Article pubs.acs.org/jced
Solid−Liquid Equilibria, Excess Molar Volumes, and Deviations in the Molar Refractivity for the Binary Systems of Alamine 304‑1 + Decane, Dodecane, or Dodecanol In-Yong Jeong,† Rak-Hyun Kwon,† So-Jin Park,*,† and Young-Yoon Choi‡ †
Department of Chemical Engineering, Chungnam National University, 220 Gung-Dong, Yuseong-Gu, Daejeon, 305-764, Republic of Korea ‡ Minerals and Materials Processing Division, Korea Institute of Geoscience and Mineral Resources, Daejeon 305-350, Republic of Korea ABSTRACT: Solvent extraction is widely used for the separation of metals from aqueous acid leaching solutions of metal ore. Employing the appropriate solvents and diluents for different metal ores is very important not only for developing appropriate extraction and purification processes but also for recycling the solvent and diluents. Crystallization is an inexpensive recycling process. In this work, therefore, solid−liquid equilibrium (SLE) data for systems containing Alamine 304-1, a commercial amine solvent, were collected at atmospheric pressure. Specifically, the following systems were studied: {Alamine 304-1 + decane}, {Alamine 304-1 + dodecane}, and {Alamine 304-1 + 1-dodecanol}. The experimental data were correlated using the nonrandom-two-liquid (NRTL) model. In addition, the physical properties, excess molar volumes (VE) and deviations in the molar refractivity (ΔR) of these binary systems at 298.15 K were reported. The measured VE and ΔR data fit the Redlich−Kister equation well.
1. INTRODUCTION Scientists and engineers are interested in recovering solvents and diluents from various extraction processes to develop environmentally friendly separation technologies. The use of various metals, especially molybdenum (Mo), has steadily increased because of their strength, hardenability, and corrosion resistance, which makes them useful in many applications, including aircraft parts, electrical contacts, industrial motors and filaments. However, the reserves of high-grade Mo ore are decreasing daily due to the ceaseless exploitation of resources worldwide; therefore, separation technology for low-grade Mo ore must be developed.1,2 Solvent extraction is widely used to separate Mo from acidic aqueous solutions of leached Mo ore. The solvents, diluents, and modifiers must be separated and recycled to make the extraction process cost-effective and clean.3,4 Crystallization is one of the key inexpensive separation techniques used to recover solutions after extraction.5 To design a crystallization process, reliable solid−liquid equilibrium (SLE) data of the crystallization system must be available. Alamine 304-1, a water insoluble commercial amine-type solvent (tri-n-dodecyl amine), has been found to be a good selective solvent or floating agent, and long-chain alkanes or alkanols are widely used as diluents or modifiers in the Mo extraction process.6,7 Therefore, in the present study, experimental SLE data were obtained visually at atmospheric pressure for the following binary systems: {Alamine 304-1 (1) + decane (2)}, {Alamine 304-1 (1) + dodecane (2)} and {Alamine 304-1 (1) + 1dodecanol (2)}. The experimental data were correlated using © 2014 American Chemical Society
the nonrandom-two-liquid (NRTL) model and compared to the resulting calculated data.8 In addition, the densities (ρ) and refractive indices (nD) were measured for the binary mixtures, and the excess molar volumes (VE) and deviations in the refractive indices (ΔR) at 298.15 K were then calculated using the ρ and nD data. The mixture properties were used to gain insight into the molecular interactions in the nonideal systems and to design an extraction process. The calculated binary VE and ΔR data were fit to the Redlich−Kister polynomial.9
2. EXPERIMENTAL SECTION 2.1. Materials. The selective solvent Alamine 304-1 (Cognis Co., tert. amine content > 0.99), was used as received. Commercial-grade decane (Fluka Co., >0.99), dodecane (TCI Co., >0.99) and 1-dodecanol (Aldrich Co., >0.99) were used without further purification. Their purity was verified by gaschromatographic analysis, and by comparing their densities to the literature values. Only a single sharp peak was observed in the gas-chromatograms of the pure alkane and alkanol solvents, indicating an absence of significant impurities. The thermophysical properties, melting points, measured densities, and refractive indices of the chemicals and their corresponding literature values are listed in Table 1and Table 2.10−15 Received: June 27, 2013 Accepted: December 29, 2013 Published: January 6, 2014 289
dx.doi.org/10.1021/je400606c | J. Chem. Eng. Data 2014, 59, 289−294
Journal of Chemical & Engineering Data
Article
uncertainty in the mole fraction of the sample mixtures was less than ± 1·10−4. A digital precision refractometer (KEM, model RA-520N, Japan) was used to measure nD of the pure substances and mixtures. Then, ΔR was determined from the experimental nD data. According to the manufacturer, the uncertainty of the refractometer is ± 5·10−5 within the range from 1.32 to 1.40 and ± 1·10−4 within the range from 1.40 to 1.58. The repeatability of the densitometer and refractometer measurements coincided with the uncertainties given in the manufacturer’s specifications.
Table 1. Material Description water contentb (wt %)
chemical
CAS No
source
mass fraction puritya
Alamine304-1 (tri-n-dodecylamine) decane dodecane 1-dodecanol
102-87-4
Cognis
0.994
0.01
124-18-5 112-40-3 112-53-8
Fluka TCI Aldrich
0.999 0.999 0.999
< 0.01 < 0.01 < 0.01
a
Gas-chromatography bKarl Fischer titrator. bThe standard uncertainty u is u(g) = 5·10−6 g/g.
3. RESULTS AND DISCUSSION 3.1. Solid−Liquid Equilibrium. At the solid−liquid equilibrium, the fugacity of component i in the liquid phase must be equal to the fugacity of that component in the solid phase (see, eq 1):
2.2. Apparatus and Procedures. The SLE data were collected using a triple jacketed glass still, in which the melting process could be observed visually. The melting point (equilibrium temperature) of a given composition was carefully measured at the moment when the last crystal of the mixture melted. The apparatus10 used to collect the SLE data consisted of a glass still, cryostat, and temperature measuring system. The exterior vacuum jacket of the glass still prevented atmospheric water from freezing on the glass surface at low temperatures, allowing for visual observation of the melting process. The cryostat medium (ethanol) was circulated through the center of the jacket to insulate the equilibrium cell. A nitrogen atmosphere was used in the equilibrium cell for dehumidification. The temperature was measured with a digital thermometer (ASL F250, U.K.). First, the superficial melting point of a given compositions was determined when the last crystal melted. Next, the cryostat medium temperature was regulated to the superficial melting point, and the true melting point was then carefully determined using the same procedures. The accuracy of the melting temperature was determined to be ± 0.02 K, and the estimated uncertainty in the mole fraction was less than ± 1·10−4. The composition of the sample mixture was determined gravimetrically using an A&D microbalance (HA202, Japan) with an accuracy of ± 1·10−5 g. To determine VE, the sample mixture ρ was measured using a digital vibrating glass tube densitometer (Anton Paar, model DMA 5000, Austria). The uncertainty in the densities was less than ± 5·10−6 g·cm−3 in the range of 0 to 3 g·cm−3, and the accuracy of the temperature was ± 0.01 K. The calibration and measurement procedures used here have been described in the literature.16 Before each series of measurements, the apparatus was calibrated with doubly distilled water and dried air. The samples were prepared by placing approximately 5 cm3 of total volume into a glass vial, and the mass of each reagent was recorded using a microbalance (A&D, HA202, Japan) with a precision of ± 1·10−5 g. To minimize vaporization effects, the higher boiling component was charged first. The estimated
f iS = fiL
(1)
In this study, when the solid−solid phase transition did not occur within the considered temperature range, the SLE was described using a simplified form, as in eq 2:17 ln(γixi) = −
ΔfusHi ⎡ 1 1 ⎤ ⎢ − ⎥ R ⎢⎣ T Tfus, i ⎥⎦
(2)
where xi is the mole fraction in the liquid phase, γi is the activity coefficient in the liquid phase, ΔfusHi is the molar enthalpy of fusion, Tfus,i is the melting temperature, T is the absolute temperature, and R is the universal gas constant. The results of the SLE measurements for the three binary systems {Alamine 304-1 (1) + decane (2)}, {Alamine 304-1 (1) + dodecane (2)} and {Alamine 304-1 (1) + 1-dodecanol (2)} are given in Table 3 and plotted in Figure 1. The solid curves are the data calculated using the NRTL equation. All of the binary systems exhibited a single eutectic point. The calculated NRTL parameters and root-mean-squared deviations (RSMDs) between the experimental and calculated data are given in Table 4. The NRTL nonrandom-two-liquid factors (α) were 4.11, 1.45, and 0.30 for the systems with decane, dodecane and 1-dodecanol, respectively. The largest RMSD value (0.67) was obtained for the {Alamine 304-1 + decane} system, while the other two systems had much smaller RMSD values. These values were calculated using eq 3: RMSD =
1 n
∑ (Texp − Tcal)2 (3)
n
The eutectic points interpolated from the NRTL equation were {x1 = 0.0249, T = 243.02 K}, {x1 = 0.1608, T = 260.74 K}
Table 2. Density (ρ), Refractive Index (nD), Melting Point (Tm), Heat of Fusion (ΔHfus) for the Alamine 304-1, Decane, Dodecane, and 1-Dodecanol at Pressure p = 0.1 MPag ρ (g·cm−3)/298.15 K chemical Alamine304-1 decane dodecane 1-dodecanol
present study 0.81923 0.72630 0.74582 0.83090
nD/298.15 K
lit. value a
0.8192 0.7262b 0.7455c 0.8308d
present study
lit. value a
1.4547 1.4102 1.4195 1.4410
ΔHfus
Tm (K) 1.4546 1.4097e 1.4151e 1.4420f
present study
lit. value
J·mol−1
289.20 243.45 263.55 296.95
289.15 243.45 263.59 296.95
63542.5a 28756.6b 36557.3b 31380.0b
b
Reference 10. bReference 11. cReference 12. dReference 13. eReference 14. fReference 15. gThe uncertainty u is u(ρ) = 1·10−5 g·cm−3 and the stability of the temperature was ±0.01 K; the uncertainty u is u(nD) = 1·10−4 and the stability of the temperature was ±5·10−2 K. a
290
dx.doi.org/10.1021/je400606c | J. Chem. Eng. Data 2014, 59, 289−294
Journal of Chemical & Engineering Data
Article
Table 3. Experimental SLE Data for the Binary Systems at Pressure p = 0.1 MPaa system Alamine 304-1 (1) + decane (2)
Alamine 304-1 (1) + dodecane (2)
Alamine 304-1 (1) + 1-dodecanol (2)
a
x1
T/K
solid phase
x1
T/K
0.0000 0.0100 0.0200 0.0300 0.0500 0.1000 0.1900 0.3000 0.4000 0.0000 0.0500 0.1000 0.1500 0.2000 0.3001 0.4100 0.0000 0.0500 0.1000 0.2000 0.3000 0.4000 0.5000
243.45 243.30 242.75 243.85 247.15 254.30 260.65 264.50 267.55 263.55 262.75 261.55 261.20 263.15 267.35 271.45 296.95 295.82 294.62 292.60 290.82 289.35 288.05
decane decane decane Alamine 304-1 Alamine 304-1 Alamine 304-1 Alamine 304-1 Alamine 304-1 Alamine 304-1 dodecane dodecane dodecane dodecane Alamine 304-1 Alamine 304-1 Alamine 304-1 1-dodecanol 1-dodecanol 1-dodecanol 1-dodecanol 1-dodecanol 1-dodecanol 1-dodecanol
0.6000 0.7100 0.8000 0.8300 0.9001 0.9500 0.9800 1.0000
272.35 274.20 275.95 276.75 278.35 280.05 282.65 289.20
Alamine Alamine Alamine Alamine Alamine Alamine Alamine Alamine
0.5000 0.6000 0.7000 0.8000 0.9000 0.9500 1.0000 0.6000 0.7000 0.8000 0.9000 0.9500 1.0000
274.65 277.85 280.65 283.75 286.65 288.35 289.20 286.85 287.25 287.75 288.24 288.68 289.20
Alamine 304-1 Alamine 304-1 Alamine 304-1 Alamine 304-1 Alamine 304-1 Alamine 304-1 Alamine 304-1 1-dodecanol Alamine 304-1 Alamine 304-1 Alamine 304-1 Alamine 304-1 Alamine 304-1
solid phase 304-1 304-1 304-1 304-1 304-1 304-1 304-1 304-1
The uncertainty u is u(x) = 1·10−4 ; the uncertainty u is u(T) = 0.02 K.
Figure 1. SLE for the binary systems: (a) {Alamine 304-1 (1) + decane} (2); (b) {Alamine 304-1 (1) + dodecane (2)}; (c) {Alamine 304-1 (1) + 1dodecanol (2)}. ●, experimental data; −, NRTL.
Table 4. NRTL Model Parameters and RMSD between the Experimental and Calculated Data system
Aij/J·mol−1
Aji/J·mol−1
α
RMSD
Alamine 304-1 (1) + decane (2) Alamine 304-1 (1) + dodecane (2) Alamine 304-1 (1) + 1dodecanol (2)
48949.9 9596.27
−2682.5 −2471.25
4.11 1.45
0.67 0.23
4080.97
124.25
0.30
0.07
V E/cm 3·mol−1 =
∑i xiMi
−
ρm
⎛xM ⎞ i i ⎟⎟ ⎝ ρi ⎠
∑ ⎜⎜ i
(4)
where xi, Mi, and ρi are the mole fraction, molar mass, and purecomponent density, respectively, of component i and ρm is the mixture density.18 ΔR was calculated from the molar refractivities (Rm) of the pure components and mixtures, which were derived from the measured densities and refractive indices using eq 5, where ϕi is the volume fraction of component i:19 ΔR /cm 3·mol−1 = R m −
and {x1 = 0.5951, T = 286.75 K} for the {Alamine 304-1 (1) + decane (2)}, {Alamine 304-1 (1) + dodecane (2)} and {Alamine 304-1 (1) + 1-dodecanol (2)} systems, respectively. 3.2. Excess Molar Volumes and Deviations in the Molar Refractivity. The VE data for the binary mixtures were calculated from the measured densities of the pure substances and mixtures using eq 4:
∑ ϕiR i i
(5)
The binary VE and ΔR data were fitted to the Redlich−Kister polynomial (eq 6): n
V E or ΔR /cm 3·mol−1 = x1x 2 ∑ Ai (xi − x 2)i − 1 i=1
291
(6)
dx.doi.org/10.1021/je400606c | J. Chem. Eng. Data 2014, 59, 289−294
Journal of Chemical & Engineering Data
Article
Table 5. Density(ρ), Excess Molar Volume (VE), Refractive Indices (nD), and Deviations in the Molar Refractivity (ΔR) for the Binary Systems at 298.15 K and at Pressure p = 0.1 MPaa system Alamine 304-1 (1) + decane (2)
Alamine 304-1 (1) + dodecane (2)
Alamine 304-1 (1) + 1-dodecanol (2)
x1
ρ/g·cm−3
VE/cm3·mol−1
nD
ΔR/cm3·mol−1
0.0499 0.0998 0.2000 0.3002 0.3999 0.5000 0.6000 0.6998 0.7993 0.9000 0.9498 0.0500 0.0999 0.2000 0.3000 0.4000 0.5000 0.6000 0.7000 0.8000 0.9000 0.9500 0.0501 0.0999 0.200 0.2999 0.3999 0.5000 0.5999 0.7000 0.8001 0.9000 0.9500
0.7314 0.7361 0.7451 0.7539 0.7627 0.7719 0.7811 0.7906 0.8001 0.8097 0.8146 0.7491 0.7526 0.7596 0.7668 0.7740 0.7813 0.7887 0.7963 0.8039 0.8115 0.8154 0.8299 0.8293 0.8285 0.8277 0.8269 0.8258 0.8246 0.8235 0.8223 0.8209 0.8202
−0.0017 −0.0027 −0.0034 −0.0035 −0.0033 −0.0032 −0.0029 −0.0026 −0.0022 −0.0013 −0.0009 0.0001 0.0000 −0.0003 −0.0006 −0.0008 −0.0009 −0.0009 −0.0008 −0.0007 −0.0004 −0.0003 0.0005 0.0006 0.0001 −0.0005 −0.0010 −0.0011 −0.0011 −0.0011 −0.0011 −0.0008 −0.0005
1.4121 1.4141 1.4182 1.4225 1.4269 1.4314 1.4359 1.4405 1.4451 1.4497 1.4523 1.4213 1.4229 1.4263 1.4297 1.4331 1.4366 1.4401 1.4437 1.4473 1.4509 1.4528 1.4417 1.4425 1.4441 1.4455 1.4470 1.4484 1.4497 1.4510 1.4523 1.4535 1.4541
−0.0006 −0.0010 −0.0014 −0.0014 −0.0013 −0.0012 −0.0011 −0.0010 −0.0008 −0.0006 −0.0003
