Environmental Engineering Reference
In-Depth Information
Distyryl biphenyl
The aqueous solutions of distyryl biphenyl (DSBP) show two fluorescence peaks at
Ex/Em
=
350/436 nm (C-region) and at 235-265/435-445 nm (A-region) (Fig.
3
w,x;
Table
1
). The EEM images and the fluorescence peaks of DSBP (Fig.
3
w, x) are
similar to those of autochthonous fulvic acid (C-like), showing strong fluorescence
intensity at the peak C-region than at the peak A-region (Fig.
3
h-j). The DSBP com-
ponent (C-like) has been detected at Ex/Em
=
350-355/430-436 nm in the peak
C-region and at 235-265/431-446 nm in the peak A-region for a DSBP standard
dissolved in Milli-Q water, and at 345/435 and 245/437 nm for DSBP dissolved in
seawater (Table
1
) (Mostofa et al.
2010
; Komaki and Yabe
1982
; Nakajima
2006
).
DSBP is one of the key components of fluorescent whitening agents in natural waters
(Managaki and Takada
2005
). DSBP is rapidly decomposed by natural sunlight, at a
much faster rate compared to DAS1 in natural waters (Mostofa et al.
2005a
; Poiger
et al.
1999
). The molecular structure of (DSBP), 4,4′-bis[(2-sulfostyryl) biphenyl,
is shown in (Fig.
3
y), with a molecular weight of 562 Da. The DSBP photoinduced
decomposition is considered to be caused by an oxidative cleavage of the double
bond, followed by the production of various aldehydes such as 2-sulfonic acid ben-
zaldehyde, 4-aldehyde-4′-(2-sulfostyryl)biphenyl (4-benzaldehyde-2′-sulfonic acid-
stilbene) and 4,4′-bisaldehyde biphenyl (Guglielmetti
1975
; Kramer et al.
1996
).
Diaminostilbene-type
The Diaminostilbene-type (DAS1) shows several fluorescence excitation-emission
maxima at Ex/Em
=
335-355/430-449 nm (peak C-region) and at 240-250/433-
446 nm (peak A-region) in aqueous solution (Fig.
3
z; Table
1
). DAS1 fluorescence
peaks have been identified at Ex/Em
=
335-355/435-449 and 240-250/434-446 nm
for standard DAS1 in Milli-Q water and at 345/436 and 250/433 nm for standard
DAS1 dissolved in sea water; and at 340-343/430-432 nm for standard DAS1 in
aqueous solutions (Fig.
3
z) (Mostofa et al.
2010
; Komaki and Yabe
1982
; Nakajima
2006
). DAS1 is rapidly decomposed by natural sunlight, although it undergoes rela-
tively slower photodegradation compared to DSBP (Mostofa et al.
2005a
; Poiger et
al.
1999
). The molecular structure of DAS1, 4,4′-bis[(4-anilino-6-morphilino-s-tria-
zine-2-yl)amino] 2,2′-stilbenedisulfonate is shown in (Fig.
3
a′). Itsphotodegradation
yields alcohols, aldehydes and some unidentified products. It is reported that the
degradation of DSBP decreases in the presence of DOM, but it is not hindered by
DOM in natural waters (Kramer et al.
1996
). Its molecular weight is 924 Da.
Detergents (Commercial or Household)
The household detergents are composed of two fluorescent components identi-
fied using PARAFAC modeling on the EEM spectra of the detergents solutions
(Fig.
3
b′, c′). The first component is denoted as detergent component (C-like),
