Bn

Tugba Olmez-Hanci , Duygu Dursun , Egemen Aydin , Idil Arslan-Alaton , Binhan Girit , Luigi Mita ,Nadia Diano b,c, Damiano G. Mitaa Istanbul Technical University, Civil Engineering Facultyb I.N.B.B. National Laboratory on Endocrine Disruptorsc Seconda Universit di Napoli, Department of ExperimedUniversit di Napoli Federico II, Department of Biology

bonate plastics, employed in food and drink packaging applica-tions, baby bottles and dental sealants (Staples et al., 1998). Ithas been reported that BPA is ubiquitous in the environment,including surface water, groundwater and treated drinking water(Umar et al., 2013). In natural waters, BPA is usually present atlower concentrations (20 min)and TOC removals were considerably retarded (by 40%) in the raw freshwater matrix most probablydue to its natural organic matter content (TOC = 5.1 mg L1). H2O2/UV-C and S2O82/UV-C treatment inraw freshwater did not result in toxic degradation products.

2014 Elsevier Ltd. All rights reserved.a r t i c l e i n f o

Article history:Received 30 December 2013Received in revised form 15 May 2014Accepted 11 June 2014Available online xxxx

Handling Editor: J. de Boer

Keywords:Bisphenol AAcute toxicityYeast Estrogen Screen (YES) assayS2O82/UV-C and H2O2/UV-C treatmentsb, Marco Guida b,d

, Environmental Engineering Department, 34469 Maslak, Istanbul, Turkey, Via Pietro Castellino 111, 80131 Napoli, Italyntal Medicine, Via de Crecchio 7, 80138 Napoli, Italy, Via Cinthia ed. 7, 80126 Napoli, Italy

a b s t r a c t

The performance of S2O82/UV-C and H2O2/UV-C treatments was investigated for the degradation and

detoxication of Bisphenol A (BPA). The acute toxicity of BPA and its degradation products was examinedwith the Vibrio scheri bioassay, whereas changes in estrogenic activity were followed with the YeastEstrogen Screen (YES) assay. LC and LCMS/MS analyses were conducted to determine degradation prod-ucts evolving during photochemical treatment. In addition, BPA-spiked real freshwater samples were alsosubjected to S2O82/UV-C and H2O2/UV-C treatment to study the effect of a real water matrix on BPAremoval and detoxication rates. BPA removal in pure water was very fast (67 min) and complete viaboth H2O2/UV-C and S2O8

2/UV-C treatment, accompanied with rapid and signicant mineralization ratesranging between 70% and 85%. V. scheri bioassay results indicated that degradation products being moretoxic than BPA were formed at the initial stages of H2O2/UV-C whereas a rapid and steady reduction intoxicity was observed during S2O8

2/UV-C treatment in pure water. UV-C treatment products exhibiteda higher estrogenic activity than the original BPA solution while the estrogenicity of BPA was completelya, a a a a bS2O82/UV-C and H2O2/UV-C treatment ofof toxicity, estrogenic activity, degradatiowater

journal homepage: www.elsisphenol A: Assessmentproducts and results in real

le at ScienceDirect

phere

er.com/locate /chemospherectivity,

ment time were optimized (Olmez-Hanci et al., 2013). Samples

mosAdvanced oxidation processes (AOPs) have received great atten-tion and academic interest in recent years as complementarymethods to conventional water treatment or as alternative treat-ment strategies for industrial wastewater prior to discharge intosewage or into receiving water bodies (Parsons, 2004). There is agrowing interest in investigating the use of ultraviolet (UV) irradi-ation and UV based AOPs for treatment of EDCs (Chen et al., 2006;Gultekin and Ince, 2007; Huang and Huang, 2009). The effective-ness of direct UV-C photolysis is governed by the absorption spec-tra of the contaminant and the quantum yield, the addition ofhydrogen peroxide (H2O2) or persulfate (S2O82) to generate highlyactive free radicals such as hydroxyl (HO) and sulfate (SO4) oftensignicantly lowers the UV dose required for oxidation as com-pared to direct photolysis (Antoniou et al., 2010; Gao et al., 2012;Olmez-Hanci and Arslan-Alaton, 2013).

Activation of symmetrical peroxides such as H2O2 and S2O82

under UV-C radiation results in the formation of two HO and SO4,respectively (Eqs. (1) and (2)) through the homolytic cleavage of theperoxide (OO) bond (Baxendale and Wilson, 1957; Mark et al.,1990; Anipsitakis and Dionysiou, 2004):

H2O2 hm! 2HO U 1:0 1

S2O28 hm!2SO4 U1:4 de-oxygenated; 1:8 oxygen saturated 2Both of these radicals are extremely active and short-lived

(103 ls for HO and 3040 ls for SO4) due to their high reductionpotentials (Eo = 1.892.72 eV for HO and Eo = 2.53.1 eV for SO4;Pikaev and Zolotarevskii, 1967; Buxton et al., 1988; Neta et al.,1988).

During the application of AOPs, the main concern relates to theformation of various degradation products that can potentially bemore toxic, estrogenic and persistent than the original compound(Ioan et al., 2007; Li et al., 2007). Thus, the identication of degra-dation products accompanied with a comprehensive toxicityassessment becomes important when deciding for the feasibilityand ecotoxicological risk of an oxidative treatment application(Huang and Huang, 2009; Rizzo, 2011; Catapane et al., 2013). Inorder to increase the reliability of toxicity assessment, especiallyif EDCs and their degradation products are questioning, bioassayscovering different modes of toxic action (e.g. estrogenicity ornon-specic toxicity) must be used. In recent works examiningoxidation and the corresponding removal of estrogenic activityassociated with EDCs via AOPs, a consistency between removal ofestrogenic activity, toxicity and parent compound abatementswas discovered (Chen et al., 2006; Neamtu and Frimmel, 2006;Frontistis et al., 2011).

The presence of carbonate species (HCO3, CO32), natural organicmatter (NOM) and other organic and inorganic compounds in nat-ural water matrices might signicantly affect the efciency of AOPs(Trov et al., 2009; Snchez-Polo et al., 2013). Moreover, the degra-dation products formed during the application of AOPs in pure andnatural water might be different and consequently their ecotoxico-logical behavior might differ as well (Trov et al., 2009; Aydin,2014). It is not exactly known how EDCs will behave in real watermatrices during photochemical treatment; probably different thanin pure water. From the practical point of view it would be of inter-est to investigate treatability of EDCs in real water samples (Fatta-Kassinos et al., 2011).

In the present study the treatability of BPA via H2O2/UV-C andS2O82/UV-C was comparatively evaluated. Changes in acute toxic-ity and estrogenic activity patterns were studied by employing twodifferent bioassays; namely the Vibrio scheri (V. scheri) test pro-tocol and the Yeast Estrogen Screen (YES) assay. Liquid chromatog-

2 T. Olmez-Hanci et al. / Cheraphy-tandemmass spectrometry-mass spectrometry (LCMS/MS)analysis was carried out to identify the BPA degradation products.Moreover, carboxylic acids were quantied via high performance

Please cite this article in press as: Olmez-Hanci, T., et al. S2O82/UV-C and H2O2degradation products and results in real water. Chemosphere (2014), http://dxwere taken at regular time intervals for up to 120 min and ana-lyzed for BPA, total organic carbon (TOC), S2O82 or H2O2 and pH.Although the initial BPA concentration investigated was extremelyhigh as compared to the concentrations typically detected in waterand wastewater, it was decided to select a high BPA concentrationto enable accurate kinetic, toxicological and analytical assessmentliquid chromatography (HPLC) to enable comparison of reactionpathways of the selected treatment processes. In the nal part ofthe study, a series of S2O82/UV-C and H2O2/UV-C experiments wereconducted in raw freshwater spiked with BPA to elucidate thetreatability and detoxication behavior of BPA in real watermatrices.

2. Materials and methods

2.1. Materials

BPA (228 g mol1; C15H16O2; CAS No: 80-05-7, purity: 99.9%)and potassium persulfate (K2S2O8; purityP99.5%) were purchasedfrom SigmaAldrich (USA) and used as received. Hydrogen perox-ide (H2O2; 35% w/w) of analytical grade and acetonitrile of chro-matographic grade were obtained from Merck (Germany).Aqueous BPA solutions were prepared with distilled water. Ultra-pure water for the chromatographic measurements was preparedwith an Arium 611UV water purication system (Sartorius AG,Germany). All other chemicals required for analytical and experi-mental procedures were at least of analytical grade.

2.2. The raw freshwater sample

Raw (untreated) freshwater sample was obtained from a localwater treatment plant of the Istanbul Metropolitan Municipality.Raw freshwater sample was shipped in 25 L plastic bottles andstored in a cool room at 4 C until the experiments were per-formed. The environmental characterization of the raw freshwatersample is shown in Table 1. TOC and absorbance at 254 nm (UV254)constitute a signicant indication of the NOM present in raw fresh-water. The experimental conditions for raw freshwater samplespiked with 20 mg L1 BPA were similar to those carried out inpure water however the initial pH was the natural pH of raw fresh-water (8.6).

2.3. The UV-C photoreactor and experimental procedure

UV-C, H2O2/UV-C and S2O82/UV-C treatment experiments wereconducted at room temperature (25 2 C) in an octagonal photo-chemical reaction chamber (diameter: 30 cm) equipped with a dig-itally controlled thermometer, a chronometer and a magneticstirrer. The chamber consisted of a maximum of six UV-C lamps(8 W each), with three of them being placed on two (left and right)reactor walls. The maximum emission band of the UV-C lamps was253.7 nm. The UV-C light uency was determined as 2.27 W L1

via H2O2 actinometry (Nicole et al., 1990). All experiments wererun in a 2500 mL-capacity cylindrical quartz reactor that was con-tinuously stirred at a constant rate of 100 rpm with a magnetic stirbar from the reactor bottom to keep the reaction mixture mixed.No temperature control was provided since the low pressure UV-C lamp used in the present work did not heat up during the exper-iments. 20 mg L1 (88 lM) of BPA aqueous solutions were treatedat pH 6.5 in all experiments based on preliminary baseline exper-iments, where oxidant concentration, pH and photochemical treat-

phere xxx (2014) xxxxxxof BPA and its degradation products. All experiments were done atleast in duplicate and average values were used in presenting theresults.

/UV-C treatment of Bisphenol A: Assessment of toxicity, estrogenic activity,.doi.org/10.1016/j.chemosphere.2014.06.020

mosp2.4. Analytical procedures

2.4.1. BPA analysisBPA was quantied with an Agilent 1100 Series HPLC equipped

with a Diode-Array Detector (DAD; G1315A, Agilent Series) set at214 nm. A C18 Symmetry column (3.9 mm 150 mm; 5 lm parti-cle size; Waters, USA) was employed as a stationary phase, whilethe mobile phase was a mixture of acetonitrile/water used at aratio of 50/50 (v/v). The ow rate and temperature of the columnwere set as 1.0 mL min1 and 25 C, respectively. The instrumentdetection and quantication limit of BPA for an injection volumeof 50 lL was calculated as 70 lg L1 and 210 lg L1, respectively.

2.4.2. Vibrio scheri bioassayThe acute toxicity toward the luminescent bacteria V. scheri

was measured during UV-C, H2O2/UV-C and S2O82/UV-C treat-ments in pure and raw freshwater spiked with BPA using a com-mercial assay kit marketed as BioTox (Aboatox Oy, Finland)according to the test protocol ISO 11348-3 (2007). Prior to theassay the pH and salinity of all samples was adjusted to 7.0 0.2

Table 1Environmental characterization of the raw freshwater sample.

Parameter Unit Value

TOC mg L1 5.1Alkalinity mg CaCO3 L1 124Hardness mg CaCO3 L1 116Color PtCo 10Turbidity NTU 1.5SS mg L1 bdla

pH 8.6UV254 0.0795UV280 0.0640UV400 0.0085UV436 0.0063Cl mg L1 25.5F mg L1 0.11NO2 mg L1 bdla

NO3 mg L1 1.6SO42 mg L1 13PO43 mg L1 bdla

BPA mg L1 bdla

a Below the detection limit.

T. Olmez-Hanci et al. / Cheand 2% (w/v), respectively. After mixing 500 lL of untreated orphotochemically treated BPA solutions with 500 lL luminescentbacterial suspensions, the light emission after 15 min contact timewas measured at a temperature of 15 C. Percent relative inhibitionrates were calculated on the basis of a toxicant-free control. A posi-tive control sample with potassium dichromate was also includedfor each test and all bioassays were run in triplicate. In order toeliminate their positive effect on toxicity measurements, resid-ual/unreacted H2O2 or S2O82 in the reaction solution was removedwith sodium thiosulfate (Merck; Germany) and enzyme catalase(made from Micrococcus lysodeikticus; Fluka; Sweden), respec-tively. Control samples were prepared for catalase and thiosulfateexactly at the concentration used to remove the above mentionedoxidants. Their presence in the test solution did not cause any sig-nicant bioluminescence inhibition (

of the TOC content of degradation products (TOCDP; in mg L )

or (photo)catalyst, no signicant TOC removal was observed during

the TOC content of the degradation products (TOCDP) reached theirhighest value of 13.8 mg L1 and the removal of TOCDP coincidedwith the measured TOC. As it can be also followed from Fig. 1(c),BPA removal was complete after 5 min treatment for the S2O82/UV-C process. As in the case of H2O2/UV-C oxidation, TOC graduallydecreased and the overall, nal TOC removal efciency of 70% wasreached at the end of 120 min treatment. Residual S2O82 concentra-tions followed a similar trend to TOC removal patterns; after120 min treatment time, S2O82 was completely consumed (datanot shown). After 5 min, where BPA was entirely converted to itsdegradation products, TOCDP concentration peaked at a level of13.5 mg L1 and decreased steadily to 4.4 mg L1 after 120 min.During photochemical treatment, oxidant abatement was also fol-lowed (not shown data). H2O2 and S2O82 were totally consumedin 6090 and 120 min, respectively, indicating that sufcientamounts of oxidants to produce HO and SO4 were available in

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Fig. 1. UV-C (a) H2O2/UV-C (b) and S2O82/UV-C (c) treatment of aqueous BPA.Experimental conditions: BPA = 20 mg L1 (88 lM); TOC = 16 mg L1; Oxidantdose = 2.5 mM; initial reaction pH = 6.5; Applied UV-C dose = 21 W h L1.

mostreatment (Molkenthin et al., 2013). Furthermore, TOCDP graduallyincreased during the course of UV-C treatment supporting evidenceof the formation and subsequent accumulation of degradationproducts. Different from UV-C photolysis, BPA removal was verybeing calculated by subtracting the organic carbon content comingfrom the remaining BPA (OCBPA; organic carbon equivalent of resid-ual BPA; in mg L1) from the measured TOC (in mg L1) were alsoshown in Fig. 1. As it is evident in Fig. 1(a), direct UV-C photolysisof BPA was slow and hence incomplete, resulting in an overall BPAremoval of 52% after 120 min.

In principle, complete mineralization of organic pollutants maybe achieved by means of UV-C photolysis. However, this wouldrequire extended irradiation times and large energy quantities. Itis generally expected that degradation (photolysis) products mightbe more problematic from a toxicological point of view, like in thecase of hydroxylamines (Huber et al., 2003), phenols, quinones car-boxylic acids and aldehydes (Toor and Mohseni, 2007). Thus, theoxidation efciencymeasured in terms of the TOC parameter mightbemore important than the removal of the parent compound due toecotoxicological safety concerns. As expected, for a degradationprocess carried out in the absence of any enhancing oxidant and/(adjusted with methanesulphonic acid). The ow rate and injectionvolume were 0.6 mL min1 and 50 lL, respectively. The organicacids were qualied via DAD at 210 nm and the column tempera-ture was set as 30 C.

2.4.5. Other measurementsTOC was measured on a Shimadzu VPCN analyzer (Japan)

equipped with an autosampler by catalytic oxidative combustionat 680 C, using an infrared detector. An Orion (USA) 720 + modelpH-meter was used for pH measurements. Residual H2O2 andS2O82 concentrations were traced by employing the iodometricmethod according to Wahba et al. (1959) and Ofcial Methods ofAnalysis (1980), respectively. The UV absorbance of the pure andraw freshwater samples was measured on a Perkin Elmer Lambda25 spectrophotometer in 1 cm quartz cuvettes. Anion analysiswas conducted using a Dionex ICS-1500 ion chromatography unitequipped with a conductivity detector, a Dionex IonPac AG14A(4 50 mm) guard column and a Dionex IonPac AS14A(4 250 mm) analytical column. The ion chromatography unitwas operated in auto-suppression mode with 1 mM sodium bicar-bonate/8 mM sodium carbonate eluent at a ow rate of 1 mL min1.

3. Results and discussion

3.1. H2O2/UV-C and S2O82/UV-C treatment of BPA

In order to assess the capacities of H2O2/UV-C and S2O82/UV-Ctreatment processes to degrade BPA and its organic carbon content,experiments were conducted with 20 mg L1 (88 lM) aqueous BPAsolutions at an initial oxidant concentration and pH of 2.5 mM and6.5, respectively. Selection of these experimental reaction condi-tions was based on preliminary baseline experiments that wereconducted to establish most suitable oxidant concentration andreaction pH to enhance BPA treatment by H2O2/UV-C and S2O82/UV-C processes (Olmez-Hanci et al., 2013).

Fig. 1 displays the time dependent changes in BPA and TOCremoval efciencies for direct UV-C photolysis (a), H2O2/UV-C (b)and S2O82/UV-C (c) treatment experiments which were conductedin order to evaluate the degradation pattern of BPA. The evolution

1

4 T. Olmez-Hanci et al. / Chefast and complete in a few min during H2O2/UV-C treatment. TOCremoval also proceeded rapidly; a gradual decrease was observedresulting in 85% TOC removal. After complete degradation of BPA,

Please cite this article in press as: Olmez-Hanci, T., et al. S2O82/UV-C and H2O2degradation products and results in real water. Chemosphere (2014), http://dx0

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phere xxx (2014) xxxxxxthe reaction solution during treatment.Under the studied reaction conditions, BPA and TOC removals

as well as S2O82 and H2O2 consumption rates followed pseudo

/UV-C treatment of Bisphenol A: Assessment of toxicity, estrogenic activity,.doi.org/10.1016/j.chemosphere.2014.06.020

rst-order kinetics with high correlation coefcients (R2P 0.96).Table 2 presents the apparent rst-order BPA and TOC removalsas well as S2O82 and H2O2 consumption rate constants k (in min1)calculated for photochemical treatment in pure water (PW) andraw freshwater (RW). From Table 2 it can be seen that BPA removal

3.60 min, 4.47 min, and 3.60 min retention times, respectively.133 m/zwas observed starting from the 1stminute of theUV-C pho-tolysis and reached its maximum peak area after 30 min treatment.149 m/zwas observedwith very small peaks reaching itsmaximumat 30 min. 213 m/z appearance started after 60 min treatment andreached itsmaximumpeak area in120 min. 218.9 m/zwasobservedafter 10 min treatment and reached its maximum peak area in30 min. The maximum peak area for 308.9 m/z was present in the90 min sample and rst appeared after 7 min (Supporting Informa-tion Fig. S1). Spectra of MS/MS transitions for possible transforma-tion products of BPA during UV-C treatment were provided inSupporting Information Figs. S2S5. No matches were found forthese spectra in Massbank Library. 135 m/z, 194.6 m/z, 201 m/z,and 276 m/zwith 2.60 min, 4.35 min, 2.32 min, and 2.16 min reten-tion times, respectively were the possible transformation productsfor H2O2/UV-C process. 135 m/z was formed 1st minute of the pro-cess and was observed in all samples. It was reached its maximumpeak area in 30 min. 194.6 m/z was observed between 1 and

T. Olmez-Hanci et al. / Chemosprates were similar for both processes whereas TOC and oxidantabatements rates were slightly higher for H2O2/UV-C process.

3.2. Acute toxicity results

The toxicity analysis of the BPA solutions during different stagesof UV-C, H2O2/UV-C and S2O82/UV-C treatments in pure water wasmonitored with V. scheri (Fig. 2). Toxicity results indicated thatthe untreated BPA sample caused an inhibitory effect of 75%. Nev-ertheless, as UV-C photolysis progressed, a general reduction in theinhibitory effect of BPA was evident speaking for the fact that UV-Cphotolysis products of BPA were not more toxic than the originalBPA solution. However photo-intermediates generated duringUV-C photolysis were not further transformed and thus, they,and their associated toxicity (64%), remained in solution at theend of the 120 min treatment (corresponding to a UV dose of21 W h L1). V. scheri appeared to be very sensitive; reacting rap-idly to the decrease in BPA concentration as well as formation ofdegradation products during H2O2/UV-C treatment. As can be seenfrom Fig. 2, a prompt decrease down to 14% (5 min) was observed,followed by a re-increase to 94% after 30 min treatment. Beyondthis treatment period the inhibitory effect decreased to practicallynon-toxic levels (13% relative inhibition) after 120 min oxida-tion due to the ultimate oxidation of BPA degradation productsthat resulted in over 80% TOC abatement. From the ndings it isapparent that rapid BPA degradation accompanied with efcientTOC elimination during H2O2/UV-C treatment also decreased theacute toxicity of BPA and its degradation products. In case ofS2O82/UV-C treatment, the toxic effect of BPA solution rapidlydecreased to practically non-toxic levels (

1000(a)

mosthat 135 m/z is 3-methylbenzoic acid thanks to very good match(score = 0.94) withMassbank library (Fig. 4). 201 m/z was proposed

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Fig. 3. Estrogenic activity of estradiol expressed in MU (a) and changes inestrogenic activity of the reaction solutions during photochemical treatments (b).Estrogenic activity reductions were expressed as percent MU with respect to t = 0.Experimental conditions as in Fig. 1.1200E2

6 T. Olmez-Hanci et al. / Cheas 4-sulfobenzoic acid with a match with Massbank library having0.88 score (Fig. 5). No Massbank library match could be found withthe MS/MS spectra of other ions (Supporting Information Figs. S7S9). Since no MS/MS transitions can be found for the S2O82/UV-Cprocess samples, any transformation product cannot be proposedfor this process.

In previous studies it was reported that oxidative cleavage ofaromatic compounds led to ring opening products consisting ofshort chain aliphatic acids such as maleic and fumaric acids as wellas simpler organic acids including acetic, formic, glyoxylic and oxa-lic acids (Skoumal et al., 2008; Karci et al., 2012). Oxalic and formicacids are regarded as the ultimate carboxylic acids because theyare directly oxidized to carbon dioxide (Garcia-Segura et al.,2012). In the present study HPLC analysis of H2O2/UV-C andS2O82/UV-C treatment of BPA in pure water revealed the genera-tion of oxalic, succinic and fumaric acids. As aforementioned, UV-C photolysis was found to be inefcient in BPA degradation intoring opening products, as veried by the absence of carboxylicacids. Oxalic acid, being the common short-chain carboxylic acidfor the studied treatment processes was formed at 3040 min oftreatment (Fig. 6). In case of H2O2/UV-C treatment, oxalic acidremained in the efuent at the end of 60 min treatment. In con-trast, succinic and fumaric acids were only generated during theinitial stages of H2O2/UV-C treatment only at relatively low levels.Conclusively, the presence of some common carboxylic acidsevolving as later-stage photochemical degradation at varying con-centrations products speak for similarities in the reaction path-ways of S2O82/UV-C and H2O2/UV-C processes.

3.5. S2O82/UV-C and H2O2/UV-C treatment of BPA in raw freshwater

Normalized BPA and TOC abatements being obtained duringapplication of S2O82/UV-C and H2O2/UV-C processes in pure water

Please cite this article in press as: Olmez-Hanci, T., et al. S2O82/UV-C and H2O2degradation products and results in real water. Chemosphere (2014), http://dx(PW) and raw freshwater (RW) are shown in Fig. 7(a) and (b),respectively. In addition, previously shown in Table 2 comparesapparent rst-order rate constants in terms of BPA, TOC and oxidantabatements for raw freshwaterwith rate constants obtained in purewater. From Fig. 7 it is obvious that, as expected, BPA degradationwas appreciably faster in pure water than in raw freshwater; whensubjected to S2O82/UV-C treatment, BPA removal in pure water wasvery rapid and complete in less than 4 min, whereas 99% removaltook 10 min in the raw freshwater matrix. In the case of H2O2/UV-C oxidation, BPA degradation carried out in pure water andraw freshwater was complete within 7 min and 20 min, respec-tively, implying that the raw water components cause a signicantinhibition in BPA oxidation rates. Controversial to BPA abatements,appreciably faster TOC removal rates were observed for H2O2/UV-Ctreatment as compared to S2O82/UV-C process. Similar results werereported for surfactant treatment, where S2O82/UV-C appeared tobe more selective for the removal of the parent compound ratherthan for mineralization of oxidation intermediates (Arslan-Alatonet al., 2013; Olmez-Hanci et al., 2014). This retardation is also evi-dent from the TOC results of the same treatment experiments. Infact, inhibition rates were more pronounced for the TOC parameter.TOC removal efciency decreased from 70% to 28% after 120 minS2O82/UV-C treatment, whereas TOC removals dropped from 85%to 45% for H2O2/UV-C treatment for the same reaction period(Fig. 7(b)). The decrease in treatment efciencies is thought to bea consequence of decreased UV-C photolysis of oxidants (S2O82,H2O2) being hindered by the NOM content of the raw freshwatermatrix (TOC = 5.1 mg L1; UV254 = 0.0794 cm1) that competed forUV irradiation. In addition it should be mentioned that inhibitionof oxidation rates is also attributable to HO and SO4 scavengingeffect of the raw freshwater components. Considering the low alka-linity, chloride, phosphate and sulfate content of the raw freshwa-ter sample (Table 1), the major parameter causing reducedtreatment performance is thought to be its NOM (TOC) content.

According to Table 2, BPA removal rates decreased by a factor ofapproximately 2 and 3 in raw freshwater for S2O82/UV-C and H2O2/UV-C processes, respectively. Results in terms of the TOC parame-ter was also negatively affected; 4 and 3-fold reduction in TOCremoval rates were found for S2O82/UV-C and H2O2/UV-C treat-ments, respectively. In the S2O82/UV-C process S2O82 consumptionrate constant decreased from 0.0298 min1 to 0.0050 min1

whereas the same constant decreased from 0.0415 min1 to0.0111 min1 for the H2O2/UV-C process. These results impliedthat S2O82/UV-C process was more selective in terms of BPAremoval and vulnerable in terms of ultimate oxidation thanH2O2/UV-C process.

Different degradation patterns resulting in different ecotoxico-logical responses depending on the water matrix have been shownby several researchers (Zwiener and Frimmel, 2000; Trov et al.,2009; Richard et al., 2014). Thus the effect of S2O82/UV-C andH2O2/UV-C treatments on the acute toxicity of BPA in raw freshwa-ter samples was also elucidated in the present study. Fig. 8 displayschanges in acute toxicity of raw freshwater samples spiked withBPA (20 mg L1) for the S2O82/UV-C and H2O2/UV-C treatments.Initial inhibition percentage of raw freshwater samples spiked withBPA was found as 71%, thus being very close to values obtained intoxicity tests with pure water samples. As can be seen from Fig. 8the acute toxicity evolutions showed similar trends for S2O82/UV-Cand H2O2/UV-C treated raw freshwater BPA samples; a generalreduction in the relative inhibitions was observed being faster forS2O82/UV-C process. Complete detoxication was achieved withthe S2O82/UV-C and H2O2/UV-C treatments in raw freshwater,where relatively poor treatment efciencies were obtained com-

phere xxx (2014) xxxxxxpared to pure water. Despite the H2O2/UV-C oxidation of BPA inpure water, where uctuations were realized in inhibition values,no increase in toxicities was observed in raw freshwater. The

/UV-C treatment of Bisphenol A: Assessment of toxicity, estrogenic activity,.doi.org/10.1016/j.chemosphere.2014.06.020

mospT. Olmez-Hanci et al. / Cheinhibitory effect occurred only in pure water and not in raw fresh-water with BPA might be associated to the matrix effect (Zwienerand Frimmel, 2000; Trov et al., 2009; Richard et al., 2014). As a

Fig. 4. Massbank match of 135 m

Fig. 5. Massbank match of 201 m

Please cite this article in press as: Olmez-Hanci, T., et al. S2O82/UV-C and H2O2degradation products and results in real water. Chemosphere (2014), http://dxhere xxx (2014) xxxxxx 7consequence of competing reactions and different degradationmechanism, the H2O2/UV-C treatment of BPA in raw freshwaterdid not lead the formation of toxic degradation products.

/z and 3-methylbenzoic acid.

/z and 4-sulfobenzoic acid.

/UV-C treatment of Bisphenol A: Assessment of toxicity, estrogenic activity,.doi.org/10.1016/j.chemosphere.2014.06.020

90

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2-/UV-CSuccinic Acid -H2O2/UV-CFumaric Acid -H2O2/UV-C

8 T. Olmez-Hanci et al. / Che4. Conclusions

The present work aimed at comparatively investigating thetreatability of BPA with the H2O2/UV-C and S2O82/UV-C processesin pure and raw freshwater samples. The study mainly focusedon examination of toxicity and estrogenic activity changes beingobserved during photochemical treatment. Besides, identicationand quantication of photochemical degradation products viaLCMS/MS and HPLC analyses was targeted. The following conclu-sions could be drawn from the obtained experimental results:

UV-C photolysis of BPA solution resulted in poor BPA degrada-tion and TOC removals. This was also ecotoxicologically con-rmed by the V. scheri and YES bioassays. Hence, advanced

0.00 1 2 3 4 5 7 10 20 30 40 50 60

Treatment time (min)

Fig. 6. Evolution of carboxylic acids during H2O2/UV-C and S2O82/UV-C treatmentof BPA. Experimental conditions as in Fig. 1.

S2O82-/UV-C - RW S2O82-/UV-C - PW H2O2/UV-C - RW H2O2/UV-C - PW

S2O82-/UV-C - RWS2O82-/UV-C - PW H2O2/UV-C - RW H2O2/UV-C - PW

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Fig. 7. Changes in normalized BPA (a) and TOC (b) concentrations during H2O2/UV-C and S2O82/UV-C treatments of BPA in raw freshwater. Experimental conditions:BPA = 20 mg L1 (88 lM); TOC = 21 mg L1; oxidant dose = 2.5 mM; initial reactionpH = 8.6; applied UV-C dose = 21 W h L1.

Please cite this article in press as: Olmez-Hanci, T., et al. S2O82/UV-C and H2O2degradation products and results in real water. Chemosphere (2014), http://dxoxidation processes have to be applied for the efcient treat-ment and complete detoxication of aqueous BPA.

H2O2/UV-C treatment in pure water resulted in a rapid and com-plete BPA degradation accompanied with high TOC removalsexceeding 80%. Acute toxicity tests revealed that V. scheriwerevery sensitive to photochemically induced changes in the reac-tion solution. The YES test results indicated an abrupt reductionof the estrogenic activity within the rst 5 min of photochemicaltreatment. As long as the organic carbon content of BPA wastransformed to various degradation products, V. scheri toxicitykept on uctuating, but decreased as TOC removal progressed.

S2O82/UV-C treatment in pure water also brought about rapidand complete BPA as well as TOC removals. Different fromH2O2/UV-C oxidation, the inhibitory effect of BPA on V. scheridecreased gradually, almost parallel to BPA abatement andremained stagnant thereafter. Concerning estrogenic activity,there were no signicant differences, in terms of effectiveness,between the two AOPs.

3-Methylbenzoic and 4-sulfobenzoic acid were proposed as theH2O2/UV-C degradation products. Although at different concen-trations, oxalic acid was generated as the common ring openingproduct of H2O2/UV-C and S2O82/UV-C treatments whereas suc-cinic and fumaric acids were additionally detected during H2O2/UV-C treatment.

The raw freshwater matrix (TOC: 5.1 mg L1; pH: 8.6; alkalin-ity: 124 mg L1 CaCO3) exhibited a negative effect on BPA andTOC abatements. The reduced degradation and mineralization

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Fig. 8. Evolution of V. scheri toxicity during H2O2/UV-C and S2O82/UV-C treatmentof BPA in raw freshwater samples. Experimental conditions as in Fig. 7.100H2O2/UV-C S2O8

2-/UV-C

phere xxx (2014) xxxxxxof BPA might be attributable to the high natural organic mattercontent that signicantly hindered UV-C absorption by S2O82

and H2O2 but also acted as a SO4/HO scavenger. Nevertheless,the raw freshwater samples were found to be non-toxic afterBPA treatment. The water matrix seemed to be playing a signif-icant role in the toxicity changes in the presence of BPA and itsdegradation products.

The presence of BPA in the environment is likely to disturb theecosystems and negatively affect human health. Thus, the need fordeveloping advanced processes for water and wastewatertreatment remains of major environmental concern. Comparisonof different photochemical processes on the basis of their treat-ment and detoxication performance for emerging contaminantsfound in real water and wastewater remains a challenging task.

Acknowledgements

The nancial support of the Scientic and TechnologicalResearch Council of Turkey (TUBITAK) under Project No:

/UV-C treatment of Bisphenol A: Assessment of toxicity, estrogenic activity,.doi.org/10.1016/j.chemosphere.2014.06.020

mosp111Y257 is gratefully acknowledged. The authors are thankful toProf. Dr. Isk Kabdasl for her support during Vibrio scheri analysis.Idil Arslan-Alaton is a member of the Academy of Science, Turkey.

Appendix A. Supplementary material

Supplementary data associated with this article can be found, inthe online version, at http://dx.doi.org/10.1016/j.chemosphere.2014.06.020.

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/UV-C treatment of Bisphenol A: Assessment of toxicity, estrogenic activity,.doi.org/10.1016/j.chemosphere.2014.06.020

S2O82/UV-C and H2O2/UV-C treatment of Bisphenol A: Assessment of toxicity, estrogenic activity, degradation products and results in real water1 Introduction2 Materials and methods2.1 Materials2.2 The raw freshwater sample2.3 The UV-C photoreactor and experimental procedure2.4 Analytical procedures2.4.1 BPA analysis2.4.2 Vibrio fischeri bioassay2.4.3 YES bioassay2.4.4 Degradation products analyses2.4.5 Other measurements

3 Results and discussion3.1 H2O2/UV-C and S2O82/UV-C treatment of BPA3.2 Acute toxicity results3.3 YES bioassay results3.4 Degradation products3.5 S2O82/UV-C and H2O2/UV-C treatment of BPA in raw freshwater

4 ConclusionsAcknowledgementsAppendix A Supplementary materialReferences