Role of iron species in the photo-transformation of phenol in artificial and natural seawater

Abstract

The role played by iron oxides (goethite and akaganeite) and iron(II)/(III) species as photosensitizers toward the transformation of organic matter was examined in saline water using phenol as a model molecule. The study was carried out in NaCl 0.7 M solution at pH 8, artificial (ASW) and natural (NSW) seawater, in a device simulating solar light spectrum and intensity. Under When NSW is spiked with phenol and iron oxides, Fe(II) or Fe(III), halophenols production is enhanced. A close analogy exists between Fe(III), Fe(II)/goethite in ASW and NSW products. Different halophenols production in the natural seawater samples depends on Fe(II)/goethite (above all for 3-chlorophenol, 2,3-dichlorophenol and 4-bromophenol formation) and on Fe(III) colloidal species (3-chlorophenol).3

The role of Fe(III) on phosphate released during the photo-decomposition of organic phosphorus in deionized and natural waters

“…In fact, the dissolved Fe(III) is often present as Fe(OH) 2þ in aqueous solutions, which can absorb solar irradiation (l > 290 nm) and yield $OH and Fe 2þ according to Eqs. (1) and (2) (Hammerschmidt and Fitzgerald, 2010;Calza et al, 2012). $OH could initiate the oxidative degradation of organic phosphorus to release phosphorus as reported (Shah et al, 2015;Fisher et al, 2006).…”

Role of H2O2 in the photo-transformation of phenol in artificial and natural seawater

“…A study performed on solutions spiked with Fe(II)/Fe(III) had shown that phenol disappearance rate was scarcely influenced by the presence/absence of precipitate iron (Calza et al, 2012). Similar considerations arose from the analysis of the data summarised in (Calza et al, 2012;Pelizzetti and Calza, 2002).…”

“…Similar considerations arose from the analysis of the data summarised in (Calza et al, 2012;Pelizzetti and Calza, 2002). Again, it implies that light absorption is needed to promote the phenol transformation.…”

“…Chloride ions show a negligible effect on phenol disappearance rate, while in ASW t 1/2 increases from 5h (pH 8) to 13 h (ASW), most likely due to scavenging of ·OH radicals by the carbonate ions (King and Farlow, 2000;Calza et al, 2012).…”

“…This paper is the second of a set on which the link among the natural photosensitizers and the secondary pollutants formed is for the first time evidenced. Firstly, the ability of iron species to act as photo-sensitizers in seawater was examined (Calza et al, 2012). In this work, we aimed to clarify the role played by hydrogen peroxide in the organic matter transformation and its interaction with iron species.…”