%0 Journal Article
%T Phenylalanine as a hydroxyl radical-specific probe in pyrite slurries
%A Shawn C Fisher
%A Martin AA Schoonen
%A Bruce J Brownawell
%J Geochemical Transactions
%D 2012
%I BioMed Central
%R 10.1186/1467-4866-13-3
%X Reactive oxygen species (ROS) are highly reactive compounds that have been studied extensively in biological and environmental systems and have been linked to numerous human health issues, including Parkinson's disease [1] and lung cancer [2]. In addition to forming naturally in cells as a function of respiration [3] and in the atmosphere [4], recent studies have observed that ROS can form at the surface of some minerals in water [5-7]. In particular, pyrite (FeS2) has been shown to be efficient at forming hydrogen peroxide (H2O2) and hydroxyl radical (.OH) in the presence of oxygenated solutions [6,8]. Of significant interest in pyrite slurries is .OH, as it is transient and will rapidly react with any organic compound. The abundance of naturally-occurring pyrite in environments such as coal mines, where fine dust particles are frequently inhaled by workers, introduces the potential risk of human exposure to mineral-induced ROS. As an abundant mineral in many sediments and geological deposits, pyrite may also play a role in transformations of natural organic matter. Finally, the potential usefulness of pyrite as a tool for remediation of wastewater is also being considered as engineers continue to look for new methods of removing anthropogenic compounds before discharging effluent back into the environment.Several mechanisms for surface-derived ROS in systems containing pyrite have been proposed that include iron-catalyzed, electron-transfer reactions. Schoonen et al. [6] suggests molecular oxygen is reduced to form H2O2 by reacting with iron-II (Fe(II)) sites at the pyrite surface. H2O2 may either remain adsorbed on the surface and be further reduced to .OH (Equation 1), or desorb and undergo Fenton chemistry with dissolved ferrous iron (Fe2+) to form .OH in solution (Equation 2); with pyrite dissolution acting as the source of Fe2+.The proportion of H2O2 that reacts to form .OH on the pyrite surface versus in solution is not known, although it has been proposed t
%U http://www.geochemicaltransactions.com/content/13/1/3