Density, Speed of Sound, Viscosity and Surface Tension of 3

Article pubs.acs.org/jced

Density, Speed of Sound, Viscosity and Surface Tension of 3‑Dimethylamino-1-propylamine + Water, 3‑Amino-1-propanol + 3‑Dimethylamino-1-propanol, and (3-Amino-1-propanol + 3Dimethylamino-1-propanol) + Water from T = (293.15 to 323.15) K Antonio Blanco, Alicia García-Abuín, Diego Gómez-Díaz,* and José M. Navaza Departamento de Enxeñaría Química, ETSE, Universidade de Santiago de Compostela, Rúa Lope, Gómez de Marzoa s/n, Santiago de Compostela, Galicia E-15786, Spain S Supporting Information *

ABSTRACT: The present research work characterizes aqueous solutions of amines with possible implementation in acidic gases separation processes, regarding different physical properties. Specifically this study compares the behavior of aqueous solutions of a diamine (3-dimethylamino-1-propylamine + water, DMAPA) and ternary mixtures using aqueous amine blends (3-amino-1propanol, AP + 3-dimethylamino-1-propanol, DMAP + water) with the same type and number of amino groups. These experimental data contribute useful information to analyze the most suitable system with respect to the physical properties, to be used in operations controlled by mass transfer. The binary system composed of the two amines used for the tertiary system (3-amino-1-propanol + 3dimethylamino-1-propanol) has also been studied. The studies analyze the influence of mixture composition and temperature upon several properties such as density, speed of sound, dynamic viscosity, and surface tension. On the basis of these studies, some significant differences have been observed that can cause important effects on the behavior of mass transfer-based separation processes.

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efficiency of the operation avoiding the presence of dry zones.6 On the other hand when a bubbling contactor is used, the effect of surface tension upon the size of bubbles that can enhance or reduce the gas−liquid interfacial area. Also this property can cause changes in the phenomena of bubbles rupture and coalescence.7 The solvents proposed in present work are based on the use of 3-amino-1-propanol and similar molecules owing to the suitable behavior previously obtained for carbon dioxide separation taking into account the reaction mechanism.8

INTRODUCTION In the past few years an important number of studies have been focused on the development of new solvents (both physical and chemical) to obtain a more efficient separation of carbon dioxide. The aim of these studies is to increase the overall process rate (faster and more favorable chemical kinetics),1 decrease solvent losses (due to evaporation and degradation), and decrease the energy penalty corresponding to solvent regeneration,2 etc. Some physical properties of solvents used in gas absorption can affect the separation rate and efficiency. Physical properties of aqueous solutions can play an important role in mass transfer operations and more specifically the value of dynamic viscosity and surface tension generally have a high weight on different aspects involved in the behavior of gas−liquid contactors. Dynamic viscosity of solvents can produce important changes in the overall behavior because it increases the resistance at interface and also decreases the molecules diffusivity in the liquid bulk.3−5 This physical property depends on the value of density and kinematic viscosity. Speed of sound data can be used to explain the viscosity behavior on the basis of molecular interactions and to determine changes in solvent concentration with a fast measurement. Surface tension has shown high importance in this type of operation. For instance in a packed column, the influence of this property upon the packing wettability can modify the © 2017 American Chemical Society

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EXPERIMENTAL SECTION Materials. Table 1 shows information on compounds used in the present work. Bidistilled water has been used to prepare aqueous solutions of amines.When the mixture of amines is used in the ternary blend, a molar ratio 3-amino-1-propanol/3dimethylamino-1-propanol (AP/DMAP) = 1 was employed.This ratio was used to maintain the number and type of amino groups. Samples were prepared by mass using an analytical balance (Kern 770-15) with an accuracy of 0.2 mg. Methods. Density and Speed of Sound. The density (ρ) and speed of sound (c) of pure components and the mixtures of

Received: January 16, 2017 Accepted: July 3, 2017 Published: July 13, 2017 2272

DOI: 10.1021/acs.jced.7b00042 J. Chem. Eng. Data 2017, 62, 2272−2279

Journal of Chemical & Engineering Data

Article

supplied by Krüss. This plate was cleaned and flame-dried before each measurement. The accuracy of this instrument is 0.02 mN·m−1. Each surface tension value reported came from an average of five measurements. The samples were thermostated in a closed stirring vessel before the surface tension measurements to avoid evaporation. Table 2 shows a comparison between experimental and literature data for pure components that shows a good agreement and indicates that the experimental procedures are suitable to determine these kinds of properties.

Table 1. Sample Description Table chemical name

CAS number

molecular weight g·mol−1

source

109-55-7

102.18

DMAPb

3179-63-3

103.16

APc

156-87-6

75.11

SigmaAldrich SigmaAldrich SigmaAldrich

DMAPA

a

initial mole fraction purity ≥0.99 ≥0.99 ≥0.99

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a 3-Dimethylamino-1-propylamine. b3-Dimethylamino-1-propanol. c3Amino-1-propanol.

RESULTS AND DISCUSSION As previously commented in the introduction and materials and methods sections, the present work compares the behaviors (regarding physical properties with interest in mass transfer operations) of different solvents (for carbon dioxide separation) with the same type and number of amine groups. One of them uses a diamine and the other one an equimolar mixture of amines (see Table 1). Table 2 shows the experimental data corresponding to pure components with a comparison with literature data in order to check the experimental procedures employed in the present work. A deeper comparison between experimental and literature values for pure components is shown in Supporting Information Figure S1. Table 3 shows experimental data of density, speed of sound, dynamic viscosity, and surface tension corresponding to the system 3dimethylamino-1-propylamine (DMAPA) + water. Table 4 shows the same type of experimental data for the equivalent system using a mixture of amines in aqueous solution: 3-amino1-propanol (AP) + 3-dimethylamino-1-propanol (DMAP) + water. The binary mixture of amino-1-propanol (AP) + 3dimethylamino-1-propanol (DMAP) was also studied, and the experimental data are shown in Table 5. Figure 1 shows the behavior for the system DMAPA + water in relation with density and speed of sound. The experimental data corresponding to density show a decrease in the value of this property with diamine concentration. This decrease is attenuated in the diamine-rich zone. A comparison with literature data corresponding to the density of diamine + water system7 is included in Figure 1. On the other hand a similar behavior was observed for the speed of sound (a decrease in its value with diamine concentration) in the main part of the composition range. At a DMAPA low concentration region, the behavior was the opposite: an abrupt increase in the speed of sound until a maximum is reached. This type of

different compounds were measured with an Anton Paar DSA 5000 vibrating tube densimeter and sound analyzer. The transducer emits sound waves at a frequency of 3 MHz. The adjustment of DSA 5000 was performed with air and bidistilled water using the supplier instructions. The instrument accuracies are 5 × 10−6 g·cm−3 and 0.5 m·s−1 for density and speed of sound, respectively. Viscosity. The kinematic viscosity (ν) was determined from the transit time of the liquid meniscus through capillary Ubbelohde viscometers supplied by Schott. In this work capillaries I, Ic, and II were used connected to a Schott-Geräte AVS 350 Ubbelohde viscometer. Equation 1 was employed to calculate the viscosity from the transit time, v = 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 and automatic (optical sensors) stopwatch with a resolution of 0.01 s was used to measure efflux times. In the measurements, a Schott-Geräte AVS 350 Ubbelohde viscometer was used. The accuracy of this equipment is 0.01%. Five measures were used to determine the average value. 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. η = vρ (2) Surface Tension. The surface tension (σ) was determined by employing a Krüss K-11 tensiometer using the Wilhelmy plate method. The plate employed was a commercial platinum plate

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

exp

lit.

DMAPA ρ/g·cm−3 c/m·s−1 η/mPa·s σ/mN·m−1

0.81287 1.0499

0.8802510

0.812784 1336.31 0.9823 27.03

5.83910 29.0110

0.983586 1712.28 30.5037 43.84

0.9970514 1496.715 0.89014 72.0116

AP ρ/g·cm−3 c/m·s−1 η/mPa·s σ/mN·m−1

0.983611 30.433812 43.913

exp DMAP 0.880817 1377.94 5.9824 29.68 Water 0.997074 1496.76 0.8908 72.08

a

Standard uncertainties u are u(T) = 0.01 K, u(p) = 2 kPa, u(x) = 0.0007, and the combined expanded uncertainties Ur (level of confidence = 0.95, k = 2) are Ur(ρ) = 0.001, Ur(c) = 0.003, Ur(η) = 0.05, and Ur(σ) = 0.04. 2273



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

T/K 293.15

0.0000 0.0200 0.0402 0.0600 0.0802 0.1000 0.1195 0.1400 0.1603 0.1998 0.2998 0.4004 0.5003 0.5989 0.6992 0.8005 0.8999 1.0000

0.998210 0.990857 0.985645 0.979538 0.975159 0.970025 0.964475 0.958174 0.951769 0.939214 0.913011 0.891156 0.869895 0.855405 0.842611 0.831115 0.822640 0.817180

0.0000 0.0200 0.0402 0.0600 0.0802 0.1000 0.1195 0.1400 0.1603 0.1998 0.2998 0.4004 0.5003 0.5989

1482.68 1588.70 1672.38 1724.15 1745.68 1747.72 1738.64 1724.38 1708.86 1666.73 1595.53 1535.45 1478.24 1441.72

T/K 303.15 ρ/g·cm−3 0.995897 0.985689 0.979029 0.973631 0.968159 0.962381 0.956449 0.949940 0.943437 0.930694 0.902270 0.882276 0.861305 0.846326 0.833912 0.821995 0.813890 0.808382 c/m·s−1 1509.36 1598.08 1665.19 1704.38 1718.86 1718.04 1708.23 1693.41 1676.82 1632.75 1557.22 1498.17 1441.15 1401.83

T/K 313.15

x1

T/K 323.15

0.992287 0.981536 0.973801 0.967317 0.960972 0.954586 0.948304 0.941578 0.934947 0.921694 0.894350 0.873276 0.852564 0.837326 0.825096 0.812995 0.805127 0.799461

0.988105 0.976650 0.968014 0.960625 0.953528 0.944640 0.940010 0.933066 0.926295 0.913335 0.884953 0.864635 0.843691 0.828487 0.816182 0.804035 0.796210 0.790494

1529.07 1603.80 1655.54 1683.85 1692.33 1688.48 1677.35 1661.71 1643.98 1599.65 1518.91 1461.09 1402.84 1361.95

1541.54 1603.03 1642.97 1662.61 1665.31 1658.64 1645.47 1628.79 1609.97 1566.60 1480.94 1424.32 1364.87 1322.81

T/K 293.15

0.6992 0.8005 0.8999 1.0000

1413.97 1388.83 1371.87 1358.17

0.0000 0.1000 0.1998 0.2998 0.4004 0.5003 0.5989 0.6992 0.8005 0.8999 1.0000

0.9933 8.1055 13.6167 11.4866 7.4367 4.6609 3.1676 2.2245 1.6905 1.3269 1.0786

0.0000 0.1000 0.1998 0.2998 0.4004 0.5003 0.5989 0.6992 0.8005 0.8999 1.0000

72.62 42.52 36.08 32.40 31.09 29.31 28.88 28.15 27.66 27.46 27.34

T/K 303.15 c/m·s−1 1375.10 1350.87 1330.69 1314.63 η/mPa·s 0.7974 5.0843 8.0935 7.0485 4.8402 3.2221 2.2495 1.6995 1.2938 1.0703 0.8997 σ/mN·m−1 71.08 40.78 34.88 31.65 30.25 29.04 28.27 27.41 27.19 27.13 26.69

T/K 313.15

T/K 323.15

1335.21 1309.10 1289.51 1271.09

1295.65 1269.74 1248.80 1229.54

0.6535 3.4212 5.3292 4.5862 3.2957 2.3386 1.7810 1.3334 1.0463 0.8872 0.7611

0.5465 2.3616 3.6049 3.1416 2.3587 1.7591 1.3629 1.0757 0.8667 0.7500 0.6553

69.22 39.22 33.60 30.49 29.22 28.21 27.39 26.42 26.40 26.33 26.02

67.67 37.52 32.37 29.62 28.36 27.75 26.74 26.18 25.90 25.59 25.36

a Standard uncertainties u are u(T) = 0.01 K, u(p) = 2 kPa, u(x) = 0.0007, and the combined expanded uncertainties Ur (level of confidence = 0.95, k = 2) are Ur(ρ) = 0.001, Ur(c) = 0.003, Ur(η) = 0.05, and Ur(σ) = 0.04.

Figure 2 also shows the behavior of a binary mixture (AP +DMAP) and the ternary mixture (AP + DMAP + water) that reaches significantly higher values than aqueous solutions of DMAPA, maintaining the amine groups concentration. Density experimental values were used to calculate the molar excess volume for the different mixtures employed in the present work. Figure 3 shows that all mixtures (DMAPA+water, AP+DMAP, AP+DMAP+water) take negative values that indicate an increase in packing effects in the mixture in comparison with pure components. The more negative values are obtained for the DMAPA+water mixture, while the binary mixture of amines (AP+DMAP) shows values near to zero. The presence of water in the mixture with AP and DMAP enhances the packing effect. The minimum in the value of molar excess volume is reached at a composition near to 0.5 of mole fraction. This behavior is in agreement with a previous study using MAPA aqueous solutions17 that conclude a higher importance of amino groups than hydroxyl ones.These data, corresponding to binary mixtures, have been fitted using a Redlich−Kister type eq (eq 3) and the fitting parameters are included in Table 6. Low values of standard deviation (δ) for excess volume fittings were obtained.

behavior has been observed for other amine + water systems with an increase in the value of speed of sound with concentration in diluted mixtures. With respect to the influence of temperature upon these properties, the same effect has been observed: a decrease in the experimental value of density and speed of sound when this variable was increased showing a linear trend. In the same way that composition influences the speed of sound, the effect of temperature upon this property has a complex behavior: at low amine concentration, an increase in temperature causes also an increase in the speed of sound. But low additions of amine can produce a change in this behavior observing the opposite influence of temperature (a decrease in speed of sound with temperature). This change in the influence of temperature upon speed of sound is due to the formation of a temperatureresistant structure (such as clathrates) due to the interactions between amine and water molecules. Another comparison has been performed using other diamine with only one methyl group in the nitrogen atom (3-methylamino-1-propylamine, MAPA).16 Figure 2 shows the influence of composition and the type of diamine upon the value of density. The presence of another methyl group (DMAPA) causes a decrease in the value of density in comparison with MAPA and AP + DMAP aqueous solutions. 2274



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Table 4. Density ρ, Speed of Sound c, Dynamic Viscosity η, and Surface Tension σ of (AP+DMAP) (1) + water (2) from T = (293.15 to 323.15) K at p = 105 Paa x1

T/K 293.15

0.0000 0.0249 0.0500 0.0747 0.1000 0.1250 0.1503 0.1747 0.1998 0.2232 0.2499 0.2761 0.2997 0.4008 0.5024 0.6004 0.7021 0.7992 0.9007 1.0000

0.998210 0.995524 0.995322 0.995119 0.995055 0.994363 0.993145 0.991022 0.988908 0.987396 0.984774 0.981999 0.979540 0.969549 0.959544 0.951830 0.944113 0.938393 0.932668 0.927491

0.0000 0.0249 0.0500 0.0747 0.1000 0.1250 0.1503 0.1747 0.1998 0.2232 0.2499 0.2761 0.2997 0.4008

1482.68 1571.33 1644.36 1694.72 1727.28 1745.22 1753.33 1752.59 1750.84 1742.09 1731.79 1722.21 1713.67 1673.20

T/K 303.15 ρ/g·cm−3 0.995897 0.992366 0.991240 0.990114 0.989209 0.987869 0.986101 0.983737 0.981430 0.979701 0.977033 0.973992 0.971630 0.961614 0.951593 0.943915 0.936238 0.930482 0.924729 0.919507 c/m·s−1 1509.36 1583.76 1644.55 1683.68 1708.37 1721.68 1727.32 1724.60 1721.94 1712.41 1701.37 1690.30 1681.68 1642.37

T/K 313.15

x1

T/K 323.15

0.992287 0.988406 0.986494 0.984581 0.982906 0.981072 0.978871 0.976257 0.973899 0.971864 0.969130 0.965901 0.963638 0.953606 0.943594 0.935932 0.928271 0.922510 0.916753 0.911489

0.988105 0.983752 0.981143 0.978533 0.976294 0.973972 0.971516 0.968568 0.965910 0.963503 0.961053 0.957789 0.955530 0.945552 0.935494 0.927850 0.920182 0.914440 0.908680 0.903478

1529.07 1591.46 1641.38 1670.57 1688.46 1697.59 1700.40 1695.96 1692.34 1681.97 1670.12 1659.61 1649.10 1608.34

1541.54 1594.61 1634.89 1655.38 1667.40 1672.63 1672.35 1666.53 1661.59 1650.02 1637.89 1626.10 1615.19 1575.79

0.5024 0.6004 0.7021 0.7992 0.9007 1.0000

1637.65 1605.32 1580.61 1557.64 1541.98 1527.08

0.0000 0.1000 0.1998 0.2997 0.4008 0.5024 0.6004 0.7021 0.7992 0.9007 1.0000

0.9933 5.5851 15.0930 25.1281 30.8229 32.9272 31.4342 27.7981 24.3447 21.3590 18.4856

0.0000 0.1000 0.1998 0.2997 0.4008 0.5024 0.6004 0.7021 0.7992 0.9007 1.0000

72.62 43.46 39.92 38.24 36.78 35.55 34.57 33.92 33.54 33.17 33.15

T/K 303.15 c/m·s−1 1603.66 1574.50 1546.29 1525.33 1506.37 1490.92 η/mPa·s 0.7974 3.7594 9.0503 14.7134 18.0149 19.1689 18.6499 16.7400 14.9100 13.1931 11.7263 σ/mN·m−1 71.08 42.66 38.84 37.10 35.87 34.73 33.88 33.21 32.89 32.60 32.42

T/K 313.15

T/K 323.15

1569.57 1541.01 1511.30 1489.99 1470.68 1455.14

1535.19 1505.70 1476.16 1454.65 1435.14 1419.09

0.6535 2.5501 5.6072 9.0755 11.3250 11.7683 11.2331 10.5059 9.6744 8.6284 7.8188

0.5465 1.9577 3.0185 4.5435 6.0998 7.6382 7.5314 6.9782 6.4901 5.9076 5.3894

69.22 41.58 37.83 36.11 34.97 33.82 32.87 32.22 32.14 31.75 31.61

67.67 40.54 36.78 35.11 34.04 32.79 32.12 31.37 31.31 31.03 30.77

a

Standard uncertainties u are u(T) = 0.01 K, u(p) = 2 kPa, u(x) = 0.0007, and the combined expanded uncertainties Ur (level of confidence = 0.95, k = 2) are Ur(ρ) = 0.001, Ur(c) = 0.003, Ur(η) = 0.05 and Ur(σ) = 0.04.

j=3

important role on the value of viscosity. Figure 4 also shows that an increase in temperature causes a significant decrease in viscosity with an Arrhenius-type behavior. By analyzing the influence of the type of molecules upon the value of viscosity, it is possible to observe that the ternary system (AP + DMAP + water), with the same type and number of amino groups as DMAPA + water, reaches significantly higher values in the main part of compositions. The overall behavior for the binary system is similar, and a maximum is also reached but with a lower amount of amine (x1 ∼ 0.2). To analyze the influence of temperature upon this physical property, Figure 4 shows experimental data corresponding to different temperatures. The behavior is similar than the previously one commented for the ternary mixture. The dynamic viscosity has been fitted with the Arrhenius−Andrade type equation (eq 4).

V E = x1x 2∑ Aj (1 − 2x 2) j j=0

T/K 293.15

(3)

where x1 and x2 are diamine and water mole fraction respectively and Aj are fitting parameters. Figure 4 shows the influence of mixture composition and temperature upon one of the most important properties (dynamic viscosity) in mass transfer operations such as gas− liquid absorption. The experimental data show different types of behaviors. On one hand the binary mixture of AP + DMAP shows higher values of viscosity for pure components and binary samples in the amines-rich zone, in comparison with the ternary mixture (AP + DMAP + water). The presence of water in the ternary mixture causes an important increase in this property in spite of low water viscosity. This enhancement in viscosity caused by the presence of water reaches values higher than the corresponding ones for the amines binary mixture between 0.2 and 0.7 mole fraction range. Then a maximum value on viscosity is reached at a composition near to x1 ∼ 0.5. This type of behavior is due to the high interaction between unlike molecules that is in agreement with previous data of molar excess volume. On the other hand temperature plays an

η = a eb / T

(4)

where a and b are fitting parameters, and T the sample temperature in Kelvin. The values corresponding to fitting parameters are included in Table 7. 2275



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Table 5. Density ρ, Speed of Sound c, Dynamic Viscosity ηand Surface Tension σ, of AP (1) + DMAP (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

0.868727 0.876168 0.884096 0.892574 0.901767 0.911468 0.921952 0.933103 0.945178 0.958052 0.971533

0.860616 0.868207 0.876096 0.884638 0.893767 0.903541 0.913952 0.925137 0.937209 0.949941 0.963427

1319.46 1344.03 1365.49 1393.53 1422.36 1455.14 1491.39 1529.46 1572.77 1618.09 1667.47

1283.06 1307.81 1329.59 1357.49 1386.53 1419.09 1455.61 1493.23 1536.99 1581.95 1631.54

4.0066 4.3495 5.0989 5.8378 6.6284 7.8188 8.7822 9.9076 11.6238 13.2154 15.2670

3.0819 3.2297 3.7198 4.2060 4.6676 5.3894 6.0343 6.7786 7.8621 8.8895 10.2196

28.48 28.41 28.64 29.70 30.47 31.49 32.62 34.18 35.74 37.67 40.52

27.60 27.71 28.08 28.87 29.66 30.78 31.81 33.27 34.82 36.24 38.17

−3

0.0000 0.1000 0.1998 0.2997 0.4008 0.5024 0.6004 0.7021 0.7992 0.9007 1.0000

0.884722 0.892187 0.900106 0.908514 0.917767 0.927478 0.937952 0.949074 0.961168 0.974136 0.987618

0.0000 0.1000 0.1998 0.2997 0.4008 0.5024 0.6004 0.7021 0.7992 0.9007 1.0000

1393.58 1417.54 1438.49 1466.03 1494.60 1527.08 1563.11 1601.56 1644.21 1689.04 1728.72

0.0000 0.1000 0.1998 0.2997 0.4008 0.5024 0.6004 0.7021 0.7992 0.9007 1.0000

7.4202 8.8827 10.6084 12.7100 15.0971 18.4856 21.4086 24.6723 29.6290 34.6588 40.4228

0.0000 0.1000 0.1998 0.2997 0.4008 0.5024 0.6004 0.7021 0.7992 0.9007 1.0000

30.03 29.90 30.37 31.39 32.22 33.07 34.33 35.81 38.17 41.04 44.92

ρ/g·cm 0.876762 0.884204 0.892096 0.900589 0.909767 0.919518 0.929952 0.941043 0.953124 0.966117 0.979596 c/m·s−1 1356.53 1380.99 1401.95 1429.74 1458.44 1490.92 1527.25 1565.70 1608.57 1654.27 1697.18 η/mPa·s 5.2281 6.0621 7.0397 8.3218 9.8236 11.7263 13.4778 15.3634 18.0948 20.6363 23.8696 σ/mN·s−1 29.28 29.22 29.56 30.67 31.40 32.37 33.52 35.14 37.08 39.57 42.71

Figure 1. Influence of composition and temperature upon density and speed of sound using DMAPA (1) + water (2). Density: ×, T = 293.15 K;7 ○, T = 293.15 K; ●, T = 323.15 K. Speed of sound: □, T = 293.15 K; ■, T = 323.15 K.

Figure 2. Influence of composition and type of components upon density: ○, MAPA (1) + water (2);16 ●, DMAPA (1) + water (2); □, (AP + DMAP) (1) + water (2); ■, AP (1) + DMAP (2). T = 293.15 K.

a

Standard uncertainties u are u(T) = 0.01 K, u(p) = 2 kPa, u(x) = 0.0007, and the combined expanded uncertainties Ur (level of confidence = 0.95, k = 2) are Ur(ρ) = 0.001, Ur(c) = 0.003, Ur(η) = 0.05, and Ur(σ) = 0.04.

The experimental data corresponding to dynamic viscosity was employed to calculate the viscosity deviation regarding the ideal behavior using eq 5, and the obtained behavior is shown in Figure 5. It is possible to observe the different behavior between aqueous solutions in comparison with the system in

Figure 3. Effect of composition upon molar excess volume. ○, DMAPA (1) + water (2); ●, (AP + DMAP) (1) + water (2); □, AP (1) + DMAP (2). Solid lines correspond to Redlich−Kister equation. T = 293.15 K. 2276



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

parameter

T/K = 303.15

T/K = 313.15

DMAPA + Water −10.29 −10.18 −10.26 −6.98 −6.59 −6.69 −0.308 0.123 0.367 −0.832 −1.28 −0.782 0.04 0.05 0.04 AP + DMAP −0.868 −0.887 −0.933 0.349 0.254 0.338 −0.166 −0.131 −0.215 0.015 0.341 0.154 0.01 0.01 0.01 (AP + DMAP) + Water −5.11 −4.99 −4.92 −2.86 −2.52 −2.31 −0.596 −0.423 −0.416 2.06 1.78 1.69 0.02 0.02 0.01

A0 A1 A2 A3 δ/cm3·mol−1 A0 A1 A2 A3 δ/cm3·mol−1 A0 A1 A2 A3 δ/cm3·mol−1

Table 7. Fit Parameters Corresponding to Arrhenius− Andrade Equation for Dynamic Viscosity η from T/K = 293.15 to 323.15 x1

T/K = 323.15

0.0000 0.1000 0.1998 0.2998 0.4004 0.5003 0.5989 0.6992 0.8005 0.8999 1.0000

−10.36 −6.63 0.694 −0.547 0.05 −1.02 0.374 −0.258 −0.108 0.03

0.0000 0.1000 0.1998 0.2997 0.4008 0.5024 0.6004 0.7021 0.7992 0.9007 1.0000

−4.85 −2.03 −0.206 1.28 0.01

0.0000 0.1000 0.1998 0.2997 0.4008 0.5024 0.6004 0.7021 0.7992 0.9007 1.0000

a·10−3/mPa·s

b/K

DMAPA + Water 1.58 1887.9 0.01 3883.4 0.01 4178.1 0.01 4095.7 0.03 3631.0 0.13 3076.1 0.41 2621.1 0.88 2296.5 1.28 2103.2 2.84 1800.7 4.98 1575.7 AP + DMAPA 0.61 2752.9 0.16 3192.9 0.14 3287.6 0.09 3482.4 0.05 3711.2 0.03 3889.5 0.02 4007.4 0.02 4090.3 0.02 4193.3 0.01 4293.9 0.01 4336.3 AP + DMAPA + Water 1.58 1887.9 0.06 3352.9 0.00 5017.9 0.00 5305.4 0.00 5035.6 0.00 4618.4 0.01 4545.5 0.01 4372.7 0.02 4169.9 0.02 4058.6 0.03 3889.5

δ/mPa·s 0.003 0.067 0.188 0.098 0.053 0.035 0.045 0.009 0.017 0.006 0.002 0.088 0.064 0.121 0.118 0.064 0.096 0.098 0.130 0.201 0.359 0.450 0.003 0.071 0.343 0.717 0.573 0.219 0.237 0.148 0.147 0.163 0.096

Figure 4. Influence of composition, temperature, and mixture type upon dynamic viscosity: AP (1) + DMAP (2): △, T = 293.15 K. (AP + DMAP) (1) + water (2): □, T = 293.15 K; ■, T = 323.15 K. DMAPA (1) + water (2): ○, T = 293.15 K; ●, T = 323.15 K.

absence of water (AP + DMAP). In the last system negative deviations are observed. With respect to aqueous solutions, a similar behavior as that previously discussed in Figure 4 is observed. Higher deviations were observed for the tertiary system in agreement with the magnitude of viscosity. 2

Δη = η −

∑ xiηi i=1

(5)

Surface tension tends to affect upon the wettability of packing and the bubbles characteristics in gas−liquid reactors/ contactors. The observed behaviors (see Figure 6) corresponding to aqueous systems (DMAPA + water and AP + DMAP + water) are similar and they consist in an abrupt decrease of surface tension at low amines concentration, due to molecules accumulation at the gas−liquid interface.18,19 When the solute concentration increases in the mixture, the decrease is slight until a relatively constant value is reached. Aqueous solutions of

Figure 5. Influence of composition upon viscosity deviations, T = 293.15 K: ○, DMAPA (1) + water (2); □, (AP + DMAP) (1) + water (2); △, AP (1) + DMAP (2).

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Figure 6. Influence of composition upon surface tension: ○, DMAPA (1) + water (2); ●, (AP + DMAP) (1) + water (2); □, AP (1) + DMAP (2). T = 293.15 K. Solid lines correspond to Connors model.

Figure 7. Effect of temperature upon surface tension. DMAPA (1) + water (2) system: ●, x1 = 0.1; ■, x1 = 0.2998; ▲, x1 = 0.5003; ◆, x1 = 0.8999. (AP + DMAP) (1) + water (2): ○, x1 = 0.1; □, x1 = 0.2997; △, x1 = 0.5024; ◇, x1 = 0.9007.

diamine (DMAPA) reach lower values of surface tension than the ternary mixture. This behavior makes the solvent (DMAPA + water) suitable to increase the gas−liquid interfacial area because a low surface tension helps to decrease the size of the bubbles.20 This fact decreases the size and increases the efficiency of bubbling contactors. Figure 6 also shows the behavior corresponding to the binary mixture of amines (AP + DMAP) in the absence of water that shows slight changes with composition, increasing the surface tension value with the concentration of AP in the blend. The influence of mixture composition upon surface tension has been fitted with the Connors model (see eq 6) taking into account the suitable behavior previously shown for other amine solvents.21,22 ⎛ d·x2 ⎞ σ2 − σ = ⎜1 + ⎟x1 1 − cx 2 ⎠ σ2 − σ1 ⎝

solutions. On one hand a linear trend regarding the influence of temperature was observed in all cases, with a decrease in the value of surface tension with temperature. On the other hand with independence of the temperature, the ternary system (AP + DMAP + water) take higher values of surface tension than the diamine aqueous solutions (DMAPA + water).

■

CONCLUSIONS The present work analyzes several physical properties (density, speed of sound, dynamic viscosity, and surface tension) of two solvents with the same number and type of amino groups (3dimethylamino-1-propanol + water and 3-amino-1-propanol +3-dimethylpropylamine + water) with possible use for carbon dioxide and other acidic gases separation by physical or chemical absorption. These physical properties contribute suitable information about the behavior upon mass transfer rate in this type of operations. In general diamine aqueous solutions showed better characteristics because a lower viscosity in the main part of composition range, and low surface tension tends to enhance the mass transfer rate. Molar excess volume always shows contractive behaviors for all the systems analyzed in the present work. On the other hand temperature-resistant structures were observed in the low concentration aqueous solutions for both types of solvents by using the speed of sound experimental data.

(6)

where c and d are adjustable parameters related to partition coefficient and reduced surface tension. The fitting parameters are included in Table 8. The behavior of this model shows a suitable behavior in Figure 6. In relation with the influence of temperature upon the value of surface tension for the analyzed systems, Figure 7 shows the experimental data corresponding to some blends in aqueous

■

Table 8. Fit Parameters Corresponding to Connors Equation for Surface Tension σ from T/K = 293.15 to 323.15 parameter c d δ/mN·m−1 c d δ/mN·m−1 c d δ/mN·m−1

T/K = 293.15

T/K = 303.15

T/K = 313.15

DMAPA + Water 0.942 0.949 0.951 0.949 0.940 0.947 0.2 0.2 0.2 AP + DMAP −1.377 −0.768 −0.335 −2.024 −1.549 −1.241 0.2 0.2 0.2 (AP + DMAP) + Water 0.969 0.967 0.967 0.895 0.903 0.908 0.4 0.3 0.3

ASSOCIATED CONTENT

* Supporting Information

T/K = 323.15

S

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.jced.7b00042. Comparison between experimental and literature data of pure components use in present work (PDF)

0.958 0.938 0.1

■

0.205 −0.751 0.1

AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. ORCID

Diego Gómez-Díaz: 0000-0002-3271-1638

0.967 0.912 0.3

Notes

The authors declare no competing financial interest. 2278



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Article

Blended Amines and Systems with Nonionic Surfactants. Fluid Phase Equilib. 2001, 185, 165−175. (19) Blanco, A.; García-Abuín, A.; Gómez-Díaz, D.; Navaza, J. M. Surface Tension and Refractive Index of Benzylamine and 1,2Diaminopropane Aqueous Solutions from T = (283.15 to 323.15) K. J. Chem. Eng. Data 2012, 57, 2437−2441. (20) Loubiere, K.; Hébrard, G. Influence of Liquid Surface Tension (Surfactants) on Bubble Formation at Rigid and Flexible Orifices. Chem. Eng. Process. 2004, 43, 1361−1369. (21) Connors, K. A.; Wright, J. L. Dependence of Surface Tension on Composition of Binary Aqueous-Organic Solutions. Anal. Chem. 1989, 61, 194−198. (22) Romero, C. M.; Páez, M. S.; Miranda, J. A.; Hernández, D. J.; Oviedo, L. E. Effect of Temperature on the Surface Tension of Diluted Aqueous Solutions of 1,2- hexanediol, 1,5-hexanediol, 1,6-hexanediol and 2,5-hexanediol. Fluid Phase Equilib. 2007, 258, 67−72.

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Density, Speed of Sound, Viscosity and Surface Tension of 3

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