Raffinate Phases Research Articles

Parametric Identification of a Countercurrent Aqueous Hydrolysis Process for the Production of Glycerine under Higher Pressure and Temperature

AbstractGlycerine is produced by aqueous hydrolysis of tallow fat in the Twitchell process under high pressure (40–60 bar) and temperature (250–270 °C). An effort was made to improve the degree of hydrolysis under optimal operating conditions by varying the feed ratio in a 20‐L Parr reactor. The 1:4 blend of water/tallow at 256 °C and 60 bar was recorded as optimal operating conditions (non‐catalytic), yielding a degree of hydrolysis of 98.4 %. A survey shows that there is a need to find alternate operating control strategies for achieving better efficiency and safe operation. Material and energy balances across the countercurrent hydrolysis tower were developed to calculate the glycerine and free fatty acids in the raffinate and extract phases, using the first principle for dynamic analysis. The model equations were validated and used to identify simple model structures suitable for designing model‐based strategies to control the process temperature in the extraction process.

The Aptness of Organic Diluents with Tri‐n‐Butyl Phosphate for Liquid‐Liquid Equilibria of Acrylic Acid

AbstractSeparation of carboxylic acids from downstream is a bottleneck in the chemical industry since it takes nearly 30–50 % of the overall production cost. In view of this, an attempt was made for the extraction of acrylic acid from aqueous solution with tri‐n‐butyl phosphate dissolved in organic diluents like benzene, toluene, xylene, hexane, and petroleum ether. The results are explained in terms of distribution coefficient (σ), extraction efficacy (η%), equilibrium complexation constant (Kε), loading ratio (ϕ), and coextraction of water. At lower concentration of acrylic acid and higher concentration of tri‐n‐butyl phosphate for the acrylic acid‐tri‐n‐butyl phosphate system, maximum extraction efficacy and distribution coefficient for benzene was found as 88.60 % and 7.772, respectively. Coextraction of water in the extract phase and law of mass action were discussed, too. Diffusivity of acrylic acid to the interface of extract (organic) and raffinate (aqueous) phases was calculated using the Wilke‐Chang equation and Reddy‐Doraiswamy equation. In view of designing a continuous extraction column, the number of theoretical stages and minimum solvent‐to‐feed ratio were also determined.

Experimental and theoretical assessment of phenomena linked with separation and purification of biodiesel from Ricinus communis seed oil

This study investigated the phenomena associated with the separation and purification of biodiesel produced from Ricinus communis oil seeds using experimental and theoretical approaches. The alkaline transesterification technique was used to produce the biodiesel from the Ricinus communis oil seeds which were later compared with standards based on EN and ASTM. Experimental investigation of the components in the mixture for separation and purification was conducted using the standard turbidimetric method for binodal solubility and tie-line compositions. The gas chromatographic technique was used to determine the composition of the homogeneous mixture. Novel components separation and purification of the Ricinus communis seed oil biodiesel was achieved using ternary diagrams highlighting the constituent components of the biodiesel at different temperatures for enhanced separation and purification. At the coexisting extract and raffinate phases, the orientation angle of the component compositions increases as the methanol concentration increases and temperature increases. The analysis of seed oil in terms of its physicochemical properties showed density, refractive index, acid value, and free fatty acid values of 905 kg/m3, 1.486, 0.79 mg KOH/g, and 0.390 mg KOH/g respectively. The fatty acid composition of the seed oil and biodiesel revealed that the major characteristics of the oil and biodiesel were defined by the presence of linoleic acid (C18:2) and a ricinoleic acid hydroxyl group (C18:1, OH) with compositions of approximately 30% and 20% respectively. Fourier Transform Infra-Red (FTIR) spectrometry analysis of the oil and biodiesel showed that the absorption spectrum in terms of the wave number (cm−1) ranged from 1000 to 4000 cm−1 with esters as the main functional group providing the main structural backbone. The presence of different fatty acids leads to lateral homogeneity of the biodiesel molecules which can serve to organize the molecules into discrete domains with different properties for enhanced separation and purification at the investigated temperatures. Optimal separation and purification were achieved at the different temperatures showing the castor oil biodiesel, glycerol, and methanol components system at the prevailing composition, time, and temperatures from the tie-lines and binodal solubility compositions. This approach provides a means for the design of a more efficient separation process for optimal biodiesel purification after production with knowledge of how the components are distributed in the ternary mixture after the transesterification reaction. This, leads to greater efficiency of the process, reducing material and operational costs and eliminating environmental issues linked with the biodiesel production process as the volume of wastewater generated would be hugely eradicated. The findings of this study will be useful in the setting up of a small-to-medium-size biodiesel production facility with improvement in the efficiency of product separation and purification.

Performance of alcoholic solvents in the continuous countercurrent spent coffee grounds oil extraction

Ethanol and isopropanol, absolute (ET0, IPA0) and hydrated with 6 and 12 water mass% (ET6, IPA12), were evaluated as solvents in the oil extraction from spent coffee grounds (SCGO). Alcohols' performance evaluation was based on the SCGO partitioning between extract and raffinate phases and the extractor design. An SCGO concentration limit in systems containing ET indicates extract phase saturation. In this case, a Langmuir-type equation provided a satisfactory SCGO partitioning data mathematical description, while the IPA data presented a linear behavior. The increase in temperature from 60 to 80 °C did not affect SCGO partitioning when IPA0 was used as a solvent. ET6 required higher solvent proportions concerning SCG, leading to extractors with a higher number of theoretical stages. The minimum flow rates of ET6 were 1.9 times higher than those required by ET0 and IPA12 and up to 3.2 times higher than the IPA0 flow rate at 60 °C. At 80 °C, the SCGO extraction performance with ET0 and IPA0 was similar. A solvent-to-feed ratio of at least five must be used when an extractor with five theoretical stages operating at 80 °C is considered. In this case, extracts with about 5 mass% of SCGO are obtained.

Extraction of Phenolic Compound from Model Pyrolysis Oil Using Deep Eutectic Solvents: Computational Screening and Experimental Validation

Green Deep Eutectic Solvents (DESs) are considered here as an alternative to conventional organic solvents and ionic liquids (IL) for the extraction of phenolic compounds from pyrolysis oil. Although ionic liquids have shown a promising future in extraction processes, DESs possess not only most of their remarkable physico-chemical properties, but are also cheaper, easier to prepare and non-toxic, increasing the infatuation with these new moieties to the detriment of ionic liquids. In this work, phenol was selected as a representative of phenolic compounds, and toluene and heptane were used to model the pyrolysis oil. COSMO-RS was used to investigate the interaction between the considered Dess, phenol, n-heptane, and toluene. Two DESs (one ammonium and one phosphonium based) were subsequently used for experimental liquid–liquid extraction. A ternary liquid–liquid equilibrium (LLE) experiment was conducted with different feed concentrations of phenol ranging from 5 to 25 wt% in model oil at 25 °C and at atmospheric pressure. Although both DESs were able to extract phenol from model pyrolysis oil with high distribution ratios, the results showed that ammonium-based DES was more efficient than the phosphonium-based one. The composition of phenol in the raffinate and extract phases was determined using gas chromatography. A similar trend was observed by the COSMO-RS screening for the two DESs.

Modelling of Liquid-Liquid Equilibria Using NRTL and UNIFAC Equations in the Extraction of Bio-Oil-Based Phenolics Produced from the Pyrolysis of Sugarcane Bagasse

An exploration on renewable energy resources has been paid more attention due to the depletion of the fossil-based energy resource. In addition, their safe and environmentally friendly properties have attracted experts’ interest. One of the renewable energy resources is the bio-oil produced from sugarcane bagasse. The bio-oil was produced through a pyrolysis at 500°C. However, the produced bio-oil showed a high content of phenolics, c.a. 40-60%. A liquid-liquid extraction to remove the phenolics using methanol-chloroform solvents would be beneficial to improve the stability of the bio-oil as well as to obtain high purity phenolics. Modelling of the liquid-liquid equilibria in the extraction was then developed using NRTL and UNIFAC equations. The empirical quantitative data of phase equilibrium system were calculated on both the extract and raffinate phases. The lowest RMSD value of 0.043160 was obtained from the calculations using NRTL equation at an extraction temperature of 50°C. Thus, the most suitable model was achieved using NRTL equation.

Liquid–Liquid Extraction of Lower Alcohols Using Menthol-Based Hydrophobic Deep Eutectic Solvent: Experiments and COSMO-SAC Predictions

The lower alcohols tend to form azeotropic solution with water which makes the separation challenging. The current work primarily focuses on the synthesis and application of a menthol-based hydrophobic deep eutectic solvent (DES) for the removal of lower alcohols from its aqueous solutions. The DES is synthesized by the addition of DL-menthol and lauric acid (dodecanoic acid) with a molar ratio of 2:1. Liquid–liquid equilibria (LLE) experiments are then performed to evaluate the performance of the synthesized DES for the extraction of lower alcohols such as ethanol, 1-propanol, and 1-butanol. LLE corresponding to the pseudo ternary systems of lower alcohols (1-butanol, ethanol, and 1-propanol) + hydrophobic DES + water are measured at T = 303.15 K and p = 1 atm. The composition of the tie lines were evaluated using 1H NMR analysis for both extract and raffinate phases. Thereafter, the extraction efficiency of the DES is analyzed and compared by determining the solute distribution coefficients and the sele...

Liquid Liquid Equilibria measurements for the extraction of poly aromatic nitrogen hydrocarbons with a low cost Deep Eutectic Solvent: Experimental and theoretical insights

A low cost Deep Eutectic Solvent (DES) is used in this work to evaluate the selective extraction of poly aromatic hydrocarbons (PAH) from heptane. The DES synthesized is a combination of methyltriphenylphosphonium bromide salt and ethylene glycol as HBD at a molar ratio of 1:4. Quinoline and indoline as model PAH were then extracted from the toluene-heptane mixture at T=35°C. The Liquid-Liquid Equilibrium (LLE) data for the ternary system namely: DES (1)+indoline (2)+heptane (3) and quaternary systems; namely DES (1)+quinoline (2)+indoline (3)+heptane (4), DES (1)+quinoline (2)+toluene (3)+heptane (4) and DES (1)+indoline (2)+toluene (3)+heptane (4) were then measured at atmospheric pressure. The PAH concentrations in the system were varied from 5 to 70wt% to understand the extraction efficiency of DES. The composition of the respective components in both extract and raffinate phases were measured by 1H NMR technique. It was observed that all the systems followed a type-II phase behavior where a positive slope was seen towards the PAH peak. The distribution coefficient and selectively values for PAH in extract phase were two times higher than toluene. The reliability of the measured tie line data was then correlated with the local thermodynamic models namely NRTL and UNIQUAC models which gave a root mean square deviation (RMSD) of <1%. Further, Quantum chemical based COnductor like Screening MOdel for Real Solvents (COSMO-RS) model was also employed to predict the phase behavior of investigated systems.

Extraction of nitrogen compounds from model fuel using 1-ethyl-3-methylimidazolium methanesulfonate

Removal of nitrogen compounds is an essential process in the fuel processing industry. In this work, the extraction performance of 1-ethyl-3-methylimidazolium methanesulfonate ([Emim][MeSO3]) ionic liquid in removing pyrrole, indoline, pyridine and quinoline from cyclohexane is investigated. The ternary liquid-liquid equilibria for four systems containing [Emim][MeSO3] + pyrrole/indoline/pyridine/quinoline + cyclohexane were predicted using COSMO-RS and validated experimentally at 298.15 K under atmospheric pressure, with feed concentrations of nitrogen compounds ranging from 5 to 50 wt%. Othmer-Tobias and Hand correlations confirmed the consistency of the experimental data. The tie-lines obtained experimentally and predicted with COSMO-RS were in good agreement. Additionally, the non-random two-liquid (NRTL) model was successfully employed to correlate the experimental tie-lines. The effects of basicity of nitrogen compounds toward extraction efficiency were also investigated. The selectivity and distribution ratio results demonstrated the suitability of [Emim][MeSO3] as an extraction solvent for removing nitrogen compounds from fuel. Finally, the multicomponent extraction confirmed the performance of [Emim][MeSO3] for extractive denitrogenation. In all ternary systems investigated in this work, the concentration of cyclohexane in the extract phase was very small and the presence of the IL in the raffinate phase was negligible indicating minimum cross contamination between the extract and raffinate phases.

Liquid-liquid separation of azeotropic mixtures of ethanol/alkanes using deep eutectic solvents: COSMO-RS prediction and experimental validation

Separation of azeotropic mixtures is a topic of great industrial interest. In this work, liquid-liquid extraction using deep eutectic solvents (DESs) is explored to separate binary azeotropic mixtures of ethanol and n-hexane, n-heptane or n-octane. Ten DESs were screened using the COSMO-RS approach by predicting the activity coefficient at infinite dilution, γ∞ of ethanol and n-alkanes in each DES. Then, three DESs were selected for experimental validation where Tetrabutylammonium bromide/Levulinic acid (TBAB/LA) with a molar ratio (1:2) gave the best extractive performance for all systems. Ternary liquid-liquid extraction experiments were conducted at room temperature with this DES. It was found that the tie-lines of all systems have positive slopes, indicating that a small amount of solvent is required to extract ethanol. Moreover, the distribution ratio and selectivity values are all greater than unity and the DES was not detected in the raffinate phase which indicate minimal cross-contamination between extract and raffinate phases. Finally, COSMO-RS predictions of the ternary tie-lines were in excellent agreement with experimental data, with an average RMSD value of 1.65%. The experimental data were also successfully correlated with NRTL model with an average RMSD value of 1.50%.

Mass Transfer Coefficientin Stirred Tank for p-Cresol Extraction Process from Coal Tar

Indonesia is a country that has a lot of coal resources. The Indonesian coal has a low caloric value. Pyrolysis is one of the process to increase the caloric value. One of the by-product of the pyrolysis process is coal tar. It contains a lot of aliphatic or aromatic compounds such asp-cresol (11% v/v). It is widely used as a disinfectant. Extractionof p-Cresol increases the economic value of waste of coal. The aim of this research isto study about mass tranfer coefficient in the baffled stirred tank for p-Cresolextraction from coal tar. Mass transfer coefficient is useful for design and scale up of industrial equipment. Extraction is conducted inthe baffled stirred tank equipped with a four-bladed axial impeller placed vertically in the vessel. Sample for each time processing (5, 10, 15, 20, 25 and 30minutes) was poured into a separating funnel, settled for an hour and separated into two phases. Then the two phases were weighed. The extract phases and raffinate phases were analyzed by Spectronic UV-Vis. The result showed that mixing speed of p-Cresol extraction increasesthe yield of p-Cresol and the mass transfer coefficient. The highest yield of p-Cresol is 49.32% and the highest mass transfer coefficient is 4.757 x 10-6kg/m2s.

Simulation and process design of continuous countercurrent ethanolic extraction of rice bran oil

The overwhelming majority of all vegetable oils is extracted using solvent extraction, and the most widely used solvent is hexane. However, the use of ethanol has attractive advantages, including low toxicity, good operational security, as well as being obtained from a biorenewable source. In this study, a multiple-batch solid-liquid extraction system has been successfully employed to simulate continuous countercurrent ethanolic extraction of rice bran oil. Results showed that the extraction process using ethanol as solvent is feasible and facilitated by increases in temperature. The number of equilibrium stages required for rice bran oil extraction was theoretically determined, and it was shown that in the extraction process using hexane the number of ideal stages is lower than the number required when ethanol is used as solvent. Furthermore, a mathematical expression for determining the minimum flow of solvent depending on the equilibrium relationship between the extract and raffinate phases has been developed and implemented for both solvents. Given the potential fire hazard and harmful emissions risks of using hexane as solvent, extraction with ethanol showed to be a promising alternative to conventional extraction, completely exhausting the solid matrix with only five stages.

Evaluation of Deep Eutectic Solvent for the selective extraction of toluene and quinoline at T = 308.15 K and p = 1 bar

The current work reports the selective separation of aromatic and poly aromatic hydrocarbon (PAH) with Deep Eutectic Solvents (DES). The low cost DES are based on a mixture of a hydrogen bond donor and organic salt. The organic salt namely Methyltriphenylphosphonium bromide(MTBP) along with the hydrogen bond donor (HBD) were taken in a ratio of 1:4 to synthesize potential DES. DES were then varied based on the selection of two hydrogen bond donor namely ethylene glycol(DES1) and glycerol(DES2). In order to study their effectiveness, Liquid-liquid Equilibrium experiments were performed for the removal of toluene and quinoline respectively. LLE data corresponding to the ternary systems:[DES1(1) + Toluene(2) + Heptane(3)],[DES2(1) + Toluene(2) + Heptane(3)], [DES1(1) + Quinoline(2) + Heptane(3)] and [DES2(1) + Quinoline(2) + Heptane(3)] were generated at 308.15 K and atmospheric pressure. 1H NMR analysis were then used for the quantification of both extract and raffinate phases. Distribution coefficient (β) and selectivity (S) were subsequently obtained and it was found that toluene had a poor selectivity than quinoline. The cross contamination of DES and heptane across either phases were found to be nearly zero. Further the Non-random two liquid (NRTL) and UNiversal QUAsi Chemical (UNIQUAC) thermodynamic model were used to compare the experimental tie line data. This gave an excellent fit with a root mean square deviation (RMSD) values for both models ranging from (0.28–0.31%) and (0.22–0.73%) respectively. DES1, namely Methyltriphenylphosphonium bromide + ethylene glycol was thus recommended as a potential solvent for the separation of aromatic and PAH component.

Extractive denitrogenation of diesel fuel using ammonium- and phosphonium-based deep eutectic solvents

Recently, we published the results of screening the performance of 94 deep eutectic solvents (DESs) by COSMO-RS for potential use in the extractive denitrogenation of diesel. In this work and based on our previous predictions, tetrabutylammonium bromide+ethylene glycol and tetrabutylphosphonium bromide+ethylene glycol DESs at molar ratio 1:2 were explored experimentally for the removal of pyrrole, pyridine, indoline and quinoline from a model diesel compound, n-hexadecane. Ternary (liquid+liquid) equilibrium experiments were conducted at room temperature with nitrogen concentrations in the feed ranging from (5 to 50)wt%. 1H NMR spectroscopy was used for compositional analysis of the extract and raffinate phases. No amount of the solvent in the raffinate phases was detected; indicating minimal cross contamination. Also, it was found that all systems exhibit Type I phase behavior with positive slopes which indicate that small amount of solvents is required to remove the nitrogen compounds. Moreover, the distribution ratio and selectivity values are all greater than unity with higher values reported for non-basic nitrogen compounds. COSMO-RS predictions of the ternary tie lines were in good agreement with experimental data with average RMSD value of 2.51%. The experimental data were also well correlated with NRTL model with average RMSD value of 0.60%.

Analysis of the three-step cyclic process of countercurrent extraction

A mathematical model of the three-step cyclic process of countercurrent extraction has been developed. Each cycle consists of two half periods, i.e., the half period of the motion of the flow of the first solvent phase and the half period of the motion of the flow of the second solvent phase. The first half period is composed of two steps, i.e., the step of feed supply (first solvent containing an initial mixture of components) and the step of the supply of the first solvent (without the initial mixture). The analytical dependences that describe the concentration profiles in a cascade of equilibrium stages at all three steps of the process for each cycle and a change in the concentrations in the output flows of the raffinate and extract phases were obtained. An analysis of the influence of operating parameters on the efficiency of the process of separation of a binary mixture was performed.

Separation of aromatic solvents from oil refinery reformates by a newly designed ionic liquid using gas chromatography with flame ionization detection.

The aim of this study was to determine whether the new ionic liquid, N,N-dimethyl-2-oxopyrrolidonium iodide, synthesized in our laboratory is a suitable solvent for the separation of aromatic components benzene, toluene, ethylbenzene, and xylenes from petroleum mixtures (reformates) in liquid-liquid extraction. In pursuance of the above aim, a method to extract all components of a mixture, containing four aromatic components simultaneously, was developed. A new ionic liquid and a previously used liquid were compared for their extraction abilities. These ionic liquids were, respectively, N,N-dimethyl-2-oxopyrrolidinium iodide and 1-ethyl-3-methyl imidazolium ethyl sulfate. The concentrations of each benzene, toluene, ethylbenzene, and xylenes component in the extract and raffinate phases were measured by gas chromatography with flame ionization detection as volume percent to determine the extraction ability of the ionic liquids. The results obtained for both the reformate samples and model mixtures indicated that the new ionic liquid was effective as an extracting solvent for the recovery of aromatic components from reformates. Also the analysis results, using gas chromatography with flame ionization detection, for the reformate samples were as good as the results obtained by a local oil refinery. The extraction results also show that the developed method is very suitable for the separation and analysis of aromatic components in reformates.

Design and Synthesis of Thermoresponsive Ionic Liquid Polymer in Acetonitrile as a Reusable Extractant for Separation of Tocopherol Homologues

We report the design and development of a series of novel ionic liquid polymers (PILs) which possess thermoresponsive properties in organic solvent. The PILs were synthesized via reversible addition–fragmentation chain transfer (RAFT) copolymerization of 1-vinyl-3-butylimidazolium bromide and N-isopropylacrylamide, followed by anion exchange of bromide to amino acid d-alanine. The PILs possessed 0.36–0.76 molar fraction of ionic liquid with number-average molecular weight of 2.70–8.17 kg/mol and polydispersity index ranging between 1.12 and 1.25. The copolymerizations followed first-order reaction kinetics, and they were well-controlled, as indicated by the linear increase of molecular weight with monomer conversion. The PILs were thermoresponsive in acetonitrile with upper critical solution temperatures (UCST) varying from 25.7 to 34.8 °C, owing to the introduction of anion of amino acid. The PILs could be completely precipitated out by lowering the solution temperature. The PIL/acetonitrile solutions were used as extract phase for separation of tocopherol homologues in hexane. The distribution coefficient of δ-tocopherol between the extract and raffinate phases (Dδ) and the selectivity coefficient of δ-tocopherol to α-tocopherol (Sδ/α) reached as high as 7.86 and 13.0, respectively, while Dβ&γ was 3.63 and Sβ&γ/α was 6.0. The mole ratio of α-tocopherol in the raffinate phase increased from 0.08 to 0.27 after one stage extraction. The PILs could be reused for multiple extraction cycles with negligible change in the tocopherol distribution and selectivity coefficients. The thermoresponsivity of the PILs is of great benefit by eliminating the normally required back extraction steps. This work demonstrates the potential of thermoresponsive polymers for use in high performance separation of natural products.

Subcritical water extraction of steviol glycosides from Stevia rebaudiana leaves and characterization of the raffinate phase

The objectives of this work were to obtain steviol glycosides of S. rebaudiana leaves, possessing natural and noncaloric sweetener properties, using subcritical water extraction; to assess optimum extraction conditions; to determine biological activities of Stevia extracts and to characterize the raffinate phase. A Box–“Bhenken” statistical design was used to evaluate the effects of various values of temperature (100–150°C), time (30–60min) and flow rate (2–6ml/min) at a pressure of 230bar applying a solid/liquid ratio of 1:10 (m:v). The most effective parameter was temperature (p<0.005). Optimum extraction conditions were elicited as 125°C, 45min, 4ml/min flow rate which yielded 38.67mg/g stevioside and 35.68mg/g rebaudioside A. The total phenolic, flavonoid contents and DPPH free radical scavenging activity were found as 48.63mg gallic acid/g extract, 29.81mg quercetin/g extract and 92.50%, respectively. After extraction, total chlorophyll, carotenoid contents and dietary fibers were quantified as 31.91mg/100g, 5.71mg/100g and 4.98% in the raffinate phase. Hence, both extract and raffinate phases of S. rebaudiana leaves can be utilized as sources of natural sweeteners, fibers and coloring agents in the industry.

Deterpenation of eucalyptus essential oil by liquid + liquid extraction: Phase equilibrium and physical properties for model systems at T = 298.2 K

As the principal source in Brazil of eucalyptus essential oil extracts, Eucalyptus citriodora contains citronellal, an oxygenated compound responsible for the flavour characteristics. Deterpenation processes, consisting of the removal of terpenic hydrocarbons with the subsequent concentration of the oxygenated compounds, can be used to improve the aromatic characteristics of this essential oil. The purpose of this work was to perform a study of the technical feasibility of using a liquid+liquid extraction process to deterpenate eucalyptus essential oil. Model systems with various mixtures of limonene and citronellal (representing eucalyptus essential oil) as well as solvent (ethanol with various water mass fractions) were used to obtain liquid+liquid equilibrium data. The raffinate and extract phases were also analyzed to characterize the physical properties (density and viscosity). The equilibrium data were used to adjust the NRTL and UNIQUAC parameters. Two empirical models, the simple mixing rule and the Grunberg–Nissan model, were evaluated for use in the descriptions of the densities and viscosities, respectively, of the samples. Increasing the water content in the solvent resulted in decreases in the limonene and citronellal distribution coefficients, with consequential increases in the solvent selectivity values. Increasing values of the densities and viscosities, especially for the solvent-rich phases, were associated with systems using high amounts of hydrated ethanolic solvents.

Solvent extraction of oxidized diesel fuel: Phase equilibrium

An oxidative-desulfurization (ODS) process was used, instead of the conventional hydrodesulfurization (HDS) process, to remove sulfur from diesel fuel. This ODS process comprises two stages: oxidation using H2O2 and acetic acid, followed by solvent extraction with dimethylsulfoxid (DMSO) which having the capability to dissolve sulfur and aromatic compounds. The extraction efficiency for diesel fuel was improved by preceding the extraction with oxidation.The phase equilibrium data and the ternary miscibility diagram of the system oxidized diesel fuel-DMSO have been investigated and determined. Countercurrent multiple contact extraction results for the previous system were derived from the phase equilibrium data both by construction and calculation methods. The minimum and maximum amounts of the solvents (Smin and Smax) that may be used, which define the final extract and raffinate phases (Em and Rm) were estimated from the ternary equilibrium diagram. Also the number of theoretical stages needed for the production of the desired product (Rm), yield, aromatic and sulfur contents of the raffinate and extract products using the studied solvent at various solvent/feed ratios (S/F) were determined. Thus this combination processes is capable of removing up to 98.6wt.% of the sulfur compounds in diesel fuel at acceptable yield.