Comment/Reply pubs.acs.org/jced
Reply to “Comments on ‘Vapor−Liquid Equilibrium for Ternary and Binary Mixtures of Tetrahydrofuran, Cyclohexane, and 1,2Propanediol at 101.3 kPa’” Zhigang Zhang, Peng Jia, and Wenxiu Li* Liaoning Provincial Key Laboratory of Chemical Separation Technology, Shenyang University of Chemical Technology, Shenyang 100142,China
T
he comments from Wisniak et al.,1 which are focused on “Vapor−Liquid Equilibrium for Ternary and Binary Mixtures of Tetrahydrofuran, Cyclohexane, and 1,2-Propanediol at 101.3 kPa”,2 are appreciated. At first, I felt sorry for our carelessness on data treatment. To avoid misleading other researchers, the mistakes were indicated and corrected in this reply article. Our explanations for the questions proposed by the comments authors were also given. First of all, we found that the values of γ3 listed in Table 7 in our published paper were wrong, after checking our original manuscript and verifying our original data. We apologize for our mistakes. We recalculated the data, and the right values of γ3 are shown in Table A.
right sequence of table items are shown in Table B to replace Table 11 in the published paper. Then, the explanations for the questions proposed by the comments authors were given as follows. First, the comments authors deem that it can be observed that 1,2-propanediol deviates positively from ideal behavior while cyclohexane does it negatively, suggesting an absurd situation. Consequently, it is not possible to declare the data thermodynamically consistent, and it would make no sense in fitting them with a model.1 We are so sorry about our mistakes since they have misled the comments authors. Their determination of thermodynamic inconsistency was based on the wrong data. We calculated it based on the correct data. The results are shown in Table 8.2 Second, we would like to address the comment that the authors deem that it is a meaningless result because we calculated the relative volatility of cyclohexane to tetrahydrofuran based on solvent free in the vapor phase.1 This is a common way to express the separation ability. This means of expression was also used by other researchers. For example, it is adopted in Figure 3 in ref 3 and in Figure 6 in ref 4. The relative volatility was all described in different mole fractions on a solvent free basis. The relative volatility in different mole fractions of solvent was obtained in our research, and the disappearance of azeotrope is shown in Figure 6 and Figure 7 in our paper. Third, the comments authors suggest that “In the conclusions of the article, the authors mentioned that based on their experimental results 1,2-propanediol was a good solvent because the azeotrope was broken and the relative volatility was improved significantly for the system of tetrahydrofuran and cyclohexane. This is an unfounded conclusion. The azeotrope belongs to the binary system and has not changed.”1 We think that the azeotrope moved with the increase of mole fraction of 1,2-propanediol. We found that the azeotrope had already been broken in Figure 6 in our paper when the mole fraction of 1,2-propanediol was about 0.3. Moreover, we can see that 1,2-propanediol improves the relative volatility effectively in Figure 7 in our published paper. Fourth, the comments authors claim that “There is no experimental evidence of the absence or presence of a ternary azeotrope in the part of the ternary diagram not investigated.”1
Table A. Modified VLE Data for Cyclohexane (2) + 1,2Propanediol (3) System at 101.325 kPa T/K
x3
y3
γ3 (modified data)
460.87 455.62 449.62 443.81 438.34 433.20 428.39 423.92 418.76 414.89 411.30 406.37 401.93 396.66 390.92 385.95 380.78 374.92 369.96 363.75 358.62 353.83
0.000 0.019 0.041 0.062 0.083 0.101 0.124 0.141 0.161 0.181 0.202 0.232 0.262 0.303 0.353 0.478 0.564 0.645 0.712 0.858 0.915 1.000
0.000 0.115 0.222 0.318 0.385 0.471 0.541 0.632 0.700 0.741 0.789 0.809 0.848 0.890 0.925 0.957 0.976 0.985 0.990 0.996 0.998 1.000
1.000 1.066 1.166 1.271 1.416 1.492 1.583 1.530 1.556 1.602 1.547 1.781 1.779 1.712 1.626 1.453 1.241 1.270 1.343 1.509 1.667
Second, we should like to apologize for another mistake in the sequence of table items in Table 11 in our published paper where the sequence of table items were x1, y1, x2, y2. In fact, the right sequence of them should be x1, x2, y1, y2. Fortunately, after rechecking the data, we found the activity coefficients were right since they were calculated based the right sequence. The © 2016 American Chemical Society
Received: January 28, 2016 Accepted: April 5, 2016 Published: April 21, 2016 1964
DOI: 10.1021/acs.jced.6b00089 J. Chem. Eng. Data 2016, 61, 1964−1965
Journal of Chemical & Engineering Data
Comment/Reply
Table B. Modified Sequence of Table Items about Experimental VLE Data for Tetrahydrofuran (1) + Cyclohexane (2) + 1,2Propanediol (3) at 101.3 kPa T/K
x1
x2(modified item)
y1(modified item)
y2
γ1
γ2
γ3
343.75 344.29 345.01 345.25 346.26 346.68 346.79 347.44 347.54 347.87 348.03 348.72 349.02 349.19 349.23 349.27 349.39 349.48 350.25 350.89 351.00 351.60 352.24 353.33 353.36 354.40 354.56 355.27 360.12 362.67
0.733 0.640 0.201 0.544 0.231 0.705 0.585 0.114 0.541 0.496 0.736 0.366 0.106 0.360 0.029 0.337 0.331 0.312 0.547 0.252 0.425 0.094 0.170 0.148 0.147 0.598 0.086 0.068 0.463 0.435
0.133 0.224 0.204 0.318 0.209 0.068 0.172 0.342 0.181 0.213 0.019 0.198 0.384 0.363 0.428 0.312 0.117 0.504 0.085 0.544 0.100 0.468 0.489 0.634 0.581 0.013 0.604 0.740 0.018 0.013
0.806 0.703 0.158 0.609 0.194 0.846 0.661 0.083 0.610 0.548 0.948 0.377 0.080 0.388 0.020 0.344 0.362 0.373 0.694 0.303 0.520 0.180 0.172 0.185 0.168 0.930 0.093 0.095 0.835 0.849
0.193 0.296 0.837 0.390 0.800 0.152 0.336 0.910 0.387 0.449 0.050 0.618 0.912 0.607 0.971 0.650 0.633 0.621 0.302 0.690 0.475 0.815 0.818 0.804 0.821 0.066 0.894 0.890 0.157 0.142
0.947 0.931 0.653 0.921 0.670 0.944 0.886 0.558 0.864 0.839 0.973 0.761 0.556 0.785 0.496 0.742 0.791 0.863 0.896 0.832 0.845 1.291 0.672 0.805 0.733 0.970 0.673 0.848 0.954 0.960
2.003 1.784 5.425 1.602 4.846 2.796 2.435 3.250 2.603 2.540 3.233 3.664 2.755 1.934 2.621 2.405 6.189 1.412 3.977 1.392 5.190 1.008 1.761 1.291 1.437 4.962 1.452 1.155 7.308 8.164
1.295 1.648 1.288 2.131 1.328 1.241 1.728 1.717 1.444 1.515 0.974 1.382 1.924 2.202 2.028 1.855 1.140 3.460 1.118 3.781 1.129 1.322 2.850 4.780 3.881 0.971 3.919 6.707 0.984 0.980
Excellent Talents in University (Project No. 2012013) for partial financial support of this project.
Our experimental data were obtained by experiment, and the experiment process was introduced in the Experimental Section of our paper. We have described the residue curve map in our paper: “As can be seen from the residue curve map, all the residue curves begin from the tetrahydrofuran−cyclohexane binary azeotrope point and terminate to the tetrahydrofuran1,2-propanediol face; it means that the tetrahydrofuran and 1,2propanediol mixture will be obtained in the bottom and cyclohexane in the distillate. The behavior of binary systems can be expected via these features.” The comments authors suggest that some researchers may be confused since we had not given the azeotropic point in Figure 5 in our published paper. However, the boiling point of azeotrope was given in the Introduction section in our paper. So we did not repeat the azeotropic point in Figure 5. Additionally, we are very sorry for our mistakes that may confuse readers, and we very much appreciate the comments from the comments authors. These comments provide us with more experiences, leading us to pay more attention to details in future studies and perform more strict and rigorous investigations. We thank the reviewers, editors, and readers.
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Notes
The authors declare no competing financial interest.
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REFERENCES
(1) Wisniak, J.; Tawatchai, C.; Andrés, M. Comments on “VaporLiquid Equilibrium for Ternary and Binary Systems of Tetrahydrofuran, Cyclohexane, and 1,2-Propanediol at 101.3 kPa; J. Chem. Eng. Data, 2016, DOI: 10.1021/acs.jced.5b01068 (2) Zhang, Z.; Jia, P.; Huang, D.; Lv, M.; Du, Y.; Li, W. Vapor− Liquid Equilibrium for Ternary and Binary Mixtures ofTetrahydrofuran, Cyclohexane, and 1,2-Propanediol at 101.3 kPa. J. Chem. Eng. Data 2013, 58, 3054−3060. (3) Beatriz, B.; Maria, T.; Sanz, S.; Jose, L. Vapor-Liquid Equilibria of the Ternary System Benzene + n-Heptane + N-Methylpyrrolidone (NMP) at 101.33 kPa. J. Chem. Eng. Data 2002, 47, 1167−1170. (4) Harris, R. A.; Ramjugernath, D.; Letcher, T. M.; Raal, J. D. Monoethanolamine as an Extractive Solvent for the n-Hexane + Benzene, Cyclohexane + Ethanol, and Acetone + Methanol BinarySystems. J. Chem. Eng. Data 2002, 47, 781−787.
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NOTE ADDED AFTER ASAP PUBLICATION This paper was originally published ASAP on April 21, 2016. In Table B, for the temperature 3351.60, the values for x2 and γ3 were corrected, and the paper was reposted on April 29, 2016.
AUTHOR INFORMATION
Corresponding Author
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[email protected]. Funding
The authors acknowledge to the National Science Foundation of China (Project No. 21076126) and Program for Liaoning 1965
DOI: 10.1021/acs.jced.6b00089 J. Chem. Eng. Data 2016, 61, 1964−1965
