Liquid–Liquid Equilibrium for Ternary Systems Containing Water

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Liquid−Liquid Equilibrium for Ternary Systems Containing Water, Oleic Acid, and Alcohols at 313.15 K. Effect of Alcohol Chain Length Joanna S. Santos,† Alexandre P. L. Craig,† Jéssica Mayara O. Santana,† Alexandre F. Santos,†,‡ Montserrat F. Heredia,† Marcos L. Corazza,‡ Elton Franceschi,† and Cláudio Dariva*,† †

Núcleo de Estudos em Sistemas ColoidaisPEP/PBI/UNIT, Campus Farolândia, Avenida Murilo Dantas 300, Aracaju, Sergipe 49032-490, Brazil ‡ Department of Chemical Engineering, Federal University of Paraná (UFPR), Polytechnic Center, 82530-990 Curitiba, Paraná, Brazil ABSTRACT: This work aims to report liquid−liquid equilibrium (LLE) experimental data for six ternary systems of interest in esterification reactions, composed of water, oleic acid, and alcohols (ethanol, 1-propanol, isopropanol, 1-butanol, 1-hexanol, and 1octanol) at 313.15 K. The tie lines were determined by quantification of components in biphasic systems at distinct overall compositions. The experimental results showed that as the alcohol carbonic chain length increases, its solubility decreases in the aqueous phase. The experimental data were correlated with the NRTL and UNIQUAC models. The overall deviations obtained between the experimental and calculated values ranged from (0.27 to 1.29) % and from (0.40 to 1.40) % for NRTL and UNIQUAC models, respectively, suggesting that both models are able to describe the phase behavior of the investigated systems.

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INTRODUCTION Esters derived from the esterification of fatty acids and alcohols have applications in several industrial sectors, such as food, cosmetics, lubricants, fuels, flavors, and fragrances.1 For example, the alkyl esters derived from long chain fatty acids can result in biodiesel;2 butyl oleate has applications in flavors, plasticizers in waterproofing products, and grease and polishing;3 the hexyl and octyl oleates are called waxy esters.4 The enzymatic esterification/alcoholysis of fatty acids has become a promising method due to the mild reaction conditions, high catalytic efficiency, and selectivity inherent to the biocatalysts, resulting in higher purity products.1,5−8 The application of enzymes in nanoemulsions, where sub-micrometer scale emulsions are generated by the dispersion of organic liquids in water through the application of high shear forces,9−12 has been receiving attention in polymerization processes,13 for obtaining optically active organic compounds,14 and in esterification reactions.1,15 For enzymatic esterification in nanoemulsion systems, the most polar alcohols (e.g., ethanol) tend to concentrate in the aqueous medium, reducing its content inside the micelle. Aschenbrenner et al.15 studied the influence of alcohol in the esterification in nanoemulsions using ω-phenyl alcohols (C1− C5) and found that the solubility of alcohol in aqueous solution decreases with the increasing length of the alcohol, resulting in greater stability of the nanoemulsion and a more efficient reaction. In that sense, it is extremely important to study the phase behavior of the systems that emulate the medium of the esterification reaction in nanoemulsions. The alcohol partition between the continuous and dispersed phases, as well as the stability of nanoemulsion to maintain the maximum surface © 2015 American Chemical Society

area of the micelle, plays a fundamental role in designing efficient enzymea for catalyzing these systems. Besides the importance of the phase behavior of alcohols, water, and fatty acids in this area, there is a lack of information regarding a systematic study presenting the influence of alcohol chain length on the liquid−liquid equilibrium (LLE) of these systems. Zhang and Hill16 studied the LLE involving oleic acid, water, and ethanol under conditions highly diluted in ethanol at temperatures of (273.15, 303.15, 318.15, and 333.15) K. The authors observed that temperature has a stronger effect on the ethanol solubility in the organic phase than in the aqueous phase and that the oleic acid is very little soluble in the aqueous phase. Winkelman et al.17 present a study for ternary and quaternary systems involving oleic acid, water, butanol, and nheptane at temperatures of (301.15, 308.15, and 313.15) K. This work provides new experimental information about the LLE for ternary systems involving oleic acid, water, and linear alcohols with different sizes of carbon chain (ethanol, 1propanol, 2-propanol, 1-butanol, 1-hexanol, and 1-octanol) at 313.15 K and ambient pressure, in order to provide support for esterification of oleic acid in nanoemulsion via enzymatic catalysis. The experimental LLE results were correlated with the NRTL and UNIQUAC models.

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EXPERIMENTAL SECTION Materials. The characteristics of all chemicals used in the Experimental Section are summarized in Table 1. The following Received: December 29, 2014 Accepted: June 10, 2015 Published: June 26, 2015 2050

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Table 1. Sources and Purity of Chemicals Used in This Work chemical name

source

mass fraction purity

sodium hydroxide BSTFA + TMCS, 99:1a oleic acid oleic acid methanol ethanol 1-propanol 2-propanol 1-butanol 1-hexanol 1-octanol chloroform dichloromethane Karl Fischer reagent

Labsynth Laboratory Products, Ltd. Sigma-Aldrich Co., Ltd. Sigma-Aldrich Co., Ltd. Vetec Quimica Fina, Ltd. Vetec Quimica Fina, Ltd. Vetec Quimica Fina, Ltd. Vetec Quimica Fina, Ltd. Vetec Quimica Fina, Ltd. Vetec Quimica Fina, Ltd. Vetec Quimica Fina, Ltd. Vetec Quimica Fina, Ltd. Vetec Quimica Fina, Ltd. Vetec Quimica Fina, Ltd. Vetec Quimica Fina, Ltd.

0.990 for derivatization ≥ 0.999 ≥ 0.810 0.998 0.998 0.995 0.995 0.994 0.990 0.990 0.998 0.995 0.995

analysis method

GC-MSb

a BSTFA + TMCS, 99:1, N,O-bis(trimethylsilyl)trifluoroacetamide (99 %) + trimethylchlorosilane (1 %). bGC-MS, gas chromatography coupled to a mass spectrometer detector.

pressure (1.01 bar). The experimental data were always measured in triplicate. For the LLE experiments, the mass of each component of the ternary system was weighed on a precision balance (Shimadzu-AX200, ± 0.0001 g, Tokyo, Japan) and added to the equilibrium cells with internal volume of 10 mL. Then, the mixture was stirred vigorously for 15 min using a magnetic stirrer. After stirring, the system was left to rest for 12 h under controlled temperature of 313.15 K (± 0.2 K) with the aid of an ultrathermostatic bath (Quimis model Q214M2, Campanário, Brazil). Preliminary runs indicated that this period was sufficient to allow complete phase separation and leave the system in thermodynamic equilibrium. After the time of phase separation, aliquots of both phases, organic and aqueous, were collected and analyzed for the concentration of each component of the mixture. The water content was determined by titration with Karl Fischer reagent (Titrino 870 plus Mettler-Toledo, Columbus, OH, USA). The uncertainty of the method for water determination was 0.01 wt %. Considering the authentical triplicate runs performed in each point, it was determined that the uncertainty in the water content was always lower than 0.03 wt %. The concentration of oleic acid in each phase was determined by titration with a standardized solution of sodium hydroxide with phenolphthalein as an indicator, in accordance with the German Standard Method18 adapted for Melo-Júnior et al.2. Based on the uncertainty of the titration methodology and standard deviation of the replications, the uncertainty of oleic acid content was lower than 0.05 wt %. The alcohol content was determined by mass balance. Modeling. The NRTL and UNIQUAC models were used for LLE modeling. For all six ternary systems investigated, the NRTL and UNIQUAC interaction parameters for each binary pair were estimated using an simulated annealing stochastic algorithm, as described in detail by Ferrari et al.19 The overall root-mean-square deviations (RMSD) for the models was calculated by eq 1, using a molar fraction basis:

reagents were used as received for the LLE experiments: oleic acid for synthesis, absolute ethanol (Vetec, 99.8 wt %), 1propanol (Vetec, 99.5 wt %), 2-propanol (isopropanol; Vetec, 99.5 wt %), 1-butanol (Vetec, 99.4 wt %), 1-hexanol (Vetec, 99.0 wt %), and 1-octanol (Vetec, 99.0 wt %). Ultrapure water was used in all experiments (Milli-Q/MegaPurity). Absolute ethanol and sodium hydroxide (Synth, 99.0 wt %) were used for the quantification of oleic acid present in the equilibrium phases. Chloroform (Vetec, 99.8 %), anhydrous methanol (Vetec, 99.8 %), and Karl Fischer reagent without pyridine (Vetec, 99.5 %) were used to quantify the water content in the equilibrium phases. Purity of Oleic Acid. The purity of the oleic acid was analyzed by gas chromatography using dichloromethane (Vetec, 99.5 %) as diluent, and oleic acid GC (Sigma-Aldrich, ≥ 99.9 %) as authentic standard. BSTFA (Sigma-Aldrich, for derivatization, GC/GC-MS) was used as silylating agent with 1 % TMCS as silylation catalyst for samples derivatization. A 20 μL aliquot of BSTFA + TMCS was added to 20 mg of the sample, mixed well, and allowed to stand for 5−10 min until the sample was dissolved. Then, an aliquot of this mixture was diluted with 10 mL of dichloromethane in a volumetric flask to prepare a 1000 ppm solution for analysis. The analysis of fatty acids present in the oleic acid (Vetec) was checked in a gas chromatograph coupled to a mass spectrometer detector (GC-QP2010 Plus MS, Shimadzu). A Rtx-5MS (30 m × 0.25 mm × 0.25 μm) capillary column was employed in the equipment using helium as carrier gas at a flow rate of 1 mL·min−1. A 1 μL aliquot of the sample was injected in split mode (1:10). The injector was maintained at 553.15 K and the interface at 573.15 K. The oven heating program was as follows: initial temperature of 393.15 K, maintained for 5 min, and final temperature of 553.15 K, with heating rate of 10 K· min−1, and keeping the final temperature for 20 min. The Wiley library of the GC-MS system indicated, in addition to esters of oleic acid, esters of palmitic and linoleic acids in small concentrations. From the results, it was determined that the oleic acid purity was greater than 81 wt %. LLE Experiments. In this work experimental data of liquid−liquid phase equilibria were determined for six different ternary systems involving oleic acid, water, and alcohols with different chains (ethanol, 1-propanol, isopropanol, 1-butanol, 1hexanol, or 1-octanol) at 313.15 K and at ambient constant

NP

RMSD = 100

nf

nc

expt 2 calc ∑k = 1 ∑ j = 1 ∑i = 1 (xijk − xijk )

NP × nf × nc

(1)

where NP is the number of experimental points, nf is the number of phases, and nc is the number of components in the system. 2051

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Table 2. Experimental Data of Liquid−liquid Phase Equilibrium for Ternary Systems of Oleic Acid (1) + Water (2) + Ethanol (3), Oleic Acid (1) + Water (2) + 1-Propanol (4), Oleic Acid (1) + Water (2) + 2-Propanol (5), Oleic Acid (1) + Water (2) + 1Butanol (6), Oleic Acid (1) + Water (2) + 1-Hexanol (7), and Oleic Acid (1) + Water (2) + 1-Octanol (8) at Temperature of 313.15 K and 1 atma Oleic Acid (1) + Water (2) + Ethanol (3) overall composition

organic phase

w1

w2

w3

0.4999 0.5000 0.4997 0.4000 0.3499 0.2445 0.1603

0.3998 0.3198 0.3002 0.3001 0.3002 0.3265 0.3699

0.1003 0.1802 0.2001 0.2999 0.3499 0.4290 0.4698

w1

w2

aqueous phase w3

0.8920 0.0189 0.0891 0.8262 0.0403 0.1335 0.7853 0.0508 0.1639 0.6765 0.0793 0.2442 0.6130 0.1014 0.2856 0.4725 0.1485 0.3790 0.4353 0.1548 0.4099 Oleic Acid (1) + Water (2) + 1-Propanol (4)

overall composition

w1

w2

w3

0.0019 0.0020 0.0023 0.0037 0.0058 0.0164 0.0243

0.8650 0.7499 0.7198 0.6096 0.5554 0.5045 0.4691

0.1331 0.2481 0.2779 0.3867 0.4388 0.4791 0.5066

organic phase

w1

w2

w4

0.5012 0.4098 0.3500 0.3077 0.2497 0.1801

0.4488 0.4497 0.4501 0.4325 0.4494 0.4500

0.0500 0.1405 0.1999 0.2598 0.3009 0.3699

w1

w2

aqueous phase w4

0.9670 0.0154 0.0176 0.8345 0.0398 0.1257 0.7376 0.0592 0.2032 0.6123 0.0869 0.3008 0.5139 0.1171 0.3690 0.3491 0.1909 0.4600 Oleic Acid (1) + Water (2) + 2-Propanol (5)

overall composition

w1

w2

w4

0.0018 0.0018 0.0017 0.0017 0.0021 0.0044

0.9123 0.8492 0.8127 0.7806 0.7595 0.7005

0.0859 0.1490 0.1856 0.2177 0.2384 0.2951

organic phase

w1

w2

w5

0.4998 0.4100 0.3500 0.3079 0.2498 0.1802

0.4500 0.4500 0.4499 0.4327 0.4496 0.4500

0.0502 0.1400 0.2001 0.2594 0.3006 0.3698

w1

w2

0.9380 0.8221 0.6230 0.5624 0.4248 0.7292 Oleic Acid (1) +

overall composition

aqueous phase w5

0.0143 0.0477 0.0343 0.1436 0.0803 0.2967 0.1043 0.3333 0.1705 0.4047 0.0543 0.2165 Water (2) + 1-Butanol (6)

w1

w2

w5

0.0015 0.0017 0.0017 0.0015 0.0067 0.0020

0.9680 0.8950 0.7651 0.7331 0.6598 0.8223

0.0305 0.1033 0.2332 0.2654 0.3335 0.1757

organic phase

w1

w2

w6

0.4035 0.3522 0.3147 0.2518 0.1850 0.1250

0.5107 0.5149 0.5090 0.5290 0.5050 0.5500

0.0858 0.1329 0.1763 0.2192 0.3100 0.3250

w1

w2

0.8051 0.7030 0.6273 0.5006 0.3418 0.2587 Oleic Acid (1) +

overall composition

aqueous phase w6

0.0285 0.1664 0.0400 0.2570 0.0506 0.3221 0.0846 0.4148 0.1044 0.5538 0.1139 0.6274 Water (2) + 1-Hexanol (7)

w1

w2

w6

0.0018 0.0013 0.0021 0.0030 0.0019 0.0019

0.9929 0.9897 0.9674 0.9733 0.9394 0.9402

0.0053 0.0090 0.0305 0.0237 0.0587 0.0579

organic phase

w1

w2

w7

0.5000 0.4997 0.3998 0.2998 0.2200 0.1353

0.3999 0.4498 0.4001 0.4003 0.4545 0.5373

0.1001 0.0505 0.2001 0.2999 0.3255 0.3274

w1

w2

0.8331 0.8625 0.6575 0.4930 0.3818 0.2655 Oleic Acid (1) +

overall composition

aqueous phase w7

0.0198 0.1471 0.0169 0.1206 0.0304 0.3121 0.0389 0.4681 0.0508 0.5674 0.0455 0.6890 Water (2) + 1-Octanol (8)

w1

w2

w7

0.0016 0.0019 0.0017 0.0014 0.0016 0.0013

0.9828 0.9957 0.9846 0.9882 0.9944 0.9874

0.0156 0.0024 0.0137 0.0104 0.0040 0.0113

organic phase

aqueous phase

w1

w2

w8

w1

w2

w8

w1

w2

w8

0.4996 0.4501 0.3999 0.2999 0.2002 0.1353

0.4001 0.4998 0.4002 0.4001 0.4996 0.5374

0.1003 0.0501 0.1999 0.3000 0.3002 0.3273

0.8159 0.8759 0.6659 0.5000 0.3878 0.2652

0.0145 0.0147 0.0203 0.0242 0.0255 0.0297

0.1696 0.1094 0.3138 0.4758 0.5867 0.7051

0.0018 0.0017 0.0018 0.0017 0.0014 0.0012

0.9784 0.9954 0.9927 0.9983 0.9986 0.9940

0.0198 0.0029 0.0055 0.0000 0.0000 0.0048

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Table 2. continued a

Standard uncertainties are u(T) = 0.2 K, u(w1) = 0.0005, and u(w2) = 0.0003. Alcohol content was determined by mass balance

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RESULTS AND DISCUSSION For clarity of analysis, in this study, the compounds used in the LLE experiments were identified as follow: oleic acid (1), water (2), ethanol (3), 1-propanol (4), 2-propanol (5), 1-butanol (6), 1-hexanol (7), and 1-octanol (8). Table 2 presents the experimental equilibrium data for each ternary system investigated, in terms of compounds mass fraction. Table 3 presents the estimated parameters for the UNIQUAC and NRTL equations, using the approach cited previously. Table 3. Binary Interaction Parameters of UNIQUAC and NRTL Models for the Systems Oleic Acid (1) + Water (2) + Ethanol (3), Oleic Acid (1) + Water (2) + 1-Propanol (4), Oleic Acid (1) + Water (2) + 2-Propanol (5), Oleic Acid (1) + Water (2) + 1-Butanol (6), Oleic Acid (1) + Water (2) + 1Hexanol (7), and Oleic Acid (1) + Water (2) + 1-Octanol (8) at 313.15 K NRTL

Figure 1. Liquid−liquid experimental data for the ternary system containing oleic acid (1) + water (2) + 1-butanol (6) at 313.15 K. Comparison of data: □, obtained in this work; Δ, literature (Winkelman et al.17).

Δgji

Δgij i−j

K

1−2 1−3 2−3 1−4 2−4 1−5 2−5 1−6 2−6 1−7 2−7 1−8 2−8

588.88 −2415.68 431.77 −4672.15 −3087.56 −199.17 997.98 −217.80 1248.19 1471.63 2038.92 779.87 1923.56

αij

K 3960.19 2273.47 −1173.31 2996.21 −656.42 −232.72 −282.55 −1348.63 130.57 −2932.34 −213.17 −2502.62 398.32 UNIQUAC

0.1400 0.1911 0.1471 0.4233 0.3488 0.3542 0.3173 0.3243 0.3669 0.3622 0.1766 0.3745 0.2929

Δuij

Δuji

i−j

K

K

1−2 1−3 2−3 1−4 2−4 1−5 2−5 1−6 2−6 1−7 2−7 1−8 2−8

441.79 −758.36 −734.78 −1339.93 −564.93 −432.62 82.26 −229.75 450.80 −482.11 219.98 −1936.19 606.10

860.98 −386.54 −359.06 1743.12 −328.95 −198.94 −338.16 260.64 −129.81 200.65 20.09 3222.22 55.69

RMSD 1.15 0.81 0.71 1.29 0.30 0.27

RMSD 0.95 0.76

Figure 2. Liquid−liquid equilibrium data for the system composed of oleic acid (1) + water (2) + ethanol (3) at temperature of 313.15 K: ■, experimental data; --, NRTL model; , UNIQUAC model. Data are presented in mass fraction.

0.40 1.40

agreement in the experimental data and also regarding the thermodynamic model with the experimental results. Figures 1 to 6 demonstrate that the solubility of alcohols in the aqueous phase decreases with increasing number of carbons in its chain, also leading to the changes on the slopes of the tie lines from positive (for the system with ethanol) to negative (from the other systems). As the chain length of the alcohol increases, the slopes are negatively more pronounced due to decreased solubility of the alcohol in the aqueous phase. This fact is attributed to the smaller polarity of alcohol as its chain size is enhanced. This find corroborates the works of Aschenbrenner et al.15 and Barros et al.1 that investigated the

0.76 0.59

The experimental LLE results obtained for the ternary systems investigated along with the results from the thermodynamic models for the LLE are depicted in Figures 1 to 6. Figure 1 presents a comparison between experimental data obtained in this work and literature study17 for the system oleic acid/water/1-butanol, from where it can be evidenced good 2053

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Figure 3. Liquid−liquid equilibrium data for the system composed of oleic acid (1) + water (2) + 1-propanol (4) at temperature of 313.15 K: ■, experimental data; --, NRTL model; , UNIQUAC model. Data are presented in mass fraction.

Figure 5. Liquid−liquid equilibrium data for the system composed of oleic acid (1) + water (2) + 1-hexanol (7) at temperature of 313.15 K: ■, experimental data; --, NRTL model; , UNIQUAC model. Data are presented in mass fraction.

Figure 4. Liquid−liquid equilibrium data for the system composed of oleic acid (1) + water (2) + 2-propanol (5) at temperature of 313.15 K: ■, experimental data; --, NRTL model; , UNIQUAC model. Data are presented in mass fraction.

Figure 6. Liquid−liquid equilibrium data for the system composed of oleic acid (1) + water (2) + 1-octanol (8) at temperature of 313.15 K: ■, experimental data; --, NRTL model; , UNIQUAC model. Data are presented in mass fraction.

effect of the size of the chain alcohols on esterification reactions performed in miniemulsion systems. These authors found that alcohols with smaller chain size showed higher solubility in the continuous phase (water). Figures 1 to 6 also show that the NRTL and UNIQUAC models were able to satisfactorily correlate the experimental data for all systems investigated. An inspection of Table 2 indicates that for alcohols of small carbon chain (C2 and C3) the overall deviations (RMSDs) for UNIQUAC were lower (0.40 to 0.95) compared to the NRTL model, whereas for alcohols of higher carbon chain (C4, C6, and C8), the NRTL model presented a slighted better result than UNIQUAC. Zhang and Hill16 used the NRTL equation to model the system oleic acid/ethanol/water for concentrating the ethanol produced by fermentation and found that NRTL is able to describe the system. Authors also found that the UNIQUAC

model is more sensitive to the purity of the species in the liquid phase. Recent studies on the edible oil deacidification by liquid−liquid extraction, involving similar systems (unsaturated triacylglycerol + water + ethanol) also corroborate these findings.20,21 In general, for other alcohols, there is a lack of information in the literature regarding LLE experimental results. From Figures 2 to 4 it can be observed that NRTL and UNIQUAC models were able to describe the experimental results obtained in this work. On the other hand, the capability of these models to correlate similar systems can be found in the literature. For the system water/2-propanol/ethyl acetate, isopropyl acetate, or ethyl acetate caproate, Hong et al.23 correlate the LLE data with NRTL and UNIQUAC models through simultaneous adjustment of six effective binary interaction parameters. Cháfer et al.24 found that the UNIQUAC equation produced good results 2054

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for the LLE of dipropyl ether/n-propanol/water. Lintomen et al.25 investigating systems composed by water/citric acid/1butanol or 2-butanol found that the NRTL model showed an average deviation in composition slightly smaller compared to the that from the UNIQUAC model. The LLE for the system water/1-hexanol/acetic acid were correlated by NRTL and ́ and Bernardo-Gil.26 UNIQUAC models by Esquivel Figures 5 and 6 present the results for higher alcohols, from where it can be noted a very low solubility of water in the organic phase. Gilani et al.22 evaluated the LLE for the system 1-octanol + water + phosphoric acid at three temperatures ((298.15, 308.15, and 318.15) K) and found that the solubility of 1-octanol in the aqueous phase was negligible, attributing this fact to the higher hydrophobicity of the alcohol. On the other hand, the water presented some solubility on the organic phase. The solubility of alcohols has a direct impact on the esterification in nanoemusions, where the alcohol content not only affects the yield of ester but also contributes to maintaining the stability of the nanoemulsion and enzyme. Aschenbrenner et al.15 evidenced the importance of the solubility of the alcohol in the aqueous medium for the enzymatic esterification of carboxylic acids (C7−C12) alcohols and ω-phenyl (C1−C5). Barros et al.1 evaluated the esterification in miniemulsion catalyzed by Lipase PS Amano for the synthesis of hexanoate, heptanoate, octanoate, decanoate, or ethyl oleate and hexyl. The rates of esterification of 1-hexanol were higher than those with ethanol, suggesting that a batchwise addition of alcohol to prevent the inhibiting effect on enzymatic activity. In this sense, the results of the present work can also be used to design optimize enzymatic esterification reaction in nanoemulsion systems with distinct chain length alcohols.

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CONCLUSIONS From the experimental data obtained in this work it can be concluded that the size of the alcohol chain has a strong effect on its solubility in aqueous and organic phases. As the chain length of alcohols is improved, the hydrophobicity of the alcohols is also enhanced, and then when using higher alcohols such as 1-hexanol and 1-octanol, the immiscibility region is higher compared to other smaller C2−C4 alcohols. The NRTL and UNIQUAC models satisfactorily described the experimental LLE for all of the systems investigated, with overall error always lower than 1.5%.

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AUTHOR INFORMATION

Corresponding Author

*Tel.: +55-79-32182157. Fax: +55-79-32182190. E-mail: [email protected]. Funding

We express our gratitude to CAPES (Nanobiotec Brasil Program) and CNPq/FAPITEC/SE (PRONEX Program) for scholarships and for providing financial support of the work. Notes

The authors declare no competing financial interest.

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REFERENCES

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DOI: 10.1021/je501174y J. Chem. Eng. Data 2015, 60, 2050−2056

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Octanol) at T = (298.2, 308.2, and 318.2) K. Fluid Phase Equilib. 2012, 316, 109−116. (23) Hong, G. B.; Lee, M. J.; Lin, H. M. Liquid−Liquid Equilibria of Ternary Mixtures of Water + 2-Propanol with Ethyl Acetate, Isopropyl Acetate, or Ethyl Caproate. Fluid Phase Equilib. 2002, 202, 239−252. (24) Cháfer, A.; Burguet, M. C.; Monton, J. B.; Lladosa, E. Liquid− Liquid Equilibria of the Systems Dipropyl Ether + n-Propanol + Water and Dipropyl Ether + n-Propanol + Ethylene Glycol at Different Temperatures. Fluid Phase Equilib. 2007, 262, 76−81. (25) Lintomen, L.; Pinto, R. T. P; Batista, E.; Meirelles, A. J. A.; Maciel, M. R. W. Liquid−Liquid Equilibrium of the Water + Citric Acid + Short Chain Alcohol + Tricaprylin System at 298.15 K. J. Chem. Eng. Data 2001, 46, 546−550. (26) Esquível, M. M.; Bernardo-Gil, M. G. Liquid-Liquid Equilibria For The Systems: Water/1-Pentanol/Acetic Acid and Water/1Hexanol/Acetic Acid. Fluid Phase Equilib. 1991, 62, 97−107.

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DOI: 10.1021/je501174y J. Chem. Eng. Data 2015, 60, 2050−2056