Article pubs.acs.org/jced
Densities of Aqueous 2‑Dimethylaminoethanol Solutions at Temperatures of (293.15 to 343.15) K Zulkifli Idris,†,‡ Jia Chen,† and Dag A. Eimer*,†,‡ †
Faculty of Technology, Natural Sciences and Maritime Sciences, University College of Southeast Norway, Kjølnes Ring 56, Porsgrunn 3918, Norway ‡ Tel-Tek, Kjølnes Ring 30, Porsgrunn 3918, Norway ABSTRACT: Densities of aqueous 2-dimethylaminoethanol (2DMAE) solutions with and without carbon dioxide (CO2) were measured over the entire concentration range of 2DMAE and temperatures of (293.15 to 343.15) K. The thermal expansion coefficients and excess molar volumes were determined from the experimental density data. A second-order Redlich−Kister equation satisfactorily correlated the excess molar volumes against 2DMAE mole fractions. The Weiland model was used to correlate the densities of CO2-loaded 2DMAE solutions, and the deviation between experimental and calculated values is discussed.
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INTRODUCTION Carbon dioxide (CO2) and hydrogen sulfide (H2S) are two examples of acidic gases found in gas streams of industrial processes such as in petroleum and chemical production.1 Alkanolamines such as ethanolamine, diethanolamine, and methyl diethanolamine are employed to absorb these acidic gases in postcombustion CO2 capture to help control global warming.2 New and potentially better solvents are also being studied.3,4 The focus of this study is 2-dimethylaminoethanol (2DMAE), and a schematic diagram of this molecule is shown in Figure 1. 2DMAE is a tertiary amine and has been claimed to
relevant alkanolamines that may become suitable candidates for CO2 capture.
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MATERIALS AND METHODS The purities and suppliers of the chemicals used in this work are detailed in Table 1. All chemicals were used as received Table 1. Chemical Descriptions chemical name 2-dimethylaminoethanol (2DMAE) carbon dioxide (CO2) a
Figure 1. Structure of 2-dimethylaminoethanol (2DMAE) studied in this work.
source
purification
≥0.99
Alfa Aesar
no
0.9999
AGA Norge AS
no
As obtained from the supplier.
without any purification. To prepare unloaded aqueous solutions of 2DMAE at different concentrations, the required amounts of degassed Milli-Q water (resistivity 18.2 MΩ·cm) and pure 2DMAE were weighed using an analytical balance (Mettler Toledo XS-403S, standard uncertainty 1 × 10−7 kg). The actual concentrations of 2DMAE solutions were determined using an acid−base titration method, as discussed in our earlier publication.17 The calculated average absolute mass fraction deviation between these two procedures was 0.001, suggesting that our routine sample preparation and titration method work well. The CO2-loaded solutions of 2DMAE were prepared by bubbling CO2 gas through the
show good chemical stability and moderate regeneration energy requirements.5 Physical and chemical data of this amine are required before it can potentially be applied as an absorbent for chemical processes. Studies of properties such as the viscosity and density of 2DMAE were reported earlier by several research groups.6−14 Recently, the densities and viscosities of partially carbonated 2DMAE were published by Zhang et al.12 In this work, we present the densities of unloaded and CO2loaded 2DMAE solutions over a wider range of mass fractions and temperatures than previously reported. We have also utilized the Redlich−Kister and Weiland methods to correlate the experimental data.15,16 This work is a concerted effort in our laboratory to collect thermophysical data of potentially © 2017 American Chemical Society
mole fraction puritya
Received: October 18, 2016 Accepted: February 17, 2017 Published: February 28, 2017 1076
DOI: 10.1021/acs.jced.6b00888 J. Chem. Eng. Data 2017, 62, 1076−1082
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Table 2. Densities ρ, Thermal Expansion Coefficients αp, and Excess Molar Volumes VEm, of Aqueous 2DMAE Solutions at Different Temperatures T, Mass w2, and Mole Fractions x2 of 2DMAEa T/K
ρ/kg·m−3
αp × 10−4/K−1
293.15 298.15 303.15 308.15 313.15 318.15
994.8 993.3 991.6 989.7 987.6 985.3
4.65 4.66 4.67 4.68 4.69 4.70
293.15 298.15 303.15 308.15 313.15 318.15
992.8 990.8 988.6 986.2 983.6 980.9
5.52 5.54 5.56 5.57 5.59 5.60
293.15 298.15 303.15 308.15 313.15 318.15
990.8 988.1 985.2 982.2 979.1 975.8
6.59 6.62 6.64 6.66 6.68 6.71
293.15 298.15 303.15 308.15 313.15 318.15
981.7 978.0 974.2 970.4 966.5 962.6
8.11 8.15 8.18 8.21 8.25 8.28
293.15 298.15 303.15 308.15 313.15 318.15
963.0 959.0 954.9 950.8 946.6 942.4
8.89 8.93 8.97 9.01 9.05 9.09
293.15 298.15 303.15 308.15 313.15 318.15
955.3 951.3 947.2 943.0 938.8 934.5
9.04 9.08 9.13 9.17 9.21 9.25
293.15 298.15 303.15 308.15 313.15 318.15
935.1 931.1 926.9 922.7 918.5 914.2
9.27 9.31 9.35 9.40 9.44 9.49
293.15 298.15 303.15 308.15 313.15 318.15
911.3 906.9 902.2 897.9 893.5 889.1
10.03 10.08 10.13 10.18 10.23 10.29
293.15 298.15 303.15
888.2 884.0 879.8
9.86 9.91 9.96
VEm × 10−6/m3·mol−1 w2 −0.177 −0.177 −0.181 −0.182 −0.182 −0.183 w2 −0.414 −0.411 −0.412 −0.410 −0.408 −0.408 w2 −0.705 −0.695 −0.689 −0.681 −0.673 −0.668 w2 −1.274 −1.254 −1.238 −1.223 −1.208 −1.196 w2 −1.542 −1.523 −1.508 −1.492 −1.476 −1.463 w2 −1.613 −1.597 −1.584 −1.571 −1.556 −1.545 w2 −1.515 −1.508 −1.501 −1.493 −1.485 −1.480 w2 −1.040 −1.012 −0.964 −0.955 −0.943 −0.935 w2 0 0 0
ρ/kg·m−3
αp × 10−4/K−1
VEm × 10−6/m3·mol−1
= 0.10, x2 = 0.022 323.15 328.15 333.15 338.15 343.15
982.9 980.3 977.6 974.7 971.7
4.72 4.73 4.74 4.75 4.76
−0.187 −0.189 −0.188 −0.188 −0.190
= 0.20, x2 = 0.048 323.15 328.15 333.15 338.15 343.15
978.4 975.1 972.0 968.8 965.5
5.62 5.63 5.65 5.67 5.68
−0.416 −0.410 −0.407 −0.407 −0.408
= 0.30, x2 = 0.080 323.15 328.15 333.15 338.15 343.15
972.5 969.1 965.5 961.9 958.2
6.73 6.75 6.77 6.80 6.82
−0.666 −0.663 −0.656 −0.653 −0.651
= 0.49, x2 = 0.160 323.15 328.15 333.15 338.15 343.15
958.6 954.5 950.3 946.1 941.8
8.32 8.35 8.39 8.42 8.46
−1.188 −1.180 −1.169 −1.161 −1.154
= 0.64, x2 = 0.261 323.15 328.15 333.15 338.15 343.15
938.0 933.7 929.2 924.7 920.2
9.13 9.18 9.22 9.26 9.30
−1.452 −1.442 −1.429 −1.419 −1.410
= 0.69, x2 = 0.309 323.15 328.15 333.15 338.15 343.15
930.1 925.7 921.2 916.7 912.1
9.30 9.34 9.38 9.43 9.47
−1.536 −1.527 −1.514 −1.506 −1.497
= 0.79, x2 = 0.437 323.15 328.15 333.15 338.15 343.15
909.8 905.4 900.9 896.4 891.8
9.53 9.58 9.62 9.67 9.72
−1.474 −1.470 −1.462 −1.456 −1.450
= 0.90, x2 = 0.647 323.15 328.15 333.15 338.15 343.15
884.0 879.3 874.8 870.4 865.8
10.34 10.39 10.45 10.50 10.56
−0.877 −0.851 −0.841 −0.846 −0.840
= 1.00, x2 = 1.000 323.15 328.15 333.15
862.4 858.0 853.5
10.16 10.21 10.26
T/K
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Table 2. continued T/K
ρ/kg·m−3
αp × 10−4/K−1
308.15 313.15 318.15
875.5 871.2 866.8
10.01 10.06 10.11
VEm × 10−6/m3·mol−1 0 0 0
T/K
w2 = 1.00, x2 = 1.000 338.15 343.15
ρ/kg·m−3
αp × 10−4/K−1
849.0 844.4
10.32 10.37
VEm × 10−6/m3·mol−1 0 0
a Experiments were performed at atmospheric pressure (P = 1013 mbar). Standard uncertainties u are u(T) = 0.03 K, u(w) = 0.01, and u(P) = 20 mbar. Instrument standard uncertainty = 0.05 kg·m−3. The combined standard uncertainty for density measurements uc(ρ) is 2.61 kg·m−3.
solution. The actual concentrations of CO2 in 2DMAE solutions were determined using a previously published acid− base titration method.18 The densities of unloaded and CO2-loaded 2DMAE solutions were measured using an Anton Paar DMA 4500 density meter. To demonstrate the reliability of the instrument, routine density checks at 293.15 K were performed using degassed Milli-Q water. The density check is accepted if the deviation between experimental and stored reference density data is smaller than 0.1 kg·m−3, as suggested by the manufacturer. In the case when the deviation is larger than the suggested value, air and water adjustments were performed according to the manufacturer’s manual. The density data of water at different temperatures were also determined as a quality check. An average experimental standard deviation of 0.03 kg·m−3 was calculated between our measurements and the available literature data of water from Bettin and Spieweck.19
Figure 2. Comparison of density data for pure 2DMAE among this work (□), Hawrylak et al.6 (▲), Bernal-Garciá et al.7 (●), Zhang et al.8 (△), Chowdhury et al.9 (▼), Pinto et al.10 (◀), Touhara et al.11 (■), Zhang et al.12 (▽), and Maham et al.13 (○). The correlation between densities and temperatures is shown as a dotted line.
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UNCERTAINTY ANALYSIS The measured density values are subject to several uncertainty factors such as temperature fluctuations during the measurement, the error in the mass fraction of 2DMAE, and instrument error. To quantify the uncertainty of our measurements, we have used the procedures published in the Guide to the Expression of Uncertainty in Measurement (GUM).20 The given standard uncertainties for the temperature and density of DMA 4500 are 0.03 K and 0.05 kg·m−3, respectively. In the case of unloaded aqueous 2DMAE solutions, a value of 0.027 kg·m−3·K−1 was calculated for the change in density against temperatures based on our experimental data. For the change in density against mass fractions of 2DMAE, an uncertainty value of 2.61 kg·m−3 was calculated. The combined standard uncertainty can be calculated using a root sum of squares formula of the factors, and the value obtained was 2.61 kg·m−3. The combined standard uncertainty for CO2-loaded aqueous 2DMAE solutions can also be calculated by using the factors discussed above plus the contribution from the error in CO2loading values. A value of 0.01 mol CO2/mol 2DMAE was calculated for the uncertainty in CO2 loading in this work. A value of 4.65 kg·m−3 was calculated as the combined standard uncertainty for CO2-loaded 2DMAE solutions.
N
AAD(kg·m−3) = 1/N ∑ |ρi E − ρiC |
(1)
i=1
where N, ρEi , and ρCi are the number of data and the experimental and reference density values, respectively. The calculated AAD values between our data and the data from the literature are shown in Table 3. Generally, pure 2DMAE Table 3. Comparison of Average Absolute Deviation (AAD) Values for Pure 2DMAE between This Work and Literature Data AAD (kg·m−3) 6
Hawrylak et al. Bernal-Gracia et al.7 Zhang et al.8 Chowdhury et al.9 Pinto et al.10 Touhara et al.11 Zhang et al.12 Maham et al.13
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0.40 0.56 0.89 1.51 7.88 1.82 0.21 1.45
density data from this work agree well with literature data reported earlier: calculated AAD values are less than our calculated combined standard uncertainty value of 2.61 kg·m−3. These low deviations indicate a good representation of pure 2DMAE densities and that our measurements are reliable. However, it should also be pointed out that a larger deviation was calculated with the data from Pinto et al.10 in comparison to other literature data and this work. Figure 3 illustrates density as a function of temperature for aqueous 2DMAE solutions. As expected, at all 2DMAE mass fractions studied in this work, the densities decrease with
RESULTS AND DISCUSSION Densities of aqueous 2DMAE solutions are presented in Table 2. Experiments in this work were performed at temperatures of (293.15 to 343.15) K at different 2DMAE mass fractions of 0.10 to 1. Figure 2 compares the densities of pure 2DMAE from this work and available literature data to validate our measurement systems. We also calculated the average absolute deviations (AADs) between this work and the literature data using eq 1, 1078
DOI: 10.1021/acs.jced.6b00888 J. Chem. Eng. Data 2017, 62, 1076−1082
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in which x, M, and ρ represent the mole fraction, molecular weight, and density, respectively. Subscript integers 1 and 2 refer to water and 2DMAE, respectively. The density of the 2DMAE solution is labeled as ρ without the subscript. Values of the excess molar volume for 2DMAE solutions at different temperatures and compositions are tabulated in Table 2. As can be seen, over the entire mole fraction range of 2DMAE studied in this work, the 2DMAE + water binary system shows negative VEm values corresponding to the contraction of the mixture upon mixing. Similar observations were also reported in other water− alkanolamine systems.21−24 The correlation between VEm and the mole fraction of 2DMAE, x2, can be represented using a Redlich−Kister equation i=n
Figure 3. Density data of aqueous 2DMAE solutions at different mass fractions w2: 0.10 (□), 0.20 (○), 0.30 (△), 0.49 (left-pointing △), 0.64 (☆), 0.69 (■), 0.79 (●), 0.90 (left-pointing ▲), and 1.00 (▲). Correlations between densities and temperatures are shown as dotted gray lines.
VmE = x 2(1 − x 2) ∑ Ai (1 − 2x 2)i
where Ai is the adjusted coefficient with the order varying between 0 and n. Typical plots of VEm against x2 at temperatures of (293.15, 313.15, and 333.15) K are shown in Figure 4. In this
increasing temperature. Furthermore, the relationship between the density of 2DMAE solution, ρ, and temperature, T, is linear and can be correlated using eq 2, ρ(kg·m−3) = AoT + Bi
(5)
i=0
(2)
Values of the gradient, Ao, and y intercept, Bi, of the linear plots together with the statistical R2 coefficients are tabulated in Table 4. By using eq 3, the Ao and Bi parameters can also be Table 4. Parameters Ao and Bi for the Linear Relationship between the Density of Aqueous 2DMAE Solution and Temperature at Different Mass w2 and Mole Fractions x2a w2
x2
A0
Bi
R2
0.10 0.20 0.30 0.49 0.64 0.69 0.79 0.90 1.00
0.022 0.048 0.080 0.160 0.261 0.261 0.437 0.647 1.000
−0.463 −0.549 −0.654 −0.797 −0.857 −0.864 −0.867 −0.914 −0.876
1131.87 1154.95 1183.36 1215.83 1214.56 1209.15 1189.70 1179.48 1145.29
0.9888 0.9936 0.9977 0.9994 0.9996 0.9996 0.9996 0.9998 0.9998
Figure 4. Excess molar volumes of aqueous 2DMAE solutions at temperatures of 293.15 K (□), 313.15 K (left-pointing △), and 333.15 K (◊). Dotted lines represent data from the Redlich−Kister equation.
work, satisfactory results were obtained by fitting eq 5 to a second-order polynomial (n = 2). Table 5 shows the values of the coefficients at the temperatures studied in this work, together with the R2 values of the fitted lines. Comparing the
a
The levels of confidence, R2, of the correlated straight lines are also included.
Table 5. Redlich−Kister Second-Order Parameters Ai at Different Temperatures Ta used to calculate thermal expansion coefficients, αp, for 2DMAE solutions, and these values are shown in Table 2. As evident from the table, the thermal expansion values increase minimally with the increment of temperature and mass fraction of 2DMAE. αp(K−1) =
[−Bi ] [Ao + Bi T ]
(3)
The experimental density data were also used to determine the excess molar volumes, VEm, of aqueous 2DMAE solutions according to eq 4 VmE × 10−6/m 3· mol−1 =
[x1M1 + x 2M 2] [x M ] [x M ] − 1 1 − 2 2 ρ ρ1 ρ2
T/K
A0
A1
A2
R2
293.15 298.15 303.15 308.15 313.15 318.15 323.15 328.15 333.15 338.15 343.15
−5.72 −5.66 −5.57 −5.53 −5.49 −5.46 −5.36 −5.31 −5.27 −5.25 −5.22
−4.39 −4.49 −4.75 −4.71 −4.70 −4.67 −5.03 −5.15 −5.14 −5.04 −5.01
−0.85 −0.56 −0.16 −0.09 0.04 0.10 0.49 0.70 0.78 0.72 0.71
0.9963 0.9967 0.9977 0.9981 0.9983 0.9986 0.9989 0.9989 0.9989 0.9990 0.9990
a
The levels of confidence, R2, of the correlated straight lines are also included.
(4) 1079
DOI: 10.1021/acs.jced.6b00888 J. Chem. Eng. Data 2017, 62, 1076−1082
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Table 6. Density of CO2-Loaded Aqueous 2DMAE Solutions at a 0.30 Mass Fraction of 2DMAE at Different Temperatures, CO2 Loading Values α, and CO2 Mole Fractions x3a α/(mol CO2/mol 2DMAE)
0.10
0.20
0.27
0.40
0.54
x3
0.008
0.016
0.021
0.031
0.041
1051.2 1048.2 1045.0 1041.8 1038.4 1035.0 1031.5 1028.0 1024.3 1020.7 1016.9
1063.7 1060.7 1057.6 1054.4 1051.1 1047.7 1044.3 1040.8 1037.3 1033.7 1030.0
ρ/kg·m−3
T/K 293.15 298.15 303.15 308.15 313.15 318.15 323.15 328.15 333.15 338.15 343.15
1008.4 1005.5 1002.5 999.5 996.2 992.8 989.2 985.8 982.4 977.9 974.0
1023.7 1020.8 1017.7 1014.5 1011.2 1007.6 1003.9 999.9 995.4 991.1 986.4
1029.3 1026.2 1023.1 1019.9 1016.6 1013.1 1009.6 1006.2 1002.5 998.5 993.7
a
Experiments were performed at atmospheric pressure (P = 1013 mbar). Standard uncertainties u are u(T) = 0.03 K, u(α) = 0.01, u(P) = 20 mbar, and u(x3) = 0.002. Instrument standard uncertainty = 0.05 kg·m−3. The combined standard uncertainty for the density measurement uc(ρ) is 4.65 kg· m−3.
The method based on the work of Weiland et al.16 was used to correlate the density of CO2-loaded 2DMAE solutions. According to this method, the density of a solution containing CO2 is given by eq 6,
calculated densities based on the Redlich−Kister method and our experimental densities, an average absolute deviation of 0.54 kg·m−3 is calculated. The low deviation value indicates good representation of the experimental data using the secondorder Redlich−Kister equation. Density measurements for CO2-loaded solutions at 0.30 2DMAE mass fraction were also performed in this work. Experiments were conducted at five different CO2 loadings and at temperatures of (293.15 to 343.15) K. The density data are tabulated in Table 6, and a graphical representation of the density data against temperatures is shown in Figure 5. It can
ρ=
[x1M1 + x 2M 2 + x3M3] V
(6)
where ρ and V represent the density and total molar volume of the solution, and x and M represent the mole fraction and molecular weight of components present in the solution. Integers 1, 2, and 3 designate water, 2DMAE, and CO2, respectively. In the case of an ideal solution, the molar volume can be calculated by the summation of the partial molar volumes multiplied by the mole fraction for each of the components in the solution. Because the CO2-loaded solution is not ideal, additional terms taking into consideration interactions between amine + water V* and amine + CO2 V** are added: V = x1V1 + x 2V2 + x3V3 + x1x 2V * + x 2x3V **
(7)
According to Weiland et al.,16 the molar volume due to the interaction between amine + CO2 is given by eq 8, V ** = c + dx 2
(8)
where c and d are parameters of the linear relationship between V** and x2. The molar volumes of pure water V1 and pure amine V2 were calculated on the basis of the coefficient values from Cheng et al.26 and from the experimental data in this work, respectively. Equations 6−8 can be solved simultaneously, and the values of the fitted coefficients are listed in Table 7. The calculated densities based on this method were also incorporated onto Figure 5 as dotted gray lines. It can be
Figure 5. Experimental density data of CO2-loaded 2DMAE solutions at 0.30 2DMAE mass fraction. Experiments were performed at different CO2 loading values of 0.10 (□), 0.20 (○), 0.27 (△), 0.40 (▽), and 0.54 (◊). The correlated densities based on the Weiland method are shown as dotted gray lines.
be seen that the density decreases with increasing temperature, as expected. Furthermore, the density of CO2-loaded 2DMAE solutions is also higher than the density of unloaded 2DMAE solutions. The density decreases when 2DMAE solutions are exposed to higher temperatures because molecules become more excited, which leads to more space between them. Rearrangements of molecules due to the exothermic reaction between CO2 and 2DMAE molecules may explain the increased density as CO2 loading increases. Similar observations for other amines have also been reported previously.12,25
Table 7. Parameters of the Density Correlation for CO2Loaded Aqueous 2DMAE Solutions parameter
value
c d VCO2
1177.07 −5090.62 −59.83
V* 1080
−9.21 DOI: 10.1021/acs.jced.6b00888 J. Chem. Eng. Data 2017, 62, 1076−1082
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Properties of Amines for Post Combustion Capture of CO2. J. Chem. Thermodyn. 2012, 51, 97−102. (6) Hawrylak, B.; Burke, S.; Palepu, R. Partial Molar and Excess Volumes and Adiabatic Compressibilities of Binary Mixtures of Ethanolamines with Water. J. Solution Chem. 2000, 29, 575−594. (7) Bernal-García, J. M.; Hall, K. R.; Estrada-Baltazar, A.; IglesiasSilva, G. A. Density and viscosity of aqueous solutions of N,Ndimethylethanolamine at p = 0.1 MPa from T = (293.15 to 363.15) K. J. Chem. Thermodyn. 2005, 37, 762−767. (8) Zhang, F.-Q.; Li, H.-P.; Dai, M.; Zhao, J.-P.; Chao, J. P. Volumetric Properties of Binary Mixtures of Water with Ethanolamine Alkyl Derivatives. Thermochim. Acta 1995, 254, 347−357. (9) Chowdhury, F. I.; Khan, M. A. R.; Saleh, M. A.; Akhtar, S. Volumetric Properties of Some Water + Monoalkanolamine Systems Between 303.15 and 323.15 K. J. Mol. Liq. 2013, 182, 7−13. (10) Pinto, D. D. D.; Monteiro, J.; Johnsen, B.; Svendsen, H. F.; Knuutila, H. Density Measurements and Modelling of Loaded and Unloaded Aqueous Solutions of MDEA (N-methyldiethanolamine), DMEA (N,N-dimethylethanolamine), DEEA (diethylethanolamine) and MAPA (N-methyl-1,3-diaminopropane). Int. J. Greenhouse Gas Control 2014, 25, 173−185. (11) Touhara, H.; Okazaki, S.; Okino, F.; Tanaka, H.; Ikari, K.; Nakanishi, K. Thermodynamic Properties of Aqueous Mixtures of Hydrophilic Compounds 2. Aminoethanol and its Methyl Derivatives. J. Chem. Thermodyn. 1982, 14, 145−156. (12) Zhang, J.; Fennell, P. S.; Trusler, J. P. M. Density and Viscosity of Partially Carbonated Aqueous Tertiary Alkanolamine Solutions at Temperatures between (298.15 and 353.15) K. J. Chem. Eng. Data 2015, 60, 2392−2399. (13) Maham, Y.; Teng, T. T.; Hepler, L. G.; Mather, A. E. Volumetric properties of aqueous solutions of monoethanolamine, mono- and dimethylethanolamines at temperatures from 5 to 80 °C I. Thermochim. Acta 2002, 386, 111−118. (14) Collins, C.; Tobin, J.; Shvedov, D.; Palepu, R.; Tremaine, P. R. Thermodynamic properties of aqueous diethanolamine (DEA), N,Ndimethylethanolamine (DMEA), and their chloride salts: apparent molar heat capacities and volumes at temperatures from 283.15 to 328.15 K. Can. J. Chem. 2000, 78, 151−165. (15) Redlich, O.; Kister, A. T. Algebraic Representation of Thermodynamic Properties and the Classification of Solutions. Ind. Eng. Chem. 1948, 40, 345−348. (16) Weiland, R. H.; Dingman, J. C.; Cronin, D. B.; Browning, G. J. Density and Viscosity of Some Partially Carbonated Aqueous Alkanolamine Solutions and Their Blends. J. Chem. Eng. Data 1998, 43, 378−382. (17) Idris, Z.; Ang, L.; Eimer, D. A.; Ying, J. Density Measurements of Unloaded and CO2-Loaded 1-Dimethylamino-2-propanol at Temperatures (298.15 to 353.15) K. J. Chem. Eng. Data 2015, 60, 1419−1425. (18) Han, J. Y.; Jin, J.; Eimer, D. A.; Melaaen, M. C. Density of Water (1) + Monoethanolamine (2) + CO2 (3) from (298.15 to 413.15) K and Surface Tension of Water (1) + Monoethanolamine (2) from (303.15 to 333.15) K. J. Chem. Eng. Data 2012, 57, 1095−1103. (19) Spieweck, F.; Bettin, H. Solid and Liquid Density Determination: Review. Tech. Mess. 1992, 59, 285−292. (20) JCGM Evaluation of Measurement Data - Guide to the Expression of Uncertainty in Measurement. http://www.iso.org/sites/ JCGM/GUM/JCGM100/C045315e-html/C045315e. html?csnumber=50461, accessed Jan 20, 2017. (21) Muhammad, A.; Mutalib, M. I. A.; Murugesan, T.; Shafeeq, A. Density and Excess Properties of Aqueous N-Methyldiethanolamine Solutions from (298.15 to 338.15) K. J. Chem. Eng. Data 2008, 53, 2217−2221. (22) Narayanaswamy, K.; Rayer, A. V.; Kadiwala, S.; Henni, A. Volumetric Properties, Viscosities, Refractive Indices and Surface Tensions for (Dimethylpropanolamine (DMPA) + Water) Mixtures from 298.15 to 343.15 K. Thermochim. Acta 2012, 543, 218−225. (23) Chan, C.; Maham, Y.; Mather, A. E.; Mathonat, C. Densities and volumetric properties of the aqueous solutions of 2-amino-2-methyl-1-
seen that minimal deviations occur between our experimental and calculated data, suggesting that this method is reliable for correlating the densities of CO2-loaded 2DMAE solutions, and an average absolute deviation of 2.11 kg·m−3 was calculated.
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CONCLUSIONS In this work, measurements of the liquid densities of aqueous 2DMAE solutions with and without CO2 from temperatures of (293.15 to 343.15) K were performed at atmospheric pressure. There is a linear dependency between the density of aqueous 2DMAE solutions and temperature for the range of 2DMAE mole fractions studied in this work, as expected. Thermal expansion and excess molar volumes were also determined on the basis of the experimental data. A minimal increase in the thermal expansion values was observed with increased temperature and mole fraction of 2DMAE. At all concentrations studied in this work, negative excess molar volumes corresponding to a contraction in the volumes of solutions were calculated. A second-order Redlich−Kister equation satisfactorily correlated the excess molar volumes and mole fractions of 2DMAE solutions. A small average absolute deviation of 0.54 kg·m−3 was calculated between the experimental and correlated density values. This value is smaller than our combined standard uncertainty of 2.61 kg·m−3. Densities of partially carbonated 2DMAE solutions were also investigated at a 0.30 2DMAE mole fraction. Experiments were performed at five different CO2 concentrations and at temperatures of (293.15 to 343.15) K. The Weiland method was employed to correlate the experimental data, and an average absolute deviation of 2.11 kg·m−3 was calculated. This value is also smaller than our combined standard uncertainty of 4.65 kg·m−3. The reported density data in this work is complementary to the other physical data available for a potentially relevant amine absorbent for CO2-capture-associated processes.
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AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected]. Tel: +47 3557 4000. ORCID
Zulkifli Idris: 0000-0001-7905-9686 Funding
The authors are grateful to The Research Council of Norway through the CLIMIT Program (grant number 199890) for financial support. Notes
The authors declare no competing financial interest.
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