J. Chem. Thermodynamics 142 (2020) 106011
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Separation of azeotrope 2,2,3,3-tetrafluoro-1-propanol and water: Liquid-liquid equilibrium measurements and interaction exploration Liwen Zhao a, Zhaojie Wang a, Hui Yang b, Dongmei Xu a, Lianzheng Zhang a, Jun Gao a,⇑, Yinglong Wang c a
College of Chemical and Environmental Engineering, Shandong University of Science and Technology, Qingdao 266590, China School of Biological and Chemical Engineering, Qingdao Technical College, Qingdao 266555, China c College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao 266042, China b
a r t i c l e
i n f o
Article history: Received 23 September 2019 Received in revised form 9 November 2019 Accepted 13 November 2019 Available online 25 November 2019 Keywords: 2,2,3,3-Tetrafluoro-1-propanol Cyclohexanone Liquid-liquid equilibrium Extraction Azeotrope
a b s t r a c t Due to the existence of azeotropic point for the mixture 2,2,3,3-tetrafluoro-1-propanol (TFP) and water, liquid-liquid extraction was adopted to separate TFP from its aqueous mixture with cyclohexanone as extractant in this work. The liquid-liquid phase behaviour for the mixture (TFP + water + cyclohexanone) was investigated at T = (293.15, 303.15 and 313.15) K and p = 101.3 kPa. Both selectivity and partition ratio were used for evaluating the extraction performance of cyclohexanone. Also, the NRTL activity coefficient model was applied to fit the measured LLE data with the regressed the parameters. Meanwhile, the binary interaction parameters were validated to be coherent with the measured LLE data based on the mixing surface analysis of Gibbs energy topology. The calculated values of root-mean-square deviation are 0.024, 0.017 and 0.018 at three temperatures, respectively, which indicates the correlated results agree well with the experimental values. Furthermore, the interaction energies between the components were investigated using DMol3 module to explore the molecular interactions between the components in the mixture. Ó 2019 Elsevier Ltd.
1. Introduction 2,2,3,3-tetrafluoro-1-propanol (TFP) is one of fluorinated alcohols with formula of HCF2CF2CH2OH, which has many benign properties such as high surface activity and good biological activity and can be applied as intermediate for preparation of pesticides, surfactants and detergents [1,2]. Also, TFP can be used as a good cleaning agent in electronic industry. During preparation and application of TFP, a large amount of mixture of water and TFP is produced [3–5]. However, water and TFP can form an azeotrope at 365.2 K, and the compositions of the azeotrope are 72.5% (mass fraction) for TFP and 27.5% (mass fraction) for water [6,7]. So, it is impossible to recover TFP from its aqueous solution by conventional distillation. Generally, some special distillations, for instance, extractive distillation [8–12], salt distillation [13,14] and azeotropic distillation [15,16] are usually required to separate azeotropic mixtures. Compared with these special distillations, liquid–liquid extraction was adopted to extract TFP from its aqueous solution due to its advantages of energy-saving and good selectivity. ⇑ Corresponding author. E-mail address: [email protected]
(J. Gao). https://doi.org/10.1016/j.jct.2019.106011 0021-9614/Ó 2019 Elsevier Ltd.
Up to now, only a few researchers have reported the separation for the aqueous mixture TFP and water. Xu et al.  employed ethyl acetate and isopropyl acetate as extractants to separate TFP from its aqueous mixture by liquid–liquid extraction method. Jia et al.  selected anisole and 1-octanol as extractants to separate TFP and water and calculated the partition ratio and selectivity based on the measured LLE data. Besides, isopropyl ether and tert-butyl methyl ether were applied in extracting TFP from the aqueous mixture by Li et al.  at 298.2 and 308.2 K. In this work, cyclohexanone was applied to recover TFP from its aqueous solution because of its benign properties of chemical stability and low volatility. The LLE phase behaviour for the mixture of (water + TFP + cyclo hexanone) was investigated at different temperatures and 101.3 kPa in this wok. Selectively (S) and partition ratio (D) were calculated based on the measured tie-line data. The ternary LLE data for the mixture of (water + TFP + cyclohexanone) was fitted by the NRTL activity coefficient model . Meanwhile, the NRTL model parameters were determined for simulating and optimizing the separation process. In addition, for interaction exploration, the interaction energies between the components in the mixture were calculated using the DMol3 module in Materials Studio.
L. Zhao et al. / J. Chem. Thermodynamics 142 (2020) 106011
Table 1 Information of the chemicals used in this work.
Purity (mass fraction)
2,2,3,3-Tetrafluoro-1propanol Cyclohexanone Deionized water
Shandong Zhongfu Chemical Technology Co., Ltd. Aladin reagent company Lab-made
Table 2 Experimental LLE data on mole fraction x, partition ratio (D) and selectivity (S) for the ternary system water (1) + TFP (2) + cyclohexanone (3) at T = 293.15, 303.15 and 313.15 K under 101.3 kPa.a Organic phase
– 0.0032 0.0164 0.0447 0.0788 0.1038 0.1362 0.1564 0.1878
0.2413 0.2516 0.2565 0.2632 0.2763 0.2927 0.3154 0.3749 0.4428
– 0.0031 0.0138 0.0466 0.0786 0.1071 0.1307 0.1529 0.1853 – 0.0028 0.014 0.0356 0.0698 0.0959 0.1274 0.1529 0.1844
293.15 K 0.9802 0.9773 0.9626 0.9334 0.9006 0.8754 0.8425 0.8217 0.7885 303.15 K 0.9831 0.9803 0.9687 0.9352 0.9026 0.8735 0.8488 0.8254 0.7923 313.15 K 0.9845 0.9825 0.9698 0.9473 0.9124 0.8856 0.8534 0.8275 0.7952
Analyzed by the suppliers.
2. Experimental 2.1. Materials 2,2,3,3-Tetrafluoro-1-propanol and cyclohexanone were obtained commercially from Shandong Zhongfu Chemical Technology Co., Ltd. and Aladin reagent company, respectively. Both reagents were used directly. An ultra-pure water machine (CSR1D, Beijing Aisitaike Technology Development Co., Ltd.) was used to produce the deionized water. The chemical names, CAS No., purities and sources are listed in Table 1. 2.2. Apparatus and procedures For the LLE measurements, the mixture (water + TFP + cyclohex anone) was prepared and added into an equilibrium still with a volume of 25 mL which was presented in the literature . Then, the equilibrium still was placed into the thermostatic water bath (DF-101S, Jintan Baita Xinbao Instrument Factory) at a fixed temperature. The mixture was stirred continuously for 2 h. After that, the equilibrium still was settled for 12 h to ensure the upper and lower phases to be layered completely. The system temperature was measured using a mercury thermometer, and the accuracy of the mercury thermometer is ±0.1 K. All the samples were withdrawn from the organic and aqueous layers by syringe for analysis.
– 0.0524 0.1433 0.2475 0.2876 0.3465 0.3798 0.4157 0.4166
– 16.38 8.74 5.54 3.65 3.34 2.79 2.66 2.22
– 63.61 32.79 19.64 11.90 9.98 7.45 5.83 3.95
0.2622 0.2704 0.2786 0.2943 0.3187 0.3375 0.3649 0.3948 0.4345
– 0.0535 0.1275 0.2352 0.3054 0.3512 0.3865 0.4057 0.4128
– 17.26 9.24 5.05 3.88 3.28 2.96 2.65 2.23
– 62.57 32.12 16.04 11.00 8.49 6.88 5.55 4.06
0.2837 0.2895 0.2938 0.3026 0.3115 0.3218 0.3499 0.3882 0.4357
– 0.0416 0.1281 0.2154 0.2743 0.3257 0.3658 0.3986 0.4011
– 14.86 9.15 6.05 3.93 3.40 2.87 2.61 2.18
– 50.42 30.20 18.94 11.51 9.35 7.00 5.56 3.97
Standard uncertainties au are u(T) = 0.25 K, u(P) = 1 kPa, and u(x) = 0.0085.
of cyclohexanone and water determined in this work are consistent with the literature values. 3.2. Partition ratio and selectivity
2.3. Analysis of GC For sample analysis, GC (SP-7820, Shandong rainbow Chemical Co., Ltd.) was used which was equipped with a column (KB-FFAP 30 m 0.32 mm 0.50 lm) and a thermal conductivity detector (TCD). The temperatures of the column, injector and detector were fixed to (393.15, 433.15 and 433.15) K, respectively. The carrier gas was high-purity hydrogen gas with mass fraction 0.99999 and the flowrate was 15 mL min1. The GC was calibrated by five known composition samples which were obtained by an electronic balance (AR124CN, Aohaosi Instruments (Changzhou) Co., Ltd.). For ensuring accuracy, every sample was analysed three times. The uncertainty of composition was determined by GUM [22–24].
Partition ratio (D) and selectivity (S) [27–29] were adopted for evaluation of the extraction performance of cyclohexanone to
3. Results and discussion 3.1. liquid-liquid equilibrium data The experimental LLE data (mole fraction) for the investigated mixtures were determined at three different temperatures under 101.3 kPa. The experimental values of the system water (1) + TFP (2) + cyclohexanone (3) are tabulated in Table 2 and shown in Figures 1–3. From the figures, the heterogeneous regions in the ternary phase diagrams decrease with increasing temperature. At the same time, the mutual solubilities of cyclohexanone and water were measured and compared with those from the literatures [25,26]. As can be seen in Figures 1–3, the mutual solubility data
Fig. 1. Ternary phase diagram for the system water + TFP + cyclohexanone at 293.15 K under 101.3 kPa: (j), experimental data; (h), correlated by the NRTL model; ( ) and ( ), literature values [25,26].
L. Zhao et al. / J. Chem. Thermodynamics 142 (2020) 106011
Fig. 4. Partition ratio (D) plotted against with mole fraction of TFP in the organic phase (xⅡ2 ) at 101.3 kPa: (j) 293.15 K, (d) 303.15 K, (▲) 313.15 K. Fig. 2. Ternary phase diagram for the system of water + TFP + cyclohexanone at 303.15 K under 101.3 kPa: (d), experimental data; (s), correlated by the NRTL model, ( ) and ( ), literature values [25,26].
Fig. 5. Selectivity (S) plotted against with mole fraction of TFP in the organic phase (xⅡ2 ) at 101.3 k Pa: (j) 293.15 K, (d) 303.15 K, (▲) 313.15 K.
Fig. 3. Ternary phase diagram for the system of water + TFP + cyclohexanone at 313.15 K under 101.3 kPa: (▲) experimental data; (4) NRTL model, ( ) and ( ), literature values [25,26].
recover TFP from its aqueous mixture, which are expressed as follows:
xII2 =xI2 xII1 =xI1
extractant is suitable for separating the mixture. In Table 2, all the values of S and D are greater than unity, which shows the feasibility of extraction by cyclohexanone. Figs. 4–5 are the diagrams of S and D against with the concentration of TFP in the organic phase. As seen from the figures, the values of S and D decrease with increasing the amount of TFP in organic phase. When the mole fraction of TFP is >0.30, the effect of temperature on D and S is not obvious. 3.3. LLE data correlation
where superscript Ⅰ stands for the aqueous layer, and Ⅱ indicates the organic layer; subscripts 1 and 2 refer to water and TFP, x is mole fraction. As expressed in Eq. (1), D reflects the distribution behaviour of cyclohexanone between the two phases at equilibrium. A higher value of D reflects a less quantity of cyclohexanone used in the liquid extraction process [30,31]. S indicates a measure of the ability of cyclohexanone to recover TFP from its aqueous mixture . When the value of S is greater than unity, it indicates that the
For correlation of the measured data, the NRTL model, which is expressed as follows [32–34], was applied in this work:
j¼1 ji Gji xj
ln ci ¼ Pn
k¼1 Gki xk
sij ¼ aij þ
n X j¼1
xj Gij Pn k¼1 Gkj xk
bij sij –sji T
Gij ¼ exp aij sij aij ¼ aji
xi sij Gij k¼1 Gkj xk
sij Pi¼1 n
where subscripts i, j stands for the components, x is mole fraction, aij, bij are the binary parameters, aij is the non-randomness parameter and was set to 0.30.
L. Zhao et al. / J. Chem. Thermodynamics 142 (2020) 106011
Table 3 Regressed values of binary parameters and rmsd for the system water (1) + TFP (2) + cyclohexanone (3). i-j
Binary interaction parameters
293.15 K 1–2 1–3 2–3
1.05 1.73 3.19
0.16 0.10 20.01
425.41 481.14 766.56
81.82 226.06 6638.48
303.15 K 1–2 1–3 2–3
0.25 1.43 7.25
0.23 0.69 9.19
64.01 711.07 2438.16
64.90 422.32 3659.37
313.15 K 1–2 1–3 2–3
0.12 6.41 0.48
0.89 5.14 92.94
32.54 1471.28 144.85
273.52 837.92 29069.40
For obtaining the NRTL model binary parameters, the following objective function (OF) was used [35,36]:
3 X 2 X n 2 X cal xexp ijk xijk i¼1
Labarta [38,39] was applied in this work. In the Supplementary Materials, the validation results are shown in Figs. S1–S18. As seen from Figures S1–S18, the checked results show that the NRTL parameters meet the requirement of coherent consistency.
where superscripts exp and cal denote the measured data and calculated value; x is mole fraction; subscripts i, j, and k stand for the components, phases and tie lines. The parameters of the NRTL model for the system (water + TFP + cyclohexanone) are listed in Table 3. The calculated tie-lines are also presented in Figs. 1–3 for comparison. The root-mean-square deviation (rmsd)  was calculted to evaluate the correlation performance of the NRTL model, which is defined as follows:
vﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃ uP P P 2 u 3 2 n exp t i¼1 j¼1 k¼1 xijk xcal ijk
where x stands for mole fraction, subscripts i, j, k are components, n is the experimental tie-line number. The calculated values of rmsd are presented in Table 3. From Table 3, the maximum rmsd value is 0.024, which means the NRTL model can provide the correlated results satisfactorily. To validate the coherent consistency of the regressed NRTL parameters, the topological analysis method developed by Reyes-
Table 4 Interaction energies of cyclohexanone with H2O and TFP. System H2O TFP Cyclohexanone Cyclohexanone + H2O Cyclohexanone + TFP a
E/(hartreea) 76.463 591.546 309.986 386.457 901.543
1hartree = 2625.753 kJ mol1.
E/(kJ mol1) 2.008 1.553 8.139 1.015 2.367
4E/(kJ mol1) 5
10 106 105 106 106
– – – –22.138 27.563
3.4. Interaction energy For exploring the interactions between the components in the mixture, the DMol3 module incorporated the density functional theory (DFT), which is available in Accelrys’ Materials Studio, was applied to calculate interaction energy. The detailed calculation process is presented in the literatures [40,41]. To make the results more accurately, the interaction energy should include the BSSE (Basis Set Superposition Error) correction by means of counterpoise method , which is expressed by eq (8). The BSSE correction was described as a difference in energies of both subsystems in the full system basis set and the subsystems alone as shown in Eq. (9).
DE ¼ EAB EA EB þ EBSSE
EBSSE ¼ EA EðA;ABÞ þ EB EðB;ABÞ
where EA, EB mean the energies of the subsystems A, B; E(A,AB) refers to the energy of the subsystem A in the full system basis set AB; E(B,AB) means the energy of the subsystem B in the full system basis set AB. The calculated results are presented in Table 4. As listed in Table 4, the interaction energy of cyclohexanone with H2O and cyclohexanone with TFP are –22.138 and 27.563 k J mol1, respectively, which indicates that cyclohexanone can interact with TFP stronger than water. In addition, the optimized geometries of cyclohexanone with H2O and TFP are presented in Figure 6. As shown in Figure 6, the lengths of hydrogen bonds for cyclohexanone with TFP (a) and cyclohexanone with H2O (b) are (1.852 and 1.898) Å, respectively. Therefore, cyclohexanone attracts TFP more strongly than H2O, which is consistent with the energy calculation results.
Fig. 6. Optimized geometries: (a) cyclohexanone + TFP, (b) cyclohexanone + H2O.
L. Zhao et al. / J. Chem. Thermodynamics 142 (2020) 106011
4. Conclusions For separating TFP from its aqueous mixture using liquid-liquid extraction, cyclohexanone was selected as extractant, and the LLE data for the mixture water + TFP + cyclohexanone were investigated at T = (293.15, 303.15 and 313.15) K and p = 101.3 kPa. The selectively and partition ratio were calculated to explore the extraction performance of cyclohexanone. The results show that TFP can be extracted from its aqueous solution by cyclohexanone. Meanwhile, the experimental values were regressed by the NRTL model. The calculated rmsd values for the system at three temperatures are 0.024, 0.017 and 0.018, which demonstrates the thermodynamic model can fit the measured data well. Besides, the coherent consistency of the regressed NRTL parameters was validated by the topological analysis method. Furthermore, the interaction energies between the components in the mixture were calculated using the DMol3 module in Materials Studio. The results show that the interaction energy between cyclohexanone and TFP is higher than that between cyclohexanone and H2O, which is consistent with the experimental results. Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Acknowledgements The authors are grateful to the financial support of the National Natural Science Foundation of China (No. 21978155), Shandong Provincial Key Research & Development Project (2018GGX107001), a Project of Shandong Province Higher Educational Science and Technology Program (J18KA072). Appendix A. Supplementary data Supplementary data to this article can be found online at https://doi.org/10.1016/j.jct.2019.106011. References  P. Hurtel. Process for the preparation of fluorinated alkyl(meth)-acrylates, EP Patent 0206899, 1986.  F. Yamaguchi, T. Katsube, Method for recovering fluorine-containing solvents, EP Patent 0995736 A2, 2000.  S.H. Huang, W.S. Hung, D.J. Liaw, C.H. Lo, W.C. Chao, C.C. Hu, C.L. Li, K.R. Lee, J.Y. Lai, Inter facially polymerized thin-film composite polyamide membranes: effects of annealing processes on pervaporative dehydration of aqueous alcohol solutions, Sep. Purif. Technol. 72 (2010) 40–47.  M.S. Chou, K.L. Chang, Decomposition of aqueous 2,2,3,3-tetra-fluoro-propanol by UV/O3 process, J. Environ. Eng. 133 (2007) 979–986.  T. Zhao, J. Zheng, G. Sun, Synthesis and applications of vegetable oil-based fluorocarbon water repellent agents on cotton fabrics, Carbohydr. Polym. 89 (2012) 193–198.  Y. Fumihiko, K. Toshiyuki, Method for recovering fluoroalcohol, US Patent 6313357 (2001).  C.H. Rochester, J.R. Symonds, Thermodynamics studies of fluoroalcohols. Part 1. Vapour pressures and enthalpies of vaporization, J. Chem. Soc., Faraday Trans. 1: Phys. Chem. Condens. Phases. 69 (1973) 1267.  J.Y. Wu, D.M. Xu, P.Y. Shi, J. Gao, L.Z. Zhang, Y.X. Ma, Y.L. Wang, Separation of azeotrope (allyl alcohol + water): isobaric vapour-liquid phase equilibrium measurements and extractive distillation, J. Chem. Thermodyn. 118 (2018) 139–146.  Y. Zhang, K. Liu, Z.J. Wang, J. Gao, L.Z. Zhang, D.M. Xu, Y.L. Wang, Vapor–liquid equilibrium and extractive distillation for separation of azeotrope isopropyl alcohol and diisopropyl ether, J. Chem. Thermodyn. 131 (2019) 294–302.  Z.G. Lei, R.Q. Zhou, Z.T. Duan, Application of scaled particle theory in extractive distillation with salt, Fluid Phase Equilib. 200 (2002) 187–201.  Y.H. Dong, C.N. Dai, Z.G. Lei, Extractive distillation of methylal/ methanol mixture using ethylene glycol as entrainer, Fluid Phase Equilib. 462 (2018) 172–180.
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