scholarly journals Separation of Benzene-Cyclohexane Azeotropes Via Extractive Distillation Using Deep Eutectic Solvents as Entrainers

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 336
Author(s):  
Fang Bai ◽  
Chao Hua ◽  
Jing Li

The separation of benzene and cyclohexane azeotrope is one of the most challenging processes in the petrochemical industry. In this paper, deep eutectic solvents (DES) were used as solvents for the separation of benzene and cyclohexane. DES1 (1:2 mix of tetrabutylammonium bromide (TBAB) and levulinic acid (LA)), DES2 (1:2 mix of TBAB and ethylene glycol (EG)) and DES3 (1:2 mix of ChCl (choline chloride) and LA) were used as entrainers, and vapor-liquid equilibrium (VLE) measurements at atmospheric pressure revealed that a DES comprised of a 2:1 ratio of LA and TBAB could break this azeotrope with relative volatility (αij) up to 4.763. Correlation index suggested that the NRTL modelling approach fitted the experimental data very well. Mechanism of extractive distillation gained from FT-IR revealed that with hydrogen bonding and π–π bond interactions between levulinic acid and benzene could be responsible for the ability of this entrainer to break the azeotrope.

Author(s):  
M. A. Toikka ◽  
A. A. Samarov ◽  
A. A. Sadaev ◽  
A. A. Senina ◽  
O. L. Lobacheva

New experimental data on the chemical equilibrium in the propionic acid - ethanol - ethyl propionate - water system at 293.15 K and atmospheric pressure are presented. Chemically equilibrium compositions corresponding to the liquid-liquid equilibrium were obtained by gas chromatographic analysis. Using the method of nuclear magnetic resonance, homogeneous chemically equilibrium compositions were determined and the concentration equilibrium constant is calculated. The surface of chemical equilibrium and the region of splitting chemically equilibrium compositions are represented in the square of the transformed concentration variables. Comparison of the data obtained in the work with the literature was carried out at 303.15 and 313.15 K. It was found that the region of such compositions decreases with increasing temperature, while the surface of chemical equilibrium does not change the shape and position in the concentration space in the temperature range 293.15-313.15 K and atmospheric pressure. Liquid-liquid equilibrium compositions have also been obtained by gas chromatographic analysis for ethanol and ethyl propionate in the pseudo-ternary system using deep eutectic solvents (DES) based on choline chloride and glycerol / urea in whole range of concentration. The analysis of the extraction properties of DES showed the highest efficiency of DES based on choline chloride and urea. Experimental data on phase equilibrium are processed using Othmer-Tobias and Hand models. The calculated correlation coefficient (more than 0.99) indicates a high internal consistency of the experimental data obtained in this work.


Molecules ◽  
2020 ◽  
Vol 25 (17) ◽  
pp. 3816
Author(s):  
Taleb H. Ibrahim ◽  
Muhammad A. Sabri ◽  
Nabil Abdel Jabbar ◽  
Paul Nancarrow ◽  
Farouq S. Mjalli ◽  
...  

The thermal conductivities of selected deep eutectic solvents (DESs) were determined using the modified transient plane source (MTPS) method over the temperature range from 295 K to 363 K at atmospheric pressure. The results were found to range from 0.198 W·m−1·K−1 to 0.250 W·m−1·K−1. Various empirical and thermodynamic correlations present in literature, including the group contribution method and mixing correlations, were used to model the thermal conductivities of these DES at different temperatures. The predictions of these correlations were compared and consolidated with the reported experimental values. In addition, the thermal conductivities of DES mixtures with water over a wide range of compositions at 298 K and atmospheric pressure were measured. The standard uncertainty in thermal conductivity was estimated to be less than ± 0.001 W·m−1·K−1 and ± 0.05 K in temperature. The results indicated that DES have significant potential for use as heat transfer fluids.


RSC Advances ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 7328-7335 ◽  
Author(s):  
Nerea Rodriguez Rodriguez ◽  
Lieven Machiels ◽  
Bieke Onghena ◽  
Jeroen Spooren ◽  
Koen Binnemans

A mixture of levulinic acid and choline chloride can be used to selectively leach zinc from industrial residues with iron-rich matrices.


Processes ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 1706
Author(s):  
Fang Bai ◽  
Chao Hua ◽  
Yongzhi Bai ◽  
Mengying Ma

Deep eutectic solvents (DESs) have properties that make them suitable candidates to be used as entrainers for extractive distillation. In the previous work, it was proven that DES(1:2) (tetrabutylammonium bromide: levulinic acid, 1:2, molar ratio) can break the cyclohexane-benzene azeotrope. In the present work, the HBA and HBD ratio and molar concentration of DES were optimized to obtain a better constitute and condition of DES to be utilized in cyclohexane and benzene extractive distillation. The physical properties and structure of the prepared DESs were characterized. Vapor–liquid equilibrium data of the ternary system (benzene + cyclohexane + DESs) were also measured at atmospheric pressure. All experimental equilibrium data were correlated with Wilson, nonrandom two-liquid (NRTL), and universal quasichemical (UNIQUAC) activity coefficient models, from which the coefficient of determination (R2) of the three pseudo-ternary systems fitting was calculated. From the obtained results, the best HBA and HBD ratio in the DESs is elucidated as 1:2, the best molar concentration of DES is 0.1, and the NRTL model predicts the experimental data more accurately than the Wilson and UNIQUAC models. From the derived mechanism, the formation of stronger hydrogen bond and π–π bond interactions between DES and benzene is obtained when HBA and HBD ratio in DES is 1:2. In other conditions, the azeotrope cannot be broken, or the efficiency is low. The present work provides an environmentally friendly method to separate aromatic/aliphatic mixtures and act as a guide for further study of DESs in extractive distillation.


2018 ◽  
Author(s):  
◽  
Sanele Enough Msibi

Air pollution by combustion of fossil fuels is of global concern in this decade and beyond. The presence of nitrogen and sulphur impurities pose deleterious effects to refinery equipment, the environment, and human health. Therefore, many governments continue to impose stringent environmental regulations and standards on transportation fuels emissions. The current study evaluates alternate processing solutions to complement or replace the currently used processes to refine these impurities to meet the increasingly stringent fuel standards. This study evaluates the use of a class extractive solvents called Deep Eutectic Solvents (DES) for the removal of basic nitrogen impurities from refining streams by liquid-liquid extraction. This process is evinced as energy saving and environmentally friendly. The removal of pyridine and quinoline by the direct analytical method with choline chloride based deep eutectic solvent (DES) was studied. Liquid-liquid equilibrium measurements data were undertaken at 298.15 K and atmospheric pressure for n-heptane + pyridine/quinoline + [choline chloride + glycerol] DES and n-heptane + pyridine/quinoline + [choline chloride + ethylene glycol] DES systems. The obtained data were then regressed using the Non Random Two Liquid and Universal Quasi-Chemical models activity coefficient, and their mathematical reliability was validated using the Othmer Tobias and Hand correlations. A mixture of choline chloride and glycerol (DES1) showed greater extraction potential for basic nitrogen containing compounds compared to choline chloride and ethylene glycol with a distribution coefficient and selectivity of 22.7 and 2056 for pyridine, and 3.3 and 164.9 for quinoline respectively. The studied solvents showed comparability to organic and ionic liquids solvents in selectivity and distribution coefficients. The obtained liquid-liquid equilibrium data can be used in the design of a solvent extraction equipment, as phase diagrams plays an important role in separation process design.


Molecules ◽  
2021 ◽  
Vol 26 (18) ◽  
pp. 5595
Author(s):  
Mohaned Aboshatta ◽  
Vitor Magueijo

Amine absorption (or amine scrubbing) is currently the most established method for CO2 capture; however, it has environmental shortcomings and is energy-intensive. Deep eutectic solvents (DESs) are an interesting alternative to conventional amines. Due to their biodegradability, lower toxicity and lower prices, DESs are considered to be “more benign” absorbents for CO2 capture than ionic liquids. In this work, the CO2 absorption capacity of choline-chloride/levulinic-acid-based (ChCl:LvAc) DESs was measured at different temperatures, pressures and stirring speeds using a vapour–liquid equilibrium rig. DES regeneration was performed using a heat treatment method. The DES compositions studied had ChCl:LvAc molar ratios of 1:2 and 1:3 and water contents of 0, 2.5 and 5 mol%. The experimental results showed that the CO2 absorption capacity of the ChCl:LvAc DESs is strongly affected by the operating pressure and stirring speed, moderately affected by the temperature and minimally affected by the hydrogen bond acceptor (HBA):hydrogen bond donator (HBD) molar ratio as well as water content. Thermodynamic properties for CO2 absorption were calculated from the experimental data. The regeneration of the DESs was performed at different temperatures, with the optimal regeneration temperature estimated to be 80 °C. The DESs exhibited good recyclability and moderate CO2/N2 selectivity.


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