Environmental Engineering Reference
In-Depth Information
of Fe(II) with H
2
O
2
in aqueous media (Fenton
1894
). The Fenton's reaction has
been studied by several researchers afterwards (Haber and Weiss
1934
; Barb et al.
1951
; Hardwick
1957
; Wells and Salam
1967
,
1968
; Po and Sutin
1968
; Skinner
et al.
1980
; Rush and Bielski
1985
; Moffett and Zika
1987a
,
b
; Lloyd et al.
1997
;
Kremer
1999
; Lindsey and Tarr
2000
). Haber and Weiss in
1934
firstly postulated
that the reactivity of the Fenton's reagent is due to the generation of HO
.
in aqueous
solution, and that Fe(II) acts as a catalyst for the decomposition of H
2
O
2
into HO
•
.
The Fenton's reaction can be used to promote the oxidation of organic compounds
(Walling
1975
) and has been widely studied to this purpose in the last 25 years
(Sychev and Isak
1995
; Chen and Pignatello
1997
; Gallard et al.
1998
; Barbeni
et al.
1987
; Lindsey and Tarr
2000
; Kang et al.
2002
; Pignatello et al.
2006
).
Hydroxyl radical is also a photo-product of many photolysis reactions that
occur in natural waters (Zafiriou
1974
; Zafiriou and True
1979a
,
b
; Mill et al.
1980
; Draper and Crosby
1981
; Russi et al.
1982
; Zafiriou et al.
1984
; Cooper
et al.
1988
; Mopper and Zhou
1990
; Gjessing and Källqvist
1991
; Dister and
Zafiriou
1993
; Takeda et al.
2004
; Vione et al.
2006
,
2009a
,
b
; al Housari
et al.
2010
). In particular, HO
•
−
can be produced photolytically from NO
2
−
and NO
3
(Zafiriou and True
1979a
,
b
; Russi et al.
1982
; Takeda et al.
2004
;
Zafiriou and Bonneau
1987
; Zepp et al.
1987
; Zellner et al.
1990
; Brezonik and
Fulkerson-Brekken
1998
; Mack and Bolton
1999
) and upon irradiation of vari-
ous dissolved organic matter (DOM) components (Mill et al.
1980
; Mopper and
Zhou
1990
; Vaughn and Blough
1998
; Holder-Sandvik et al.
2000
). Hydroxyl
radical can be experimentally determined by use of selective probe molecules
such as cumene (isopropylbenzene) and pyridine in dilute solution, benzene, tere-
phthalic acid and and
para
-chlorobenzoic acid (
p
CBA) (Mill et al.
1980
; Takeda
et al.
2004
; Fang et al.
1996
). The rate of HO
•
production mostly depends on the
quantity and quality of DOM, on the concentration of other chemical species such
as nitrate and nitrite, and on the pH of natural waters.
The chemical reactivity of the Fenton's reaction (Fe
2
+
and H
2
O
2
) is signifi-
cantly increased by UV/Visible irradiation (
λ
< 580 nm), which has for instance
been shown to enhance the mineralization of organic pollutants (Haag and
Hoigné
1985
; Cooper et al.
1991
; Zepp et al.
1992
; Ruppert et al.
1993
; Faust
1994
; Voelker et al.
1997
; Arakaki et al.
1998
; Bossmann et al.
1998
; Rossetti
et al.
2002
; Zepp
2002
; Southworth and Voelker
2003
; White et al.
2003
).
Similarly, the H
2
O
2
/UV process can produce HO
•
that can decompose organic
substances in aqueous solution (Draper and Crosby
1981
; Zellner et al.
1990
;
Hunt and Taube
1952
; Baxendale and Wilson
1956
; Volman and Chen
1959
;
Ho
1986
; Vel Leitner and Dore
1996
; Berger et al.
1999
; Wang et al.
2001
;
Goldstein and Rabani
2008
) as well as in ice (Chu and Anastasio
2005
). An
advanced process that exploits the photo-Fenton system is the photo-ferrioxa-
late/H
2
O
2
reaction, where UV/visible irradiation (
λ
< 550 nm) is combined with
the presence of excess oxalate (Huston and Pignatello
1996
; Safazadeh-Amiri
et al.
1996
,
1997
; Wu et al.
1999
; Arslan et al.
2000
; Nogueira and Guimaraes
2000
; Emilio et al.
2002
; Lee et al.
2003
; Hislop and Bolton
1999
; Jeong and
Yoon
2005
). The HO
•
radical can also be generated in aqueous suspensions of
