Abstract
The kinetics of photochemical reduction of Fe(III) coupled with organic ligands has been investigated to understand the photoredox cycling of Fe and the significance of this cycling in the production of photo-oxidants and transformation of S (IV) and organic pollutants in atmospheric waters. The photo-reduction of ferrioxalate ion is first order with respect to Fe(III) and has a rate constant of 4.0 ± 0.4 × 10 −2 s −1 in anoxic solutions at summer clear-day-noon time. In the presence of oxygen, the oxalate radical formed in the primary photoreaction further reduces O 2 to HO 2 • O 2 • , leading to the reoxidation of Fe(II) and the formation of H 20 2. At a photochemical steady-state, the ratio of Fe(II) Fe(III) is determined by: [ Fe(II)] ss [ Fe(III)] ss =[ k s k 9 [ HO 2 • O 2 • ] where subscript ss denotes steady-state, k s, and k 9 are the rate constants for photoreduction of Fe(III) complex and the oxidation of Fe(II) by HO 2 •/O 2 • , respectively, and [HO 2 •/O 2 • ] is the concentration of HO 2 • O 2 • . During sunny daytime, a large fraction of Fe is present as Fe(II), which provides a significant source of dissolved Fe(II) for the primary productivity in surface water systems.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
