Volumetric properties of monoethanolamine and alcohol binary mixtures at different temperatures and 0.1 MPa

Accepted Manuscript Volumetric properties of monoethanolamine and alcohol binary mixtures at different temperatures and 0.1 MPa Zhen Li, Dan Zhao, Yun Zhuang, Fang Yang, Xiuwu Liu, Yuhuan Chen PII: DOI: Reference:

S0021-9614(18)31150-9 https://doi.org/10.1016/j.jct.2019.01.025 YJCHT 5700

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J. Chem. Thermodynamics

Received Date: Revised Date: Accepted Date:

15 November 2018 26 January 2019 28 January 2019

Please cite this article as: Z. Li, D. Zhao, Y. Zhuang, F. Yang, X. Liu, Y. Chen, Volumetric properties of monoethanolamine and alcohol binary mixtures at different temperatures and 0.1 MPa, J. Chem. Thermodynamics (2019), doi: https://doi.org/10.1016/j.jct.2019.01.025

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Volumetric properties of monoethanolamine and alcohol binary mixtures at different temperatures and 0.1 MPa Zhen Li, Dan Zhao, Yun Zhuang, Fang Yang, Xiuwu Liu, Yuhuan Chen School of Chemical Engineering, Hebei University of Technology, Tianjin, 300130, China

Abstract In this experimental, the densities of monoethanolamine (MEA) + alcohol binary mixtures were measured at temperatures from (293.15 to 333.15) K at 0.1 MPa. The studied alcohols include straight-chain ones, ethanol, npropanol and n-butanol, and branched-chain ones, isopropanol, isobutanol and tertbutanol. From the experimental density values, we calculated the molar volume (Vm), the thermal expansion coefficient (αp) and excess molar volume (VmE ). The VmE values for the six binary systems are all negative ranging from (-1.020 to -0.064) cm3·mol-1. For straight-chain alcohol mixtures, the VmE values follow the increasing order of ethanol < n-propanol < n-butanol. And for the branched-chain alcohol mixtures, the VmE values follow the increasing sequence of tertbutanol < isobutanol < n-butanol. All these result from the intermolecular interactions and structural characteristics. For smaller ethanol molecule and MEA, the molar volume is quite similar to each other. However, VmE value for ethanol + MEA system is the most negative. Therefore, the formation of hydrogen bonds plays a leading role for excess molar volume in small molecule alcohol systems. On the other hand, for larger butanol molecule + MEA systems, steric effect leads to a decrease in excess molar volume with the increase in butanol molar volume. Furthermore, the VmE values were correlated with Redlich-Kister polynomial equation with the largest deviation of 0.048. Keywords: Monoethanolamine; Alcohol; Binary mixture; Density; Excess molar volume 1. Introduction Atmospheric greenhouse effect and global warming is becoming more and more serious in recent years. Accordingly, CO2, the important component of greenhouse gases has captured a worldwide attention. For carbon dioxide capture, one of the widely used approaches is chemical absorption by alkanolamines [1-8], such as



Corresponding author.

E-mail address: [email protected]. 1

monoethanolamine (MEA), methyldiethanolamine (MDEA) and diethanolamine (DEA). Among them, MEA is the simplest molecule and has a larger industrial application space due to the advantages of fast absorption rate, low price, and easy recycling of capacity. However, pure alkanolamine exhibits highly alkaline and highly viscous, which could result in corroding equipment and reducing efficiency. Therefore, water [1-3], alcohol [4-6] and other solvents [7,8] are introduced to solve the problem. In consequence, the studies on thermodynamic properties of the sorbents is essential to the design, scale up and optimization of industrial process, since the thermodynamic properties can provide information on molecular structures and interactions between the two compounds. Yin et al. [2] measured the densities and viscosities of binary absorbents, 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]) + H2O, [Bmim][BF4] + MEA and MEA + H2O and ternary mixtures, [Bmim][BF4] + MEA + H2O. And they also calculated the excess molar volume (VmE ), viscosity deviation and excess Gibbs energy of activation of viscous flow. Alvarez et al. [6] also determined the densities and speed of sound of the binary mixtures composed ethanol and MDEA/triethanolamine. All these studies are important to heat/mass transfer and gas-liquid kinetics in absorption/desorption process. For further perceiving the information about the effect of chemical structure and interaction between the two compounds on thermodynamic properties, MEA and alcohol binary systems are selected to have a systematical investigation in this work. The alcohol includes straight-chain ones, ethanol, n-propanol and n-butanol, and branched-chain ones, isopropanol, isobutanol and tertbutanol. The densities of have been measured over the entire composition range expressed by the mole fraction at temperatures (293.15-323.15) K and 0.1 MPa. According to the experimental values, the excess molar volume and thermal expansion coefficient were calculated. All the results were discussed in terms of molecular interaction and molecular structure. 2. Experimental 2.1 Materials All reagents are analytical grade with a stated mass fraction purity ≥ 0.99. The MEA was obtained from Fuyu Fine Chemicals Co., Ltd. (Tianjin, China) and was used after drying at 343.15 K for about 12 h under vacuum. The ethanol was obtained from Hengshan Chemical Technology Co., Ltd. (Tianjin, China). The isopropanol was purchased from Jindong Tianzheng Fine Chemical Reagents Factory. (Tianjin, China). The n-propanol, n-butanol, isobutanol and tertbutanol were purchased from Fuchen Chemical Reagent Factory. (Tianjin, China). All the alcohols were dried with molecular sieves (0.3 nm) for days before use. The specific details of reagents are listed in Table 1. 2

2.2. Apparatus and procedure The binary mixture of MEA +alcohol was prepared by mass. And the mass measurements were made using an electronic balance (FA1204, Shanghai, China) accurate to ±10-4 g. The total mass of the binary mixture with fixed mole fraction is of 5 g. The uncertainty in mole fractions is estimated to be ±0.01. The density was measured by means of an oscillating U-tube digital densimeter (DA-645 KEM Japan) with a stated accuracy of ±1 × 10-5 g·cm-3. The temperatures ranged from (293.15 to 323.15) K with an uncertainty of ±0.03K. Calibration of the apparatus was performed using dry air and ultrapure water. The experimental uncertainty in density is within ±2 × 10-3 g·cm-3. All the experimental were performed in triplicate. 3. Results and discussion 3.1. Density The density data for pure compounds, MEA, ethanol, n-propanol, isopropanol, n-butanol, isobutanol and ntertbutanol at different temperatures (293.15-323.15) K and ambient pressure are listed in Table 2 together with reported values [9-43]. The deviations between the density data in this work and in literature work are visually shown in Figure1. From Figure 1, it can be observed that the measured density date are in good agreement with published values and the deviations for all the studied compounds are within ±0.2% . From the density values, the molar volume can be calculated and the Vm values follow the increasing trend: ethanol (58.68 cm3·mol-1) < MEA (60.32 cm3·mol-1) < n-propanol (75.15 cm3·mol-1) < isopropanol (78.13 cm3·mol1)

< n-butanol (91.97 cm3·Mol-1) < isobutanol (92.88 cm3·mol-1) < tertbutanol (94.95 cm3·mol-1) at 298.15 K. It can

be clearly seen that ethanol is the smallest molecule and the molar volume is quite similar to that of MEA. And butanol is a larger one, especially the structural isomers, tertbutanol. The density values of binary systems, ethanol + MEA, n-propanol + MEA, isopropanol + MEA, n-butanol + MEA, isobutanol + MEA and tertbutanol + MEA, with the whole compositions (xMEA = 0-1) are presented in Supplemental Files. And Figure 2 graphically shows ρ variation as a function of temperature. The results show that the density values for the binary systems increases with the increase in MEA concentration, and decreases with the increase in temperature. For ethanol + MEA, n-propanol + MEA and isopropanol + MEA systems, comparison with the published work [15,44-46] is graphically shown in Figure 3. Form Figure 3, it can be drawn the conclusion that the agreement is well for the studied systems with the reported data at different temperatures. 3.2. Thermal expansion coefficient The density values for binary mixtures can be well fitted by the following Eq. (1) [47]: 3

  a  bT

(1)

where ρ is the density, T is the absolute temperature, and a and b are the fitting parameters. Figure 2 illustrates that ρ presents a good linear relation to temperature ranging from (293.15 to 323.15) K with a correlation coefficient R2 > 0.9998. The isobaric thermal expansion coefficient (αp) of the mixture is defined as following Eq. (2): αp 

(2)

1   ln       Vm   T  p Vm    T  p

where Vm and ρ are the molar volume and density of the binary mixture, respectively, and p is the pressure in kPa. The αp values can be obtained from Eq. (1) and the results are shown in Figure 4. For pure components, the αp values are in a decreasing sequence of ethanol (1.13 × 10-3 K-1) > n-propanol (1.04 × 10-3 K-1) > n-butanol (9.83 × 10-4 K-1) for straight-chain alcohols. For branched-chain alcohols, the αp values are in a decreasing sequence of tertbutanol (1.37 × 10-3 K-1) > isobutanol (1.01 × 10-3 K-1) > n-butanol (9.83 × 10-4 K-1). The values agree well with the reported data 1.006 × 10-3 K-1 for n-propanol [24], 0.988 × 10-3 K-1 for isobutanol [37] and 1.3 × 10-3 K-1 for tertbutanol [43]. Figure 4 also indicates that the thermal expansion coefficient for the six systems decreases with the increase in MEA concentration. 3.3. Excess molar volumes The excess molar volume VmE can be calculated according to the following Eq. (3):

VmE 

x1 M 1

 mix



x2 M 2

 mix



x1 M 1

1



x2 M 2

2

(3)

where x1, x2 are the mole fractions of MEA (1) and alcohol (2), respectively. M1 and M2 refer to the molar mass of 1 and 2, and ρ1, ρ2 and ρmix are the densities of 1, 2 and the binary mixture, respectively. The calculated VmE values for the binary systems at different temperatures are listed in Supplemental files and visually shown in Figure 5. And all the obtained VmE values are fitted to Redlich-Kister polynomials [48]: p

VmE  x1 x 2  Ai ( x1  x 2 ) i i 0

(4)

where the parameter Ai is the polynomial coefficient and is obtained by fitting the equation to the experimental values using least squares method. P is the degree of polynomial expansion, and i is the exponent. The fitting coefficients and the standard deviation σ are presented in Table 3. And standard deviation σ is defined by the 4

following Eq. (5):



 n V E  V E exp cal    i 1 n p  



2

   

1/ 2

(5)

E

E where Vexp is the experimental value, and Vcal is the calculated value according to Eq. (4), n is the number of

experimental data points, P denotes the number of fitting parameters. Figure 5 shows that the excess molar volumes for the studied systems are all negative in the range of whole composition. And the maximum negative VmE values at 298.15 K are (-0.696, -0.460, -0.546, -0.277, -0.409 and 0.608) cm3·mol-1 with xMEA = (0.4300, 0.4960, 0.5961, 0.5482, 0.5482 and 0.4472) for ethanol + MEA, n-propanol + MEA, isopropanol + MEA, n-butanol + MEA, isobutanol + MEA and tertbutanol + MEA mixtures, respectively. Furthermore, binary mixtures containing the same alcohol with the same concentration are similar in VmE values. Therefore, it can be concluded that deviations from ideal behavior in alcohol + MEA mixture is modest, taking into account of the uncertainties. For straight-chain alcohol mixtures, the VmE values follow the increasing order of ethanol + MEA < n-propanol + MEA < n-butanol + MEA at 298.15 K, as shown in Figure 5 (g). In other words, the real mixture containing the smaller ethanol molecule and MEA deviates furthest from ideal mixtures compared with others containing larger alcohol molecules, such as n-propanol and n-butanol. Generally, the closer the molecular volumes of the two compounds are, the more similar the interactions between unlike molecules are, and the more "ideal" the behavior of the solution becomes. However, the VmE

value for ethanol + MEA is the most negative, indicating

intermolecular hydrogen bonding (−H2N⋯HO− and −HO⋯HO−) between the two components are much stronger. The formation of hydrogen bonds tends to shrink the volume of the mixed system and leads to the negative deviation of the real mixtures from the ideality. As a result, interaction forces are responsible for the most negative

VmE value of ethanol + MEA solution. With the increasing of carbon chain length, the hydrogen bond interaction between alcohol and MEA becomes weakened. In consequence, the real solution approaches ideality and the excess molar volume increases. For branched-chain alcohol mixtures, the VmE values show the increasing order of tertbutanol + MEA < isobutanol + MEA < n-butanol + MEA at 298.15 K. The solution’s deviation from ideality is not only dependent on hydrogen bond but also on structural steric effect. For butanol bianry systems, the space steric effect becomes 5

dominant with hydrogen bonds weakening. For structural isomers, n-butanol, isobutanol and tertbutanol, the molar volume increases with the increase in amounts of branching, as stated in section 3.1. In consequence, the smaller molecule MEA can be easily inserted into a larger molecular void, which results in a volumetric shrinkage and leads to more negative excess molar volume, such as tertbutanol + MEA system. 4. Conclusions The density of a series of binary mixtures, ethanol + MEA, n-propanol + MEA, isopropanol + MEA, n-butanol + MEA, isobutanol + MEA and tertbutanol + MEA were measured at temperatures from (293.15 to 298.15) K over whole range of composition at 0.1 MPa. The results show that the density of binary system decreases with the increase in temperature and increases with the increase in MEA concentration. And the excess molar volume is mainly affected by hydrogen bonding and space steric effect. For straight-chain alcohol mixtures, the VmE values are dominated by hydrogen bond and follow the sequence of ethanol + MEA < n-propanol + MEA < n-butanol + MEA. On the other hand, for branched-chain alcohol mixtures, the VmE values are dominated by space steric hindrance effect and follow the order of tertbutanol + MEA < isobutanol + MEA < n-butanol + MEA. Acknowledgements This work was supported by the National Natural Science Foundation of China [grant number 21576064] and Natural Science Foundation of Hebei Province, China [grant number B2016202290). References [1] D.D.D. Pinto, J.G.M.S. Monteiro, B. Johnsen, H.F. Svendsen, H. Knuutila, Density measurements and modelling of loaded and unloaded aqueous solutions of MDEA (N-methyldiethanolamine), DMEA (N,Ndimethylethanolamine), DEEA (DiethylethanoLamine) and MAPA (N-methyl-1,3-diaminopropane), Int. J. Greenh. Gas Con. 25 (2014) 173-185. [2] Y.R. Yin, C.Y. Zhu, Y.G. Ma, Volumetric and viscometric properties of binary and ternary mixtures of 1-butyl3-methylimidazolium tetrafluoroborate, monoethanolamine and water, J. Chem. Thermodyn. 102 (2016) 413-428. [3] H.X. Gao, B. Xu, L. Han, X. Luo, Z.W. Liang, Mass transfer performance and correlations for CO2 absorption into aqueous blended of DEEA/MEA in a random packed column, AICHE J. 63 (2017) 3048-3057. [4] S. Lin, H.F. Lu, Y.Y. Liu, C.J. Liu, B. Liang, K.J. Wu, Density studies of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) glycerol and CO2-DBU-glycerolsolutions at temperatures between 288.15 K and 328.15 K, J. Chem. Thermodyn. 123 (2018) 8-16. [5] P.G. Jessop, S.M. Mercer, D.J. Heldebrant, CO2-triggered switchable solvents, surfactants, and other materials, 6

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10

Figure Captions FIGURE 1. Deviations 100( ρExp - ρLit ) / ρExp between experimental density values and literature values as a function of temperature at 0.1 MPa: (a) MEA; (b) ethanol; (c) n-propanol; (d) isopropanol; (e) n-butanol; (f) isobutanol; (g) tertbutanol: ■, [9]; ●, [10]; ▲, [11]; ◆, [12]; ★, [13]; ○, [14]; △, [15]; ◇, [16]; ☆, [17]; ✳, [18]; ×, [19]; ＋ , [20]; － , [21]; ⊕, [22]; ⊖, [23]; ⊠, [24];

⊟, [25]; □, [26]; ⊞, [27];∣, [28]; ◓, [29]; ⊗, [30]; ▼, [31]; ◑, [32]; ◧, [33]; ◨, [34]; ▽, [35]; ◫, [36]; ◀, [37]; ▷, [38]; ▶, [39]; ◭, [40]; ◮, [41]; ◐, [42]; ▲, [43]. FIGURE 2. ρ variation as a function of temperature for six binary systems with different compositions at 0.1 MPa: (a) ethanol + MEA systems; (b) n-propanol + MEA systems; (c) isopropanol + MEA systems; (d) n-butanol + MEA systems; (e) isobutanol + MEA systems; (f) tertbutanol + MEA systems. FIGURE 3. Comparison of measured densities for (a) ethanol + MEA systems; (b) n-propanol + MEA systems; (c) isopropanol + MEA systems in this work with literature data [15,44-46]. FIGURE 4. Plots of isobaric thermal expansion coefficient against composition for six binary systems at different temperatures: ■, ethanol + MEA; ◆, n-propanol + MEA; ▲, isopropanol + MEA; ▼, n-butanol + MEA; ◀, isobutanol + MEA; ▶, tertbutanol + MEA. FIGURE 5. Plot of excess molar volume versus xMEA for six binary systems at different temperatures: (a) ethanol + MEA systems; (b) n-propanol + MEA systems; (c) isopropanol + MEA systems; (d) n-butanol + MEA systems; (e) isobutanol + MEA systems; (f) tertbutanol + MEA systems; (g) six systems at 298.15 K. Solid curves were calculated from the Redlich-Kister equation.

11

0.09

0.10

(a)

(b)

0.06

100( Exp-Lit) /Exp

100( Exp-Lit) /Exp

0.05

0.03

0.00

0.00

-0.05

-0.03

-0.10

-0.06

290

300

310

320

330

290

300

T/K

T/K

310

320

330

0.05

0.10

(d)

(c) 0.00

100( Exp-Lit) /Exp

100( Exp-Lit) /Exp

0.05

-0.05

0.00

-0.10

-0.05

-0.10 290

-0.15

-0.20 300

310

320

290

330

300

310

320

330

T/K

T/K

0.03 0.08

(f)

(e) 0.00

100( Exp-Lit) /Exp

100( Exp-Lit) /Exp

0.04

0.00

-0.04

-0.03

-0.06

-0.08

-0.09 -0.12 290

300

310

T/K

320

330

290

300

310

320

330

T/K

12

0.08

(g)

100( Exp-Lit) /Exp

0.06

0.04

0.02

0.00

-0.02

-0.04 290

300

310

320

330

T/K

FIGURE 1. Deviations 100( ρExp - ρLit ) / ρExp between experimental density values and literature values as a function of temperature at 0.1 MPa: (a) MEA; (b) ethanol; (c) n-propanol; (d) isopropanol; (e) n-butanol; (f) isobutanol; (g) tertbutanol: ■, [9]; ●, [10]; ▲, [11]; ◆, [12]; ★, [13]; ○, [14]; △, [15]; ◇, [16]; ☆, [17]; ✳, [18]; ×, [19]; ＋ , [20]; － , [21]; ⊕, [22]; ⊖, [23]; ⊠, [24];

⊟, [25]; □, [26]; ⊞, [27];∣, [28]; ◓, [29]; ⊗, [30]; ▼, [31]; ◑, [32]; ◧, [33]; ◨, [34]; ▽, [35]; ◫, [36]; ◀, [37]; ▷, [38]; ▶, [39]; ◭, [40]; ◮, [41]; ◐, [42]; ▲, [43].

13

(a)

(b)

1.00

1.00

xMEA = 0.0000

xMEA = 0.0000

xMEA = 0.0773

-3

0.90

xMEA = 0.4300 xMEA = 0.5308

xMEA = 0.2966 xMEA = 0.3961

-3

xMEA = 0.3346

xMEA = 0.1974

0.95

/(gcm )

xMEA = 0.2443

/(gcm )

xMEA = 0.0986

xMEA = 0.1586

0.95

xMEA = 0.4960

0.90

xMEA = 0.5961 xMEA = 0.6966

xMEA = 0.6377

0.85

xMEA = 0.7974

0.85

xMEA = 0.7511

xMEA = 0.8985

xMEA = 0.8716

0.75

xMEA = 1.0000

xMEA = 1.0000

0.80

290

300

310

320

330

0.80

290

340

300

310

T/K

T/K

320

330

340

(c)

(d)

1.00

1.00

xMEA = 0.0000

xMEA = 0.0000

xMEA = 0.0986

0.95

xMEA = 0.1188

xMEA = 0.1974

0.95

0.90

xMEA = 0.4960 xMEA = 0.5961 xMEA = 0.6966

0.85

xMEA = 0.2328 xMEA = 0.3421

-3

xMEA = 0.3961

/(gcm )

-3

/(gcm )

xMEA = 0.2966

xMEA = 0.4472 0.90

xMEA = 0.5482 xMEA = 0.6454 xMEA = 0.7390

xMEA = 0.7974

0.85

xMEA = 0.8985

xMEA = 0.8291 xMEA = 0.9161

xMEA = 1.0000

0.80

xMEA = 1.0000 0.80

0.75 290

300

310

T/K

320

330

290

340

300

310

T/K

320

330

340

(f)

(e) 1.00

1.00

xMEA = 0.0000

xMEA = 0.0000 xMEA = 0.1188

0.90

xMEA = 0.5482 xMEA = 0.6454 xMEA = 0.7390

0.85

xMEA = 0.2328 xMEA = 0.3421

-3

/(gcm )

xMEA = 0.4472

-3

/(gcm )

xMEA = 0.3421

xMEA = 0.1188

0.95

xMEA = 0.2328

0.95

xMEA = 0.4472

0.90

xMEA = 0.5482 xMEA = 0.6454 xMEA = 0.7390

0.85

xMEA = 0.8291

xMEA = 0.8291 xMEA = 0.9161 xMEA = 1.0000

0.80

xMEA = 0.9161 0.80

xMEA = 1.0000

0.75

290

300

310

T/K

320

330

340

300

310

T/K

320

330

FIGURE 2. ρ variation as a function of temperature for six binary systems with different compositions at 0.1 MPa: (a) ethanol + MEA systems; (b) n-propanol + MEA systems; (c) isopropanol + MEA systems; (d) n-butanol + MEA systems; (e) isobutanol + MEA systems; (f) tertbutanol + MEA systems.

14

1.00

0.95 -3

-3

0.90

0.85

(b)

298.15 K in this work 303.15 K in this work 308.15 K in this work 313.15 K in this work 318.15 K in this work 323.15 K in this work 303.15 K [15] 313.15 K [15] 323.15 K [15] 298 K [45] 308 K [45] 318 K [45]

1.00

 /(g.cm )

0.95

 /(g.cm )

(a)

303.15 K in this work 313.15 K in this work 323.15 K in this work 303.15 K [44] 313.15 K [44] 323.15 K [44]

0.90

0.85

0.80

0.80 0.75 0.0

0.2

1.10

1.00 -3

xMEA

0.6

0.8

0.95 0.90 0.85

1.0

0.0

0.2

0.4

xMEA

0.6

0.8

1.0

(c)

293.15 K in this work 298.15 K in this work 303.15 K in this work 308.15 K in this work 313.15 K in this work 318.15 K in this work 323.15 K in this work 293.15 K [46] 303.15 K [46] 313.15 K [46] 323.15 K [46] 298.15 K [45] 308.15 K [45] 318.15 K [45]

1.05

 /(g.cm )

0.4

0.80 0.75 0.0

0.2

0.4

xMEA

0.6

0.8

1.0

FIGURE 3. Comparison of measured densities for (a) ethanol + MEA systems; (b) n-propanol + MEA systems; (c) isopropanol + MEA systems in this work with literature data [15,44-46].

15

1.4 1.3 1.2

ap

1.1 1.0 0.9 0.8 0.7

0.0

0.2

0.4

xMEA

0.6

0.8

1.0

FIGURE 4. Plots of isobaric thermal expansion coefficient against composition for six binary systems at different temperatures: ■, ethanol + MEA; ◆, n-propanol + MEA; ▲, isopropanol + MEA; ▼, n-butanol + MEA; ◀, isobutanol + MEA; ▶, tertbutanol + MEA.

16

0.0

0.0 293.15 K 298.15 K 303.15 K 308.15 K 313.15 K 318.15 K 323.15 K

-1

-0.2

3

3

-0.3

(b)

293.15 K 298.15 K 303.15 K 308.15 K 313.15 K 318.15 K 323.15 K

-0.1

-1

-0.2

Vm /( cm ·mol )

-0.1

Vm /( cm ·mol )

(a)

E

E

-0.4 -0.5 -0.6

-0.3

-0.4

-0.7

-0.5

-0.8 0.0

0.2

0.4

0.6

xMEA

0.8

1.0

0.0

0.8

1.0

-1

-0.10

-0.15

E

3

-0.3

(d)

293.15 K 298.15 K 303.15 K 308.15 K 313.15 K 318.15 K 323.15 K

-0.05

Vm /( cm ·mol )

-0.2

-1 3

0.6

0.00

(c)

293.15 K 298.15 K 303.15 K 308.15 K 313.15 K 318.15 K 323.15 K

-0.1

E

0.4

xMEA

0.0

Vm /( cm ·mol )

0.2

-0.4 -0.5

-0.20

-0.25

-0.6

-0.30

-0.7 0.0

0.2

0.4

0.6

0.8

-0.35 0.0

1.0

0.2

0.4

0.0

-1

Vm /( cm ·mol )

3

-0.4

-0.3

-0.6

E

E

1.0

(f)

298.15 K 303.15 K 308.15 K 313.15 K 318.15 K 323.15 K

-0.2

3

-1

Vm /( cm ·mol )

-0.2

0.8

0.0

(e)

293.15 K 298.15 K 303.15 K 308.15 K 313.15 K 318.15 K 323.15 K

-0.1

0.6

xMEA

xMEA

-0.4

-0.8

-0.5

-1.0

0.0

0.2

0.4

0.6

xMEA

0.8

1.0

0.0

0.2

0.4

xMEA

0.6

0.8

1.0

17

0.0

(g)

-0.4

E

3

-1

Vm /( cm ·mol )

-0.2

-0.6

-0.8

-1.0 0.0

ethanol + MEA n-propanol + MEA isopropanol + MEA n-butanol + MEA isobutanol + MEA tertbutanol + MEA 0.2

0.4

x MEA

0.6

0.8

1.0

FIGURE 5. Plot of excess molar volume versus xMEA for six binary systems at different temperatures: (a) ethanol + MEA systems; (b) n-propanol + MEA systems; (c) isopropanol + MEA systems; (d) n-butanol + MEA systems; (e) isobutanol + MEA systems; (f) tertbutanol + MEA systems; (g) six systems at 298.15 K. Solid curves were calculated from the Redlich-Kister equation.

18

Table Captions Table 1 Specifications of the reagents in this work. Table 2 Experimental and literature values of density for pure compounds at different temperatures and 0.1 MPa. Table 3 Fitting coefficients of the Redlich-Kister equation and standard deviation (σ) of excess molar volumes for the mixtures at different temperatures and 0.1 MPa.

19

Table 1 Specifications of the reagents in this work. a

Compound

CAS No.

Source

Mass fraction

MEA

141-43-5

Tianjin Fuyu Fine Chemicals Co., Ltd

Vacuum drying

Ethanol

64-17-5

Tianjin Hengshan Chemical Technology Co., Ltd

≥ 0.990 purity ≥ 0.997

n-Propanol ethanoletha Isopropanol nol n-Butanol

71-23-8

Tianjin Fuchen Chemical Reagent Factory

≥ 0.998

molecular sieves (3 Å)

67-63-0

Tianjin Jindong Tianzheng Fine Chemical Reagents Factory

≥ 0.997

molecular sieves (3 Å)

71-36-3

≥ 0.995

molecular sieves (3 Å)

Isobutanol

78-83-1

Tianjin Fuchen Chemical Reagent Factory Factory Tianjin Fuchen Chemical Reagent Factory

≥ 0.990

molecular sieves (3 Å)

Tertbutanol

75-65-0

Tianjin Fuchen Chemical Reagent Factory

≥ 0.99

molecular sieves (3 Å)

a The

Purification method

molecular sieves (3 Å)

purity is reported by supplier.

.

20

Table 2 Experimental and literature values of density for pure compounds at different temperatures and 0.1 MPa. Compound

MEA

Ethanol

T/K

ρ/(g·cm-3) Experimental

Literature

293.15

1.01647

1.0179 [9], 1.0164 [10], 1.01665 [11], 1.01610 [12]

298.15

1.01253

1.0125 [10], 1.0123 [13]

303.15

1.00847

1.0085 [10], 1.00874 [11], 1.00817 [12], 1.00828 [14], 1.009 [15]

308.15

1.00449

1.0046 [10], 1.00431 [14]

313.15

1.00050

1.0006 [10], 1.00077 [11], 1.00021 [12], 1.0003 [13], 1.00034 [14], 0.9999 [15]

318.15

0.99639

0.99635 [14]

323.15

0.99241

0.99275 [11], 0.99219 [12], 0.9923 [13], 0.9918 [15]

293.15

0.78940

0.78954 [11], 0.78946 [16], 0.78824 [17], 0.789921 [18]

298.15

0.78513

0.78520 [16], 0.78510 [19], 0.78522 [20], 0.785085 [21], 0.785631 [18], 0.78591 [22]

n-Propanol

Isopropanol

303.15

0.78075

0.78094 [11], 0.78075 [16], 0.78073 [17], 0.781313 [18], 0.78072 [23]

308.15

0.77641

0.77642 [16],0.776961 [18], 0.77643 [19]

313.15

0.77204

0.77220 [11], 0.77181 [16], 0.77198 [17], 0.772569 [18], 0.77261 [23]

318.15

0.76752

0.76738 [16], 0.768129 [18], 0.76762 [19]

323.15

0.76304

0.76329 [11], 0.763643 [18]

293.15

0.80377

0.80371 [16], 0.80364 [17], 0.80350 [24], 0.80356 [23], 0.80365 [25]

298.15

0.79969

0.79974 [16], 0.799527 [21], 0.79996 [22], 0.79971 [23], 0.79949 [24], 0.7996 [26]

303.15

0.79558

0.79577 [16], 0.79548 [17], 0.79558 [23], 0.79546 [24], 0.79561 [25], 0.7955 [26]

308.15

0.79152

0.79180 [16], 0.7915 [26]

313.15

0.78742

0.78783 [16], 0.78702 [17], 0.78734 [23], 0.78728 [24], 0.78743 [25], 0.7873 [26]

318.15

0.78317

0.78386 [16], 0.7833 [26]

323.15

0.77896

0.77897 [23], 0.77892 [24], 0.77906 [25], 0.7790 [26]

293.15

0.78510

0.78518 [23], 0.78513 [24], 0.78535 [27], 0.78545 [28]

298.15

0.78091

0.78088 [19], 0.780824 [21], 0.78136 [22], 0.78131 [23], 0.78093 [24], 0.78110 [27] 0.78126 [28], 0.78082 [29],0.7809 [30], 0.781482 [31]

303.15

0.77657

0.77666 [23], 0.77666 [24], 0.7766 [26], 0.77712 [27], 0.77797 [28] 21

n-Butanol

308.15

0.77224

0.77227 [19], 0.7723 [26], 0.77288 [27], 0.77259 [28]

313.15

0.76782

0.76783 [23], 0.76787 [24], 0.7679 [26]

318.15

0.76319

0.76330 [19], 0.7633 [26], 0.76397 [27]

323.15

0.75855

0.75871 [23], 0.75869 [24], 0.7586 [26]

293.15

0.80977

0.80952 [23], 0.80917 [32]

298.15

0.80592

0.805778 [21], 0.80612 [22], 0.80588 [23], 0.805953 [31], 0.80554 [32], 0.80540 [33], 0.805877 [34]

Isobutanol

Tertbutanol

303.15

0.80200

0.80199 [23], 0.80190 [32], 0.80192 [35], 0.80221 [36]

308.15

0.79814

0.79825 [32], 0.79814 [33], 0.79827 [35], 0.79834 [36]

313.15

0.79424

0.79434 [23], 0.79460 [32], 0.794354 [34], 0.79463 [35], 0.79442 [36]

318.15

0.79020

0.79097 [32], 0.79019 [33], 0.79099 [35], 0.79046 [36]

323.15

0.78621

0.78667 [23], 0.78645 [36]

293.15

0.80185

0.80190 [25], 0.8020 [37], 0.8019 [38]

298.15

0.79799

0.7981 [37], 0.7980 [38], 0.7974 [39], 0.79784 [40]

303.15

0.79403

0.79414 [25], 0.79406 [36], 0.7942 [37], 0.7942 [38], 0.79399 [41]

308.15

0.79009

0.79012 [36], 0.7903 [37], 0.7908 [38], 0.79004 [41]

313.15

0.78612

0.78620 [25], 0.78612 [36], 0.7863 [37], 0.78604 [41]

318.15

0.78197

0.78206 [36], 0.78198 [41]

323.15

0.77786

0.77801 [25], 0.77793 [36], 0.77785 [41]

298.15

0.78061

0.7782 [39]

303.15

0.77542

0.7752 [42]

308.15

0.77021

0.77036 [36], 0.7698 [42], 0.77015 [43]

313.15

0.76492

0.764887 [34], 0.76507 [36], 0.7644 [42]

318.15

0.75942

0.75967 [36], 0.7590 [42]

323.15

0.75395

0.75419 [36], 0.7536 [42], 0.75394 [43]

Standard uncertainties u are u(T) = ±0.03 K, u(ρ) = ±2 × 10-3 g·cm-3 and u(p) = ±0.01 MPa.

22

Table 3 Fitting coefficients of the Redlich-Kister equation and standard deviation (σ) of excess molar volumes for the mixtures at different temperatures and 0.1 MPa. T/K

A0

A1

A2

A3

σ

Ethanol + MEA 293.15

-2.6880

0.3506

0.0832

0.0339

0.011

298.15

-2.7340

0.3544

0.0822

0.0533

0.011

303.15

-2.7810

0.3699

0.0891

0.0477

0.011

308.15

-2.8340

0.3678

0.1019

0.0807

0.011

313.15

-2.8920

0.3633

0.1172

0.1058

0.010

318.15

-2.9450

0.3922

0.1133

0.0735

0.010

323.15

-3.0050

0.4309

0.1080

0.0868

0.011

n-Propanol + MEA 293.15

-1.6890

0.1687

-0.3353

-0.0703

0.015

298.15

-1.7160

0.1360

-0.3000

-0.0375

0.014

303.15

-1.7360

0.1339

-0.2910

-0.0310

0.014

308.15

-1.7620

0.1447

-0.2689

-0.0618

0.014

313.15

-1.7880

0.1369

-0.2649

-0.0623

0.014

318.15

-1.8200

0.1501

-0.2594

-0.1051

0.014

323.15

-1.8470

0.1701

-0.2853

-0.1524

0.016

Isopropanol + MEA 293.15

-2.0350

-1.1120

0.6188

0.7637

0.032

298.15

-2.0850

-1.1340

0.6347

0.8168

0.033

303.15

-2.1440

-1.1360

0.6510

0.8469

0.033

308.15

-2.2060

-1.1370

0.6486

0.8924

0.034

313.15

-2.2820

-1.1230

0.6413

0.9206

0.034

318.15

-2.3770

-1.1050

0.6400

0.9543

0.035

323.15

-2.4860

-1.0710

0.6219

0.9890

0.036

23

n-Butanol + MEA 293.15

-1.0191

-0.2272

-0.6050

0.7518

0.019

298.15

-1.0320

-0.2116

-0.5637

0.6709

0.018

303.15

-1.0410

-0.2072

-0.5254

0.6024

0.018

308.15

-1.0500

-0.1968

-0.5091

0.5306

0.022

313.15

-1.0610

-0.1982

-0.5032

0.5201

0.019

318.15

-1.0730

-0.1965

-0.4890

0.4815

0.019

323.15

-1.0950

-0.1933

-0.4813

0.4560

0.020

Isobutanol + MEA 293.15

-1.6870

-0.1391

0.6636

-0.1976

0.047

298.15

-1.6900

-0.1374

0.7231

-0.1895

0.048

303.15

-1.7090

-0.1510

0.7516

-0.1919

0.047

308.15

-1.7370

-0.1324

0.7680

-0.2530

0.047

313.15

-1.7690

-0.1227

0.7929

-0.2938

0.048

318.15

-1.8090

-0.0952

0.8091

-0.3639

0.047

323.15

-1.8580

-0.0743

0.8240

-0.4135

0.047

Tertbutanol + MEA 298.15

-2.2440

-0.9675

-1.5790

-0.3225

0.041

303.15

-2.5240

-0.7942

-1.7080

-0.3027

0.040

308.15

-2.8210

-0.6152

-1.8590

-0.2520

0.040

313.15

-3.1330

-0.4454

-2.0040

-0.2053

0.040

318.15

-3.4650

-0.2619

-2.1530

-0.1670

0.040

323.15

-3.8090

-0.0788

-2.2670

-0.1592

0.040

Standard uncertainties u are u(T) = ±0.03 K and u(p) = ±0.01 MPa.

Highlights 1. The densities for amine + alcohol six binary solutions were measured. 2. The VmE values are negative with xMEA from 0 to 1.

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3. For straight chain alcohol mixtures, VmE values follow: ethanol < n-propanol < n-butanol. 4. For branched chain alcohol mixtures, VmE values follow: tertbutanol < isobutanol < n-butanol. 5. VmE values were correlated with Redlich-Kister polynomial equation.

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