Data di Pubblicazione:
2012
Abstract:
In previous works, it was observed that phenol photo-induced transformation in natural seawater (NSW)
mediated by natural photosensitizers occurs and leads to the formation of numerous hydroxylated, condensed,
halogenated and nitroderivatives. Irradiation of NSWadded with phenol and iron species had provided the
enhanced formation of several halophenols, suggesting a central role played by iron species on the phenol
halogenation in marine water.
In this paper, we focus on hydrogen peroxide, another key photosensitizer, and its interaction with iron
species. The ability of Fe(II)/Fe(III) and H2O2 species to act as photo-sensitizers towards the transformation
of organic compounds in seawater was investigated under simulated solar radiation.
Light activation is necessary to induce the transformation of phenol, as no degradation occurs in the dark
when either H2O2 or iron/H2O2 are initially added to artificial seawater (ASW). Fe(II) is easily transformed
into Fe(III), assessing that a Fenton reaction (dark, Fe(II)/H2O2) does not take place inmarine environment,
in favour of a photo-activated reaction involving Fe(III) and H2O2.
When NSW is spiked with H2O2 and Fe(III), halophenols' and nitrophenols' concentration decreases and
completely disappears at high hydrogen peroxide concentration. Since Fe(II) and Fe(III) in spiked seawater
induce an enhanced formation of haloderivatives, an excess of hydrogen peroxide act as scavenger towards
the photo-produced chloro/bromo radicals, so hindering halogenation process in seawater. Hence, even if hydrogen
peroxide efficiently induces the •OH radical formation, and could then promote the phenol phototransformation,
nevertheless it is negligibly involved in the production of the intermediates formed during phenol photolysis in
seawater, whose formation is necessarily linked to other photosensitizer species.
Tipologia CRIS:
03A-Articolo su Rivista
Keywords:
Hydrogen peroxide; Seawater; Phototransformation; Phenol; Iron species
Elenco autori:
P. Calza; L. Campra; E. Pelizzetti; C. Minero
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