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Application of surfactant Tween 80 to enhance Fenton oxidation of polycyclic aromatic hydrocarbons (PAHs) in soil pre-treated with Fenton reagents

Application of surfactant Tween 80 to enhance Fenton oxidation of polycyclic aromatic... GeoloGy, ecoloGy, and landscapes, 2017 Vol . 1, no . 3, 197–204 https://doi.org/10.1080/24749508.2017.1361152 INWASCON OPEN ACCESS Application of surfactant Tween 80 to enhance Fenton oxidation of polycyclic aromatic hydrocarbons (PAHs) in soil pre-treated with Fenton reagents Sucai Yang, Jiabin Li and Yun Song Beijing Key laboratory of Remediation of Industrial pollution sites, environmental protection Research Institute of light Industry, Beijing, china ABSTRACT ARTICLE HISTORY Received 20 april 2017 Successive Fenton oxidation (up to three times) was conducted to enhance the removal efficiency a ccepted 12 July 2017 of nine USEPA priority PAHs in aged soil highly contaminated with PAHs. Results showed that PAHs concentrations decreased rapidly and the removal efficiency was relatively high during KEYWORDS one-time Fenton oxidation. However, PAHs in soil exhibited a slow removal trend and decreased surfactant; desorption; at an extremely slow rate during two- and three-times Fenton oxidation. Surfactant Tween Fenton oxidation; paHs; 80 was used to increase the amount of PAHs available for hydroxyl radical (·OH) and enhance aged soil Fenton oxidation efficiency of PAHs in aged soil pre-treated with Fenton reagents in this study. Results showed that little effect of Tween 80 on desorption of nine USEPA priority PAHs was −1 observed in treatment with low dose of Tween 80 (800 mg L ). However, high dose of Tween −1 80 (6400 mg L ) could improve desorption of 3- and 4-PAHs (10–18%) in soil pre-treated with Fenton reagents, therefore, Tween 80 could significantly improve degradation efficiency of 3- and 4-PAHs relative to control (13–22%). The results in this study offer a possible alternative to the removal of PAHs from soils. 1. Introduction Over the last two decades, Fenton treatment has Polycyclic aromatic hydrocarbons (PAHs) are a class of emerged as a promising remediation technology for organic compounds with two or more fused benzene PAHs-polluted soils (Gan, Lau, & Ng, 2009; Gan et al., rings in linear, angular or cluster structural arrange- 2013; Lemaire et al., 2013; Martens & Frankenberger, ments (Antizar-Ladislao, Lopez-Real, & Beck, 2004; 1995; Rosas, Vicente, Santos, & Romero, 2013; Saxe, Rivas, 2006). They are wide-spread environmental con- Allen, & Nicol, 2000; Venny, Gan, & Ng, 2012; Yap, Gan, taminants that are mainly formed during the incom- & Ng, 2011). Fenton oxidation processes are environmen- plete combustion of fossil fuels (Antizar-Ladislao et al., tally clean technologies which depend on the formation 2004; Jonsson et al., 2007; Rivas, 2006). Industrial sites of reactive and non-selective hydroxyl (·OH) radicals associated with petroleum refining, manufactured gas for oxidation (Diyáuddeen, Aziz, & Daud, 2012). The plants, wood treatment facilities, steel-making factories, generated ·OH radicals can aggressively react with vir- coking plants and thermal power plants are oen hig ft hly tually all organic compounds (Munter, 2001). However, contaminated with PAHs (Jonsson et al., 2007; Lemaire, there are many limitations in applying sole Fenton oxi- Buès, Kabeche, Hanna, & Simonnot, 2013). PAHs are dation to remediate soils polluted with PAHs (Gan et al., very persistent in soils due to their properties, such as 2013; Martens & Frankenberger, 1995; Rosas et al., 2013; low volatility, low water solubility and low biodegra- Saxe et al., 2000; Yap et al., 2011). A major challenge dability (López-Vizcaíno, Sáez, Cañizares, & Rodrigo, in Fenton treatment of PAHs-contaminated soils is the 2012). PAHs have been recognized as a potential health limited mass transfer of PAHs from the sorbed phase risk due to their bioaccumulation and potential toxic- into the aqueous phase due to their strong sorption and ity to humans and wildlife (Lemaire et al., 2013; Rivas, low aqueous solubility (Yap et al., 2011). Limited mass 2006). Therefore, remediation of soil contaminated with transfer results in limited PAH available for the hydroxyl PAHs has received great attention (Antizar-Ladislao et radical (·OH) which was generated in the aqueous phase al., 2004; Gan, Yap, & Ng, 2013; Jonsson et al., 2007; (Venny et al., 2012). Therefore, integrating solubulizing Lemaire et al., 2013; López-Vizcaíno et al., 2012; Rivas, agents (such as, co-solvent, surfactant, cyclodextrin and 2006). To remediate and restore functions of soil pol- vegetable oil) with Fenton treatment is a possible alter- luted by PAHs, effective technologies are necessary. native (Gan et al., 2009; Martens & Frankenberger, 1995; CONTACT sucai y ang liepi_yangsc@163.com © 2017 The a uthor(s). published by Informa UK limited, trading as Taylor & Francis Group. This is an open a ccess article distributed under the terms of the creative c ommons a ttribution license (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. 198 S. YANG ET AL. Rosas et al., 2013; Saxe et al., 2000; Venny et al., 2012; Factory, China. Standard solutions of PAHs were pur- Yap et al., 2011). chased from Accustandard Inc, which, including naph- Surfactants consist of organic molecules with hydro- thalene (NAP), acenaphthylene (ANY), acenaphthene phobic and hydrophilic parts and can interact with polar (ACE), fluorine (FLU), phenanthrene (PHE), anthra- and non-polar surfaces. At low concentrations in aque- cene (ANT), fluoranthene (FLT), pyrene (PYR), ben- ous solution, single molecules (i.e., monomers) are pres- zo(a)anthracene (BaA), chrysene (CHR), benzo(b) ent. However, the surfactant molecules will aggregate, uo fl ranthene (BbFA), benzo(k)fluoranthene (BkFA), form micelles and reduce the thermodynamic energy in benzo(a)pyrene (BaP), indeno(1,2,3,-cd)pyrene (IPY), the system at above a certain concentration (Ahn, Kim, dibenzo(a,h)anthracene (DBA) and benzo(ghi)perylene Woo, & Park, 2008). These micelles lead to the increased (BPE). pseudo-water-solubilities of hydrophobic organic com- pounds (HOCs), therebyincreasing the concentration 2.2. PAH contaminated soil gradient and mass transfer rates (Rosas et al., 2013). Sub-surface soil contaminated with PAHs at depths Many studies have observed that surfactants can facil- ranging from 3 to 4 m below ground surface was col- itate the solubility and Fenton oxidation of HOCs (i.e., lected from abandoned steel-making factory in Beijing, PAHs, TNT and p-Cresol) in soil (Li et al., 1997; Martens China. The steel-making factory started in 1950s, and & Frankenberger, 1995; Rosas et al., 2013; Saxe et al., closed in 2007. Upon collection, the soil samples were 2000; Wang, Hoag, Collins, & Naidu, 2013), and sur- homogenized and sieved (2 mm) to assure uniformity, factants usually were introduced as a pre-treatment step and stored in a refrigerator (4 °C) until used. The soil was before Fenton oxidation in these studies. However, there characterized as: sand soil (87.88% sand, 10.18% silt and is a lack of knowledge about the potential of surfactant −1 1.94% clay), pH 8.07, total organic carbon 16.33 g kg , Tween 80 to enhance the Fenton oxidation of PAHs in total iron 3.05% and moisture 7.26%. The initial con- aged soil pre-treated with Fenton reagents. centrations of PAHs are shown in Table 1. ACE, FLU, Apparent removal of PAHs had been observed in PHE, FLT, PRY, CHR, BbFA, BaP and DBA were the soil aer F ft enton oxidation in many studies (Martens & main components of PAHs in soil used in this study, Frankenberger, 1995; Nam, Rodriguez, & Kukor, 2001; which accounted for 98% of the total amount of PAHs. Saxe et al., 2000; Valderrama et al., 2009), but significant amount of PAHs in soil was also remained aer a ft pply- ing sole Fenton oxidation in their studies. Therefore, it 2.3. Experimental procedure is necessary to further reduce concentration of PAHs To evaluate the effect of Fenton reagents on PAHs oxida - aer a ft pplying sole Fenton oxidation to remediate soils tion, experiments were carried out in 250 mL flasks with contaminated with PAHs. However, PAHs are low water 15 g of fresh soil (wet weight) and 34 mL deionized water. solubility, which might impede Fenton oxidation of en, F Th enton reagents contained FeSO ·7H O solution 4 2 PAHs in soils (Yap et al., 2011). Surfactants can increase −1 (446 mmol L ) and hydrogen peroxide (30%, w/w) were solubility of PAHs, thereby increasing the concentra- applied to flasks (except for control). Four treatments tion gradient and mass transfer rates (Rosas et al., 2013). were then initiated: (1) zero-time Fenton oxidation, no er Th efore, it may be a possible alternative that applying FeSO ·7H O solution and no H O were added; (2) one- 4 2 2 2 surfactants to enhance desorption and Fenton oxidation time Fenton oxidation, 2 mL FeSO ·7H O solution and 4 2 of PAHs in soil pre-treated with Fenton reagents. 3.33  mL H O were added; (3) two-times Fenton oxi- 2 2 e o Th bjectives of this study were to: (1) investigate dation, 4 mL FeSO ·7H O solution and 6.66 mL H O 4 2 2 2 the ec ffi iency of successive Fenton oxidation (up to three were added; (4) three-times Fenton oxidation, 6  mL times) on the removal of PAHs; (2) investigate the effect FeSO ·7H O solution and 10 mL H O were added up. 4 2 2 2 of surfactant Tween 80 on desorption and Fenton oxida- Each treatment included 3three replicates. The exper - tion of PAHs in an aged soil (from abandoned steel-mak- imental setups are summarized in Table 2. The soil ing factories) pre-treated with Fenton reagents. samples in the flasks were placed in an orbital shaking −1 incubator (100 rpm min ) at 25 °C in the dark. Soil mud 2. Materials and methods in flasks was filtered aer 6  ft h of incubation and soil was wrapped in pre-cleaned aluminium foil and immediately 2.1. Chemicals and reagents stored at −20 °C until analysis. All solvents used for sample processing and analysis To evaluate the effect of surfactant Tween 80 on des- (acetone, dichloromethane) were HPLC grade from J.T. orption and Fenton oxidation efficiency of PAHs, both Baker Chemical Company (USA). Anhydrous sodium desorption and Fenton oxidation experiments were sulphate (Na SO , AR, Beijing Chemical Factory, China) 2 4 carried out in 250 mL flasks. The experimental setups was oven-dried at 450  °C for 6  h to act as desiccant. also are summarized in Table 2. Fifteen grams fresh soil Hydrogen peroxide (30%, w/w), FeSO ·7H O and sur- 4 2 (wet weight) and 34 mL deionized water were applied factant Tween 80 were obtained from Beijing Chemical −1 to each flask. Then 2 mL FeSO ·7H O (446 mmol L ) 4 2 GEOLOGY, ECOLOGY, AND LANDSCAPES 199 Table 1. s ome chemical properties of the 16 polycyclic aromatic hydrocarbons (paHs) and concentration of paHs in soil used in this study. a verage n = 3 ± s.d. a −1 b −1 Compound name Abbreviation Rings Solubility (mmol L ) Log Kow Concentration (mg kg ) −1 naphthalene nap 2 2.4 × 10 3.37 nd a cenaphthylene any 3 – 3.72 nd −2 a cenaphthene ace 3 2.9 × 10 3.92 428.25 ± 22.68 −2 Fluorene FlU 3 1.2 × 10 4.18 349.76 ± 24.16 −3 phenanthrene pHe 3 7.2 × 10 4.46 171.29 ± 9.31 −2 anthracene anT 3 7 × 10 4.45 9.20 ± 2.15 −3 Fluoranthene FlT 4 1.3 × 10 5.30 261.48 ± 3.63 −4 pyrene pyR 4 7.2 × 10 5.32 106.96 ± 8.71 Benz[a] anthracene Baa 4 – 5.61 4.87 ± 0.26 −5 chrysene cHR 4 1.3 × 10 5.61 69.31 ± 5.52 Benzo[b] fluoranthene BbFa 5 – 6.11 27.43 ± 3.61 Benzo[k] fluoranthene BkFa 5 – 6.11 5.12 ± 3.9 −5 Benzo[a] pyrene Bap 5 1.5 × 10 6.11 28.56 ± 1.56 −6 dibenz(a,h)anthracene dBa 5 1.8 × 10 6.63 31.87 ± 3.77 Indeno(1,2,3-cd)pyrene Ipy 6 – 6.69 nd −5 Benzo[ghi] perylene Bpe 6 2 × 10 6.70 6.51 ± 2.08 ∑16 paHs 1500.61 note: nd = not detected. From antizar-ladislao et al. (2004). From chong et al. (2014). ∑16 paHs: sum of the concentrations of the 16 paHs listed by the Us -epa as priority pollutants. Table 2. parameters and conditions used in our experiments. Reagents (surfactant Tween 80, Fenton reagents or deionized water) were added at 0 h, 2 h, 4 h and 12 h. The experiments were performed in 250 ml glass flask at 25 °c in orbital shaking incubator −1 (100 rpm min ). 0 h 2 h 4 h 12 h DW (mL) FENT (mL) DW (mL) FENT (mL) DW (mL) FENT (mL) TW (mL) FENT (mL) Fenton oxidation only Zero-time 39.33 0 5.33 0 5.33 0 one- time 34 5.33 5.33 0 5.33 0 Two-time 34 5.33 0 5.33 5.33 0 Three-time 34 5.33 0 5.33 0 5.33 Fenton oxidation – Surfactant Tween 80 TW0 34 5.33 0 5.33 10 0 0 TW800 34 5.33 0 5.33 0 0 10 TW6400 34 5.33 0 5.33 0 0 10 Fenton oxidation – Surfactant Tween 80 – Fenton oxidation TW0 34 5.33 0 5.33 10 5.33 TW800 34 5.33 0 5.33 0 10 5.33 TW6400 34 5.33 0 5.33 0 10 5.33 notes: dW: deionized water. −1 FenT (Fenton reagents): 2 ml Feso ·7H o solution (446 mmol l ) and 3.33 ml hydrogen peroxide (30%, w/w). 4 2 TW: surfactant Tween 80. a −1 4400 mg l . b −1 35000 mg l . and 3.33 mL H O (30%, w/w) were added to each flask. aluminium foil and immediately stored at −20 °C until 2 2 Aer t ft wo hours, this procedure was repeated. Aer f ft our analysis. hours, 10 mL Tween 80 solution was transferred to flasks −1 to make the system contain 0, 800 and 6400  mg L 2.4. PAH extraction and analysis Tween 80, respectively. For desorption experiments, the PAHs of soil samples were characterized using modi- flasks were hermetically sealed and incubated at 25 °C in −1 fied mechanical shaking method (Schwab, Su, Wetzel, an orbital shaking incubator (100 rpm min ) for 8 h to Pekarek, & Banks, 1999). Briefly, 5 g soil sample blended reach soil–liquid equilibrium. The mud in the flasks was with moderate anhydrous Na SO , was then extracted filtered to obtain soil water solution. The soil water solu - 2 4 for 1  h in 100  mL acetone/dichloromethane (1:1, v/v) tion was then filtered under vacuum through pre-ashed −1 in an orbital shaking incubator (200 rpm min ). This glass fibre filters (Whatman, GF/F) to obtain dissolved procedure was repeated, and the two extracts were com- samples. For Fenton oxidation experiments, additional −1 bined and dehydrated using anhydrous Na SO . Water 3.33 mL H O and 2 mL FeSO ·7H O (446 mmol L ) 2 4 2 2 4 2 samples were extracted using a liquid-liquid extraction were applied to the flasks to further reduce concentra- (LLE) method (Fernandez, Garcia, Garcia-Villanova, tion of PAHs. Then the mud in the flasks were filtered & Gomez, 1996). Water sample (30 mL) was extracted to obtain the soil, which was wrapped in pre-cleaned 200 S. YANG ET AL. successively with three volumes of 60 mL dichlorometh- Fenton oxidation, the PAHs in soil exhibited a slow ane. The three extracts were collected and dehydrated removal trend and decreased at an extremely slow rate. using anhydrous Na SO . The combined extracts were It is evident that the removal of PAHs has the “drag tail” 2 4 concentrated in eggplant-type bottle in a vacuum rotary phenomenon during three-time Fenton oxidation. evaporator at a temperature below 40 °C. In classical Fenton reaction, when H O is present 2 2 e iden Th tification and quantification of PAHs in in excess, more ·OH radical is available to react with the extracts were accomplished by gas chromatograph the contaminants (Venny et al., 2012). In this study, −1 mass spectrometer (GC–MS) (Thermo Trace DSQII) 2 mL FeSO ·7H O (446 mmol L ) and 3.33 mL H O 4 2 2 2 using a DB-5MS capillary column (30  m  ×  0.32  mm (30%, w/w) were added to each flask in each oxidation id, 0.25 μm film thickness; Varian, Walnut Creek, CA, process, the mass ratio of hydrogen peroxide and total USA). Helium (99.999%) was used as the GC carrier PAHs in soil is greater than seventy. Thus, H O is pres- 2 2 −1 gas at a constant flow of 1.5  mL  min . The injected ent in excess and there are enough ·OH radicals to oxi- volume was 1  μL in split mode. For the GC/MS, the dize PAHs in soil. However, the removal of PAHs has injection port, interface line and ion temperature were the “drag tail” phenomenon during three-time Fenton maintained at 300 °C, 300 °C and 275 °C, respectively. oxidation. The limited mass transfer of PAHs from the e co Th lumn temperature was programmed at 40 °C and sorbed phase into the aqueous phase might be an impor- −1 held for 5 min, then increased at 10 °C min to 280 °C tant factor because limited mass transfer results in lim- −1 and held for 4 min, 10 °C min to 300 °C and held for ited PAH available for the hydroxyl radical (·OH) which 5 min. e Th quantification of PAHs was accomplished by was generated in the aqueous phase (Yap et al., 2011). a six-point internal calibration curve using peak area. A mix of deuterated PAH containing naphthalene-d8, 3.2. Effect of Tween 80 on desorption and anthracene-d10, phenanthrene-d10, crysene-d12 and oxidation of PAHs in pre-treated soil perylene-d12 (Accustandard Inc.) was used as internal Surfactant enhanced remediation (SER) is thought to standard. be an effective, economic and quick method for the remediation of soils polluted with hydrophobic organic 3. Results and discussion compounds (Chong et al., 2014). Many studies have observed that surfactants can facilitate the solubility and 3.1. Sole Fenton oxidation of PAHs in aged soil Fenton oxidation of PAHs in soil markedly (Martens e a Th pparent removal of PAHs had not been observed in & Frankenberger, 1995; Rosas et al., 2013; Saxe et al., the control treatment without Fenton reagents (Figure 2000). Surfactants were introduced as a pre-treatment 1), which presumably represents the result of natural step with Fenton oxidation, and soil was not pre-treated degradation by microbial action or variability in PAHs with Fenton reagents in their studies. In this study, sur- concentration. The percentage removal of PAHs was less factant Tween 80 could not significantly improve the than 10%. Aer o ft ne-time Fenton oxidation, the addition Fenton oxidation efficiency of 5-ring PAHs in soil was of Fenton reagents could significantly facilitate oxidation pre-treated with Fenton reagents in this study (p < 0.05), of 3- and 4-ring PAHs, while the addition of Fenton rea- but enhanced the Fenton oxidation efficiency of 3-, and gents could facilitate the oxidation of 5-rings PAHs to 4- ring PAHs (13–22%) (Figure 2). a certain extent (Figure 1). e Th recalcitrance of PAHs Desorption experiments results in this study, showed increases with increasing number of aromatic rings and that little effect of surfactant Tween 80 on the desorp- thus molecular weight is an important reason (Henner, tion of ACE, FLU, PHE, FLT, PRY, CHR, BbFA, BaP Schiavon, Morel, & Lichtfouse, 1997). Furthermore, the and DBA was observed in treatment with low dose of −1 transfer of low molecular weight (LMW) PAHs from the Tween 80 (800 mg L ) (Table 3). High dose of Tween −1 soil is known to be more rapid than HMW PAHs due to 80 (6400  mg L ) had little effect on the 5-ring PAHs the strong sorption of high molecular weight (HMW) desorption (<1%) (Table 3), but facilitated desorption of PAHs onto microporous of particulates and their hydro- 3- and 4-ring PAHs to a certain extent in this study (10– phobicity (high Kow) (Rivas, 2006; Venny et al., 2012). 18%) (Table 3). However, the desorption rate of PAHs Two-times Fenton oxidation enhanced the percent- in this study is lower than that of the previous reports, age oxidation of 3- and 4-ring PAHs to a certain extent, (Ahn et al., 2008; Chong et al., 2014; López-Vizcaíno et but could not further significantly enhance Fenton oxi- al., 2012; Peng, Wu, & Chen, 2011; Zhou & Zhu, 2008) in dation of 5-ring PAHs in this study (p < 0.05) (Figure 1). which the soil was not pre-treated with Fenton reagents. Compared with two-times Fenton oxidation, apparent More than 80% of PAHs in soils could be removed by removal of 3-, 4- and 5-ring PAHs was not observed surfactants in their studies under suitable conditions. aer t ft hree-times Fenton oxidation (Figure 1 ). In a word, Ageing of hydrophobic organic contaminants during one-time Fenton oxidation, PAHs concentrations (HOCs) is an important attenuation process which oe ft n decreased rapidly and the removal efficiency was rel- entails an initially rapid and reversible sorption process atively high. Conversely, during two- and three-times followed by a period of slow diffusion occurring over GEOLOGY, ECOLOGY, AND LANDSCAPES 201 Figure 1. changes of paHs concentration in contaminated soil before Fenton oxidation (untreated soil) and after Fenton oxidation −1 (zero-time, one-time, two-times and three-times oxidation) under soil/slurry conditions. Two ml Feso ·7H o solution (446 mmol l ) 4 2 and 3.33 ml hydrogen peroxide (30%, w/w) are added to soil/slurry system in each oxidation process. error bars indicate standard deviations (n = 3). The different letters indicate significant differences (p < 0.05). weeks, months or even years when they released into 1997). Therefore, high desorption rate of PAHs may be the environment (Alexander, 2000; Luo, Lin, Huang, observed in soil was not pre-treated with Fenton rea- & Zhang, 2012). Ageing of hydrophobic organic con- gents, while an even much stronger effect of resistant taminants (HOCs) leads to three distinct contaminant desorption is expected in soil aer F ft enton oxidation due “pools,” equating to “rapid,” “slow” and “very slow” to the reason that strongly sorbed pollutants tend to be desorption domains (Bosma, Middeldorp, Schraa, more resistant to oxidation and vice versa (Venny et & Zehnder, 1996). This behaviour is thermodynam- al., 2012). In this study, although the desorption rate of ically driven, with movement towards the very-slow PAHs is lower than that of the previous reports (Ahn et domain (Cornelissen, van Noort, Parsons, & Govers, al., 2008; Chong et al., 2014; López-Vizcaíno et al., 2012; 202 S. YANG ET AL. Figure 2. changes of paHs concentration in pre-oxidation soil as affected by Fenton oxidation alone or in combination with Tween −1 80 (0, 800 and 6400  mg l , respectively). error bars indicate standard deviations (n  =  3). The different letters indicate significant differences (p < 0.05). Peng et al., 2011; Zhou & Zhu, 2008) in which the soil Table 3. The desorption ratios (%) of paHs from aged soil was not pre-treated with Fenton reagents, high dose of pre-treated with Fenton reagents into water solution after −1 surfactant Tween 80 added with different concentrations (0, Tween 80 (6400 mg L ) could improve desorption of −1 800 and 6400 mg l respectively) was used to accelerate the 3- and 4-PAHs (10–18%) in soil pre-treated with Fenton desorption of paHs in soil. a verage n = 3 ± s.d. reagents, therefore improve the degradation efficiency TW0 TW800 TW6400 of 3- and 4-PAHs relative to control (13–22%), which a cenaphthene (ace) 2.04 ± 0.30 1.62 ± 0.31 18.24 ± 3.3 oer a p ff ossible alternative to the removal of PAHs from Fluorine (Fl U) 0.94 ± 0.21 0.80 ± 0.14 17.72 ± 2.3 soils. phenanthrene (pHe) 0.52 ± 0.19 0.43 ± 0.34 14.06 ± 1.5 Fluoranthene (Fl T) 0.08 ± 0.05 0.08 ± 0.04 14.44 ± 2.6 pyrene (pyR) 0.05 ± 0.03 0.06 ± 0.02 15.24 ± 3.4 chrysene ( cHR) 0.04 ± 0.02 0.03 ± 0.01 10.23 ± 2.2 4. Conclusion Benzo(b)fluoranthene 0.02 ± 0.01 0.01 ± 0.008 0.59 ± 0.07 (BbFa ), In this study, successive Fenton oxidation (up to three Benzo(a)pyrene (Bap) 0.04 ± 0.01 0.04 ± 0.02 0.89 ± 0.20 times) was conducted to enhance the removal efficiency dibenzo(a,h)anthracene 0.07 ± 0.03 0.06 ± 0.02 0.48 ± 0.12 (dBa ) of nine USEPA priority PAHs (ACE, FLU, PHE, FLT, GEOLOGY, ECOLOGY, AND LANDSCAPES 203 Diyáuddeen, B. H., Aziz, A. R. A., & Daud, W. M. A. W. PRY, CHR, BbFA, BaP and DBA) in aged soil highly con- (2012). Oxidative mineralisation of petroleum refinery taminated with PAHs. Results showed that the removal effluent using Fenton-like process. Chem Eng Res Des., 90, of PAHs has the “drag tail” phenomenon during three- 298–307. time Fenton oxidation. In order to increase desorption Fernandez, M. J., Garcia, C., Garcia-Villanova, R. J., & Gomez, of PAHs in soil and increase the amount of PAH avail- J. A. (1996). Evaluation of liquid−solid extraction with a able for the hydroxyl radical (·OH), the application of new sorbent and liquid−liquid extraction for multiresidue pesticides. determination in raw and finished drinking surfactant Tween 80 was investigated to accelerate des- waters. Journal of Agricultural and Food Chemistry, 44, orption and Fenton oxidation of PAH in soil aer t ft wo 1790–1795. times Fenton oxidation in this study. Results showed Gan, S., Lau, E. V., & Ng, H. K. (2009). Remediation of soils that little effect of Tween 80 on desorption of ACE, FLU, contaminated with polycyclic aromatic hydrocarbons PHE, FLT, PRY, CHR, BbFA, BaP and DBA was observed (PAHs). Journal of Hazardous Materials, 172, 532–549. −1 Gan, S., Yap, C. L., & Ng, H. K. (2013). Investigation of the in treatment with low dose of Tween 80 (800 mg L ). impacts of ethyl lactate based Fenton treatment on soil Although the desorption rate of PAHs in this study is quality for polycyclic aromatic hydrocarbons (PAHs)- lower than that of the previous reports in which the soil contaminated soils. Journal of Hazardous Materials, 262, was not pre-treated with Fenton reagents, high dose of 691–700. −1 Tween 80 (6400  mg L ) could improve desorption of Henner, P., Schiavon, M., Morel, J. L., & Lichtfouse, E. (1997). 3- and 4-PAHs (10–18%) in soil pre-treated with Fenton Polycyclic aromatic hydrocarbon (PAH) occurrence and remediation methods. Analusis, 25, 56–59. reagents, therefore Tween 80 could significantly improve Jonsson, S., Persson, Y., Frankki, S., van Bavel, B., Lundstedt, degradation efficiency of 3- and 4-PAHs relative to con- S., & Haglund, P. (2007). Degradation of polycyclic trol (13–22%). aromatic hydrocarbons (PAHs) in contaminated soils by Fenton’s reagent: A multivariate evaluation of the importance of soil characteristics and PAH properties. Disclosure statement Journal of Hazardous Materials, 149, 86–96. Lemaire, J., Buès, M., Kabeche, T., Hanna, K., & Simonnot, No potential conflict of interest was reported by the authors. M. O. (2013). Oxidant selection to treat an aged PAH contaminated soil by in situ chemical oxidation. Journal of Environmental Chemical Engineering, 1, 1261–1268. Funding Lemaire, J., Laurent, F., Leyval, C., Schwartz, C., Buès, M., & This work was supported by the National Natural Science Simonnot, M. O. (2013). PAH oxidation in aged and spiked Foundation of China [grant number 41201516]; China soils investigated by column experiments. Chemosphere, National Special Research Fund for Non-Prot S fi ector of 91, 406–414. Environmental Protection [grant number 201409047]. Li, Z. M., Peterson, M. 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Current status and prospects Soil remediation using soil washing followed by Fenton of Fenton oxidation for the decontamination of persistent oxidation. Chemical Engineering Journal, 220, 125–132. organic pollutants (POPs) in soils. Chemical Engineering Saxe, J. K., Allen, H. E., & Nicol, G. R. (2000). Fenton Journal, 213: 295–317. oxidation of polycyclic aromatic hydrocarbons aer ft Wang, W. H., Hoag, G. E., Collins, J. B., & Naidu, R. (2013). surfactant-enhanced soil washing. Environmental Evaluation of surfactant-enhanced in situ chemical Engineering Science, 17, 233–244. oxidation (S-ISCO) in contaminated soil. Water, Air, & Schwab, A. P., Su, J., Wetzel, S., Pekarek, S., & Banks, M. K. Soil Pollution, 224, 1713–1721. (1999). Extraction of petroleum hydrocarbons from soil by Yap, C. L., Gan, S., & Ng, H. K. (2011). Fenton based mechanical shaking. Environmental Science & Technology, remediation of polycyclic aromatic hydrocarbons- 33, 1940–1945. contaminated soils. Chemosphere, 83, 1414–1430. Valderrama, C., Alessandri, R., Aunola, T., Cortina, J. L., Zhou, W. J., & Zhu, L. Z. (2008). Enhanced soil flushing of Gamisans, X., & Tuhkanen, T. (2009). Oxidation by phenanthrene by anionic-nonionic mixed surfactant. Fenton’s reagent combined with biological treatment Water Research, 42, 101–108. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Geology Ecology and Landscapes Taylor & Francis

Application of surfactant Tween 80 to enhance Fenton oxidation of polycyclic aromatic hydrocarbons (PAHs) in soil pre-treated with Fenton reagents

Geology Ecology and Landscapes , Volume 1 (3): 8 – Jul 3, 2017

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2474-9508
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10.1080/24749508.2017.1361152
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Abstract

GeoloGy, ecoloGy, and landscapes, 2017 Vol . 1, no . 3, 197–204 https://doi.org/10.1080/24749508.2017.1361152 INWASCON OPEN ACCESS Application of surfactant Tween 80 to enhance Fenton oxidation of polycyclic aromatic hydrocarbons (PAHs) in soil pre-treated with Fenton reagents Sucai Yang, Jiabin Li and Yun Song Beijing Key laboratory of Remediation of Industrial pollution sites, environmental protection Research Institute of light Industry, Beijing, china ABSTRACT ARTICLE HISTORY Received 20 april 2017 Successive Fenton oxidation (up to three times) was conducted to enhance the removal efficiency a ccepted 12 July 2017 of nine USEPA priority PAHs in aged soil highly contaminated with PAHs. Results showed that PAHs concentrations decreased rapidly and the removal efficiency was relatively high during KEYWORDS one-time Fenton oxidation. However, PAHs in soil exhibited a slow removal trend and decreased surfactant; desorption; at an extremely slow rate during two- and three-times Fenton oxidation. Surfactant Tween Fenton oxidation; paHs; 80 was used to increase the amount of PAHs available for hydroxyl radical (·OH) and enhance aged soil Fenton oxidation efficiency of PAHs in aged soil pre-treated with Fenton reagents in this study. Results showed that little effect of Tween 80 on desorption of nine USEPA priority PAHs was −1 observed in treatment with low dose of Tween 80 (800 mg L ). However, high dose of Tween −1 80 (6400 mg L ) could improve desorption of 3- and 4-PAHs (10–18%) in soil pre-treated with Fenton reagents, therefore, Tween 80 could significantly improve degradation efficiency of 3- and 4-PAHs relative to control (13–22%). The results in this study offer a possible alternative to the removal of PAHs from soils. 1. Introduction Over the last two decades, Fenton treatment has Polycyclic aromatic hydrocarbons (PAHs) are a class of emerged as a promising remediation technology for organic compounds with two or more fused benzene PAHs-polluted soils (Gan, Lau, & Ng, 2009; Gan et al., rings in linear, angular or cluster structural arrange- 2013; Lemaire et al., 2013; Martens & Frankenberger, ments (Antizar-Ladislao, Lopez-Real, & Beck, 2004; 1995; Rosas, Vicente, Santos, & Romero, 2013; Saxe, Rivas, 2006). They are wide-spread environmental con- Allen, & Nicol, 2000; Venny, Gan, & Ng, 2012; Yap, Gan, taminants that are mainly formed during the incom- & Ng, 2011). Fenton oxidation processes are environmen- plete combustion of fossil fuels (Antizar-Ladislao et al., tally clean technologies which depend on the formation 2004; Jonsson et al., 2007; Rivas, 2006). Industrial sites of reactive and non-selective hydroxyl (·OH) radicals associated with petroleum refining, manufactured gas for oxidation (Diyáuddeen, Aziz, & Daud, 2012). The plants, wood treatment facilities, steel-making factories, generated ·OH radicals can aggressively react with vir- coking plants and thermal power plants are oen hig ft hly tually all organic compounds (Munter, 2001). However, contaminated with PAHs (Jonsson et al., 2007; Lemaire, there are many limitations in applying sole Fenton oxi- Buès, Kabeche, Hanna, & Simonnot, 2013). PAHs are dation to remediate soils polluted with PAHs (Gan et al., very persistent in soils due to their properties, such as 2013; Martens & Frankenberger, 1995; Rosas et al., 2013; low volatility, low water solubility and low biodegra- Saxe et al., 2000; Yap et al., 2011). A major challenge dability (López-Vizcaíno, Sáez, Cañizares, & Rodrigo, in Fenton treatment of PAHs-contaminated soils is the 2012). PAHs have been recognized as a potential health limited mass transfer of PAHs from the sorbed phase risk due to their bioaccumulation and potential toxic- into the aqueous phase due to their strong sorption and ity to humans and wildlife (Lemaire et al., 2013; Rivas, low aqueous solubility (Yap et al., 2011). Limited mass 2006). Therefore, remediation of soil contaminated with transfer results in limited PAH available for the hydroxyl PAHs has received great attention (Antizar-Ladislao et radical (·OH) which was generated in the aqueous phase al., 2004; Gan, Yap, & Ng, 2013; Jonsson et al., 2007; (Venny et al., 2012). Therefore, integrating solubulizing Lemaire et al., 2013; López-Vizcaíno et al., 2012; Rivas, agents (such as, co-solvent, surfactant, cyclodextrin and 2006). To remediate and restore functions of soil pol- vegetable oil) with Fenton treatment is a possible alter- luted by PAHs, effective technologies are necessary. native (Gan et al., 2009; Martens & Frankenberger, 1995; CONTACT sucai y ang liepi_yangsc@163.com © 2017 The a uthor(s). published by Informa UK limited, trading as Taylor & Francis Group. This is an open a ccess article distributed under the terms of the creative c ommons a ttribution license (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. 198 S. YANG ET AL. Rosas et al., 2013; Saxe et al., 2000; Venny et al., 2012; Factory, China. Standard solutions of PAHs were pur- Yap et al., 2011). chased from Accustandard Inc, which, including naph- Surfactants consist of organic molecules with hydro- thalene (NAP), acenaphthylene (ANY), acenaphthene phobic and hydrophilic parts and can interact with polar (ACE), fluorine (FLU), phenanthrene (PHE), anthra- and non-polar surfaces. At low concentrations in aque- cene (ANT), fluoranthene (FLT), pyrene (PYR), ben- ous solution, single molecules (i.e., monomers) are pres- zo(a)anthracene (BaA), chrysene (CHR), benzo(b) ent. However, the surfactant molecules will aggregate, uo fl ranthene (BbFA), benzo(k)fluoranthene (BkFA), form micelles and reduce the thermodynamic energy in benzo(a)pyrene (BaP), indeno(1,2,3,-cd)pyrene (IPY), the system at above a certain concentration (Ahn, Kim, dibenzo(a,h)anthracene (DBA) and benzo(ghi)perylene Woo, & Park, 2008). These micelles lead to the increased (BPE). pseudo-water-solubilities of hydrophobic organic com- pounds (HOCs), therebyincreasing the concentration 2.2. PAH contaminated soil gradient and mass transfer rates (Rosas et al., 2013). Sub-surface soil contaminated with PAHs at depths Many studies have observed that surfactants can facil- ranging from 3 to 4 m below ground surface was col- itate the solubility and Fenton oxidation of HOCs (i.e., lected from abandoned steel-making factory in Beijing, PAHs, TNT and p-Cresol) in soil (Li et al., 1997; Martens China. The steel-making factory started in 1950s, and & Frankenberger, 1995; Rosas et al., 2013; Saxe et al., closed in 2007. Upon collection, the soil samples were 2000; Wang, Hoag, Collins, & Naidu, 2013), and sur- homogenized and sieved (2 mm) to assure uniformity, factants usually were introduced as a pre-treatment step and stored in a refrigerator (4 °C) until used. The soil was before Fenton oxidation in these studies. However, there characterized as: sand soil (87.88% sand, 10.18% silt and is a lack of knowledge about the potential of surfactant −1 1.94% clay), pH 8.07, total organic carbon 16.33 g kg , Tween 80 to enhance the Fenton oxidation of PAHs in total iron 3.05% and moisture 7.26%. The initial con- aged soil pre-treated with Fenton reagents. centrations of PAHs are shown in Table 1. ACE, FLU, Apparent removal of PAHs had been observed in PHE, FLT, PRY, CHR, BbFA, BaP and DBA were the soil aer F ft enton oxidation in many studies (Martens & main components of PAHs in soil used in this study, Frankenberger, 1995; Nam, Rodriguez, & Kukor, 2001; which accounted for 98% of the total amount of PAHs. Saxe et al., 2000; Valderrama et al., 2009), but significant amount of PAHs in soil was also remained aer a ft pply- ing sole Fenton oxidation in their studies. Therefore, it 2.3. Experimental procedure is necessary to further reduce concentration of PAHs To evaluate the effect of Fenton reagents on PAHs oxida - aer a ft pplying sole Fenton oxidation to remediate soils tion, experiments were carried out in 250 mL flasks with contaminated with PAHs. However, PAHs are low water 15 g of fresh soil (wet weight) and 34 mL deionized water. solubility, which might impede Fenton oxidation of en, F Th enton reagents contained FeSO ·7H O solution 4 2 PAHs in soils (Yap et al., 2011). Surfactants can increase −1 (446 mmol L ) and hydrogen peroxide (30%, w/w) were solubility of PAHs, thereby increasing the concentra- applied to flasks (except for control). Four treatments tion gradient and mass transfer rates (Rosas et al., 2013). were then initiated: (1) zero-time Fenton oxidation, no er Th efore, it may be a possible alternative that applying FeSO ·7H O solution and no H O were added; (2) one- 4 2 2 2 surfactants to enhance desorption and Fenton oxidation time Fenton oxidation, 2 mL FeSO ·7H O solution and 4 2 of PAHs in soil pre-treated with Fenton reagents. 3.33  mL H O were added; (3) two-times Fenton oxi- 2 2 e o Th bjectives of this study were to: (1) investigate dation, 4 mL FeSO ·7H O solution and 6.66 mL H O 4 2 2 2 the ec ffi iency of successive Fenton oxidation (up to three were added; (4) three-times Fenton oxidation, 6  mL times) on the removal of PAHs; (2) investigate the effect FeSO ·7H O solution and 10 mL H O were added up. 4 2 2 2 of surfactant Tween 80 on desorption and Fenton oxida- Each treatment included 3three replicates. The exper - tion of PAHs in an aged soil (from abandoned steel-mak- imental setups are summarized in Table 2. The soil ing factories) pre-treated with Fenton reagents. samples in the flasks were placed in an orbital shaking −1 incubator (100 rpm min ) at 25 °C in the dark. Soil mud 2. Materials and methods in flasks was filtered aer 6  ft h of incubation and soil was wrapped in pre-cleaned aluminium foil and immediately 2.1. Chemicals and reagents stored at −20 °C until analysis. All solvents used for sample processing and analysis To evaluate the effect of surfactant Tween 80 on des- (acetone, dichloromethane) were HPLC grade from J.T. orption and Fenton oxidation efficiency of PAHs, both Baker Chemical Company (USA). Anhydrous sodium desorption and Fenton oxidation experiments were sulphate (Na SO , AR, Beijing Chemical Factory, China) 2 4 carried out in 250 mL flasks. The experimental setups was oven-dried at 450  °C for 6  h to act as desiccant. also are summarized in Table 2. Fifteen grams fresh soil Hydrogen peroxide (30%, w/w), FeSO ·7H O and sur- 4 2 (wet weight) and 34 mL deionized water were applied factant Tween 80 were obtained from Beijing Chemical −1 to each flask. Then 2 mL FeSO ·7H O (446 mmol L ) 4 2 GEOLOGY, ECOLOGY, AND LANDSCAPES 199 Table 1. s ome chemical properties of the 16 polycyclic aromatic hydrocarbons (paHs) and concentration of paHs in soil used in this study. a verage n = 3 ± s.d. a −1 b −1 Compound name Abbreviation Rings Solubility (mmol L ) Log Kow Concentration (mg kg ) −1 naphthalene nap 2 2.4 × 10 3.37 nd a cenaphthylene any 3 – 3.72 nd −2 a cenaphthene ace 3 2.9 × 10 3.92 428.25 ± 22.68 −2 Fluorene FlU 3 1.2 × 10 4.18 349.76 ± 24.16 −3 phenanthrene pHe 3 7.2 × 10 4.46 171.29 ± 9.31 −2 anthracene anT 3 7 × 10 4.45 9.20 ± 2.15 −3 Fluoranthene FlT 4 1.3 × 10 5.30 261.48 ± 3.63 −4 pyrene pyR 4 7.2 × 10 5.32 106.96 ± 8.71 Benz[a] anthracene Baa 4 – 5.61 4.87 ± 0.26 −5 chrysene cHR 4 1.3 × 10 5.61 69.31 ± 5.52 Benzo[b] fluoranthene BbFa 5 – 6.11 27.43 ± 3.61 Benzo[k] fluoranthene BkFa 5 – 6.11 5.12 ± 3.9 −5 Benzo[a] pyrene Bap 5 1.5 × 10 6.11 28.56 ± 1.56 −6 dibenz(a,h)anthracene dBa 5 1.8 × 10 6.63 31.87 ± 3.77 Indeno(1,2,3-cd)pyrene Ipy 6 – 6.69 nd −5 Benzo[ghi] perylene Bpe 6 2 × 10 6.70 6.51 ± 2.08 ∑16 paHs 1500.61 note: nd = not detected. From antizar-ladislao et al. (2004). From chong et al. (2014). ∑16 paHs: sum of the concentrations of the 16 paHs listed by the Us -epa as priority pollutants. Table 2. parameters and conditions used in our experiments. Reagents (surfactant Tween 80, Fenton reagents or deionized water) were added at 0 h, 2 h, 4 h and 12 h. The experiments were performed in 250 ml glass flask at 25 °c in orbital shaking incubator −1 (100 rpm min ). 0 h 2 h 4 h 12 h DW (mL) FENT (mL) DW (mL) FENT (mL) DW (mL) FENT (mL) TW (mL) FENT (mL) Fenton oxidation only Zero-time 39.33 0 5.33 0 5.33 0 one- time 34 5.33 5.33 0 5.33 0 Two-time 34 5.33 0 5.33 5.33 0 Three-time 34 5.33 0 5.33 0 5.33 Fenton oxidation – Surfactant Tween 80 TW0 34 5.33 0 5.33 10 0 0 TW800 34 5.33 0 5.33 0 0 10 TW6400 34 5.33 0 5.33 0 0 10 Fenton oxidation – Surfactant Tween 80 – Fenton oxidation TW0 34 5.33 0 5.33 10 5.33 TW800 34 5.33 0 5.33 0 10 5.33 TW6400 34 5.33 0 5.33 0 10 5.33 notes: dW: deionized water. −1 FenT (Fenton reagents): 2 ml Feso ·7H o solution (446 mmol l ) and 3.33 ml hydrogen peroxide (30%, w/w). 4 2 TW: surfactant Tween 80. a −1 4400 mg l . b −1 35000 mg l . and 3.33 mL H O (30%, w/w) were added to each flask. aluminium foil and immediately stored at −20 °C until 2 2 Aer t ft wo hours, this procedure was repeated. Aer f ft our analysis. hours, 10 mL Tween 80 solution was transferred to flasks −1 to make the system contain 0, 800 and 6400  mg L 2.4. PAH extraction and analysis Tween 80, respectively. For desorption experiments, the PAHs of soil samples were characterized using modi- flasks were hermetically sealed and incubated at 25 °C in −1 fied mechanical shaking method (Schwab, Su, Wetzel, an orbital shaking incubator (100 rpm min ) for 8 h to Pekarek, & Banks, 1999). Briefly, 5 g soil sample blended reach soil–liquid equilibrium. The mud in the flasks was with moderate anhydrous Na SO , was then extracted filtered to obtain soil water solution. The soil water solu - 2 4 for 1  h in 100  mL acetone/dichloromethane (1:1, v/v) tion was then filtered under vacuum through pre-ashed −1 in an orbital shaking incubator (200 rpm min ). This glass fibre filters (Whatman, GF/F) to obtain dissolved procedure was repeated, and the two extracts were com- samples. For Fenton oxidation experiments, additional −1 bined and dehydrated using anhydrous Na SO . Water 3.33 mL H O and 2 mL FeSO ·7H O (446 mmol L ) 2 4 2 2 4 2 samples were extracted using a liquid-liquid extraction were applied to the flasks to further reduce concentra- (LLE) method (Fernandez, Garcia, Garcia-Villanova, tion of PAHs. Then the mud in the flasks were filtered & Gomez, 1996). Water sample (30 mL) was extracted to obtain the soil, which was wrapped in pre-cleaned 200 S. YANG ET AL. successively with three volumes of 60 mL dichlorometh- Fenton oxidation, the PAHs in soil exhibited a slow ane. The three extracts were collected and dehydrated removal trend and decreased at an extremely slow rate. using anhydrous Na SO . The combined extracts were It is evident that the removal of PAHs has the “drag tail” 2 4 concentrated in eggplant-type bottle in a vacuum rotary phenomenon during three-time Fenton oxidation. evaporator at a temperature below 40 °C. In classical Fenton reaction, when H O is present 2 2 e iden Th tification and quantification of PAHs in in excess, more ·OH radical is available to react with the extracts were accomplished by gas chromatograph the contaminants (Venny et al., 2012). In this study, −1 mass spectrometer (GC–MS) (Thermo Trace DSQII) 2 mL FeSO ·7H O (446 mmol L ) and 3.33 mL H O 4 2 2 2 using a DB-5MS capillary column (30  m  ×  0.32  mm (30%, w/w) were added to each flask in each oxidation id, 0.25 μm film thickness; Varian, Walnut Creek, CA, process, the mass ratio of hydrogen peroxide and total USA). Helium (99.999%) was used as the GC carrier PAHs in soil is greater than seventy. Thus, H O is pres- 2 2 −1 gas at a constant flow of 1.5  mL  min . The injected ent in excess and there are enough ·OH radicals to oxi- volume was 1  μL in split mode. For the GC/MS, the dize PAHs in soil. However, the removal of PAHs has injection port, interface line and ion temperature were the “drag tail” phenomenon during three-time Fenton maintained at 300 °C, 300 °C and 275 °C, respectively. oxidation. The limited mass transfer of PAHs from the e co Th lumn temperature was programmed at 40 °C and sorbed phase into the aqueous phase might be an impor- −1 held for 5 min, then increased at 10 °C min to 280 °C tant factor because limited mass transfer results in lim- −1 and held for 4 min, 10 °C min to 300 °C and held for ited PAH available for the hydroxyl radical (·OH) which 5 min. e Th quantification of PAHs was accomplished by was generated in the aqueous phase (Yap et al., 2011). a six-point internal calibration curve using peak area. A mix of deuterated PAH containing naphthalene-d8, 3.2. Effect of Tween 80 on desorption and anthracene-d10, phenanthrene-d10, crysene-d12 and oxidation of PAHs in pre-treated soil perylene-d12 (Accustandard Inc.) was used as internal Surfactant enhanced remediation (SER) is thought to standard. be an effective, economic and quick method for the remediation of soils polluted with hydrophobic organic 3. Results and discussion compounds (Chong et al., 2014). Many studies have observed that surfactants can facilitate the solubility and 3.1. Sole Fenton oxidation of PAHs in aged soil Fenton oxidation of PAHs in soil markedly (Martens e a Th pparent removal of PAHs had not been observed in & Frankenberger, 1995; Rosas et al., 2013; Saxe et al., the control treatment without Fenton reagents (Figure 2000). Surfactants were introduced as a pre-treatment 1), which presumably represents the result of natural step with Fenton oxidation, and soil was not pre-treated degradation by microbial action or variability in PAHs with Fenton reagents in their studies. In this study, sur- concentration. The percentage removal of PAHs was less factant Tween 80 could not significantly improve the than 10%. Aer o ft ne-time Fenton oxidation, the addition Fenton oxidation efficiency of 5-ring PAHs in soil was of Fenton reagents could significantly facilitate oxidation pre-treated with Fenton reagents in this study (p < 0.05), of 3- and 4-ring PAHs, while the addition of Fenton rea- but enhanced the Fenton oxidation efficiency of 3-, and gents could facilitate the oxidation of 5-rings PAHs to 4- ring PAHs (13–22%) (Figure 2). a certain extent (Figure 1). e Th recalcitrance of PAHs Desorption experiments results in this study, showed increases with increasing number of aromatic rings and that little effect of surfactant Tween 80 on the desorp- thus molecular weight is an important reason (Henner, tion of ACE, FLU, PHE, FLT, PRY, CHR, BbFA, BaP Schiavon, Morel, & Lichtfouse, 1997). Furthermore, the and DBA was observed in treatment with low dose of −1 transfer of low molecular weight (LMW) PAHs from the Tween 80 (800 mg L ) (Table 3). High dose of Tween −1 soil is known to be more rapid than HMW PAHs due to 80 (6400  mg L ) had little effect on the 5-ring PAHs the strong sorption of high molecular weight (HMW) desorption (<1%) (Table 3), but facilitated desorption of PAHs onto microporous of particulates and their hydro- 3- and 4-ring PAHs to a certain extent in this study (10– phobicity (high Kow) (Rivas, 2006; Venny et al., 2012). 18%) (Table 3). However, the desorption rate of PAHs Two-times Fenton oxidation enhanced the percent- in this study is lower than that of the previous reports, age oxidation of 3- and 4-ring PAHs to a certain extent, (Ahn et al., 2008; Chong et al., 2014; López-Vizcaíno et but could not further significantly enhance Fenton oxi- al., 2012; Peng, Wu, & Chen, 2011; Zhou & Zhu, 2008) in dation of 5-ring PAHs in this study (p < 0.05) (Figure 1). which the soil was not pre-treated with Fenton reagents. Compared with two-times Fenton oxidation, apparent More than 80% of PAHs in soils could be removed by removal of 3-, 4- and 5-ring PAHs was not observed surfactants in their studies under suitable conditions. aer t ft hree-times Fenton oxidation (Figure 1 ). In a word, Ageing of hydrophobic organic contaminants during one-time Fenton oxidation, PAHs concentrations (HOCs) is an important attenuation process which oe ft n decreased rapidly and the removal efficiency was rel- entails an initially rapid and reversible sorption process atively high. Conversely, during two- and three-times followed by a period of slow diffusion occurring over GEOLOGY, ECOLOGY, AND LANDSCAPES 201 Figure 1. changes of paHs concentration in contaminated soil before Fenton oxidation (untreated soil) and after Fenton oxidation −1 (zero-time, one-time, two-times and three-times oxidation) under soil/slurry conditions. Two ml Feso ·7H o solution (446 mmol l ) 4 2 and 3.33 ml hydrogen peroxide (30%, w/w) are added to soil/slurry system in each oxidation process. error bars indicate standard deviations (n = 3). The different letters indicate significant differences (p < 0.05). weeks, months or even years when they released into 1997). Therefore, high desorption rate of PAHs may be the environment (Alexander, 2000; Luo, Lin, Huang, observed in soil was not pre-treated with Fenton rea- & Zhang, 2012). Ageing of hydrophobic organic con- gents, while an even much stronger effect of resistant taminants (HOCs) leads to three distinct contaminant desorption is expected in soil aer F ft enton oxidation due “pools,” equating to “rapid,” “slow” and “very slow” to the reason that strongly sorbed pollutants tend to be desorption domains (Bosma, Middeldorp, Schraa, more resistant to oxidation and vice versa (Venny et & Zehnder, 1996). This behaviour is thermodynam- al., 2012). In this study, although the desorption rate of ically driven, with movement towards the very-slow PAHs is lower than that of the previous reports (Ahn et domain (Cornelissen, van Noort, Parsons, & Govers, al., 2008; Chong et al., 2014; López-Vizcaíno et al., 2012; 202 S. YANG ET AL. Figure 2. changes of paHs concentration in pre-oxidation soil as affected by Fenton oxidation alone or in combination with Tween −1 80 (0, 800 and 6400  mg l , respectively). error bars indicate standard deviations (n  =  3). The different letters indicate significant differences (p < 0.05). Peng et al., 2011; Zhou & Zhu, 2008) in which the soil Table 3. The desorption ratios (%) of paHs from aged soil was not pre-treated with Fenton reagents, high dose of pre-treated with Fenton reagents into water solution after −1 surfactant Tween 80 added with different concentrations (0, Tween 80 (6400 mg L ) could improve desorption of −1 800 and 6400 mg l respectively) was used to accelerate the 3- and 4-PAHs (10–18%) in soil pre-treated with Fenton desorption of paHs in soil. a verage n = 3 ± s.d. reagents, therefore improve the degradation efficiency TW0 TW800 TW6400 of 3- and 4-PAHs relative to control (13–22%), which a cenaphthene (ace) 2.04 ± 0.30 1.62 ± 0.31 18.24 ± 3.3 oer a p ff ossible alternative to the removal of PAHs from Fluorine (Fl U) 0.94 ± 0.21 0.80 ± 0.14 17.72 ± 2.3 soils. phenanthrene (pHe) 0.52 ± 0.19 0.43 ± 0.34 14.06 ± 1.5 Fluoranthene (Fl T) 0.08 ± 0.05 0.08 ± 0.04 14.44 ± 2.6 pyrene (pyR) 0.05 ± 0.03 0.06 ± 0.02 15.24 ± 3.4 chrysene ( cHR) 0.04 ± 0.02 0.03 ± 0.01 10.23 ± 2.2 4. Conclusion Benzo(b)fluoranthene 0.02 ± 0.01 0.01 ± 0.008 0.59 ± 0.07 (BbFa ), In this study, successive Fenton oxidation (up to three Benzo(a)pyrene (Bap) 0.04 ± 0.01 0.04 ± 0.02 0.89 ± 0.20 times) was conducted to enhance the removal efficiency dibenzo(a,h)anthracene 0.07 ± 0.03 0.06 ± 0.02 0.48 ± 0.12 (dBa ) of nine USEPA priority PAHs (ACE, FLU, PHE, FLT, GEOLOGY, ECOLOGY, AND LANDSCAPES 203 Diyáuddeen, B. H., Aziz, A. R. A., & Daud, W. M. A. W. PRY, CHR, BbFA, BaP and DBA) in aged soil highly con- (2012). Oxidative mineralisation of petroleum refinery taminated with PAHs. Results showed that the removal effluent using Fenton-like process. Chem Eng Res Des., 90, of PAHs has the “drag tail” phenomenon during three- 298–307. time Fenton oxidation. In order to increase desorption Fernandez, M. J., Garcia, C., Garcia-Villanova, R. J., & Gomez, of PAHs in soil and increase the amount of PAH avail- J. A. (1996). Evaluation of liquid−solid extraction with a able for the hydroxyl radical (·OH), the application of new sorbent and liquid−liquid extraction for multiresidue pesticides. determination in raw and finished drinking surfactant Tween 80 was investigated to accelerate des- waters. Journal of Agricultural and Food Chemistry, 44, orption and Fenton oxidation of PAH in soil aer t ft wo 1790–1795. times Fenton oxidation in this study. Results showed Gan, S., Lau, E. V., & Ng, H. K. (2009). Remediation of soils that little effect of Tween 80 on desorption of ACE, FLU, contaminated with polycyclic aromatic hydrocarbons PHE, FLT, PRY, CHR, BbFA, BaP and DBA was observed (PAHs). Journal of Hazardous Materials, 172, 532–549. −1 Gan, S., Yap, C. L., & Ng, H. K. (2013). 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Journal

Geology Ecology and LandscapesTaylor & Francis

Published: Jul 3, 2017

Keywords: Surfactant; desorption; Fenton oxidation; PAHs; aged soil

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