Sho Communica ion
Sonochemical deg ada ion o iclosan in wa e and was ewa e
Lucia Sanchez-P ado
a
, Ru h Ba o
a
, Ca men Ga cia-Ja es
a
, Ma ia Llompa
a
,
Ma a Lo es
a
, Ch is os Pe akis
b
, Nicolas Kaloge akis
c
, Dionissios Man za inos
c
,
Ele e ia Psillakis
c,*
a
Depa men o Analy ical Chemis y, Nu i ion and B oma ology, Uni e si y o San iago de Compos ela, E-15782 San iago de Compos ela, Spain
b
Medi e anean Ag onomic Ins i u e o Chania (MAICh), P.O. Box 85, GR-73100 Chania, G eece
c
Depa men o En i onmen al Enginee ing, Technical Uni e si y o C e e, Poly echneioupolis, GR-73100 Chania, G eece
Recei ed 6 Augus 2007; accep ed 21 Janua y 2008
A ailable online 2 Feb ua y 2008
Abs ac
The sonochemical deg ada ion o 5 lgl
1
iclosan, a p io i y mic o-pollu an , in a ious en i onmen al samples (seawa e , u ban
unoff and influen domes ic was ewa e ) as well as in model solu ions (pu e and saline wa e ) was in es iga ed. Expe imen s we e con-
duc ed wi h a ho n- ype sonica o ope a ing a 80 kHz equency and a nominal applied powe o 135 W, while solid-phase mic oex ac-
ion coupled wi h gas ch oma og aphy–elec on cap u e de ec o (SPME/GC–ECD) was employed o moni o iclosan deg ada ion.
The la e ollowed pseudo-fi s o de kine ics wi h he a e cons an being (min
1
): 0.2284 o seawa e > 0.1051 o 3.5% NaCl in deion-
ised wa e > 0.0597 o cen i uged u ban unoff 0.0523 o un ea ed u ban unoff > 0.0272 o deionised wa e > 0.0063 o was ewa-
e influen . SPME/GC–ECD and SPME coupled wi h gas ch oma og aphy–mass spec ome y (SPME/GC–MS) we e also used o
check o he o ma ion o chlo ina ed and o he oxic by-p oduc s; a he condi ions in ques ion, he p esence o such compounds
was no confi med.
Ó2008 Else ie B.V. All igh s ese ed.
Keywo ds: Deg ada ion; SPME; T iclosan; Ul asound; Wa e ma ix
1. In oduc ion
T iclosan (5-chlo o-2-(2,4-dichlo ophenoxy)phenol) is
an an imic obial agen lis ed by he 76/768/EEC Eu opean
Union council di ec i e as a p ese a i e o cosme ic
p oduc s. I s widesp ead use in consume p oduc s such
as oo hpas es, an ipe spi an s, de e gen s, cosme ics,
an imic obial c eams, lo ions and hand soaps is due o i s
bac e ios a ic pe o mance agains a b oad spec um o
mic oo ganisms as well as i s a ou able human sa e y p o-
file. T iclosan is ypically anspo ed h ough a was e dis-
posal con eyance sys em o a sewage ea men acili y.
T ace le els o iclosan no emo ed du ing was ewa e
ea men a e eleased o he ecei ing wa e s as pa o
he effluen ma ix. Acco dingly, he p esence o iclosan
in was ewa e , su ace wa e , seawa e and sedimen s has
been equen ly epo ed in Eu ope and he Uni ed S a es
and his is o conce n gi en he ac ha unde ce ain con-
di ions (such as in p esence o hypochlo i e o due o pho-
ochemical eac ions), he na i e species can be con e ed
in o mo e oxic and pe sis en pola compounds, such
as chlo ina ed phenols (mainly 2,4-dichlo o and 2,3,4-
ichlo ophenol) polychlo ina ed biphenyl e he s and
dihyd oxyla ed de i a i es as well as non-pola and bio-
accumula i e species such as me hyl iclosan and polychlo-
ina ed dibenzodioxins [1–6].
The use o high powe ul asound wi h equencies in
he ange 20–1000 kHz induces he so-called acous ic ca i-
a ion. In gene al, ca i a ion can be defined as he phenom-
ena o he o ma ion, g ow h and subsequen collapse o
mic obubbles o ca i ies occu ing in ex emely small
1350-4177/$ - see on ma e Ó2008 Else ie B.V. All igh s ese ed.
doi:10.1016/j.ul sonch.2008.01.007
*
Co esponding au ho . Tel.: +30 28210 37810; ax: +30 28210 37852.
E-mail add ess: [email p o ec ed] (E. Psillakis).
www.else ie .com/loca e/ul sonch
A ailable online a www.sciencedi ec .com
Ul asonics Sonochemis y 15 (2008) 689–694
in e als o ime and eleasing la ge magni udes o ene gy
o e a e y small loca ion [7]. Today, he e a e se e al pub-
lica ions epo ing he success ul emo al o a wide ange
o o ganic pollu an s om ela i ely dilu e aqueous solu-
ions [7,8]. Howe e and o he bes o ou knowledge,
sonolysis o iclosan in wa e s and was ewa e s has no
been epo ed be o e. Mo eo e , iclosan deg ada ion by
ad anced oxida ion p ocesses o he han sonolysis has
ecei ed me e a en ion. In ecen epo s, Yu e al. [9]
s udied he TiO
2
-media ed pho oca aly ic deg ada ion in
model aqueous solu ions, while Sua ez e al. [10] in es i-
ga ed iclosan oxida ion be means o ozone.
The aim o his wo k is o in es iga e o he fi s ime he
sonolysis o iclosan, a p io i y mic o-pollu an , in aque-
ous samples o en i onmen al impo ance. I is well known
ha he p esence o ma ix componen s (such as sal , na u-
al o ganic and pa icula e ma e ) may d ama ically al e
he efficiency o sonochemical and o he ad anced oxida-
ion p ocesses. Acco dingly, he p esen wo k in es iga es
he effec o eal sample ma ix (seawa e , u ban unoff
and influen domes ic was ewa e ) upon iclosan sonolysis.
Fo he pu pose o he p esen in es iga ions solid-phase
mic oex ac ion (SPME) was used as a iable analy ical ool
o moni o ing he deg ada ion o iclosan as well as he
possible o ma ion o chlo ina ed by-p oduc s.
2. Expe imen al
2.1. Chemicals and sample p epa a ion
T iclosan (I gasan, 97%) was ob ained om Fluka,
Sigma–Ald ich (S einheim, Ge many). Pes icide g ade
me hanol and sodium chlo ide (>99.8% pu i y) we e
ob ained om Me ck (Da ms ad , Ge many) and Riedel
de Haen (Seelze, Ge many) espec i ely. Deionised wa e
was p epa ed on a wa e pu ifica ion sys em om Lab-
conco Wa e P o
TM
PS (Kansas Ci y, Missou i, USA). In
hose cases whe e samples had o be cen i uged p io o
sonica ion, his was done o 10 min a 4000 pm wi h a
He aus Mega uge cen i uge. Fo sample p epa a ion, a
1000 mg l
1
s anda d s ock solu ion o iclosan was ini-
ially p epa ed in me hanol. Spiked aqueous solu ions we e
p epa ed daily by spiking wa e wi h he o ganic s ock
solu ion o iclosan a he concen a ion le els o in e es .
2.2. Aqueous samples
Sonica ion expe imen s we e conduc ed wi h model
solu ions p epa ed in deionised wa e as well as wi h (i) sea-
wa e collec ed om Chania, Wes e n C e e, G eece, (ii)
u ban unoff collec ed om one o he exi s o he munici-
pal s o mwa e d ain sys em o Chania discha ging in
coas al wa e and (iii) was ewa e collec ed om he inle
o he seconda y ea men o he domes ic was ewa e
ea men plan o Chania. Real samples, whose p ope ies
a e summa ised in Table 1, we e collec ed he day be o e
he sonica ion expe imen was pe o med and we e ana-
lysed o hei o al o ganic ca bon (TOC) con en using
a Shimadzu TOC 5000A ins umen and o al dissol ed
solids (TDS) d ied a 180 °C acco ding o he S anda d
Me hod 2540 C [11]. pH and salini y we e measu ed using
a po able ins umen (pH/Cond340i) supplied by WTW
GmbH (Weilheim, Ge many).
2.3. SPME ex ac ion p ocedu e
The SPME me hod used is desc ibed in de ail elsewhe e
[12,13]. In b ie , a comme cially a ailable 100 lm poly-
dime hylsiloxane SPME fib e, housed in a manual SPME
holde (Supelco, Belle on e, PA, USA) was used o all
ex ac ions. Each ime, aliquo s o wa e samples (5 ml)
we e placed in 7 ml ials and di ec SPME was pe o med
by exposing he fib e o he solu ion. The ex ac ion was
ca ied ou o 30 min a oom empe a u e while s i ing
a 1250 pm.
2.4. Gas ch oma og aphic analyses
A Hewle –Packa d (HP 5890 Se ies II) gas ch oma og a-
phy–elec on cap u e de ec o (GC–ECD) sys em equipped
wi h a spli /spli less injec o was used o all analyses. The
sys em was ope a ed by HP ChemS a ion A03.04 so wa e.
Expe imen al condi ions we e column HP5-MS, 30 m 
0.25 mm i.d. 0.25 lm film; o en empe a u e p og amme:
60 °C, hold 2 min, a e 15 °C min
1
o 210 °C hen
10 °C min
1
o 270 °C, hold 10 min. The injec o was main-
ained a 280 °C and ope a ed in he spli less mode wi h he
spli closed o 2 min (spli a io 50:1). The de ec o empe -
a u e was 290 °C. Helium (>99.999 % pu i y) was used as he
ca ie gas a a cons an head p essu e o 130 kPa. The lin-
ea i y o he SPME me hod was e alua ed o iclosan con-
cen a ions be ween 0.1 and 50 lgl
1
and was ound o be
e y good ha ing a 0.996 co ela ion coefficien ( ). The
me hod’s de ec ion limi was es ima ed o be 0.01 lgl
1
.
Samples we e also analysed by means o SPME/GC–mass
spec ome y (MS). These analyses we e ca ied ou on a Shi-
madzu GC-17A, Ve sion 3, QP-5050A Gas Ch oma og aph/
Mass Spec ome e sys em (Shimadzu Co po a ion, Kyo o,
Japan) equipped wi h he same capilla y column (HP5-MS,
30 m 0.25 mm i.d. 0.25 lm film) and ha ing iden ical
injec o condi ions and o en empe a u e p og amme. The
ioniza ion mode was elec on impac (70 eV), he in e ace
empe a u e was se a 300 °C wi h 1.40 kV de ec o ol age
Table 1
P ope ies o eal samples used in his s udy (measu ed a 20 °C)
Sample Ini ial iclosan
con amina ion
(lgl
1
)
pH Salini y
(% w: )
TDS
(mg l
1
)
TOC
(mg l
1
)
Seawa e <0.01 8 3.5 51 3.5
U ban unoff 0.07 7.7 0.018 397 6.7
Influen domes ic
was ewa e
0.4 7.6 0.029 644 256
690 L. Sanchez-P ado e al. / Ul asonics Sonochemis y 15 (2008) 689–694
and he selec ed ion moni o ing (SIM) mode o ope a ion
was used as a sensi i e analy ical ool.
2.5. Sonica ion expe imen s
An Ul ason 250 (LabPlan , Hudde sfield, UK) ho n-
ype sonica o capable o ope a ing ei he con inuously o
in pulse mode a a fixed equency o 80 kHz and a a iable
elec ic powe ou pu up o 150 W was used. Reac ions we e
ca ied ou in a 250-ml ound-bo om cylind ical all-glass
eac ion essel equipped wi h a cooling jacke , connec ed
o a empe a u e con ol uni (Polys a cc2 model manu ac-
u ed by Hube , Ge many). The eac ion essel was co e ed
wi h aluminium oil, a oiding hus any pho ochemical eac-
ions. In all cases, 200 ml solu ions con aining 5 lgl
1
o
iclosan we e subjec ed o ul asonic i adia ion a a nom-
inal powe ou pu o 135 W wi h he sonica o ope a ing in
pulse mode (30 s ‘‘on”, 30 s ‘‘off”). I should be men ioned
he e, ha he ex emely low me hanolic con en did no
al e he physicochemical p ope ies o he syn he ic sam-
ples. Resul s a e quo ed wi h espec o he ac ual sonica-
ion ime (i.e. he ‘on’ pe iod o he du y cycle) a he
han he o e all ea men ime (i.e. he ‘on’ and ‘off’ pe iod
o he du y cycle) which was wice as much as he sonica ion
ime. Pulse ope a ion was chosen o minimise hea dissipa-
ion du ing sonica ion, hus acili a ing empe a u e con-
ol. Mo eo e , p elimina y expe imen s we e conduc ed
ei he lea ing he eac o ’s empe a u e uncon olled o
keeping i cons an a 20 °C; in ei he case, iclosan deg a-
da ion emained p ac ically unchanged. Hence, in all subse-
quen expe imen s he empe a u e o he eac ion essel
was le uncon olled.
3. Resul s and discussion
Fig. 1 shows iclosan no malised concen a ion– ime
p ofiles o he a ious samples subjec ed o ul asonic i a-
dia ion. As seen, nea ly comple e iclosan emo al could
be achie ed wi hin 120 min o i adia ion o all samples
bu he influen domes ic was ewa e o which only 60%
deg ada ion was eco ded a e 180 min o eac ion. Con-
e sely, deg ada ion in seawa e p oceeded apidly yielding
o e 95% con e sion in 15 min. Fo all samples, con ol
expe imen s we e un, whe e 5 lgl
1
aqueous solu ions
o iclosan we e le in he da k a ambien empe a u e
o he same pe iod o ime and in he absence o ul asonic
i adia ion, e ealing ha he dec ease in iclosan concen-
a ion was due o he effec o sonica ion alone.
Sonochemical deg ada ion o o ganic compounds a low
concen a ions usually ollows pseudo-fi s o de kine ics
ega ding subs a e concen a ion, i.e.
dCi
d ¼kCi() ln Ci;0
Ci

¼k ð1Þ
whe e kis an appa en eac ion a e cons an , and C
i,0
and
C
i
is he subs a e concen a ion a ime ze o and espec-
i ely. I he da a o Fig. 1 a e plo ed in he o m o
Eq. (1), s aigh lines passing h ough he o igin fi he
expe imen al da a well and a e cons an s can be calcula ed
om he slopes o he espec i e s aigh lines (plo s a e no
shown o b e i y). The compu ed a e cons an s a e
0.0272 (0.983), 0.1051 (0.996), 0.2284 (0.944), 0.0523
(0.994), 0.0597 (0.997) and 0.0063 min
1
(0.982) o deion-
ised wa e , 3.5% NaCl in deionised wa e , seawa e ,
0
20
40
60
80
100
120
0 20 40 60 80 100 120 140 160 180 200
Sonica ion ime (min)
C
i
/C
o
(%)
Deionised Wa e
Seawa e
3.5 % NaCl (w: )
U ban uno wa e
Cen i uged u ban uno wa e
In luen was ewa e
Fig. 1. No malised concen a ion– ime p ofiles du ing sonica ion o a ious samples spiked wi h 5 lgl
1
iclosan.
L. Sanchez-P ado e al. / Ul asonics Sonochemis y 15 (2008) 689–694 691
un ea ed u ban unoff, cen i uged u ban unoff and influ-
en domes ic was ewa e espec i ely wi h numbe s in
b acke s showing he co ela ion coefficien s ( ) o he lin-
ea eg ession o he loga i hm o concen a ion agains
ime.
As clea ly seen, inc easing he ionic s eng h o he sam-
ple had a beneficial effec on deg ada ion; a ou o eigh -
old inc ease in he eac ion a e was eco ded when
iclosan was ea ed in deionised wa e in he p esence o
3.5% NaCl o seawa e compa ed o he un wi hou sal .
Seymou and Gup a [14] who in es iga ed he effec o
sodium chlo ide addi ion upon he sonochemical deg ada-
ion o aqueous solu ions o chlo obenzene, p-e hylphenol
and phenol a 20 kHz ound ou ha he p esence o NaCl
imp o ed subs an ially deg ada ion a es. The enhance-
men in deg ada ion a es was a ibu ed o he sal ing-
ou effec , whe e ewe wa e molecules a e a ailable o
dissol ing he analy e molecules. The e o e, he solu e is
expec ed o mig a e om he liquid bulk inside o nea
he ca i a ion bubble whe e deg ada ion ia py olysis
and/o hyd oxyl adical-induced eac ions is likely o occu
as [15,16]. The ac ha deg ada ion in seawa e was as-
e han in a ificial saline wa e may be associa ed wi h he
wa e ma ix o he o me . Ino ganic and o ganic species
can se e as ex a nuclei o ca i a ion as well as al e he
gas and in e acial p ope ies o he ca i a ion bubble influ-
encing hus he empe a u e, p essu e and chemical species
p esen du ing he bubble collapse [17].
In u he uns, iclosan deg ada ion in u ban unoff
wa e was s udied. Non-poin sou ce pollu ion, unlike pol-
lu ion om indus ial and sewage ea men plan s, comes
om many diffuse sou ces and is caused by ain all o
snowmel mo ing o e and h ough he g ound. As he
unoff mo es, i washes na u al and human-made pollu-
an s, finally deposi ing hem in o lakes, i e s, we lands,
coas al wa e s, o e en in unde g ound sou ces o d inking
wa e . Acco ding o he USEPA, u ban unoff wa e s ep-
esen one o he leading sou ces o wa e quali y impai -
men . Indeed, in he unoff wa e samples in es iga ed
he e, he p esence o iclosan was confi med (0.07 lgl
1
).
Sonochemical deg ada ion in u ban unoff was abou wice
as as as ha in deionised wa e and o e 90% con e sion
was eco ded in abou 60 min o eac ion. This can be
explained in e ms o dissol ed solids acili a ing nuclea ion
which appea s o be p edominan in he case o u ban un-
off. Keck e al. [18] who in es iga ed he sonochemical deg-
ada ion o a ious a oma ics in he p esence and absence
o ine qua z pa icles in he ange 2–25 lm epo ed ha
pe o mance was enhanced in he p esence o solids and
his was asc ibed o solids al e ing he shape o bubbles
om sphe ical o asymme ic, hus yielding la ge su aces
a ailable o eac wi h mo e solu e molecules. Fo he pu -
pose o he p esen s udies he expe imen was also
epea ed wi h he unoff sample being cen i uged p io
o iclosan con amina ion. As seen, he e was no signifi-
can change in he a es o deg ada ion which we e in bo h
cases as e han he one ound in deionised wa e . How-
e e , when compa ing he aw unoff sample wi h he cen-
i uged one, a sligh dec ease in a e (12%) was obse ed
when he sample was no cen i uged ( aw) and i appea s
ha al hough solid pa icles acili a ed nuclea ion o his
ype o was ewa e , a second and mino effec akes place
whe eby adso p ion o solu e molecules o pa icles is
esponsible o he small dec ease in deg ada ion a e.
Zhang and Hua [19] s udied he sonochemical deg ada ion
o b omobenzene, b omophenola e ion, and 2,4,5- ichlo-
obiphenyl in he p esence o 10 nm and 15 lm silica pa i-
cles and 35 lm o ganic esin ( ep esen ing as he au ho s
s a ed he ‘‘wo s case”) wi h he la e wo being sepa a ed
om he solu ion by cen i uga ion. O e all, he au ho s
ound ha he sonochemical decomposi ion a e cons an
o b omobenzene was no significan ly impac ed by e y
fine silica pa icles (10 nm) because hei diame e was
much smalle han he sound wa eleng h and as such could
no impac he sound field. In he p esence o he 15 lm sil-
ica pa icles, esul s we e simila o he ones epo ed he e
and sonica ion a es dec eased sligh ly (<7%) due o pa ial
adso p ion o he solu e molecules o he solid pa icles. As
expec ed he effec was mo e d ama ic when la ge pa icles
such as o ganic esin (35 lm) we e p esen in he sonica ed
mix u e [19]. Al hough la ge pa icles may se e as nuclei
o bubble o ma ion, hey can also so b hyd ophobic
chemicals mo e effec i ely impeding hus hei pa i ioning
wi h he collapsing ca i a ion bubble [19,20]. This is in
ag eemen wi h he esul s ob ained he e o he domes ic
was ewa e sample whe e iclosan deg ada ion was ound
o p oceed a subs an ially lowe a es han in any o he
sample es ed. I is also possible ha su ac an s, ypically
p esen in domes ic was ewa e , accumula e in he in e a-
cial egion, hus educing he numbe o si es a ailable o
iclosan deg ada ion [16,21].
The analy ical p o ocol used in his s udy was also capa-
ble o checking o he chlo ina ed by-p oduc s a ising om
iclosan deg ada ion as hese may ac ually be mo e oxic
han iclosan i sel as well as be dioxins p ecu so s. Canosa
e al. [2] de eloped a SPME-based me hod o de ec ing
iclosan and i s me aboli es, namely me hyl iclosan, 2,4-
dichlo ophenol and 2,3,4- ichlo ophenol in aqueous sam-
ples (including influen and effluen was ewa e samples o
an u ban sewage plan ). The use o SPME also enabled
moni o ing he pho ochemical deg ada ion o iclosan in
wa e and was ewa e when exposed o ul a iole (UV)
o sunligh i adia ion [4,12,13]. These s udies confi med
he iclosan o dioxin con e sion and he o ma ion o
me aboli es such as chlo ina ed phenols, chlo ohyd oxydi-
phenyl e he s, 2,8-dichlo odibenzo-p-dioxin and dichlo o-
dibenzodioxin isome o dichlo ohyd oxydibenzo u an
in a a ie y o en i onmen al ma ices. I has also been
epo ed [9] ha he UV/TiO
2
-induced pho oca aly ic
decomposi ion o iclosan was accompanied by he o ma-
ion o 2,4-dichlo ophenol, a p io i y oxic pollu an which
is known o be a dioxin p ecu so . In his wo k and unde
he p esen expe imen al condi ions, none o he a o emen-
ioned me aboli es was de ec ed in any o he samples
692 L. Sanchez-P ado e al. / Ul asonics Sonochemis y 15 (2008) 689–694
es ed. This is clea ly demons a ed in Fig. 2 whe e diffe en
SPME/GC–ECD ch oma og ams ob ained be o e (Fig. 2b)
and a e (Fig. 2c and d) sonica ion o he cen i uged u ban
unoff sample a e shown. I should be men ioned he e ha
simila ch oma og ams we e ob ained o he es o he
samples ea ed he e. Compa ison be ween he ch oma o-
g am co esponding o he o iginal, unspiked sample
(Fig. 2a) and he ones ob ained a e spiking wi h 5 lgl
1
iclosan (Fig. 2b) o e en a e sonica ion (Fig. 2c and d)
e eals ha he pa e n o he ex a peaks appea ing in
he o iginal ch oma og am emains p ac ically unchanged.
These ex a peaks appea ing in all ch oma og ams a e due
o he ma ix and/o he use o SPME as a p econcen a ion
me hod in which case he peaks a e commonly e e ed o as
SPME con aminan s. The assump ion ha iclosan sono-
chemical deg ada ion is no accompanied by he o ma ion
o oxic by-p oduc s was also c oss-checked and confi med
by means o SPME/GC–MS (SIM mode) analysis.
The absence o chlo ina ed by-p oduc s in he eac ion
mix u e may be asc ibed o he ac s ha (i) he hyd opho-
bic iclosan (i s solubili y is abou 1 mg l
1
a oom em-
pe a u e and he loga i hm o he oc anol–wa e pa i ion
coefficien is 4.8 [22]), may be localised nea he ca i a ion
bubble and unde go as he mal deg ada ion, hus mini-
mising by-p oduc o ma ion and/o (ii) he a e o by-
p oduc s o ma ion is lowe han he a e o hei sono-
chemical deg ada ion and, consequen ly, hey do no accu-
mula e in he eac ion mix u e.
Fig. 2. SPME/GC–ECD ch oma og ams o he cen i uged u ban unoff sample (a) be o e spiking; (b) a e spiking wi h 5 lgl
1
iclosan and jus be o e
sonica ion; (c) a e 15 min o sonica ion; (d) a e 120 min o sonica ion.
L. Sanchez-P ado e al. / Ul asonics Sonochemis y 15 (2008) 689–694 693

4. Conclusions
The low equency sonochemical deg ada ion o iclo-
san in se e al model and ac ual samples o en i onmen al
impo ance has been in es iga ed. In nea ly all cases,
comple e con e sion can be achie ed a easonable ea -
men imes; howe e , he a e o deg ada ion is e iden ly
affec ed by he ma ix componen s p esen in he a ious
samples. The effec may be an inc ease o dec ease depend-
ing on he beha iou o he ma ix compound. O e all,
deg ada ion dec eases in he o de : seawa e > 3.5% NaCl
aqueous solu ion > cen i uged u ban unoff un ea ed
u ban unoff > deionised wa e > was ewa e influen . A
he expe imen al condi ions in ques ion, deg ada ion was
no accompanied by he o ma ion o oxic me aboli es
which commonly appea as by-p oduc s o iclosan na u-
al a enua ion.
Acknowledgemen s
L.S.-P. and R.B. acknowledge he egional go e nmen
Jun a de Galicia o hei doc o al and a el g an s. The
au ho s would like o hank V. Koukou aki o conduc ing
TOC measu emen s.
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