A biocompatible stepping stone for the removal of emerging contaminants

A biocompatible stepping stone for the removal of emerging contaminants

Separation and Purification Technology 153 (2015) 91–98 Contents lists available at ScienceDirect Separation and Purification Technology journal hom...

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Separation and Purification Technology 153 (2015) 91–98

Contents lists available at ScienceDirect

Separation and Purification Technology journal homepage: www.elsevier.com/locate/seppur

A biocompatible stepping stone for the removal of emerging contaminants María S. Álvarez a, José M.S.S. Esperança b, Francisco J. Deive a,⇑, Mª Ángeles Sanromán a, Ana Rodríguez a,⇑ a b

Department of Chemical Engineering, University of Vigo, 36310 Vigo, Spain Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. República, 2780-157 Oeiras, Portugal

a r t i c l e

i n f o

Article history: Received 23 June 2015 Received in revised form 8 August 2015 Accepted 26 August 2015 Available online 28 August 2015 Keywords: Emerging contaminants Ibuprofen Diclofenac Ionic liquids Aqueous biphasic systems

a b s t r a c t The presence of emerging contaminants like pharmaceuticals in the environment is prompting the search of new methods to concentrate and remove them from soils, sediments and effluents. A completely biocompatible aqueous biphasic system composed of Tween 20 or Tween 80 and the ionic liquid choline chloride has been designed for extracting non-steroidal anti-inflammatory drugs from aqueous streams. After an initial evaluation of the salting out potential of the selected ionic liquid at different temperatures, the extraction capacity of these systems to be applied for ibuprofen and diclofenac removal from aqueous streams was assessed. Very high levels of contaminant removal (higher than 90%) were reached for all the temperature and feed concentrations used. The suitability of the proposed biocompatible aqueous biphasic systems for the treatment of drugs-polluted effluents from surfactant-based soil washing operations is envisaged. Ó 2015 Elsevier B.V. All rights reserved.

1. Introduction Emerging contaminants are currently gaining social awareness due to their potential deleterious effects in the environment. Nonetheless, there is still an absence of legislation ruling the presence of these pollutants [1], an only the Water Framework Directive (2000/60/EC) [2] presents vague guidelines related to the water policies in the EU. More specifically, research funds are being invested in different international joint initiatives in order to merge research efforts tackling efficient wastewater treatment processes to remove these compounds [3]. Among the emerging pollutants, non-steroidal anti-inflammatory drugs (NSAIDs) are the most utilized group of analgesic and anti-inflammatory drugs worldwide, due to their suitability to treat the pain triggered by common illnesses [4]. Thus, the last report by the Spanish Ministry of Health stresses that arylpropionic derivatives are by far the largest used pharmaceuticals (about 65.1% of the total drug consumption), being ibuprofen the one with higher intake rate (43.9%) and diclofenac, an arylacetic acid derivative, the second one [5]. This scenario has compelled to analyze the possible presence of these compounds in the environment, as they can be excreted without having been metabolized. In this sense, different authors have shed light on their presence in waste water treatment plants

⇑ Corresponding authors. E-mail addresses: [email protected] (F.J. Deive), [email protected] (A. Rodríguez). http://dx.doi.org/10.1016/j.seppur.2015.08.039 1383-5866/Ó 2015 Elsevier B.V. All rights reserved.

(WWTPs), and have concluded that these compounds are not effectively removed after the treatment [6]. More specifically, ibuprofen and diclofenac concentration has been detected in the inlet streams of different WWTPs at concentration levels of 516 and 250 ng/L, recording less than 50% and 15% of removal in the outlet effluents, respectively [7]. In this sense, NSAIDs have also been detected in ground waters (in the order of ppb and ppt) and sediments (in the order of ppm and ppb) due to the great development of new analytical techniques [8,9]. It is clear that the continuous introduction of these pollutants may seriously affect drinking water supplies, ecosystems and human health, as reviewed by Sirés and Brillas [10]. Given the observed limitations of WWTPs, new treatment strategies have been investigated such as advanced oxidation processes or membrane technologies [11,12]. However, little information can be found related to the application of liquid–liquid extraction to the removal of these contaminants. Aqueous biphasic systems, a phase splitting typically caused by a salt in the presence of aqueous solutions of polymers, have emerged as a valuable separation strategy. Coutinho and coworkers have demonstrated the suitability of this method for the removal of NSAIDs and strogens [13,14] by using ionic liquids. In the last years, the outbreak of these neoteric solvents, with appealing properties such as their negligible volatility and tunability [15], has boosted the implementation of ‘all-purpose’ aqueous biphasic systems in combination with salts and polymers [16,17].

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Recently, we have demonstrated the capacity of imidazoliumbased ionic liquids to trigger phase segregation in aqueous solutions of non-ionic surfactants with a number of advantages like their low interfacial tension, rapid phase disengagement, low cost and bulk availability of the surfactants [18]. In this work, we concluded that more hydrophilic ionic liquids were more prone to trigger liquid–liquid demixing, so the search of more hydrophilic families could open up new opportunities to be applied in polluted effluents obtained after surfactant-based soil washing processes, where this kind of surface active compounds are usually employed as contaminant solubilizers. On the basis of the abovementioned, more hydrophilic and generally recognized biocompatible ionic liquids like choline chloride (N1112OHCl) [19,20] have been proposed to trigger phase segregation in aqueous solutions of non-ionic surfactants. In this case, Tween 20 and Tween 80 have been chosen since they are considered as GRAS by the US FDA and they are classified as safe food additives in many countries (E432 and E433, respectively) [21]. The immiscibility windows of the systems were firstly investigated at different temperatures, by characterizing the binodal curves and tie line data. The results were discussed on the basis of the surfactant and ionic liquid hydrophobicity and operation temperature. The extractive performance for two model NSAIDs, ibuprofen and diclofenac, was determined in order to suggest a viable strategy for removing them from aqueous polluted effluents.

composition was quantified by measuring densities and refractive indices (estimated uncertainty of concentration ± 0.02%). 3.2. Ibuprofen and diclofenac extraction and quantification For the study of NSAIDs partition, different aqueous solutions of Tween 80 containing ibuprofen and diclofenac at concentrations of 35 mg/L were introduced in glass ampoules, since it falls in the range usually detected in environmental samples [8,9]. Choline chloride was added until the desired composition within the biphasic region was reached. The mixture was vigorously stirred and left to settle for at least 48 h at 298.15 K and 333.15 K. The layers were carefully separated in order to quantify ibuprofen and diclofenac by HPLC measurements. HPLC-DAD (Agilent 1260 infinity) is equipped with a Kinetex Biphenyl column (4.6  150 mm; internal diameter 5 lm). 10 lL of sample were eluted in gradient mode for 15 min at a flow rate of 1 mL/min, using a mixture water/ethanol at the following ratios: 65:30 for 10 min and 15:80 for the separation. Retention times for ibuprofen and diclofenac were 10.149 and 10.713 min, respectively. The calibrations were carried out with stock solutions prepared in methanol at a concentration of 3.5 mg/mL, and were appropriately diluted in Milli-Q water (0.1–10 mg/L). 4. Results and discussion

2. Experimental 2.1. Chemicals The non-ionic surfactants polyethoxylated sorbitan monolaurate (Tween 20) (>97%) and monooleate (Tween 80) (>99%), the NSAIDs ibuprofen (>98%) and diclofenac (>98.5%) were acquired from Sigma–Aldrich and employed as received without further purification. Choline chloride (>99%) was also purchased from Sigma–Aldrich and submitted to vacuum for several days at 70 °C to ensure moisture removal prior to its use. The chemical structures of all these compounds are shown in Fig. 1. 3. Experimental procedure 3.1. Binodal curves determination The binodal curves were ascertained in a magnetically stirred jacketed glass cell (Fig. S1) at temperatures ranging from 298.15 to 333.15 K. The temperature was controlled with a F200 ASL digital thermometer with an uncertainty of ±0.01 K. The cloud point method was the experimental technique for binodal data determination [18]. Briefly, binary mixtures with known compositions of ionic liquid and surfactant were prepared in a dry chamber, and drop-wise additions of water were carried out until the disappearance of solids, thus characterizing the S + 2L region. Afterwards, water was added up to turbidity vanishing in order to fully map the binodal curves. The concentration of these points was determined by weighting in an analytical Sartorius Cubis MSA balance (125P-100-DA, ±105 g). The binodal curve was also characterized by measuring densities and refractive indices at different temperatures, using an Anton Paar DSA-48 digital vibrating tube densimeter (±2  104 g cm3), and a Dr. Kernchen ABBEMAT WR refractometer (±4  105), both calibrated in accordance with the manufacture instructions. Experimental tie-lines were calculated by preparing a ternary mixture from the biphasic region, left under stirring for 1 h, and afterwards, an idle period of 48 h was left in order to reach the equilibrium. The two segregated layers were split and their

4.1. Choline chloride as segregation agent First of all, the segregation potential of the ionic liquid N1112OHCl in aqueous solutions of the non-ionic surfactants Tween 20 and Tween 80 was explored at several temperatures (298.15, 313.15, 323.15 and 333.15 K). The experimental data are compiled in Tables S1 and S2 in the SI, and they can be visualized in Figs. 2 and 3. The analysis of the influence of temperature on the binodal curves allows concluding that liquid–liquid demixing is eased at higher temperatures for both surfactants. This is attributed to the lower ability of the non-ionic surfactant to establish hydrogen bonds with water at higher temperatures, which furthers the salting out effect provided by the N1112OHCl ionic liquid. This behavior is coincident with previous results for other systems containing non-ionic surfactants like Triton X-100 and Triton X-102 with the ionic liquid C2C1imC2SO4 [18]. An exhaustive literature analysis on the effect of temperature on the immiscibility window has been carried out, and the main results are summarized in Table S5. In order to better classify the information, the table has been divided into the four main types of aqueous biphasic systems found, namely, those based in polymers, ionic liquids, surfactants and organic solvents. As can be noticed, two main behaviors can be inferred, depending on the nature of the compounds competing for the water molecules: a proportional relationship between the area of the immiscibility window and temperature is observed when organic solvents, polymers or surfactants are salted out by inorganic or organic salts, [22,23]. Contrarily to this, the systems composed of ionic liquids and inorganic or organic salts display smaller biphasic regions at higher temperatures [24,25]. The reason for these trends lies in the weakening of the hydrogen bonds between the water molecules and the hydrophilic moiety of polymers, non-ionic surfactants and organic solvents at elevated temperatures, which leads to an increased hydrophobicity of these compounds. On the contrary, the completely different properties of ionic liquids involve greater interplays with water at higher temperatures. Therefore, when non-ionic surfactant and ionic liquids are put together, a synergic effect is observed at elevated temperatures, since a greater ability for water solvation of the ionic liquid is summed

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Diclofenac

93

Ibuprofen

Tween 20 (w+x+y+z=20)

Tween 80 (w+x+y+z=20)

Choline Chloride Fig. 1. Structures of the NSAIDs, ionic liquid and non-ionic surfactants.

to the lower affinity for the water molecules of the non-ionic surfactant, thus leading to the remarkable increase of the biphasic region. The comparison between surfactants Tween 20 and Tween 80 reflects the existence of greater immiscibility regions for the latter, independently of the temperature, as a consequence of their different chemical structure. Thus, Tween 80 is more easily salted out by N1112OHCl due to the fact that it is less prone to establish hydrogen bonds with water, so the competition between the surfactant and the ionic liquid for the water molecules is more easily won by the latter. In this sense, a valuable tool to explain this effect is the degree of hydrophobicity of the surface active compounds, as can be inferred from their Hydrophilic/Lipophilic balance (HLB). This is a useful parameter widely considered for measuring the aqueous affinity of surfactants, varying between 0 and 20, from high to low hydrophobicity, respectively. The greater hydrophobicity of Tween

80 with respect to Tween 20 (HLB = 5 vs. HLB = 16.7) makes us to foresee its easier phase disengagement, in line with previous results of our group for surfactant-based aqueous biphasic systems in the presence of inorganic and organic salts, and imidazolium ionic liquids [18,26–31]. Besides the role of the aforesaid biocompatible non-ionic surfactant in the observed water demixing behavior, the selection of an environmentally benign ionic liquid is crucial to attain a truly biocompatible separation platform. The results obtained with N1112OHCl are encouraging when compared with previous aqueous biphasic systems entailing imidazolium-based ionic liquids [18], since much greater salting out potential is reached with the ammonium-based solvents. The economic and environmental gains of the implemented system can be attributed to the lower consumption of extraction agent, the lower environmental impact and the lower cost of reagents.

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Water 0

Water 0

100

10

90

20 L

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0

0

0

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0

30

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0

Tween 20

40

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100

0

0 10

20

30

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50

0:5

2 dw2

þ cw2 þ   0:5 2 w1 ¼ exp a þ bw2 þ cw þ dw2 ;

ð1Þ ð2Þ ð3Þ

where w1 and w2 are defined as the mass fraction of Tween and N1112OHCl, respectively. The minimization of the following standard deviation (r) license the calculation of a, b, c and d:

2 !1=2 PnDAT  zexp  zadjust i nDAT

60

70

80

N1112OH Cl Tween 20

All the experimental data were fitted to different common empirical models [32,33]:

ð4Þ

In this equation, zexp and zadjust are the experimental and theoretical values, respectively, and nDAT is the number of data. Thus, the parameters are listed in Tables 1–3, along with the optimized standard deviation. The analysis of these data evidences a more suitable fitting of Eq. (2), so these theoretical data were represented together with the experimental data in Figs. 2 and 3. Previous research works involving non-ionic surfactant-based aqueous biphasic systems [26,27,32,34] reveal that this kind of polynomial equations (Eq. (2)) is the best option to properly describe the

10

S + 2L

100

Fig. 2. Phase regions and tie-lines for the systems Tween 20 + N1112OHCl + H2O at 298.15 K (d), 313.15 K ( ), 323.15 K ( data, solid lines are guides to the eye and dashed lines refer to model.

w1 ¼ a  exp ðbw2  cw32 Þ;

30

L+ L

90

10

S + 2L

40

80

20

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30

L+ L

60

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80 L

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L

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Water

20



70

N1112OH Cl

100

10

w1 ¼ a þ

10

S + 2L

100

Water

0:5 bw2

20

N1112OH Cl Tween 20

Tween 20

0

30

L+ L

90

10 0

30

40

80

20 S + 2L

20

50

70

30

L+ L

10

60

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40

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0

70

50

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100

L

40

60

50

90

80

30

70

40

80

90

20

80

30

100

10

), 333.15 K (

90

100

N1112OH Cl

). Symbols represent experimental

immiscibility region, no matter the salting out agent under study (organic or inorganic salts and ionic liquids). This is against the generalized trend where exponential Merchuk-type models have been extensively applied for the fitting of polymer/salt and ionic liquids/salt-based aqueous biphasic systems. 4.2. Ibuprofen and diclofenac extraction The greater immiscibility detected in the systems containing aqueous solutions of Tween 80 suggests the possibility of getting longer tie-lines and higher concentration factors. Therefore, the first step was to experimentally determine the tie-lines of the systems at different temperatures in order to define the viable points to perform the extraction of emerging contaminants. The experimental data are presented in Figs. 2 and 3, and are listed in the SI (Table S3). Two useful parameters, the tie-line length (TLL) and the slope (S), were picked to investigate the suitability of N1112OHCl and non-ionic surfactants as a platform to remove the abovementioned NSAIDs from wastewater:

TLL ¼ S¼

h

wI1 wI2

wI1  wII1

 

wII1 wII2

;

2

 2 i0:5 þ wI2  wII2 ;

ð5Þ ð6Þ

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Water 0

Water 0

100

10

90

20

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0 40

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Tween 80

20

90

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S + 2L

100

0 10

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0 10

90

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60

L+ L

0 40

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80

90

Tween 80

40 L+ L

100

N1112OH Cl

20

0

Table 1 Parameters of Eq. (1) and standard deviation for Surfactant + N1112OHCl + H2O at several temperatures. a

b

c

r

Tween 20 298.15 313.15 323.15 333.15

1.0780 1.0632 1.0642 1.0598

1.3737 1.4308 1.5792 1.5160

22.657 37.798 55.859 101.73

0.0210 0.0217 0.0274 0.0346

Tween 80 298.15 313.15 323.15 333.15

1.0589 1.0393 1.0062 0.9942

1.1978 1.1896 0.9610 0.9830

35.862 77.331 180.30 381.77

0.0280 0.0380 0.0380 0.0637

where the superscripts I and II refer to the top and bottom phases, respectively. The results evidence that the operation in tie-lines with greater TLL allows triggering two immiscible layers, one of them almost exclusively constituted by non-ionic surfactant (concentrations near to 95%) and the other one composed of the binary mixture water–N1112OHCl. Additionally, the more hydrophobic

10

S + 2L

100

0 10

20

30

40

50

60

70

80

90

100

N1112OH Cl

Tween 80

Fig. 3. Phase regions and tie-lines for the systems Tween 80 + N1112OHCl + H2O at 298.15 K (d), 313.15 K ( ), 323.15 K ( data, solid lines are guides to the eye and dashed lines refer to model.

T/K

30

90

10

S + 2L 30

50

80

20

20

60

70

30

100

70

L

60

40

90

80

50

50

60

10

100

90

30

70

50

0

90

100

20

80

L

80

80

N1112OH Cl

100

30

70

70

Water

20

40

60

Tween 80

Water

10

10

S + 2L

100 0

N1112OH Cl

0

30

L+ L

80

20

90

30

40

70

30 L+ L

20

50

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40

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60

0

70 L

40

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80

30

70 L

80

90

20

80

30 40

100

10

), 333.15 K (

). Symbols represent experimental

Tween 80 fosters more negative S values, which would be advantageous in terms of extraction capacity when these systems are implemented in the treatment of a wastewater effluent obtained from polluted-soil washing steps.

Table 2 Parameters of Eq. (2) and standard deviation for Surfactant + N1112OHCl + H2O at several temperatures.

r

T/K

a

b

c

Tween 20 298.15 313.15 323.15 333.15

d

1.0475 1.0624 1.0460 1.0560

0.0092 1.3573 1.3072 1.3906

0.4237 0.2341 0.1377 0.0300

0.8383 2.1335 2.1522 4.3340

0.0073 0.0083 0.0167 0.0285

Tween 80 298.15 313.15 323.15 333.15

1.0483 1.0526 0.9651 1.1072

0.9580 1.2326 0.1082 2.2280

0.4346 0.2198 2.9187 3.1921

1.7981 4.8072 4.0308 22.607

0.0178 0.0252 0.0254 0.0508

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Table 3 Parameters of Eq. (3) and standard deviation for Surfactant + N1112OHCl + H2O at several temperatures. T/K

a

b

c

Tween 20 298.15 313.15 323.15 333.15

0.2600 0.4277 0.3907 0.6228

3.9566 6.3311 6.3811 9.7033

8.0117 14.780 15.620 26.982

Tween 80 298.15 313.15 323.15 333.15

0.4553 0.5733 0.6996 1.0270

6.6965 9.0963 12.612 17.618

16.374 25.414 40.755 66.843

r

d 19.993 35.055 43.393 77.543

0.0240 0.0220 0.0297 0.0338

36.388 66.564 127.61 271.82

0.0277 0.0368 0.0363 0.0268

The consistency of the experimental tie line data was assessed by the linearization of the Othmer–Tobias and Bancroft equations [35,36].

   m 1  wI1 1  wII2 ¼ n ; wI1 wII2  II   I r w3 w3 ¼ k ; wII2 wI1

ð7Þ ð8Þ

being n, m, k and r are the fitting parameters, which come from the minimization of the sum of the squared differences between the observed and predicted values of the dependent variable, through an iterative procedure based on Marquardt–Levenberg algorithm, using the Sigma Plot 11.0 software. The values of the fitting parameters and the regression coefficients are displayed in Tables 4 and 5, and reveal the reliability of the models to appropriately characterize the tie-lines, since R2 is always higher than 0.95. On the basis of the binodal and tie-line data, Tween 80 was chosen to implement the extraction of the selected emerging contaminants, ibuprofen and diclofenac, at the lowest and highest temperatures. The efficiency of the NSAIDs removal was expressed as follows:

Eð%Þ ¼

 I mi  100 mi

ð9Þ

where miI and mi is the NSAID mass content in the upper phase and the total NSAID mass content, respectively. The impact of temperature and feed concentration on the ibuprofen and diclofenac extraction can be noticed in Fig. 4. In general, it becomes patent that very high values of NSAIDs extraction to the top phase (always greater than 90%) are recorded for the temperature range and feed concentrations employed. However, the chemical nature of the contaminant seems to slightly impact the extraction yields attained, since ibuprofen is generally removed at higher rates than diclofenac. This fact may be attributed to the different affinity of the contaminants for the organic phase. Usually, one way to measure this affinity is by analyzing the log Kow

Table 5 Parameters of Bancroft equation and correlation coefficient for Surfactant + N1112OHCl + H2O at several temperatures. Surfactant

T/K

k

r

R2

Tween 20

298.15 313.15 323.15 333.15

1.0967 1.0000 1.3719 1.2662

0.3335 0.3061 0.4453 0.3157

0.999 0.985 0.967 0.980

Tween 80

298.15 313.15 323.15 333.15

2.3952 1.3463 1.5614 1.7480

0.6394 0.3318 0.4056 0.4648

0.977 0.980 0.987 0.966

values. In this particular case, log Kow for ibuprofen and diclofenac is 2.48 and 1.90, respectively [37], which further demonstrates the higher migration of ibuprofen to the surfactant-rich phase. Regarding the effect of N1112OHCl concentration in the feed (Fig. 4 and Table S4 in SI) when fixing the tie-line, it can be concluded that higher levels of ionic liquid are associated with slightly lower NSAIDs extraction levels. In this sense, it is also outstanding that the operation at room temperature does not jeopardize the achievement of high levels of pollutant removal (in some cases even near to 100%), which is a clear operational advantage from an industrial point of view. Apart from the abovementioned benefits, the operation at feed concentrations near to the N1112OHCl vertex involves contaminant concentration factors greater than 10 without compromising too much the contaminant migration to the upper phase (E higher than 90%). The proposed alternative could be suitably implemented for the removal of emerging pollutants from an aqueous effluent. The process flowsheet diagram shown in Fig. 5 integrates this one-step separation strategy after a NSAIDs-polluted soil washing stage, using an aqueous solution of Tween 80 (5%) as solubilizing agent (point 1 in both the ternary and flowsheet diagram in Fig. 5). N1112OHCl should be added up to the concentration indicated as 2 in the ternary diagram (corresponding to the same number in the flowsheet diagram) is attained, leading to an upper phase where more than 90% of ibuprofen and diclofenac have migrated and concentrated more than 10 times in a phase almost exclusively formed by Tween 80 (95%, as indicated in point 4 in the ternary plot). Given the interest of these data, the process should be optimized in order to analyze the reusability of both Tween 80 and N1112OHCl. In this sense, one of the important aspects to be tackled is to elucidate the maximum solubility of these compounds in the Tween 80-rich phase. This would give an idea of the number of cycles that the surfactant could be reused. All in all, this novel process allows a one step-removal of two of the most common emerging contaminants, which is competitive when compared with two recent processes recently reported requiring two or even three combined techniques (chemical, physical and biological) to yield similar levels of NSAIDs removal [38,39].

5. Conclusions Table 4 Parameters of Othmer–Tobias equation and correlation coefficient for Surfactant + N1112OHCl + H2O at several temperatures. Surfactant

T/K

n

m

R2

Tween 20

298.15 313.15 323.15 333.15

1.5663 1.5602 1.0000 1.0000

4.2347 3.6668 2.8284 3.6761

0.980 0.989 0.961 0.980

Tween 80

298.15 313.15 323.15 333.15

0.3959 1.0000 1.0000 1.0000

2.4965 3.9707 3.2352 2.2298

0.969 0.967 0.970 0.953

In this work we have demonstrated the suitability of a hydrophilic and biocompatible ionic liquid, N1112OHCl, to be applied for the removal and concentration of common drugs. The great segregation potential of the selected ionic liquid in aqueous solutions of non-ionic surfactants such as Tween 20 and Tween 80 at different temperatures was ascertained. The application of an aqueous system composed of ionic liquid and the most hydrophobic surfactant to a polluted effluent containing both diclofenac and ibuprofen revealed removal levels higher than 90%. Apart from the undoubted environmental and economic benefits of the proposed removal strategy (mild operating conditions, low environmental

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97

T = 333.15 K

T = 298.15 K

E (%)

100 95 90 85 80

Feed composition (w1F, w2F) Fig. 4. Extraction percentage (E (%)) of ibuprofen ( ) and diclofenac ( ) for different feed composition in systems Tween 80 + N1112OHCl + H2O at 298.15 and 333.15 K. w1F and w2F are the compositions of Tween 80 and N1112OHCl in the feed stream, respectively.

Fig. 5. Flowsheet diagram and ternary plot for the aqueous biphasic system-based removal of ibuprofen (Ibu) and diclofenac (Dcf) from waste effluents obtained after soil washing with aqueous solution of Tween 80 (5%).

impact and price and bulk availability of Tween surfactants and choline-based ionic liquid), the easy implementation of the process at industrial scale urges future optimizations of the process to analyze the viability of reusing the surfactant and the ionic liquid. Acknowledgements This work has been supported by the Spanish Ministry of Economy and Competitiveness and EDRF funds (Project CTM201452471-R). M.S. Álvarez thanks University of Vigo for funding her stay at the ITQB. F.J. Deive acknowledges Spanish Ministry of Economy and Competitiveness for funding through a Ramón y Cajal contract.

Appendix A. Supplementary material Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.seppur.2015.08. 039. References [1] K. Kümmerer, The presence of pharmaceuticals in the environment due to human use – present knowledge and future challenges, J. Environ. Manag. 90 (2009) 2354–2366. [2] Directive 2000/60/EC of the European Parliament and of the Council, of 23 October 2000 Establishing a Framework for Community Action in the Field of Water Policy. [3] http://www.waterjpi.eu/.

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