Article pubs.acs.org/jced
Thermodynamic Properties of the Water + 1‑(2-Hydroxylethyl)3-methylimidazolium Chloride System Nan Nie, Danxing Zheng,* Li Dong, and Yun Li College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029, China ABSTRACT: In this paper, the water + 1-(2-hydroxyethyl)-3-methylimidazolium chloride ([HOEtMIM]Cl) binary system was studied as a novel alternative working pair of the absorption heat pump cycle. Thermodynamic properties of the system including vapor pressure, density, and heat capacity were measured in the mole fraction range from 0.0122 to 0.3071 of [HOEtMIM]Cl. The vapor pressures of the binary system were determined by the boiling-point method in the pressure from (2.82 to 102.29) kPa and correlated by the nonrandom two-liquid (NRTL) model. The densities and heat capacities were measured in the temperature range from (298.15 to 323.15) K and (298.15 to 358.15) K, respectively, and correlated by the polynomial equations on temperature and concentration. The average relative deviations (ARDs) between the experimental and the calculated values of vapor pressure, density, and heat capacity are 1.42 %, 0.09 %, and 0.38 %, respectively.
■
INTRODUCTION As the core part of the absorption heat pump cycle, absorption working pairs are improving with the development and progress of the absorption heat pump technology. At present, the H2O + lithium bromide (LiBr) system and ammonia (NH3) + H2O system are major working pairs used in industry. However, both of the working pairs have several disadvantages, such as toxicity and explosibility of the NH3 + H2O system and corrosion and crystallization of the H2O + LiBr system.1 Thus, researchers have focused on the study and exploration of novel working pairs. Ionic liquids (ILs) are a class of melting salts that have many characteristics including nondetectable vapor pressure, thermal stability with water and air, and strong solubility to many substances and have a wide liquid working temperature range,2−4 and so forth. Due to these features mentioned above, working pairs composed of various ILs with NH3,5,6 hydrofluorocarbons (HFCs),7,8 and water have been proposed and investigated. As a potential working pair to put research forward, the safety of ILs has to be considered. However, some ILs could be flammable near the decomposition temperature, and most of the ILs are less toxic than the common organic solvents, for example, methanol, acetone, acetonitrile, and methyl tert-butyl ether (MTBE).9 Thus, thermodynamic properties essential for future applications of IL-containing systems have been reported. In recent years, many scholars have investigated the use of H2O + ILs systems as alternative working pairs for absorption cycles. Yokozeki and Shiflett10,11 have proposed using water and room-temperature ionic liquids (RTILs) as a replacement for the H2O + LiBr system for the absorption heat pump cycles, and the vapor−liquid equilibrium (VLE) data and excess properties of these H2O-ILs systems were successfully correlated and calculated. Zuo et al.12 measured the thermodynamic properties including vapor pressure, density, and heat capacity of H2O + 1-ethyl-3-methylimidazolium ethyl sulfate (EMISE) © 2012 American Chemical Society
system, and these experimental data indicated the feasibility of using the binary system as a working pair for the absorption heat pump cycle. Kim et al.9 conducted comprehensive theoretical work dealing with various mixtures of refrigerants and ILs as working pairs for the absorption refrigeration system. Dong et al.13 and Zhang et al.14 simulated a single-effect absorption cycle using H2O + 1,3-dimethylimidazolium dimethylphosphate ([Dmim]DMP) and H2O + 1-ethyl-3-methylimidazolium dimethylphosphate ([Emim]DMP) system, respectively, on the basis of their measured thermodynamic properties. Wang et al.15 proposed the application of H2O + 1,3-dimethylimidazolium chloride ([Dmim]Cl) system as an alternative working pair for absorption cycle based on the measurement of the VLE data. [Dmim]Cl, as a halide salt, is strongly hygroscopic and miscible with water. The vapor pressure data of five binary systems H2O + [Dmim]Cl, H2O + 1-butyl-3-methylimidazolium bromide ([Bmim]Br),16 H2O + 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF4),16 H2O + 1-(2-hydroxyethyl)-3methylimidazolium tetrafluoroborate ([Hydemim]BF4),16 and H2O + 1,3-dimethylimidazolium tetrafluoroborate ([Dmim]BF4)17 were compared separately. It can be seen that H2O is more strongly affinitive to the IL [Dmim]Cl, which confirms that the hydrophilic property of ILs is stronger with smaller anions.18 Through the comparison of the VLE data of H2O + [Hydemim]BF416 and H2O + 1-ethyl-3-methylimidazolium tetrafluoroborate ([Emim]BF4),19 it is noticed that [Hydemim]BF4 is more hydrophilic due to the effect of hydroxyl. On the basis of above, the IL 1-(2-hydroxyethyl)-3-methylimidazolium chloride ([HOEtMIM]Cl) was chosen as the research object. The aim of this paper is to measure and study the vapor pressure, density, and heat capacity of the binary system H2O + [HOEtMIM]Cl as a novel alternative working pair for the Received: July 16, 2012 Accepted: October 29, 2012 Published: November 5, 2012 3598
dx.doi.org/10.1021/je3007953 | J. Chem. Eng. Data 2012, 57, 3598−3603
Journal of Chemical & Engineering Data
Article
absorption heat pump cycle, in which water acts as refrigerant and IL [HOEtMIM]Cl as absorbent, to establish the thermodynamic data fundamentals for investigating the development potential.
Table 1. Vapor Pressure Comparison between the Experimental and Literature23 for NaCl Solutiona (wNaCl = 0.25)
■
EXPERIMENTAL SECTION Materials. The IL 1-(2-hydroxyethyl)-3-methylimidazolium chloride ([HOEtMIM]Cl, ≥ 99 %) was purchased from Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences. The IL 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF4, ≥ 99 %) was provided by Shanghai Chengjie Chemical Co., Ltd. The sodium chloride (NaCl, ≥ 99.5 %) was supplied by Beijing Chemical Co. The chemicals were further purified at vacuum atmosphere before use. The thermal decomposition temperature of [HOEtMIM]Cl was determined by a thermogravimetric analyzer (TGA4000, Perkin-Elmer Co. Ltd., USA) with an accuracy of temperature ± 1 K, and the decomposition temperature was about 586 K. The pure water was used to prepare the solutions and verify the apparatus. All of the used solutions were obtained by mass using a Mettler Toledo AL 204 balance with an uncertainty of 10−4 g. Vapor-Pressure Measurement. In previous works,15,20 the experimental apparatus and process were described in detail. The vapor pressure of IL is negligable compared with that of water; therefore, the vapor pressures of the H2O + [HOEtMIM]Cl system were determined by the boiling-point method.21,22 The apparatus for the vapor-pressure measurement was supplied by Tokyo Rika Kikai Co. Ltd., and the schematic diagram was shown in Figure 1. The apparatus
a b
T/K
pexp/kPa
plit/kPa
Δb/%
297.19 302.09 314.52 327.43 334.84 344.09 353.95 364.03 372.84 380.48
2.38 3.09 6.13 11.74 16.62 24.97 37.71 56.04 77.56 101.52
2.32 3.09 6.14 11.78 16.69 25.18 38.01 56.42 78.13 102.21
2.75 0.00 0.16 0.30 0.43 0.86 0.81 0.68 0.73 0.67
Standard uncertainties u are u(T) = 0.03 K and u(w) = 0.0001. Δ = 100|pexp − plit|/pexp.
Density Measurement. The densities of the H2O + [HOEtMIM]Cl binary system were measured by a digital vibrating tube densimeter (DMA 4500M, Anton Paar Co. Ltd., Austria) with the precision of density measurement ± 5·10−5 g·cm−3 and temperature ± 0.03 K. The densimeter was calibrated with dry air and bidistilled water at atmospheric pressure. The reliability of the density experiment was confirmed by measuring densities of pure IL [Bmim]BF4 at various temperatures. The results were compared with the literature24 and are listed in Table 2. It can be seen that the Table 2. Density Comparison between the Experimental and the Literature24 Values for [BmimBF4]a T/K
ρexp/g·cm−3
ρlit/g·cm−3
Δb/%
298.15 303.15 308.15 313.15 318.15 323.15
1.19946 1.19587 1.19229 1.18874 1.18521 1.18169
1.2015 1.1984 1.1954 1.1922 1.1890 1.1860
0.17 0.21 0.26 0.29 0.32 0.36
Standard uncertainties u are u(T) = 0.02 K and u(x) = 0.0001. bΔ = 100|ρexp − ρlit|/ρexp.
a
Figure 1. Schematic diagram of experimental apparatus for vapor pressure measurement: 1, U-tube mercury manometer; 2, digital meter; 3, temperature sensor; 4, constant temperature oil bath; 5, magnetic stirrer; 6, refrigerator; 7, buffer flask; 8, pressure control valve; 9, vacuum pump.
ARD is 0.27 % and the maximum relative deviation is 0.36 %, which show good agreement between the experimental and the literature values. Heat Capacity Measurement. The heat capacities of the binary system were measured by a heat flow batch calorimeter (Calvet BT2.15, Setaram Co., France) with Calisto software data collection. The sample solution weighed precisely was placed into a sample cell (12.5 mL). The measurement of the heat capacity included a blank run, a reference run, and a sample run, with the scanning rate set at 0.15 K·min−1 for all runs. A standard sapphire (α-A12O3) with a known heat capacity at the specific temperature was used as the reference substance.25−27 To check the reliability of the measurement in this work, the heat capacity of pure water was measured in the temperature range from (298.15 to 353.15) K. The experimental data were compared with the literature,28 and the results are shown in Table 3. The ARD can be seen to be 0.88 % and the maximum relative deviation 2.05 %.
mainly consisted of an equilibrium vessel (250 mL), a U-tube mercury manometer capable of reading to 1 mm, a constant temperature oil bath, a temperature transmitter with the precision of ± 0.05 K, a refrigerator, a magnetic stirrer, and a set of vacuum system. A sample solution was put into the equilibrium vessel, then evacuated and heated. The condenser was used to provide chilled temperature (270.15 K) to minimize the concentration change of the solution. When the thermal equilibrium was reached, the temperature and pressure of the solution were recorded. To verify the validity of the apparatus used in this work, the vapor pressure of NaCl aqueous solution (0.25 mass fraction of NaCl) was measured and compared with the literature.23 The results are listed in Table 1. The average relative deviation (ARD) for pressure is 0.52 %, and the maximum relative deviation is 2.75 %. 3599
dx.doi.org/10.1021/je3007953 | J. Chem. Eng. Data 2012, 57, 3598−3603
Journal of Chemical & Engineering Data
Article
Table 3. Heat Capacity Comparison between the Experimental and Literature28 Values for Pure Watera
Table 4. Measured Vapor Pressures of the H2O (1) + [HOEtMIM]Cl (2)a Binary System
T/K
Cpexp/J·g−1·K−1
Cplit/J·g−1·K−1
Δb/%
298.15 303.15 308.15 313.15 318.15 323.15 328.15 333.15 338.15 343.15 348.15 353.15
4.101 4.118 4.134 4.147 4.168 4.182 4.194 4.206 4.221 4.237 4.250 4.263
4.185 4.188 4.191 4.193 4.196 4.198 4.201 4.204 4.206 4.209 4.211 4.214
2.05 1.71 1.37 1.11 0.67 0.39 0.17 0.06 0.35 0.67 0.91 1.15
a
Standard uncertainties u are u(T) = 0.01 K and u(x) = 0.0001. b lit exp Δ = 100|Cexp p − Cp |/Cp .
■
RESULTS AND DISCUSSION Vapor Pressure. The vapor pressures of the H2O + [HOEtMIM]Cl binary system were measured in mole fraction of the [HOEtMIM]Cl range from 0.0122 to 0.3071 and experimental pressure range from (2.82 to 102.29) kPa. The measured results are listed in Table 4. There have been many models used to predict the VLE data of binary systems, such as the NRTL (nonrandom two-liquid) model, Wilson model, universal quasichemical (UNIQUAC) model, and universal functional (UNIFAC) model, and so on. In this paper, the vapor pressure of the H2O (1) + [HOEtMIM]Cl (2) system was correlated by the NRTL model. The activity coefficient of solvent i, γi, is shown as follows py φi γi = s i s pi xiφi (1) where p is the vapor pressure of the solution, psi is the saturated vapor pressure of pure component i, which can be calculated using the Antoine equation.29 xi and yi are the mole fraction of component i in the liquid and vapor phases, respectively. ϕi and ϕsi represent the fugacity coefficient of component i in the vapor mixture and saturated state, respectively. For the H2O (1) + [HOEtMIM]Cl (2) binary system, the vapor pressure of IL [HOEtMIM]Cl is neglectable and assumed to be zero, thus y1 = 1. Because the experimental pressures are very low, fugacity coefficients are nearly equal to 1. Therefore, eq 1 can be written as p γ1 = x1p1s (2) The NRTL model for the binary system can be described as follows30,31 ⎤ ⎡ ⎛ ⎞2 G21 G12τ12 ⎥ ln γ1 = x 22⎢τ21⎜ + ⎟ ⎢⎣ ⎝ x1 + x 2G21 ⎠ (x 2 + x1G12)2 ⎥⎦
(3)
G12 = exp( −ατ12)
(4)
τ12 = τ12(0) +
τ12(1) T
G21 = exp( −ατ21) (0) τ21 = τ21 +
(1) τ21 T
T/K
pexp/kPa
301.87 316.31 323.51 332.49 341.57 350.86 359.08 366.14 373.56
3.88 8.39 12.14 18.76 28.30 42.01 58.38 76.71 100.85
301.40 310.59 318.58 326.37 334.14 341.48 349.50 358.32 366.30 375.60
3.62 6.05 9.03 13.26 19.02 26.54 37.28 53.06 72.02 100.80
300.73 309.53 318.19 326.51 335.28 344.10 352.98 361.73 370.39 380.10
2.82 4.82 7.61 11.43 17.07 25.31 36.66 52.01 71.72 101.09
314.82 324.73 334.04 343.27 352.90 361.71 371.12 381.43 391.60
4.13 6.86 10.91 16.37 24.57 34.96 50.03 72.32 102.29
318.57 329.16 336.84 345.67 354.19 362.97 372.87 382.12 390.30 398.32 406.45
3.25 5.52 7.89 11.58 16.46 23.16 33.52 46.75 62.08 80.45 101.80
pcal/kPa x2 = 0.0122 3.97 8.56 12.36 19.03 28.66 42.50 59.06 77.29 101.28 x2 = 0.0453 3.48 5.86 8.97 13.26 19.17 26.68 37.58 53.68 72.87 102.12 x2 = 0.0997 2.78 4.62 7.37 11.23 17.06 25.33 36.84 52.21 72.35 102.21 x2 = 0.2054 3.98 6.70 10.57 16.13 24.38 34.78 49.73 71.85 101.03 x2 = 0.3071 3.11 5.36 7.75 11.54 16.57 23.52 34.08 47.19 61.98 79.98 102.44
γ1exp
γ1cal
0.9727 0.9768 0.9792 0.9827 0.9844 0.9857 0.9857 0.9898 0.9930
0.9963 0.9965 0.9967 0.9968 0.9969 0.9971 0.9972 0.9972 0.9973
0.9947 0.9891 0.9668 0.9618 0.9552 0.9590 0.9574 0.9548 0.9557 0.9554
0.9566 0.9586 0.9601 0.9615 0.9628 0.9639 0.9650 0.9661 0.9670 0.9680
0.8562 0.8856 0.8817 0.8728 0.8631 0.8657 0.8654 0.8698 0.8684 0.8693
0.8423 0.8480 0.8532 0.8578 0.8622 0.8662 0.8698 0.8731 0.8760 0.8789
0.6460 0.6473 0.6616 0.6576 0.6593 0.6629 0.6685 0.6733 0.6813
0.6231 0.6326 0.6407 0.6478 0.6544 0.6596 0.6644 0.6690 0.6729
0.4803 0.4825 0.4829 0.4812 0.4809 0.4800 0.4823 0.4877 0.4944 0.4977 0.4931
0.4593 0.4684 0.4740 0.4796 0.4839 0.4874 0.4903 0.4922 0.4935 0.4947 0.4962
a Standard uncertainties u are u(T) = 0.03 K, u(x) = 0.0001, and ur(p) = 0.0052.
(0) (1) (1) where the parameters α, τ(0) 12 , τ21 , τ12 , and τ12 for the NRTL model were obtained by fitting the experimental vapor
(5) 3600
dx.doi.org/10.1021/je3007953 | J. Chem. Eng. Data 2012, 57, 3598−3603
Journal of Chemical & Engineering Data
Article
Table 5. Regressed Parameters of the NRTL Model α 0.5653 a
τ(0) 12
τ(1) 12 /K
1.8004·10
−8.6493·10
3
τ(0) 21
τ(1) 21 /K
−1.0613
−3.4515·10
ARDa for p/% 2
1.42
exp exp ARD = 100∑ni=1|(pexp − pcal = experimental pressure value, pical = calculated pressure value. i i )/pi |/n; n = number of experimental points, pi
3
pressures, and are listed in Table 5. The calculated vapor pressure pcal and activity coefficient γ1cal were obtained through the NRTL model and are listed in Table 4. The ARD for pressure between calculated and experimental values is 1.42 %, and the maximum relative deviation is 4.37 % correspondingly. The uncertainties of experimental temperature, pressure, and mole fraction for the systems are also shown in Table 4. For the H2O (1) + [HOEtMIM]Cl (2) binary system, the variation of the vapor pressure versus temperature at different mole fractions of IL is shown in Figure 2. It is shown that the
ρ=
∑ (ai + biT )x2i
(6)
i=0
where ρ is the density of the determined system in g·cm−3, T is the absolute temperature in K, x2 is the mole fraction of the [HOEtMIM]Cl, and ai and bi are the regression parameters obtained through a least-squares method and listed in Table 7. Table 7. Regressed Parameters of eq 6 i
ai
0 1 2 3
1.1414 1.1279 −1.4996 −1.1405·10−1
ARDa for ρ/%
bi −4
−4.8646·10 2.2293·10−3 −2.3522·10−2 5.1757·10−2
0.09
a exp ARD = 100∑ni=1|(ρexp − ρcal i i )/ρi |/n; n = number of experimental points, ρiexp = experimental density value, ρical = calculated density value.
The ARD between the experimental and the calculated data is 0.09 % with the maximum relative deviation of 0.22 %. The uncertainties of experimental temperature, mole fraction, and density for the systems are shown in Table 6. For the H2O (1) + [HOEtMIM]Cl (2) binary system, the variation trend of density with temperature at different compositions of IL is shown in Figure 3. For a given concentration of solution, the density of the binary system slightly declines with the increase in temperature. For the same temperature, the density of the system goes up with the rise of the IL mole fraction. In short, the density of the investigated binary system is quite low, which is applicable for use in the absorption heat pump cycle. Heat Capacity. The heat capacities of the H2O (1) + [HOEtMIM]Cl (2) binary system were determined at the temperature range from (298.15 to 358.15) K and [HOEtMIM]Cl mole fraction from 0.0122 to 0.3071. The meausred results are listed in Table 8 and correlated with the following equation33
Figure 2. Experimental and correlative vapor pressures of the H2O (1) + [HOEtMIM]Cl (2) binary system at various mole fractions of [HOEtMIM]Cl: ■, x2 = 0.0122; △, x2 = 0.0453; ●, x2 = 0.0997; □, x2 = 0.2054; ▲, x2 = 0.3071; , calculated by NRTL model.
relation between log(p/kPa) and 1/(T/K) is liner for a certain concentration over the temperature and pressure ranges, which is similar to the vapor pressure behavior of pure component. It can also be seen that the vapor pressure declines with the increasing mole fraction of IL. The activity coefficients are less than 1, which represents a negative deviation from the Raoult’s law. Besides, the higher the content of IL is, the larger the deviation from the Raoult’s law will be. That is a fundamental characteristic for working pairs. Density. For the H2O (1) + [HOEtMIM]Cl (2) binary system, the density data at the temperature range from (298.15 to 323.15) K and mole fraction of [HOEtMIM]Cl from 0.0122 to 0.3071 were obtained and placed in Table 6. The experimental data were correlated with the equation below32
3
Cp =
∑ (Ai + Bi T )x2i
(7)
i=0 −1
−1
where Cp is the heat capacity in J·g ·K , T is the absolute temperature in K, x2 is the mole fraction of the [HOEtMIM]Cl, and Ai and Bi are regression parameters acquired by fitting the
Table 6. Experimental Densities for the H2O (1) + [HOEtMIM]Cl (2)a Binary System ρ/g·cm−3 at the following T/K
a
x2
298.15
303.15
308.15
313.15
318.15
323.15
0.0122 0.0453 0.0997 0.2054 0.3071
1.01685 1.05973 1.10752 1.13695 1.18793
1.01523 1.05769 1.10514 1.13443 1.18525
1.01343 1.05555 1.10271 1.13188 1.18256
1.01146 1.05330 1.10022 1.12928 1.17987
1.00927 1.05094 1.09768 1.12666 1.17716
1.00590 1.04846 1.09508 1.12399 1.17445
Standard uncertainties u are u(T) = 0.02 K, u(x) = 0.0001, and ur(ρ) = 0.002. 3601
dx.doi.org/10.1021/je3007953 | J. Chem. Eng. Data 2012, 57, 3598−3603
Journal of Chemical & Engineering Data
Article
Figure 4. Experimental and correlative heat capacities of the H2O (1) + [HOEtMIM]Cl (2) binary system at various mole fractions of [HOEtMIM]Cl: ■, x2 = 0.0122; △, x2 = 0.0453; ●, x2 = 0.0997; □, x2 = 0.2054; ▲, x2 = 0.3071; , calculated by eq 7.
Figure 3. Experimental and correlative densities of H2O (1) + [HOEtMIM]Cl (2) binary system at various mole fractions of [HOEtMIM]Cl: ■, x2 = 0.0122; △, x2 = 0.0453; ●, x2 = 0.0997; □, x2 = 0.2054; ▲, x2 = 0.3071; , calculated by eq 6.
Table 8. Experimental Heat Capacities of the H2O (1) + [HOEtMIM]Cl (2)a Binary System x2
0.0122
0.0453
0.2054
0.3071
2.247 2.268 2.291 2.311 2.340 2.367 2.393 2.421 2.452 2.487 2.516 2.550
1.996 2.018 2.041 2.066 2.093 2.117 2.142 2.169 2.200 2.234 2.265 2.300
■
CONCLUSION The binary system, H2O + [HOEtMIM]Cl, has been studied as a replaceable working pair for the absorption heat pump cycle. The basic thermodynamic properties including vapor pressure, density, and heat capacity of the system were measured in the mole fraction of the IL range from 0.0122 to 0.3071. The NRTL model was used to correlate with the vapor pressure data. Simple polynomial equations on temperature and IL mole fraction were selected to correlate with the experimental density and heat capacity data. The ARDs for vapor pressure, density, and heat capacity are 1.42 %, 0.09 %, and 0.38 %, respectively. The results show good agreement between the experimental and the calculated values. The vapor pressures of the system show strong negative deviation from the Raoult’s law, which is a basic characteristic for the absorption working pairs. The density and heat capacity data of the investigated system are quite small, which are beneficial to decrease power consumption and improve the coefficient of performance of the absorption heat pump cycle.
Cp/J·g−1·K−1
T/K 298.15 303.15 308.15 313.15 318.15 323.15 328.15 333.15 338.15 343.15 348.15 353.15
0.0997
consumption and provide important information for evaluating the performance of the studied system.13
3.809 3.827 3.846 3.863 3.886 3.905 3.924 3.942 3.963 3.989 4.006 4.028
3.256 3.280 3.303 3.325 3.354 3.379 3.402 3.426 3.454 3.486 3.509 3.537
2.726 2.752 2.778 2.803 2.834 2.861 2.888 2.915 2.945 2.980 3.006 3.036
a
Standard uncertainties u are u(T) = 0.01 K, u(x) = 0.0001, and ur(Cp) = 0.0088.
experimental data and listed in Table 9. The ARD between the experimental and the calculated values is 0.38 % with the
■
Table 9. Regressed Parameters of eq 7 i 0 1 2 3
Ai 2.9621 −3.2304·10 1.4926·102 −2.3373·102
Corresponding Author
*E-mail:
[email protected]. Tel. and fax: +86-10-64416406.
ARDa for Cp/%
Bi −3
3.5676·10 4.1855·10−2 −2.4243·10−1 4.1195·10−1
AUTHOR INFORMATION
0.38
Funding
This work was supported by the National Nature Science Foundation of China (No. 50890184) and the National Basic Research Program of China (No. 2010CB227304).
cal exp ARD = 100∑ni=1|(Cexp p,i − Cp,i )/Cp,i |/n; n = number of experimental exp points, Cp,i = experimental heat capacity value, Ccal p,i = calculated heat capacity value. a
Notes
The authors declare no competing financial interest.
■
maximum relative deviation of 0.79 %. The uncertainties of the determined temperature, mole fraction, and heat capacity of the systems are shown in Table 8. The variations of heat capacity data versus temperature at different compositions are shown in Figure 4. It can be observed that the heat capacity of the solution slightly rises with the increasing temperature at the same IL concentration and reduces with the increasing IL-content at the same temperature. In brief, the heat capacity of the H2O + [HOEtMIM]Cl system is quite small, which is conductive to diminish power
REFERENCES
(1) Srikhirin, P.; Aphornratana, S.; Chungpaibulpatana, S. A Review of Absorption Refrigeration Technologies. Renew. Sust. Energy Rev. 2001, 5, 343−372. (2) Heintz, A. Recent Developments in Thermodynamics and Thermophysics of Non-aqueous Mixtures Containing Ionic Liquids. J. Chem. Thermodyn. 2005, 37, 525−535. (3) Moise, J. C.; Mutelet, F.; Jaubert, J. N.; Grubbs, L. M.; Acree, W. E., Jr.; Baker, G. A. Activity Coefficients at Infinite Dilution of Organic Compounds in Four New Imidazolium-Based Ionic Liquids. J. Chem. Eng. Data 2011, 56, 3106−3114.
3602
dx.doi.org/10.1021/je3007953 | J. Chem. Eng. Data 2012, 57, 3598−3603
Journal of Chemical & Engineering Data
Article
(4) Gardas, R. L.; Freire, M. G.; Carvalho, P. J.; Marrucho, I. M.; Fonseca, I. M. A.; Ferreira, A. G. M.; Coutinho, J. A. P. High-Pressure Densities and Derived Thermodynamic Properties of ImidazoliumBased Ionic Liquids. J. Chem. Eng. Data 2007, 52, 80−88. (5) Yokozeki, A.; Shiflett, M. B. Vapor−Liquid Equilibria of Ammonia + Ionic Liquid Mixtures. Appl. Energy 2007, 84, 1258−1273. (6) Yokozeki, A.; Shifflet, M. B. Ammonia Solubilities in RoomTemperature Ionic Liquids. Ind. Eng. Chem. Res. 2007, 46, 1605−1610. (7) Dong, L.; Zheng, D. X.; Wu, X. H. Working Pair Selection of Compression and Absorption Hybrid Cycles through Predicting the Activity Coefficients of Hydrofluorocarbon + Ionic Liquid Systems by the UNIFAC Model. Ind. Eng. Chem. Res. 2012, 51, 4741−4747. (8) Kim, S.; Kim, Y. J.; Joshi, Y. K.; Fedorov, A. G.; Kohl, P. A. Absorption Heat Pump/Refrigeration System Utilizing Ionic Liquid and Hydrofluorocarbon Refrigerants. J. Electron. Packag. 2012, 134, 031009. (9) Kim, Y. J.; Kim, S.; Joshi, Y. K.; Fedorov, A. G.; Kohl, P. A. Thermodynamic Analysis of An Absorption Refrigeration System with Ionic-Liquid/Refrigerant Mixture as A Working Fluid. Energy 2012, 44, 1005−1016. (10) Shiflett, M. B.; Yokozeki, A. Absorption Cycle Utilizing Ionic Liquids and Water as Working Fluids. U.S. Patent, US 2007/0144186 A1, 2007. (11) Yokozeki, A.; Shiflett, M. B. Water Solubility in Ionic Liquids and Application to Absorption Cycles. Ind. Eng. Chem. Res. 2010, 49, 9496−9503. (12) Zuo, G. L.; Zhao, Z. C.; Yan, S. H.; Zhang, X. D. Thermodynamic Properties of A New Working Pair: 1-Ethyl-3Methylimidazolium Ethylsulfate and Water. Chem. Eng. J. 2010, 156, 613−617. (13) Dong, L.; Zheng, D. X.; Nie, N.; Li, Y. Performance Prediction of Absorption Refrigeration Cycle Based on the Measurements of Vapor Pressure and Heat Capacity of H2O + [DMIM]DMP System. Appl. Energy 2012, 98, 326−332. (14) Zhang, X. D.; Hu, D. P. Performance Analysis of the SingleStage Absorption Heat Transformer Using a New Working Pair Composed of Ionic Liquid and Water. Appl. Therm. Eng. 2012, 37, 129−135. (15) Wang, J. Z.; Zheng, D. X.; Fan, L. H.; Dong, L. Vapor Pressure Measurements for Water + 1,3-Dimethylimidazolium Chloride System and 2,2,2-Trifluoroethanol + 1-Ethyl-3-methylimidazolium Tetrafluoroborate System. J. Chem. Eng. Data 2010, 55, 2128−2132. (16) Kim, K. S.; Park, S. Y.; Choi, S.; Lee, H. Vapor Pressures of the 1-Butyl-3-methylimidazolium Bromide + Water, 1-Butyl-3-methylimidazolium Tetrafluoroborate + Water, and 1-(2-Hydroxyethyl)-3methylimidazolium Tetrafluoroborate Water Systems. J. Chem. Eng. Data 2004, 49, 1550−1553. (17) Wu, X. H.; Li, J.; Fan, L. H.; Zheng, D. X.; Dong, L. Vapor Pressure Measurement of Water + 1,3-Dimethylimidazolium Tetrafluoroborate System. Chin. J. Chem. Eng. 2011, 19, 473−477. (18) Huddleston, J. G.; Visser, A. E.; Reichert, W. M.; Willauer, H. D.; Broker, G. A.; Rogers, R. D. Characterization and Comparison of Hydrophilic and Hydrophobic Room Temperature Ionic Liquids Incorporating the Imidazolium Cation. Green Chem. 2001, 3, 156− 164. (19) Jork, C.; Seiler, M.; Beste, Y. A.; Arlt, W. Influence of Ionic Liquids on the Phase Behavior of Aqueous Azeotropic Systems. J. Chem. Eng. Data 2004, 49, 852−857. (20) Li, J.; Zheng, D. X.; Fan, L. H.; Wu, X. H.; Dong, L. Vapor Pressure Measurement of the Ternary Systems H2O + LiBr + [Dmim]Cl, H2O + LiBr + [Dmim]BF4, H2O + LiCl + [Dmim]Cl, and H2O + LiCl + [Dmim]BF4. J. Chem. Eng. Data 2011, 56, 97−101. (21) Jiang, X. C.; Wang, J. F.; Li, C. X.; Wang, L. M.; Wang, Z. H. Vapour Pressure Measurement for Binary and Ternary Systems Containing Water Methanol Ethanol and an Ionic Iiquid 1-Ethyl-3ethylimidazolium Diethylphosphate. J. Chem. Thermodyn. 2007, 39, 841−846. (22) Lucas, A.; Donate, M.; Rodriguez, J. F. Vapour Pressures, Densities, and Viscosities of the (Water + Lithium Bromide Potassium
Acetate) System and (Water + Lithium Bromide Sodium Lactate) System. J. Chem. Thermodyn. 2006, 38, 123−129. (23) Clarke, E. C.; Glew, D. N. Evaluation of the Thermodynamic Functions for Aqueous Sodium Chloride from Equilibrium and Calorimetric Measurements below 154 °C. J. Phys. Chem. Ref. Data 1985, 14, 489−610. (24) Zhou, Q.; Wang, L. S.; Chen, H. P. Densities and Viscosities of 1-Butyl-3-methylimidazolium Tetrafluoroborate + H2O Binary Mixtures from (303.15 to 353.15) K. J. Chem. Eng. Data 2006, 51, 905− 908. (25) Becker, L.; Gmehling, J. Measurement of Heat Capacities for 12 Organic Substances by Tian Calvet Calorimetry. J. Chem. Eng. Data 2001, 46, 1638−1642. (26) Archer, D. G.; Kirklin, D. R. NIST and Standards for Calorimetry. Thermochim. Acta 2000, 347, 21−30. (27) Diedrichs, A.; Gmehling, J. Measurement of Heat Capacities of Ionic Liquids by Differential Scanning Calorimetry. J. Fluid Phase Equilib. 2006, 244, 68−77. (28) Smith, J. M.; Van Ness, H. C.; Abbott, M. M. Introduction to Chemical Engineering Thermodynamics, 6th ed.; McGraw-Hill: Beijing, 2002. (29) Shiflett, M. B.; Harmer, M. A.; Junk, C. P.; Yokozeki, A. Solubility and Diffusivity of 1,1,1,2-Tetrafluoroethane in RoomTemperature Ionic Liquids. Fluid Phase Equilib. 2006, 242, 220−232. (30) Shiflett, M. B.; Yokozeki, A. Gaseous Absorption of Fluoromethane, Fluoroethane, and 1,1,2,2-Tetrafluoroethane in 1-Butyl-3methylimidazolium Hexafluorophosphate. Ind. Eng. Chem. Res. 2006, 45, 6375−6382. (31) Reid, R. C.; Prausnitz, J. M.; Sherwood, T. K. The Properties of Gases and Liquids, 3rd ed.; McGraw-Hill: New York, 1977. (32) Kim, K. S.; Lee, H. Densities, Viscosities, and Surface Tensions of the Trifluoroethanol + Quinoline System. J. Chem. Eng. Data 2002, 47, 216−218. (33) Kim, J. S.; Park, Y.; Lee, H. Heat Capacities of the Water + Lithium Bromide + Ethanolamine and Water + Lithium Bromide + 1,3-Propanediol Systems. J. Chem. Eng. Data 1997, 47, 371−373.
3603
dx.doi.org/10.1021/je3007953 | J. Chem. Eng. Data 2012, 57, 3598−3603
