Density, Speed of Sound, Viscosity, Surface Tension, and Excess

Article pubs.acs.org/jced

Density, Speed of Sound, Viscosity, Surface Tension, and Excess Volume of N‑Ethyl-2-pyrrolidone + Ethanolamine (or Diethanolamine or Triethanolamine) from T = (293.15 to 323.15) K Antonio Blanco, Alicia García-Abuín, Diego Gómez-Díaz, José M. Navaza,* and Ó scar L. Villaverde

Department of Chemical Engineering, ETSE, University of Santiago de Compostela, Rúa Lope Gómez de Marzoa s/n, E-15706, Santiago de Compostela, Spain S Supporting Information *

ABSTRACT: Density, speed of sound, viscosity, and surface tension of the binary mixtures N-ethyl-2-pyrrolidone (EP) + ethanolamine (MEA) (or diethanolamine (DEA) or triethanolamine (TEA)) were measured at different temperatures from (293.15 to 323.15) K over the entire range of concentrations. The excess molar volumes and isentropic compressibility deviations were calculated. Moreover, the excess molar volumes were fitted using a Redlich−Kister equation, and the surface tension data were fitted by the Connors−Wright model.

■

■

INTRODUCTION

EXPERIMENTAL SECTION Materials. Information about the reagents employed in this work is included in Table 1. Bidistilled water has been used to prepare the mixtures.

Over the past several years, blends of two alkanolamines have been proposed as suitable solvents to replace aqueous solutions of one alkanolamine in the process of carbon dioxide capture at industrial level by different researchers1 because this second amine can produce an enhancement of the absorption/ regeneration process. Several researchers have performed different characterization studies in relation with physicochemical properties for binary2,3 and ternary amine-based systems.4,5 Other alternative way to improve the carbon dioxide absorption or capture could be the substitution of water (solvent) for other substances. Several studies6 have concluded that amides, such as N-methyl-2-pyrrolidone or N-ethyl-2-pyrrolidone, show suitable behaviors to be used in carbon dioxide physical absorption in gas purification processes. Taking the above into consideration, the blend of a single alkanolamine with a physical solvent, including EP, could be an appropriated alternative to conventional processes of carbon dioxide capture. At present, both MEA, DEA, and TEA are compounds used in absorption processes to capture acid gases,7,8 and for this reason, in the present work several physical properties (density, speed of sound, viscosity, and surface tension) of different binary systems formed by amine and amide, MEA (or DEA or TEA) with EP, were measured at different temperatures from (293.15 to 323.15) K and over the entire range of compositions. These physical properties can have a high influence on the mass transfer processes and hydrodynamics,9 so their knowledge will allow us to understand the observed behaviors. © 2013 American Chemical Society

Table 1. Sample Description Table chemical name

source

initial mole fraction purity

a

Alfa Aesar Sigma-Aldrich Sigma-Aldrich Sigma-Aldrich

0.98 ≥ 0.99 0.99 ≥ 0.99

EP MEAb DEAc TEAd a

1-Ethyl-2-pyrrolidone. bEthanolamine or monoethanolamine. cDiethanolamine. dTriethanolamine.

Methods. Density and Speed of Sound. “The densities of pure components and the mixtures of different compounds were measured with an Anton Paar DSA 5000 vibrating tube densimeter and sound analyzer”.10 The uncertainties corresponding to density and speed of sound were 2·10−4 g·cm−3 and 1.2 m·s−1. Viscosity. The kinematic viscosity (ν) was determined by capillary Ubbelohde viscosimeters (supplied by Schott) through the transit time of the liquid meniscus.10 In present work capillary numbers Ic, Ia, and II have been used connected to a Received: October 16, 2012 Accepted: January 23, 2013 Published: February 19, 2013 653

dx.doi.org/10.1021/je301123j | J. Chem. Eng. Data 2013, 58, 653−659

Journal of Chemical & Engineering Data

Article

Table 2. Comparison between Density ρ, Speed of Sound c, Viscosity η, and Surface Tension σ, and Experimental and Literature Data for Pure Components at T = 298.15 K at p = 105 Pac lit.

exp.

lit.

EP ρ/g·cm−3 c/m·s−1 η/mPa·s σ/mN·m−1

1.0123011 1719.212 18.6413 48.9514

0.99624 1492.5 2.022 35.9 DEA

ρ/g·cm−3 c/m·s−1 η/mPa·s σ/mN·m−1

1.093715 1721.515 566.316 47.2118

exp. MEA 1.01198 1719.2 18.740 49.1 TEA

1.121515

1.09337 1725.3 562.7 47.3

607.017 45.9518

1.12071 1614.1 605.9 45.8

c Standard uncertainties u are u(T) = 0.01 K, u(p) = 20 Pa, u(x) = 0.0008, and the combined expanded uncertainties Uc (level of confidence = 0.95, k = 2) are Uc(ρ) = 2·10−4 g·cm−3, Uc(c) = 1.2 m·s−1, Uc(η) = 0.0026 mPa·s, and Uc(σ) = 0.3 mN·m−1.

shows clearly that the presence of amines causes an increase in the value of density in all systems. Also, the experimental data indicate that the substitution degree in amines increases the influence of amine concentration upon density. The observed behaviors are in agreement with the experimental results previously obtained using water instead the amide,19 but the effect of amine concentration upon density in aqueous solutions is different than the observed in amide mixtures because in aqueous solutions density reaches a maximum for the MEA + water system. Also for mixtures with DEA and TEA a clear change in the trend was observed in comparison with the data shown in Figure 1. If N-methyl-2-pyrrolidone (NMP) is used with alkanolamines, an increase in linearity is observed with regard to the influence of composition upon density, and the behavior is similar for systems with EP. The effect caused by temperature upon density is similar to the behavior observed for liquid mixtures, namely, a decrease in the value of density when temperature increases. From experimental density data for each system (amide + amine) the molar volume excess has been calculated for each composition and temperature using eq 3.

Schott-Geräte AVS 350 Ubbelohde viscosimeter. Equation 1 was used to obtain the viscosity on the basis of transit time

ν = K · (t − θ )

(1)

“where t is the efflux time; K is the characteristic constant of the capillary viscosimeter; and θ is a coefficient to correct end effects. Both parameters were obtained from the capillaries supplier (Schott). An electronic stopwatch with an accuracy of ± 0.01 s was used to measure efflux times. In the measurements, a Schott-Geräte AVS 350 Ubbelohde viscosimeter was used. The dynamic viscosity (η) was obtained from the product of the kinematic viscosity (ν) and the corresponding density (ρ) of the mixture, in terms of eq 2 for each mixture composition”.10 The uncertainty of the viscosity measurement was 0.0026 mPa·s. η = ν·ρ (2) Surface Tension. “The surface tension was determined by employing a Krüss K-11 tensiometer using the Wilhelmy plate method. The plate employed was a commercial platinum plate supplied by Krüss. The platinum plate was cleaned and flamedried before each measurement. Each surface tension value reported came from an average of five measurements. The samples were thermostatted in a closed stirring vessel before the surface tension measurements”.10 The highest temperature used in this study was avoided for surface tension measurements because evaporation processes could influence the measurement uncertainty. The surface tension uncertainty was 0.3 mN·m−1.

2

VE =

∑ xi·Mi ·(ρ−1 − ρi−1) i=1

(3)

where xi, Mi, and ρi are the molar fractions, molecular weights, and densities of pure components, respectively. The corresponding excess molar volume uncertainty was 0.001 cm3·mol−1. Table S1 (included in the Supporting Information) shows the calculated data corresponding to excess molar volume obtained from experimental density data (Tables 3 to 5). Figure 2 shows the excess molar volume corresponding to the EP + MEA system at different temperatures. These mixtures show the most complex behavior in these mixtures of EP with different alkanolamines, with positive and negative values depending on mixture composition. The presence of positive and negative values for molar excess volume is caused by the presence of two different kinds of behavior. On one hand the positive values for excess molar volume (at high EP composition) are due to the nonexistence of strong specific interactions between the mixtures substances. This fact could be caused by the rupture of hydrogen bonds of alkanolamine structure. On the other hand, the presence of negative values for excess molar volume in the MEA-rich region is due to the formation of a complex between amine and amide. Different

■

RESULTS AND DISCUSSION The present work analyzes the influence of composition, temperature, and the type of alkanolamine in mixtures with Nethyl-2-pyrrolidone over several physical properties and derived variables. A comparison between the values of these properties corresponding to pure components (experimental and literature data) was performed. Table 2 shows this comparison, and a good agreement between both values was obtained. In relation with the influence of composition, temperature, and type of alkanolamine used in the mixtures with N-ethyl-2pyrrolidone upon these physical properties (density, speed of sound, viscosity, and surface tension), Tables 3 to 5 show the experimental values obtained over the entire composition range and different temperatures. Figure 1 shows the experimental data allowing the analysis of the influence of mixture composition and type of alkanolamine over density. This figure 654



Article

Table 3. Density ρ, Speed of Sound c, Dynamic Viscosity η, and Surface Tension σ of EP (1) + MEA (2) from T = (293.15 to 323.15) K at p = 105 Paa x1

T/K = 293.15

T/K = 303.15

T/K = 313.15

Table 4. Density ρ, Speed of Sound c, Dynamic Viscosity η, and Surface Tension σ of EP (1) + DEA (2) from T = (293.15 to 323.15) K at p = 105 Paa

T/K = 323.15

x1

T/K = 293.15

−3

0.0000 0.1000 0.2002 0.2999 0.4002 0.4999 0.5996 0.7002 0.7999 0.8997 1.0000 0.0000 0.1000 0.2002 0.2999 0.4002 0.4999 0.5996 0.7002 0.7999 0.8997 1.0000

1.01593 1.01483 1.01206 1.00877 1.00613 1.00253 0.99947 0.99841 0.99776 0.99735 0.99791 1734.4 1694.5 1652.1 1621.1 1596.0 1575.8 1554.4 1540.5 1529.1 1519.5 1513.2

0.0000 0.1000 0.2002 0.2999 0.4002 0.4999 0.5996 0.7002 0.7999 0.8997 1.0000

24.231 16.559 11.560 8.317 6.255 4.742 3.762 3.101 2.641 2.325 2.132

0.0000 0.1000 0.2002 0.2999 0.4002 0.4999 0.5996 0.7002 0.7999 0.8997 1.0000

49.7 44.9 42.4 41.1 39.8 39.1 38.3 37.7 37.3 37.1 36.5

ρ/g·cm 1.00802 1.00671 1.00380 1.00038 0.99765 0.99390 0.99078 0.98974 0.98912 0.98875 0.98934 c/m·s−1 1702.1 1661.1 1617.0 1582.4 1560.4 1539.5 1517.3 1503.1 1491.9 1481.7 1475.0 η/mPa·s 14.986 10.658 7.680 6.051 4.760 3.526 2.912 2.446 2.147 1.918 1.777 σ/mN·m−1 47.8 43.7 41.2 39.8 38.5 37.6 36.7 36.1 36.2 35.7 35.2

T/K = 303.15

T/K = 313.15

T/K = 323.15

−3

1.00006 0.99853 0.99542 0.99188 0.98914 0.98523 0.98208 0.98106 0.98046 0.98014 0.98076 1670.1 1628.0 1582.8 1552.5 1527.9 1502.9 1480.5 1466.1 1454.9 1444.2 1437.6 9.776 7.237 5.477 4.386 3.553 2.733 2.322 1.990 1.775 1.616 1.515

0.99205 0.99031 0.98695 0.98329 0.98053 0.97653 0.97335 0.97234 0.97178 0.97150 0.97216

0.0000 0.1000 0.2005 0.3001 0.4002 0.4999 0.6000 0.7001 0.8001 0.8995 1.0000

1637.2 1594.2 1549.2 1517.9 1493.2 1467.0 1443.8 1429.5 1418.0 1407.6 1400.6

0.0000 0.1000 0.2005 0.3001 0.4002 0.4999 0.6000 0.7001 0.8001 0.8995 1.0000

6.765 5.201 4.011 3.311 2.734 2.183 1.884 1.659 1.503 1.384 1.310

47.1 42.7 40.2 38.7 37.0 35.9 34.9 34.5 35.0 34.6 34.2

1.09645 1.08434 1.07276 1.06183 1.05118 1.04090 1.03122 1.02209 1.01333 1.00523 0.99791 1739.2 1700.4 1666.7 1638.2 1611.7 1589.2 1569.3 1552.5 1538.4 1524.5 1513.2

0.0000 0.1000 0.2005 0.3001 0.4002 0.4999 0.6000 0.7001 0.8001 0.8995 1.0000

892.037 462.694 227.229 109.600 51.596 26.018 13.841 8.154 4.999 3.117 2.132

0.0000 0.1000 0.2005 0.3001 0.4002 0.4999 0.6000 0.7001 0.8001 0.8995 1.0000

47.4 44.5 42.8 41.2 40.1 39.2 38.1 37.8 37.2 36.5 36.5


1.08351 1.07086 1.05879 1.04753 1.03608 1.02543 1.01525 1.00578 0.99690 0.98838 0.98076 1685.9 1645.8 1610.1 1578.7 1550.5 1526.2 1503.7 1484.4 1469.1 1451.6 1437.6 191.317 108.678 57.659 32.134 18.378 10.799 6.732 4.419 3.014 2.058 1.515

1.07705 1.06404 1.05164 1.03980 1.02842 1.01757 1.00721 0.99761 0.98858 0.97992 0.97216 1661.1 1619.5 1582.5 1550.0 1519.9 1495.1 1471.0 1450.7 1434.7 1415.6 1400.6 102.722 57.820 33.782 20.160 12.279 7.624 5.011 3.439 2.429 1.734 1.310

46.0 42.0 40.4 38.8 38.3 37.0 36.3 35.9 34.8 34.4 34.2

a

Standard uncertainties u are u(T) = 0.01 K, u(p) = 20 Pa, and u(x) = 0.0008, and the combined expanded uncertainties Uc (level of confidence = 0.95, k = 2) are Uc(ρ) = 2·10−4 g·cm−3, Uc(c) = 1.2 m·s−1, Uc(η) = 0.0026 mPa·s, and Uc(σ) = 0.3 mN·m−1.

a


behaviors are found for each amine. Excess molar volume data have been fitted using a Redlich−Kister equation, and the fitting parameters are shown in Table 6. The speed of sound has been determined for mixtures of these three systems (EP + alkanolamines) under the different

experimental conditions (temperature and mixture composition) used in this work. The experimental data (see Tables 3 to 5) show an increase in the value of this property when amine concentration increases in the mixture. The EP + DEA system shows the highest values for speed of sound among these three 655



Article

Table 5. Density ρ, Speed of Sound c, Dynamic Viscosity η, and Surface Tension σ of EP (1) + TEA (2) from T = (293.15 to 323.15) K at p = 105 Paa x1

T/K = 293.15

T/K = 303.15

T/K = 313.15

T/K = 323.15

−3

0.0000 0.1001 0.2000 0.3000 0.4004 0.5001 0.6002 0.7002 0.8000 0.8998 1.0000 0.0000 0.1001 0.2000 0.3000 0.4004 0.5001 0.6002 0.7002 0.8000 0.8998 1.0000

1.12351 1.11250 1.10130 1.08995 1.07759 1.06606 1.05330 1.04032 1.02631 1.01214 0.99791 1626.9 1611.4 1598.1 1585.4 1574.5 1565.5 1555.6 1545.9 1536.1 1525.5 1513.2

0.0000 0.1001 0.2000 0.3000 0.4004 0.5001 0.6002 0.7002 0.8000 0.8998 1.0000

951.791 570.352 312.310 164.252 81.216 41.493 21.517 11.544 6.382 3.627 2.132

0.0000 0.1001 0.2000 0.3000 0.4004 0.5001 0.6002 0.7002 0.8000 0.8998 1.0000

46.3 44.7 43.4 42.0 40.9 40.1 39.2 38.3 37.8 36.9 36.5


1.11234 1.10070 1.08899 1.07698 1.06392 1.05174 1.03843 1.02486 1.01029 0.99557 0.98076 1587.8 1569.8 1555.1 1540.4 1524.8 1512.2 1497.6 1483.1 1468.6 1456.6 1437.6 204.567 132.885 82.056 47.470 28.402 16.843 10.071 6.178 3.794 2.379 1.515

1.10670 1.09474 1.08269 1.07036 1.05700 1.04454 1.03097 1.01711 1.00227 0.98727 0.97216

Figure 1. Influence of mixture composition upon density. ○, EP (1) + MEA (2); ●, EP (1) + DEA (2); □, EP (1) + TEA (2); ■, water (1) + MEA (2).20 T = 303.15 K.

1571.9 1551.9 1534.9 1517.4 1500.3 1485.3 1469.1 1452.3 1435.5 1422.3 1400.6 111.338 75.130 46.568 29.623 18.698 11.730 7.428 4.758 3.060 1.994 1.310

Figure 2. Excess molar volumes corresponding to EP (1) + MEA (2). ○, T = 293.15 K; ●, T = 303.15 K; □, T = 313.15 K; ■, T = 323.15 K.

agreement with the previously one for density and excess molar volume that show a low deviation from ideality in this binary mixture. In relation with the influence of temperature upon speed of sound, an increase in this variable produces a decrease in speed of sound in all cases, but the importance of the influence of temperature over this property decreases when amine substitution increases. The value of the isentropic compressibility (κS) was determined by Laplace equation (eq 4) using density and speed of sound experimental data. The corresponding value for excess isentropic compressibility was calculated using eq 5.15

44.8 43.0 41.6 40.6 39.4 38.3 37.6 36.4 35.8 35.0 34.2

a


κS =

1 ρ ·c 2

κSE = κS − κSid

systems, and on the other hand the blend using TEA generally takes the lowest values. In the last case, for the EP + TEA system a linear trend was observed (see Figure 3), while MEA and DEA mixtures show a similar behavior with a large deviation from ideality. The data corresponding to TEA are in

(4) (5)

where κES is the excess isentropic compressibility, κS is the measured isentropic compressibility, and κSid is the ideal contribution. The ideal isentropic compressibility was calculated by eq 6. 656



Article

Table 6. Fit Parameters Corresponding to the Redlich−Kister Equation for Excess Volume VE from T/K = 293.15 to 323.15 T/K = 293.15

parameter A0 A1 A2 A3 σ/cm3·mol−1

0.81 −15.5 33.3 −16.9 0.28

A0 A1 A2 A3 σ/cm3·mol−1

0.74 −0.17 −0.74 1.68 0.06

A0 A1 A2 A3 σ/cm3·mol−1

0.075 −1.85 3.23 −1.42 0.02

T/K = 303.15 EP (1) + MEA (2) 0.66 −15.2 33.9 −17.5 0.29 EP (1) + DEA (2) 1.38 −3.40 4.55 −1.05 0.06 EP (1) + TEA (2) −0.190 −0.257 0.560 −0.059 0.02

T/K = 313.15

T/K = 323.15

1.70 −19.9 41.1 −20.9 0.30

1.27 −17.7 38.3 −19.7 0.30

2.25 −8.82 14.4 −6.41 0.07

1.55 −4.64 7.90 −3.35 0.06

−0.318 0.351 −0.279 0.360 0.02

−0.498 1.13 −1.27 0.769 0.02

agreement with the previous data (sign and magnitude) obtained for molar excess volume. In relation with the dynamic viscosity data corresponding to amide + alkanolamine systems, the viscosity was determined using density and kinematic viscosity data (eq 2). Figure 4

Figure 3. Speed of sound for binary mixtures of N-ethyl-2-pyrrolidone. ○, EP (1) + MEA (2); ●, EP (1) + DEA (2); □, EP (1) + TEA (2). T = 313.15 K.

κSid =

2

⎡

i=1

⎢⎣

∑ ϕi ·⎢κSi + T ·Vi ·

αi2 ⎤ ⎥ Cpi ⎥⎦

⎡ T ·(∑2 x ·V ) ·(∑2 ϕ ·α )2 ⎤ i=1 i i i=1 i i ⎥ −⎢ 2 ⎢⎣ ⎥⎦ (∑i = 1 xi·Cpi)

Figure 4. Viscosity of binary mixtures of N-ethyl-2-pyrrolidone. ○, EP (1) + MEA (2); □, EP (1) + DEA (2); △, EP (1) + TEA (2); ●, water (1) + MEA (2);17 ■, water (1) + DEA (2);16 ▲, water (1) + TEA (2);17 +, EP (1) + water (2).23 T = 313.15 K. Solid lines correspond to the Grunberg−Nissan model.

(6)

where ϕi is the ideal state volume fraction (calculated using eq 7), αi is the isobaric thermal expansion coefficient, Cpi is the molar heat capacity, T is the temperature, xi is the mole fraction, and Vi is the molar volume. Values corresponding to molar heat capacity for pure substances are needed in eq 6, and they were obtained from literature.21,22

ϕi =

xi·Vi 2 (∑i = 1 xi·Vi )

shows the obtained behavior for this physical property and for the different binary mixtures. This figure allows us to analyze the influence of composition and the alkanolamine type upon viscosity. A trend similar to the density was observed: an increase in the substitution degree causes an increase in viscosity in this kind of mixtures. For DEA and TEA mixtures, a higher increase in viscosity is produced with the amine addition than for MEA mixtures. The effect of temperature is very important causing a high decrease in the value of viscosity. The observed behaviors for these systems show several differences in comparison with amine aqueous solutions. For example, the presence of water in EP aqueous solutions causes an increase in viscosity until reach a maximum in the water-rich region.23 For aqueous solutions of MEA, DEA, and TEA the

(7)

Isentropic compressibility and its excess are shown in the Supporting Information (Table S2). Generally the isentropic compressibility data show positive and negative values. This behavior indicates that the interactions between the molecules present in these mixtures are not important. This behavior is in 657



Article

behavior is similar to the systems using EP instead of water: an increase in viscosity with amine concentration, but water + amine mixtures take higher values of viscosity than EP + amine systems with large differences mainly in mixtures with the amine mole fraction higher than 0.2.17,24 On the other hand, for EP + amines systems the highest influence of composition upon viscosity is produced in the amine-rich composition range. The influence of mixture composition upon dynamic viscosity data has been fitted using the Grunberg−Nissan model25 (eq 8). 2

ln η =

∑ xi·ηi + x1·x2·ln G12

(8)

i=1

where η, η1, and η2 are the viscosity of mixture and pure components, respectively. G12 is the fitting parameter. Examples of the behavior of this model are shown in Figure 4 for EP + amine systems. The values calculated for the fitted parameter (G12) and standard deviations are included in Table 7.

Figure 5. Surface tension of binary mixtures of N-ethyl-2-pyrrolidone and alkanolamines. ○, EP (1) + MEA (2); ●, EP (1) + DEA (2); □, EP (1) + TEA (2); ■, water (1) + MEA (2).14 T = 303.15 K. Solid lines correspond to the Connors and Wright equation.

Surface tension experimental data for EP + alcanolamine systems have been fitted employing the Connors and Wright26 equation (see eq 9).

Table 7. Fit Parameters Corresponding to the Grunberg− Nissan Equation for Dynamic Viscosity η from T/K = 293.15 to 323.15 parameter

T/K = 293.15

G12 σ/mPa·s

0.20 0.05

G12 σ/mPa·s

0.39 7.18

G12 σ/mPa·s

1.96 9.76

T/K = 303.15

T/K = 313.15

EP (1) + MEA (2) 0.25 0.10 EP (1) + DEA (2) 0.30 2.87 EP (1) + TEA (2) 1.51 2.88

σred =

T/K = 323.15

0.29 0.06

0.32 0.04

0.27 1.55

0.22 0.14

1.38 1.92

1.18 0.96

⎛ b·x1 ⎞ σ − σ1 = ⎜1 + ⎟·x2 1 − a ·x1 ⎠ σ2 − σ1 ⎝

(9)

where σ, σ1, and σ2 are the surface tension of the mixture and pure compounds, respectively, and x1 and x2 are the mole fractions of pure substances. The values corresponding to fitted parameters and standard deviations are included in Table 8. Table 8. Fit Parameters Corresponding to the Connors− Wright Equation for Surface Tension σ from T/K = 293.15 to 323.15 parameter a b σ/mN·m−1

The last physical property analyzed in this work about the influence of the use of other solvent different than water for alkanolamine solutions was the surface tension. This property has an important effect over different separation operations and chemical processes. A lower surface tension generally causes positive behaviors in mass transfer operations which increases the effectivity of these processes. An example of the experimental results obtained for surface tension is shown in Figure 5. The behavior is similar for all of the experimental systems analyzed in this study. In these systems an increase in surface tension was always observed when alkanolamine concentration increases in the binary mixture. There are no important differences in the magnitude of surface tension between the binary systems analyzed in this study. The MEA and DEA systems have a common behavior such as for speed of sound data, while the TEA system shows a more linear trend. These behaviors are very different than for water + amine systems14,18 because low amine additions caused an important decrease in water surface tension until they reach a relatively constant value in the water-rich region. This behavior is produced by the high amine surface concentration in aqueous systems. For EP + amine systems the variation of surface tension shows a slighter trend than for aqueous solutions. A low surface tension value in this kind of systems can produce favorable effects in several industrial operations.

a b σ/mN·m−1 a b σ/mN·m−1

T/K = 293.15

T/K = 303.15

EP (1) + MEA (2) 0.840 0.764 0.716 0.776 0.08 0.15 EP (1) + DEA (2) 0.619 0.754 0.736 0.619 0.16 0.17 EP (1) + TEA (2) 0.350 0.748 0.474 0.279 0.09 0.09

T/K = 313.15 0.686 0.947 0.28 0.848 0.579 0.21 0.692 0.267 0.10

■

CONCLUSIONS This study has analyzed different physical properties of N-ethyl2-pyrrolidone + alkanolamines (MEA, DEA, and TEA): density, speed of sound, viscosity, and surface tension. The influence of composition and temperature upon each physical property has been carefully studied. In general, an increase in the substitution degree in the nitrogen atom causes an increase in the magnitude of each property. Only for the speed of sound a different behavior was observed. Different derived properties were obtained such as excess molar volume or isentropic compressibility. 658



Article

Methyldiethanolamine) at Temperatures from (293.15 to 323.15) K. J. Chem. Eng. Data 2010, 55, 994−999. (13) Geng, Y.; Chen, S.; Wang, T.; Yu, D.; Peng, C.; Liu, H.; Hu, Y. Density, Viscosity and Electrical Conductivity of 1-Butyl-3-methylimidazolium Hexafluorophosphate + Monoethanolamine and + N,NDimethylethanolamine. J. Mol. Liq. 2008, 143, 100−108. (14) Vázquez, G.; Á lvarez, E.; Navaza, J. M.; Rendo, R.; Romero, E. Surface Tension of Binary Mixtures of Water + Monoethanolamine and Water + 2-Amino-2-methyl-1-propanol and Tertiary Mixtures of These Amines with Water from 25 to 50 °C. J. Chem. Eng. Data 1997, 42, 57−59. (15) Hawrylak, B.; Burke, S. E.; Palepu, R. Partial Molar and Excess Volumes and Adiabatic Compressibilities of Binary Mixtures of Ethanolamines with Water. J. Solution Chem. 2000, 29, 575−594. (16) Teng, T. T.; Maham, Y.; Hepler, L. G.; Mather, A. E. Viscosity of Aqueous Solutions of N-Methyldiethanolamine and of Diethanolamine. J. Chem. Eng. Data 1994, 39, 290−293. (17) Maham, Y.; Liew, C.-N.; Mather, A. E. Viscosities and Excess Properties of Aqueous Solutions of Ethanolamines from 25 to 80 °C. J. Solution Chem. 2002, 31, 743−756. (18) Vázquez, G.; Á lvarez, E.; Rendo, R.; Romero, E.; Navaza, J. M. Surface Tension of Aqueous Solutions of Diethanolamine and Triethanolamine from 25 to 50 °C. J. Chem. Eng. Data 1996, 41, 806−808. (19) Tseng, Y. M.; Thompson, A. R. Densities and Refractive Indices of Aqueous Monoethanolamine, Diethanolamine, Triethanolamine. J. Chem. Eng. Data 1964, 9, 264−267. (20) Lee, M.-J.; Lin, T. K. Density and Viscosity for Monoethanolamine + Water, + Ethanol, and + 2-Propanol. J. Chem. Eng. Data 1995, 40, 336−339. (21) Chiu, L. F.; Liu, H. F.; Li, M.-H. Heat Capacity of Alkanolamines by Differential Scanning Calorimetry. J. Chem. Eng. Data 1999, 44, 631−636. (22) Becker, L.; Gmehling, J. Measurement of Heat Capacities for 12 Organic Substances by Tian-Calvet Calorimetry. J. Chem. Eng. Data 2001, 46, 1638−1642. (23) Blanco, A.; García-Abuín, A.; Gómez-Díaz, D.; Navaza, J. M.; Vidal-Tato, I. Influence of Temperature and Composition upon Density, Viscosity, Speed of Sound, and Refractive Index of Aqueous Solutions of 1-Ethyl-2-pyrrolidinone. J. Chem. Eng. Data 2010, 55, 962−965. (24) Teng, T. T.; Maham, Y.; Hepler, L. G.; Mather, A. E. Viscosity of Aqueous Solutions of N-Methyldiethanolamine and of Diethanolamine. J. Chem. Eng. Data 1994, 39, 290−293. (25) Grunberg, L.; Nissan, A. H. Mixture law for viscosity. Nature 1949, 164, 799−800. (26) Connors, K. A.; Wright, J. L. Dependence of Surface Tension on Composition of Binary Aqueous-Organic Solutions. Anal. Chem. 1989, 61, 194−198.

Important differences in properties such as viscosity and surface tension were obtained comparing alkanolamine aqueous solutions with corresponding ones using N-ethyl-2-pyrrolidone instead of water: a clear decrease in both properties were observed, and this behavior could be interesting in different mass transfer operations because it can increase the mass transfer rate.

■

ASSOCIATED CONTENT

S Supporting Information *

Excess volume and isoentropic compressibility deviation data. This material is available free of charge via the Internet at http://pubs.acs.org.

■

AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Notes

The authors declare no competing financial interest.

■

REFERENCES

(1) Mandal, B. P.; Biswas, A. K.; Bandyopadhyay, S. S. Absorption of Carbon Dioxide into Aqueous Blends of 2-Amino-2-Methyl-1Propanol and Diethanolamine. Chem. Eng. Sci. 2003, 58, 4137−4144. (2) Muhammad, A.; Mutalib, M. I. A.; Wilfred, C. D.; Murugesan, T.; Shafeeq, A. Viscosity, Refractive Index, Surface Tension, and Thermal Decomposition of Aqueous N-Methyldiethanolamine Solutions from (298.15 to 338.15) K. J. Chem. Eng. Data 2008, 53, 2226−2229. (3) Park, J. Y.; Yoon, S. J.; Lee, H.; Yoon, J. H.; Shim, J. G.; Lee, J. K.; Min, B. Y.; Eum, H. M. Density, Viscosity, and Solubility of CO2 in Aqueous Solutions of 2-Amino-2-hydroxymethyl-1,3-propanediol. J. Chem. Eng. Data 2002, 47, 970−973. (4) Rebolledo-Libreros, M. E.; Trejo, A. Density and Viscosity of Aqueous Blends of Three Alkanolamines: N-Methyldiethanolamine, Diethanolamine, and 2-Amino-2-methyl-1-propanol in the Range of (303 to 343) K. J. Chem. Eng. Data 2006, 51, 702−707. (5) Venkat, A.; Kumar, G.; Kundu, M. Density and Surface Tension of Aqueous Solutions of (2-(Methylamino)-ethanol +2-Amino-2methyl-1-propanol) and (2-(Methylamino)-ethanol + N-Methyldiethanolamine) from (298.15 to 323.15) K. J. Chem. Eng. Data 2010, 55, 4580−4585. (6) Schütz, M.; Daun, M.; Weinspach, P.-M.; Krumbeck, M.; Hein, K. R. G. Study on the CO2-Recovery from an ICGCC-Plant. Energy Convers. Manage. 1992, 33, 357−363. (7) Liao, C. H.; Li, M. Kinetics of Absorption of Carbon Dioxide into Aqueous Solutions of Monoethanolamine + N-Methyldiethanolamine. Chem. Eng. Sci. 2002, 57, 4569−4582. (8) Horng, S. Y.; Li, M. Kinetics of Absorption of Carbon Dioxide into Aqueous Solutions of Monoethanolamine + Triethanolamine. Ind. Eng. Chem. Res. 2002, 41, 257−266. (9) Á lvarez, E.; Sanjurjo, B.; Cancela, A.; Navaza, J. M. Mass Transfer and Influence of Physical Properties of Solutions in a Bubble Column. Chem. Eng. Res. Dev. 2000, 78, 889−893. (10) García-Abuín, A.; Gómez-Díaz, D.; La Rubia, M. D.; López, A. B.; Navaza, J. M. Density, Speed of Sound, Refractive Index, Viscosity, Surface Tension, and Excess Volume of N-Methyl-2-pyrrolidone + 1Amino-2-propanol {or Bis(2-hydroxypropyl)amine} from T = (293.15 to 323.15) K. J. Chem. Eng. Data 2011, 56, 2904−2908. (11) Amundsen, T. G.; Øi, L. E.; Eimer, D. A. Density and Viscosity of Monoethanolamine + Water + Carbon Dioxide from (25 to 80) °C. J. Chem. Eng. Data 2009, 54, 3096−3100. (12) Á lvarez, E.; Cerdeira, F.; Gómez-Diaz, D.; Navaza, J. M. Density, Speed of Sound, Isentropic Compressibility, and Excess Volume of (Monoethanolamine + 2-Amino-2-methyl-1-propanol), (Monoethanolamine + Triethanolamine), and (Monoethanolamine + N659


Density, Speed of Sound, Viscosity, Surface Tension, and Excess

Recommend Documents