume.  Preliminary results from laboratory and XAFS measurements suggest that arsenic is specifically adsorbed to the welding fume surface and that arsenite was oxidized to arsenate.