Article pubs.acs.org/jced
Liquid−Liquid Equilibria for the Ternary System Mesityl Oxide + Phenol + Water at 298.15, 313.15, and 323.15 K Dong Liu, Libo Li, Ran Lv, and Yun Chen* Key Laboratory of Heat Transfer Enhancement and Energy Conservation of Ministry of Education, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, 510640, P. R. China S Supporting Information *
ABSTRACT: In this work, liquid−liquid equilibria (LLE) data for the ternary system {mesityl oxide (1) + phenol (2) + water (3)} were measured at 298.15, 313.15, and 323.15 K under atmospheric pressure. The experimental LLE data were proven to be highly reliable by the Othmer−Tobias and Hand equations. The distribution coefficient and selectivity were calculated from the LLE data, which indicated mesityl oxide extracted phenol with a rather high efficiency. The NRTL and UNIQUAC models were employed to correlate the LLE data, yielding binary interaction parameters for simulating relevant extraction processes. The experimental LLE data were correlated successfully by both models.
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INTRODUCTION Phenol is an important industrial commodity, widely used as an important raw material for producing resins, fungicides, preservatives, and drugs (such as aspirin). However, phenolcontaining wastewaters greatly harm the environment, which are produced from a wide range of industries, e.g., petroleum refining, petrochemical manufacture, coal gasification and coking, pharmaceuticals, plastics, wood processing, pulp and paper industry. Phenol and its derivatives are lethal to aqueous organism at concentrations as low as 5 mg·L−1, and bring undesirable odor to water even at concentrations of ∼0.5 mg· L−1.1 Therefore, the recovery of phenols from wastewater is of great economic and environmental significance. Solvent extraction has been proven to be a desirable and efficient technique in industry to recover phenolic compounds from wastewater when their concentration is above 1000 mg·L−1.2 It is critical to develop a high efficient extractant for designing a feasible extraction process for phenolic wastewaters, especially when the concentration of phenols is as high as 1000 mg·L−1, e.g., in wastewaters produced by Lurgi coal-gasification, lignite quality improvement, and coal tar hydrogenation. Methyl isobutyl ketone (MIBK), a hydrogenated product of mesityl oxide, has been widely used in industry due to its good extraction performance.3 While methyl isobutyl ketone has been proven to be an excellent extractant for phenol, mesityl oxide remains unknown. Thus, we studied the extraction efficiency of mesityl oxide for phenol in this work. Liquid−liquid equilibrium data are the basis of solvent extraction study, and plenty of LLE data for ternary systems, (solvent + phenol + water), have been published.4 LLE data for the {MIBK + phenol + water} system were measured by Qian’s lab,5 with those for the {2-methoxy-2-methylpropane + phenol + water} system reported by the same group.6 Other LLE systems such as {methyl butyl ketone + (phenol or hydroquinone) + © XXXX American Chemical Society
water}, {aliphatic hydrocarbon (e.g., heptane or octane) + phenols + water}, and {aromatic hydrocarbon (e.g., toluene or ethylbenzene) + phenols + water} were also studied.7−9 However, LLE data for the ternary system of {mesityl oxide + phenol + water} remain unknown. In this work, LLE data for the ternary system {mesityl oxide (1) + phenol (2) + water (3)} were determined at different temperatures, e.g., 298.15, 313.15, and 323.15 K, and atmospheric pressure. The NRTL10 and UNIQUAC11 models were employed to correlate the as-measured LLE data, yielding binary interaction parameters among mesityl oxide, phenol, and water.
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EXPERIMENTAL SECTION Chemicals. The reagents’ suppliers and purities (expressed as mass fraction) were listed in Table 1. The reagents’ purity was confirmed by gas chromatography (Agilent GC-6820). The water used in this work is distilled water. All chemicals in Table 1 are used without further purification. Procedure. The experimental liquid−liquid equilibrium data in this work were determined by a gas chromatograph (GC6820, Agilent Technologies) equipped with a DB-FFAP capillary column (30 m × 0.32 mm × 0.25 μm), and an internal standard method was used to calculate the mass fraction of each component. The mass fraction of mesityl oxide and phenol were measured by a flame ionization detector (FID) equipped in the GC, and water’s mass fraction were calculated from the mass balance equation. In this work, the internal standard of phenol was 1-octanol, and that of mesityl oxide was n-propyl acetate. The calibration curves for calculating each component’s mass from Received: March 1, 2016 Accepted: June 22, 2016
A
DOI: 10.1021/acs.jced.6b00186 J. Chem. Eng. Data XXXX, XXX, XXX−XXX
Journal of Chemical & Engineering Data
Article
(phenol−water) and (water−mesityl oxide), are partially miscible, leading to a type-II LLE behavior12 for the studied ternary system, and the plait point was absent from its phase diagram. The distribution coefficient (D) and the selectivity (S) were used to assess the extraction capacity of mesityl oxide for phenol:
Table 1. Summaries for the Chemicals Used in This Work initial mass fractionb
analysis method
Xiya Reagent Research Center
0.98
GCc
GuangZhou Chemical Reagent Factory ShangHai LingFeng Chemical Reagent Co., Ltd. TianJin Kemiou Chemical Reagent Co., Ltd. Xiya Reagent Research Center
0.995
GCc
0.999
GCc
0.995
GCc
0.999
GCc
component mesityl oxidea phenol methanol n-octanol n-propyl acetate
supplier
D=
S=
a
Mesityl oxide = 4-methyl-3-penten-2-one. bInitial purity stated by the manufacturer without further purification. cGas chromatograph.
Table 2. Fitted Parameters for the Calibration Curve for Each Component fitting parameters for calibration curve, y = a + bxa a
b
R2
mesityl oxide phenol
−0.90 −0.99
0.82 1.06
0.99 0.99
w2W
(1)
(w2 /w3)O (w2 /w3)W
(2)
where superscripts O and W denote the organic and aqueous phase and w2 and w3 are the mass fraction of phenol and water, respectively. The distribution coefficient and the selectivity for phenol were shown in Table 3 in the last two columns. Distribution coefficients versus mass fraction of phenol at temperatures of 298.15, 313.15, and 323.15 K in aqueous phase were also shown in Figure 4. These results show that, the distribution coefficients of phenol in mesityl oxide range from 36.71 to 113.0 and selectivity factors from 460.1 to 2788 for the studied temperature range in this work. The distribution coefficients decrease with increasing the concentration of phenol. They also decrease with increasing the temperature, which can be explained by that, lower temperature enhances hydrogen bonding interactions between phenol and mesityl oxide, thus increase the distribution coefficients. These concentration or temperature dependence of distribution coefficient also agrees with many other LLE studies. In order to further evaluate the extraction performance of mesityl oxide, we compared it with other common phenol extractants for the similar LLE system compositions at 298.15 K. The result shows that, mesityl oxide provides phenol distribution coefficients about 100 for dilute solution. In comparison, the distribution coefficients of phenol in other frequently used industrial extractants, diisopropyl ether, 2methoxy-2-methylpropane, butyl acetate, and methyl isobutyl ketone are about 29, 55, 71, and 100. The distribution coefficients in aliphatic hydrocarbons (e.g., heptane or octane) and aromatic hydrocarbons (e.g., toluene or ethylbenzene) are even smaller than 3. To gain more intuitive comparison, the distribution coefficients of different types of extractions at 298.15 K versus the mass fraction of phenol in the aqueous phase were drawn in the Figure 5.5,6,13,14 The result shows that the distribution coefficients ketones are much larger than the ethers, esters, and alcohol extractions. These results indicate that mesityl oxide can be considered as a highly efficient solvent for phenol extraction with very promising application potential. We verified the reliability of experimental LLE data by using the Othmer−Tobias15 and Hand16 equations:
the GC signal intensity (peak area in this work) are listed in Table 2.
component
w2O
a y is the mass of component i, x = msAi/As, ms is the mass of corresponding internal standard for component i, and Ai and As are signal intensities (peak area in this work) of component i and internal standard s.
The experimental liquid−liquid equilibrium data in this work were measured with a 100 cm3 glass-sealed cell surrounded by a thermostat water jacket. The cell’s temperature was controlled by a thermostatic bath with a fluctuation of ±0.1 K. Water, mesityl oxide, and phenol were fed into the glass cell. The resulting mixture was stirred vigorously for more than 2 h by a magnetic stirrer and was left to stand for 12 h or more until the phase equilibrium was reached and the mixture was split into two distinct layers, which referred to the organic and aqueous phases, respectively. After that, each phase was sampled by a separate syringe, and the sample was placed in a microcentrifuge tube with 5 mL of methanol. Then we added internal standards into the microcentrifuge tube, mixed them thoroughly, and took 1 μL of liquid from the mixture with a microinjector for GC analysis. In GC analysis, we first kept the oven temperature at 313.15 K for 2 min, then increased it to 463.15 K in 5 min, and kept this temperature for the other 2 min. We used nitrogen as the carrier gas, and the flow rate was 30 cm3·min−1. We set the temperature of injector at 493.15 K and that of detector at 543.15 K. We analyzed each sample for more than three times and reported the average, since the standard deviation is tiny: e.g.,
