Determination and Correlation of Vapor–Liquid Equilibria for the

Article pubs.acs.org/jced

Determination and Correlation of Vapor−Liquid Equilibria for the Phosphoric Acid + Water + Cyclohexane + Ethanol System Geng Li* College of Chemical and Environmental Engineering, Yangtze University, Jingzhou 434023, Hubei, China ABSTRACT: The production of phosphoric acid by wet processes is quite energy consuming. The adoption of azeotropic distillation in the evaporation process, using cyclohexane as an entrainer, may be potentially economical. The vapor−liquid equilibria (VLE) data were determined by ebulliometric method for the following systems at 20, 40, 60, 80, and 101.3 kPa: (1) phosphoric acid + water + ethanol; (2) phosphoric acid + water + cyclohexane + ethanol; (3) phosphoric acid + water + cyclohexane. The electrolyte NRTL parameters for the following pairs were correlated from the VLE data by using Aspen Plus as a tool: H3PO4−H2O, H+[H2PO4]−−H2O, H3PO4−C2H6O, H3PO4−C6H12, and H+[H2PO4]−−C6H12. The VLE data and the obtained parameters may provide basic data for the enhancement of phosphoric acid by azeotropic distillation.

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INTRODUCTION Phosphoric acid is the second most important mineral acid with a global production of 39.8 million tons in 2008.1 It is mainly produced by the dihydrate process in which the enrichment of the acid by recycling evaporation is energy-intensive.2,3 The trial of applying azeotropic distillation in dehydration of phosphoric acid has caused many concerns.4−8 Some studies were performed by Tu and her colleagues,8−14 including the VLE measurement of benzene/xylene/octane + water binary systems,9−13 and the liquid−liquid equilibria (LLE) determination for phosphoric acid + water + benzene/octane ternary systems.9,12 However, no VLE data for phosphoric acid containing systems were determined. In order to develop the azeotropic distillation process for the enhancement of phosphoric acid, the VLE data for the systems containing phosphoric acid are essential. However, direct measurement of the VLE for the phosphoric acid + water + entrainer system is often very difficult due to the immiscibility of entrainer and water. Ethanol can be added to the system to enlarge their miscibility, and then the boiling point of the solution located in the miscible region can be measured precisely.16,18 Since cyclohexane has been used in the enrichment of waste sulfuric acid in our previous work and a satisfactory result was obtained,15 it was also chosen as the entrainer for phosphoric acid systems. In this work, the VLE data of phosphoric acid + water + cyclohexane + ethanol systems were determined. Ren and Lin17 measured the VLE data of the ethanol + water + phosphoric acid system at atmospheric pressure. The focus is on how the content of phosphoric acid influences the VLE of an ethanol + water system, and also the data are limited and no rigorous thermodynamic modeling was adopted. No data were found in the literature for the above phosphoric acid containing quaternary systems. © XXXX American Chemical Society

The thermodynamic properties of systems containing phosphoric acid have been researched broadly through the years. Pitzer model,19 the extended UNIQUAC model,20 and the electrolyte nonrandom two-liquid (electrolyte NRTL) model21 are the activity coefficient models widely adopted. By using the electrolyte NRTL model, Messnaoui and Bounahmidi 21 successfully estimated the VLE for the phosphoric acid solution and the activity of undissociated H3PO4 for concentrations up to 36 mol·kg−1 at various temperatures. Messnaoui22 also simulated the phosphoric acid concentration process with a good result, using the electrolyte NRTL model to calculate the activity coefficients of species in the aqueous solution. Mathias et al.23 successfully modeled the phosphoric acid reactor, based on the electrolyte NRTL model. Considering the future simulation of the azeotropic distillation process, the electrolyte NRTL model was chosen in this work. The purpose of this study is to determine the boiling point data for the systems containing phosphoric acid + water + cyclohexane + ethanol by ebulliometric method at the pressures of 20, 40, 60, 80, and 101.3 kPa. Using Aspen Plus (Version 7.2) as a tool, electrolyte NRTL model parameters are acquired by correlating the experimental and literature VLE data for the following pairs: H3PO4−H2O, H+[H2PO4]−−H2O, H3PO4− C2H6O, and H+[H2PO4]−−C6H12. The quality of VLE data and the newly obtained parameters are tested by the modeling result.

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EXPERIMENTAL SECTION Experimental Materials. The phosphoric acid, cyclohexane, and ethanol used in the experiments, supplied by Received: April 8, 2016 Accepted: March 16, 2017

A

DOI: 10.1021/acs.jced.6b00293 J. Chem. Eng. Data XXXX, XXX, XXX−XXX

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pyi φi = xiγipiS φiSθiS

Sinopharm Chemical Reagent Co., Ltd., were all analytical grades with mass fractions of 0.95−0.98, 0.995, and 0.997, respectively, and were used without further treatment. The deionized water used in all experiments was produced by a local laboratory. The details, including purities and sources of the materials used in this work, were also listed in Table 1.

where p is the overall pressure and pSi is the vapor pressure of pure componet calculated by the Antoine equation using the parameters listed in Table 2. xi and yi denote the liquid and vapor mole fractions, respectively. φi, γi, φSi , and θSi are the vapor phase fugacity coefficient, the liquid phase activity coefficient, the vapor fugacity coefficient of pure component, and the Poynting pressure correction, respectively. The vapor phase can be presumed to be ideal at experimental pressures, so the θSi , φi, and φSi will be unity and eq 1 will be shortened as

Table 1. Sources and Mass Fraction Purity of the Materials

a

chemical name

source

purity (mass fraction)

purification method

analysis method

ethanol cyclohexane phosphoric acid

Sinopharm Sinopharm Sinopharm

0.997 0.995 0.95−0.98

none none none

GCa GCa

(1)

pyi = xiγipiS

Gas chromatography.

(2)

Dissociation Reactions. Suitable description of chemical reactions is required when modeling the electrolyte solution. For the phosphoric acid + water + ethanol + cyclohexane systems, the electrolyte NRTL model engaged in Aspen Plus was chosen and the dissociation reactions are listed in eqs 3−5.

Experimental Apparatus. The VLE data of the systems were determined by the ebulliometric method. The detailed representation of the equipment can be found in our earlier works.18,24 Two calibrated microthermometers were used in the measuring of the boiling points. The total temperature uncertainty was estimated to be ±0.15 K, including an error of ±0.10 K for nonimmersed stem correction and an error of ±0.05 K for reading. This temperature variation may cause a maximum uncertainty of ±0.7% for pressure. Based on the holdup of the ebulliometer, the uncertainty of composition of solution was evaluated to be ±0.002.18 Experimental Procedure. The detailed description of the experimental procedure can be found in our earlier publication.18 The solution with a known composition and the water were loaded into ebulliometers separately. The composition of solution was obtained gravimetrically using a balance (model FA2004S) with a sensitivity of 0.0001 g. In order to control the system pressure, the water temperature was carefully adjusted to obtain the desired value when the equilibrium was reached. The boiling point of the solution was written down, and then the measurement was performed again at a higher water temperature. According to the Antoine equation, the system pressures of 20, 40, 60, 80, and 101.3 kPa can be obtained by holding water temperatures at 333.2, 348.75, 358.65, 366.05, and 373.15 K, respectively. The Antoine equation parameters of water used in the calculation were listed in Table 2.

H3PO4 ↔ H 2PO4 − + H+

(3)

H 2PO4 − ↔ HPO4 2 − + H+

(4)

HPO4 2 − ↔ PO4 3 − + H+

(5)

The dissociation constants of eqs 3−5 are taken from the Aspen Plus default databank. Activity Coefficient Model. The activity coefficient is a thermodynamic state function, accounting for deviations from ideal behavior in solution, developed from the excess Gibbs free energy of the solution: ⎛ ∂(n GE /RT ) ⎞ total ⎟ ln γi = ⎜ ∂ni ⎠T , p , n ⎝

(6)

j

The detailed description of the excess Gibbs energy model and the composition activity coefficients equation in the electrolyte NRTL model can be found in Chen’s work.26 Usually, the nonrandomness factors (α) for molecule− electrolyte and molecule−molecule are 0.2 and 0.3, respectively.27 The energy parameter (τ) is presumed to be temperature-dependent and written as follows:28 molecule−molecule binary parameters:

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THERMODYNAMIC MODELING Vapor−Liquid Equilibria. In general, vapor−liquid equilibrium can be presented as follows:25

τB , B ′ = CB , B ′ +

DB , B ′ (7)

T

Table 2. Antoine Equationa Parametersb of the Pure Components

a

component

C1

C2

C3

C4 × 103

C5

C6 × 1018

C7

C8/K

C9/K

water ethanol cyclohexane phosphoric acid

65.6422 74.1676 66.4301 −26.9078

−7206.7 −7827.8 −5885.9 0

0 0 0 0

0 −1.8586 −5.4710 0

−7.1385 −7.9613 −8.0304 0

4.046 × 1012 23.6730 7.3578 0

2 6 6 0

273.16 302.56 292.73 273.00

647.29 516.20 553.40 473.00

Antoine equation:

ln(pis /kPa) = C1 + C2/(T + C3) + C4T + C5 ln T + C6T C7 for C8 ≤ T ≤ C9 b

Taken from Aspen property databank (V7.2). B

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electrolyte−molecule pair parameters: τca , B = Cca , B +

Dca , B T

⎡ (T ref − T ) ⎛ T ⎞⎤ + Eca , B⎢ + ln⎜ ref ⎟⎥ ⎝ T ⎠⎦ T ⎣ (8) ref

where ca is cation−anion, T means reference temperature which is 273.15 K, and αij, Cij, Dij, andEij are the parameters that can be adjusted.28 The optimized NRTL parameters were acquired by correlating the experimental data by maximum likelihood principle through minimizing the following objective function:28 FOB

⎡ ⎛ exp ⎛ pexp − pcal ⎞2 cal ⎞2 ⎢ ⎜ Ti − Ti ⎟ i i ⎟ = ∑ ⎢f1 ⎜ ⎟ + f2 ⎜⎜ ⎟ σ σ ⎝ ⎠ T P ⎝ ⎠ i ⎣ ⎛ z exp − z cal ⎞2 ⎤ ⎥ i + f3 ⎜⎜ i ⎟⎟ ⎥ σZ ⎝ ⎠⎦

(9)

Figure 1. Isothermal vapor pressure for phosphoric acid (1) + water (2) binary system: ■, 293.15 K; ▲, 313.15 K; ⧫, 333.15 K; ▼, 353.15 K; ●, 373.15 K; −, electrolyte NRTL model.

where f denotes weight factor (all set to be 1), exp and cal mean experimental and calculated, respectively, and σ represents standard deviation (0.1 K for T, 0.5% for p, and 0 for z).

Table 4. Deviations (Δp) between Literature Data29 and the Electrolyte NRTL Model Regression for the Phosphoric Acid (1) + Water (2) Systema

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RESULTS AND DISCUSSION Binary System. The vapor pressure data 29 for the phosphoric acid + water system at various temperatures were Table 3. Electrolyte NRTL Interaction Parametersa Used in This Work no.

component i

component j

C

D

αij

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

H2O C2H6O C6H12 C2H6O C6H12 H2O H2O H3PO4 H2O H+:H2PO4− H3PO4 C2H6O H3PO4 C6H12 C6H12 H+:H2PO4−

C2H6O H2O C2H6O C6H12 H2O C6H12 H3PO4 H2O H+:H2PO4− H2O C2H6O H3PO4 C6H12 H3PO4 H+:H2PO4− C6H12

3.6220 −0.9223 0 0 0 0 4.2161 −2.8533 −0.1403 −14.4993 2.1473 1.2504 0.6253 5.6837 0.9760 −9.5619

−636.7260 284.2856 699.6826 441.2182 1449.14 2189.811 −2053.0204 282.8177 −746.2785 1321.4482 −2.3755 −1820.8342 −1.4682 66.8892 −8.7988 −10.6841

0.3 0.3 0.4485 0.4485 0.26 0.26 0.3 0.3 0.2 0.2 0.2 0.2 0.147 0.147 0.20 0.20

T/K

|Δp|av/kPa

|Δp|max/kPa

293.15 313.15 333.15 353.15 373.15 overall

0.03 0.05 0.08 0.41 1.48 0.41

0.08 0.13 0.57 1.23 3.46 3.46

n

|Δp| = |pcal − pexp|; |Δp|av = (∑i = 1 |Δp|i )/n, where n is the number of data points. a

a

Parameter nos. 1 and 2 from ref 30, Nos. 4−6 from ref 31, and nos. 7−16 obtained in this work.

employed in regressing the electrolyte NRTL parameters, as tabulated in Table 3, for the pairs of H3PO4−H2O and H+[H2PO4]−−H2O. The comparison between the literature data and correlation is illustrated in Figure 1. It can be observed from Figure 1 that the regression fits the data well and the deviation between the correlation and literature data becomes larger when temperature becomes higher. As noted in Table 4, the maximum absolute deviation (MAD) and the average absolute deviation (AAD) of pressure are only 3.46 and 0.41 kPa, respectively. The electrolyte NRTL model with newly regressed parameters was then used to predict the boiling point

Figure 2. Boiling point of phosphoric acid aqueous solution at 1 atm: ■, literature;29 ○, experiment; −, electrolyte NRTL model.

of the phosphoric acid + water binary system. The prediction, as well as the literature and experimental data, is illustrated in Figure 2. The comparison shows that the prediction fits the data well, and this verifies the parameters obtained and the experimental data. Ternary System. The boiling point data for the phosphoric acid + water + ethanol ternary system were measured at 20, 40, C

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Table 5. Isobaric Experimental Boiling Points for Temperature (T), Pressure (p), and Mole Fraction (x) for the Ternary System Phosphoric Acid (1) + Water (2) + Ethanol (3)a T/K x1

x3

20 kPa

0.0596 0.0579 0.0564 0.0553 0.0536 0.0504 0.0475 0.0419 0.0353 0.0294 0.0240 0.0180 0.0128 0.0061 0.0034 0.0000

0.0000 0.0275 0.0523 0.0721 0.0999 0.1538 0.2026 0.2964 0.4066 0.5061 0.5973 0.6978 0.7850 0.8973 0.9425 1.0000

334.92 329.98 326.80 324.92 323.31 320.80 319.94 318.50 317.59 316.83 316.32 315.92 315.56 315.26 315.21 315.14

0.1106 0.1088 0.1065 0.1029 0.0986 0.0937 0.0886 0.0824 0.0743 0.0661 0.0546 0.0446 0.0323 0.0224 0.0110 0.0063 0.0000

0.0000 0.0165 0.0371 0.0700 0.1081 0.1525 0.1985 0.2548 0.3282 0.4022 0.5063 0.5970 0.7080 0.7975 0.9003 0.9433 1.0000

337.44 333.96 330.63 327.18 324.61 322.65 321.47 320.21 318.98 318.28 317.34 316.63 316.08 315.70 315.40 315.24 315.14

0.1850 0.1796 0.1749 0.1708 0.1665 0.1570 0.1460 0.1294 0.1112 0.0920 0.0741 0.0556 0.0362 0.0195 0.0093 0.0000

0.0000 0.0294 0.0548 0.0767 0.1000 0.1511 0.2107 0.3007 0.3989 0.5027 0.5993 0.6993 0.8045 0.8948 0.9497 1.0000

343.05 336.88 333.64 331.62 329.71 326.43 324.01 321.39 319.52 318.15 317.24 316.42 315.77 315.46 315.31 315.14

40 kPa

60 kPa

x1/x2 = 0.0633 350.71 360.93 345.19 354.78 341.70 351.02 339.76 349.13 337.99 347.31 335.56 344.98 334.45 343.84 333.04 342.34 332.03 341.23 331.27 340.47 330.62 339.81 330.18 339.32 329.83 338.97 329.58 338.71 329.48 338.66 329.42 338.61 x1/x2 = 0.1244 353.34 363.66 349.33 359.34 346.14 355.68 342.13 351.61 339.19 348.82 337.17 346.64 335.96 345.32 334.56 343.81 333.38 342.64 332.74 341.99 331.64 340.77 330.74 339.96 330.33 339.47 329.88 339.06 329.68 338.81 329.52 338.71 329.42 338.61 x1/x2 = 0.2270 359.35 369.60 352.69 362.76 348.98 358.79 346.80 356.45 344.82 354.47 341.13 350.66 338.70 348.07 336.02 345.28 334.05 343.25 332.53 341.73 331.57 340.77 330.77 339.91 330.16 339.30 329.86 339.00 329.61 338.80 329.42 338.61

80 kPa

101.3 kPa

368.62 362.30 358.33 356.25 354.31 351.98 350.86 349.34 348.22 347.41 346.75 346.25 345.90 345.64 345.59 345.53

375.25 368.83 364.80 362.91 360.82 358.43 357.16 355.64 354.42 353.60 352.94 352.39 352.03 351.78 351.73 351.62

371.16 366.93 363.10 358.88 355.88 353.64 352.37 350.80 349.68 348.97 347.86 347.00 346.39 346.03 345.73 345.63 345.53

378.45 373.51 369.27 365.14 362.39 360.05 358.78 357.09 355.93 355.16 353.90 353.19 352.53 352.12 351.82 351.72 351.62

377.71 370.26 366.23 363.88 361.84 357.97 355.08 352.28 350.25 348.73 347.76 346.90 346.24 345.89 345.74 345.53

384.15 376.68 372.69 370.39 368.30 364.42 361.42 358.67 356.53 355.01 353.89 353.03 352.37 352.01 351.86 351.62

Figure 3. Isobaric VLE diagram for phosphoric acid (1) + water (2) + ethanol (3) ternary system. x1/x2 = 0.0633: ■, 20 kPa; ●, 40 kPa; ▲, 60 kPa; ⧫, 80 kPa; ▼, 101.3 kPa. x1/x2 = 0.1244: □, 20 kPa; ○, 40 kPa; Δ, 60 kPa; ◊, 80 kPa; ▽, 101.3 kPa. x1/x2 = 0.2270: ▶, 20 kPa; ▷, 40 kPa; ◀, 60 kPa; ◁, 80 kPa; ☆, 101.3 kPa. −, electrolyte NRTL model.

60, 80, and 101.3 kPa and are listed in Table 5 and shown in Figure 3. As can be seen from Figure 3, at fixed phosphoric acid/water ratios, the boiling point decreases when the proportion of ethanol (x3) increases and no azeotrope is observed. It decrease drastically when x3 is less than 0.1 but varies only marginally when x3 is larger than 0.8. The boiling point also decreases as the ratio of phosphoric acid/water is decreased. As shown in Table 3, the parameters for the pair H3PO4−C2H6O were acquired by fitting the VLE data of the ternary system. To compare with experimental data, the fitted results are also demonstrated in Figure 3. The correlation matches the experimental data pretty well with the overall AAD(T) and MAD(T) of 0.31 and 1.17 K, respectively, as shown in Table 6. Using the new parameters, the VLE of the above ternary system were also calculated and compared with the literature17 data in Figure 4. Good agreement between literature data and calculated values indicates that the newly obtained parameters, as well as the experimental data used to obtain the parameters, are of good quality. Quaternary System. The boiling points for the phosphoric acid + water + cyclohexane + ethanol quaternary system, as tabulated in Table 7 and illustrated in Figure 5, were determined at 20, 40, 60, 80, and 101.3 kPa. It can be observed in Figure 5 that as the fraction of cyclohexane (x3) increases, the boiling point first decreases to a minimum and then increases sharply when x3 is larger than 0.95. The quaternary boiling point data were engaged in correlating the parameters for pairs of H3PO4−C6H12 and H+[H2PO4]−−C6H12, by the application of the correlated and literature parameters tabulated in Table 3. A satisfactory agreement between correlation and experimental data is achieved with the overall deviations of 0.43 and 1.37 K for AAD(T) and MAD(T), respectively. The vapor pressure data of cyclohexane were also depicted in Figure 6 to compare with the literature data. As we can see from Figure 6, the experimental data are consistent with the literature32,33 values. The good agreement between experimental and literature data proves the reliability of the experimental data. Verification of the Model Parameters. The boiling temperatures of the phosphoric acid + water + cyclohexane

a

Standard uncertainties u are u(T) = 0.15 K, u(x) = 0.002, and u(p) = 0.007p. D

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Table 6. Deviations (ΔT) between the Experimental Data and Electrolyte NRTL Model Regression for Phosphoric Acid (1) + Water (2) + Cyclohexane (3) + Ethanol (4) Systemsa phosphoric acid + water + ethanol

a

phosphoric acid + water + cyclohexane + ethanol

phosphoric acid + water + cyclohexane

p/kPa

|ΔT|av/K

|ΔT|max/K

|ΔT|av/K

|ΔT|max/K

|ΔT|av/K

|ΔT|max/K

20 40 60 80 101.3 overall

0.41 0.33 0.28 0.22 0.30 0.31

0.87 0.77 0.69 0.92 1.17 1.17

0.43 0.38 0.37 0.26 0.71 0.43

0.73 0.85 0.82 0.87 1.37 1.37

0.32 0.29 0.31 0.32 0.52 0.35

0.75 0.92 0.99 0.77 1.32 1.32

n

|ΔT| = |Tcal − Texp|; |ΔT |av = (∑i = 1 |ΔT |i )/n, where n is the number of data points.

Figure 5. Isobaric VLE diagram for phosphoric acid (1) + water (2) + cyclohexane (3) + ethanol (4) quaternary system. x1/x2/x4 = 0.0143/ 0.0438/1: ■, 20 kPa; ●, 40 kPa; ▲, 60 kPa; ⧫, 80 kPa; ▼, 101.3 kPa. −, electrolyte NRTL model.

Figure 4. VLE diagram for phosphoric acid (1) + water (2) + ethanol (3) ternary system (salt free basis): ■, literature17 (P2O5 = 10%); ●, literature17 (P2O5 = 20%); ▲, literature17 (P2O5 = 30%); −, calculated (P2O5 = 10%); ···, calculated (P2O5 = 20%); --, calculated (P2O5 = 30%).

ternary heterogeneous system, as tabulated in Table 8, were measured at 20, 40, 60, 80, and 101.3 kPa and were used to test Table 7. Isobaric Experimental Boiling Points for Temperature (T), Pressure (p), and Mole Fraction (x) for the Quaternary System Phosphoric Acid (1) + Water (2) + Cyclohexane (3) + Ethanol (4)a T/K

a

x1 × 10

x2

x3

20 kPa

40 kPa

60 kPa

80 kPa

101.3 kPa

0.01369 0.01333 0.01299 0.01264 0.01234 0.01091 0.00957 0.00823 0.00684 0.00547 0.00407 0.00275 0.00135 0.00108 0.00068 0.00041 0.00000

0.0419 0.0408 0.0398 0.0387 0.0378 0.0334 0.0293 0.0252 0.0209 0.0168 0.0125 0.0084 0.0041 0.0033 0.0021 0.0013 0.0000

0.0000 0.0261 0.0506 0.0765 0.0986 0.2032 0.3007 0.3987 0.5006 0.6006 0.7023 0.7993 0.9012 0.9211 0.9501 0.9701 1.0000

315.16 311.31 307.97 305.45 304.49 300.40 299.42 299.12 298.92 298.87 298.72 298.77 298.82 299.22 299.83 301.14 307.92

329.45 326.08 322.75 320.58 319.47 315.51 314.47 314.06 313.91 313.81 313.76 313.81 314.17 314.52 315.48 317.81 325.47

338.60 335.16 332.33 329.96 329.00 325.07 324.06 323.66 323.46 323.36 323.26 323.41 323.96 324.46 325.57 328.85 337.08

345.58 342.24 339.61 337.33 336.42 332.58 331.52 331.01 330.91 330.81 330.81 330.91 331.77 332.32 333.94 337.63 346.09

351.67 348.52 346.09 343.91 343.00 339.20 338.13 337.73 337.58 337.47 337.58 337.73 338.79 339.50 341.52 345.57 354.11

Standard uncertainties u are u(T) = 0.15 K, u(x) = 0.002, and u(p) = 0.007p. E

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quality of the experimental VLE data, as well as the new parameters, since it obviously can predict azeotropic temperature for the phosphoric acid + water + cyclohexane ternary system without parametrization.

Figure 6. Vapor pressure of cyclohexane: literature;32 ○, literature.33

⧫,

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CONCLUSIONS

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AUTHOR INFORMATION

The isobaric boiling point data were measured at 20, 40, 60, 80, and 101.3 kPa by ebulliometric method for the phosphoric acid + water + ethanol, phosphoric acid + water + cyclohexane + ethanol, and phosphoric acid + water + cyclohexane systems. The experimental data were engaged to acquire the electrolyte NRTL model parameters. The modeling result validates the quality of the VLE data, as well as the newly obtained parameters, since it clearly improves the predicting ability of the electrolyte NRTL model. The experimental data and the new parameters provide basic information for the enrichment of phosphoric acid by azeotropic distillation.

experiment; Δ,

Corresponding Author

Table 8. Experimental Boiling Temperatures (T) at Pressure (p) and Phosphoric Acid Mass Fraction (w(H3PO4))a for the Heterogeneous Ternary System Phosphoric Acid (1) + Water (2) + Cyclohexane (3) Systemb

*Tel.: +86-716-8060933. E-mail: [email protected]. ORCID

Geng Li: 0000-0001-7344-4313 Notes

T/K w(H3PO4)

20 kPa

40 kPa

60 kPa

80 kPa

101.3 kPa

0.0000 0.1000 0.2000 0.3000 0.4000 0.5000 0.6000

302.55 302.77 302.97 303.27 303.77 304.59 305.19

318.45 318.65 318.75 318.85 319.67 320.48 321.85

328.50 328.70 328.80 329.05 330.01 330.92 332.45

335.97 336.27 336.47 336.65 337.85 338.70 340.15

342.55 342.75 343.05 343.65 344.65 345.48 347.50

The author declares no competing financial interest.

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REFERENCES

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a

Aqueous phase. bStandard uncertainties u are u(T) = 0.15 K, u(p) = 0.007p, and u(w) = 0.002w.

Figure 7. Isobaric boiling temperature for phosphoric acid (1) + water (2) + cyclohexane (3) ternary system: ■, 20 kPa; ●, 40 kPa; ▲, 60 kPa; ⧫, 80 kPa; ▼, 101.3 kPa; −, electrolyte NRTL model.

the new parameters. It can be found in Figure 7 that the prediction fits the experimental boiling temperature well with the overall AAD(T) of 0.35 K and MAD(T) of 1.32 K, as listed in Table 6. The result illustrated in Figure 7 validates the F

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DOI: 10.1021/acs.jced.6b00293 J. Chem. Eng. Data XXXX, XXX, XXX−XXX