Equilibrium Experiments Research Articles

Amide solvents for extraction and separation of 1-hexene from n-heptane: Effect of the amount of methyl groups

In this work, the influence mechanism of methyl group in the structure of amide solvent on the extraction and separation of alkene (1-hexene or 1-octene) from n-heptane has been studied by a combination of liquid–liquid equilibrium (LLE) experiments and quantum chemical calculations. For LLE experiments, as the number of methyl groups in the extractant structure increases, its selectivity for alkene (1-hexene or 1-octene) gradually decreases, and the distribution coefficients of alkene (1-hexene or 1-octene) and n-heptane gradually increase. In the interaction between 1-hexene and extractant, the amount and intensity of C-H⋯O interactions, as well as the presence or absence of N/C-H⋯π interactions and their intensities, are all affected by the amount (0,1,2,3) of methyl group introduced into the amide solvent. The existence of the C-H⋯O and N-H⋯π interactions were verified by the infrared spectroscopy. With increasing methyl group amounts in the extractant structure, the dispersion interaction strengthens, while the contribution percentage of electrostatic interaction and ΔEelst/ΔE declines, leading to the increase of distribution coefficient and decrease of selectivity for alkene (1-hexene or 1-octene) respectively.

Natural mineral colloids facilitated transport of EE2 in saturated porous media: Effects of humic acid and conjugate form

Steroid estrogens have posed significant ecological risks to aquatic organisms due to their potent endocrine-disrupting effects. The role of natural mineral colloids in facilitating the transport of hydrophobic organic pollutants in the environment has been confirmed, but the control mechanisms of colloids on 17α-Ethinylestradiol (EE2) migration in the subsurface environment are often still not well understood. This study combined the batch sorption equilibrium experiments and dynamic transport simulations to reveal the interface interactions and co-transport characteristics between illite colloids and EE2 at both macroscopic and microscopic levels. The existing form changes of EE2 and the influence of coexisting humic acid (HA) during transport in porous media were also specifically investigated. The batch experiments demonstrated that the primary mechanisms governing EE2 sorption onto illite colloids involved surface sorption and hydrogen bonding. The coexistence of HA could load onto the surface of illite colloids, thereby enhancing the colloidal sorption capacity for EE2. Transport experiments demonstrated that the migratory ability of EE2 in silty clay was limited, but illite colloids could significantly promote its penetration, with the peak penetration content (Ct/C0) increasing from 0.64 to 0.77. In the absence of HA, EE2 primarily transported in a dissolved form, accounting for 62.86% of the total concentrations. When HA concentrations were increased to 10 mg/L and 20 mg/L, the proportion of colloidal conjugate EE2 in the effluents reached 52.13% and 54.49%, respectively. The enhanced transport of EE2 by HA was primarily attributed to the improved migration ability of illite colloids and the increased proportion of illite-EE2 conjugate, resulting in a maximum Ct/C0 value of 0.94. The validity of these results was further confirmed by employing calculations based on the Derjaguin–Landau–Verwey–Overbeek and Colloidal Filtration Theory. This study provides new insights of understanding the transport of EE2 in subsurface environment.

Cosolvents effect on supercritical CO2 microemulsion containing ionic Liquid: Experiment and simulation

Supercritical carbon dioxide (scCO2) microemulsion containing ionic liquids (ILs) 1-ethyl-3-methylimidazolium acetate ([Emim]Ac) were prepared under mild operating conditions with the help of surfactant branched secondary alcohol ethoxylates (TMN-6) and cosolvents (water and ethanol). Phase equilibrium experiments and molecular dynamics (MD) simulations were conducted from gas-phase system, two-phase system to supercritical system. The conditions of constructing supercritical microemulsion were studied by using self-made phase equilibrium device. The effects of temperature, surfactant concentration, and cosolvent concentration on cloud point pressure (CPP) were studied. The results showed that the transparent and uniform microemulsion could not be formed in gas-phase and two-phase systems. In supercritical system, the proper addition of cosolvent water and ethanol contributed to the formation of microemulsion and the dissolution of ILs. However, the reduction effect of CPP was not obvious or even increased when only water was added. After added water and ethanol simultaneously, not only did the maximum WIL increase to 0.26, but CPP also significantly decreased. MD simulation was conducted to characterize the microstructure of three systems. Furthermore, the gyration radius, radial distribution function (RDF), and hydrogen bond dynamics were calculated to analyze the strengthening mechanism of cosolvents on self-assembly. The simulation results revealed that, water promoted the interaction between hydrophilic groups of surfactants and ionic liquids, while ethanol constructed a hydrogen bonding network between continuous and dispersed phases. Water and ethanol have synergistic effect on the preparation of supercritical microemulsion, which has a good effect on improving the self-assembly rate and aggregate stability.

Efficient extraction of lithium from alkaline solution using the synergistic extractants ethylhexyl salicylate and trialkylphosphine oxide in kerosene and stripping with acid

Efficient separation of lithium from alkaline solution with high Na/Li ratio is of great importance for the development of batteries for new energy industry. This work proposes the use of a novel extraction system composed of ethylhexyl salicylate (ES) and trialkylphosphine oxide (TRPO). The equilibrium experiment revealed that the order of metal ions extracted by ES/TRPO extraction system is Mg2+ > Ca2+ > Li+ > Na+ > K+. A recovery process including extraction, scrubbing, and stripping was designed to recover lithium from a solution of 3.25 g/L Li, 52 g/L Na and 0.8 mol/L OH−. More than 99% of lithium could be extracted to the organic phase. After stripping, a lithium-rich solution containing 25 g/L Li was obtained, and the system showed good stability in the cycling experiments. The FT-IR analysis and DFT calculation were conducted to investigate the extraction mechanism. The results demonstrated that ES mainly coordinates with metal ions through Ph-O and CO bonds to form a hexatomic ring complex, thereby allowing metal ions to enter the organic phase. The calculated binding energies of the complex are highly consistent with the equilibrium experiment. The present work may provide a novel extraction system to efficiently recover lithium from alkaline solution with high Na/Li ratio.

Adsorption behavior of Mg–Al layered double hydroxide on Pb(Ⅱ), Zn(Ⅱ), Cd(Ⅱ), and As(V) coexisting in aqueous solution

MgAl-layered double hydroxide（MgAl-LDH）was synthesized via hydrothermal method, and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption-desorption, energy dispersive spectrum (EDS). The results proved that the prepared MgAl-LDH exhibited a well-defined layered structure and mesoporous morphology with a large specific surface area, which endowed them with abundant adsorption sites and diffusion mass transfer channels for heavy metal ions. Subsequently, the MgAl-LDH was used to evaluate the adsorption efficiency for Pb(Ⅱ), Zn (Ⅱ), Cd (Ⅱ), and As(V) coexisting in aqueous solutions by batch equilibrium experiments. The results showed favorable adsorption performance of MgAl-LDH toward four coexisting ionic species, with competitive adsorption among the heavy metal ions. Under the experimental conditions, the removal rates of Pb(Ⅱ), Zn (Ⅱ), Cd (Ⅱ), and As(V) ions were 96.7%, 97.1%, 65.2%, and 98.7%, respectively, and the selective order for cation adsorption followed Pb(Ⅱ) > Zn (Ⅱ) > Cd (Ⅱ). Furthermore, the adsorption mechanisms of Pb(Ⅱ), Zn (Ⅱ), Cd (Ⅱ) and As(V) by MgAl-LDH were detailed conducted by XRD, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis, and could be ascribed to the surface complexation, precipitation and isomorphic replacement for Pb(Ⅱ), Zn (Ⅱ), Cd (Ⅱ) while surface complexation, ion exchange and electrostatic adsorption for As(V).

Efficient separation in n‐butyl ether production process from computational thermodynamics to process intensification

AbstractBiobutanol is a green solvent commonly used as gasoline additive. In this study, it is proposed the separation of azeotropic mixtures of butanol and n‐butyl ether (DBE) using ionic liquids (ILs). Suitable anions [AC]− and [H2PO4]− were screened by COSMO‐RS, and the effect of carbon chain length on the separation effect was investigated using quantum chemical calculations. It was found that the anion was primarily responsible for the separation effect, which grew as the carbon chain grew. Molecular dynamics simulations were used to verify the separation performance of the selected ILs. The separation effect of ILs was further verified using vapor–liquid phase equilibrium (VLE) experiments. The extractive distillation process with [PrMIM][AC] as the extractant was investigated to demonstrate the feasibility of ILs for the separation of butanol and DBE. This study analyzes the whole process from microscopic mechanism of action, which provides new ideas for the separation of alcohol‐ether systems.

Batch equilibrium experiments and modeling reveal weak temperature dependence of cyclic volatile methylsiloxane sorption in soil/sediment organic carbon-water systems

The organic carbon normalized partition coefficient, KOC, describes the equilibrium distribution of a chemical between water and organic carbon in soil or sediment. It is a key parameter in evaluating chemical persistence, mass distribution, and transport using multimedia fate and transport models. Considerable uncertainty remains about the KOC values of cyclic volatile methylsiloxane (cVMS) compounds, and in particular the dependence of KOC on temperature. In this study, we used a batch equilibrium (BE) method to measure KOC values and their temperature dependence between ∼5 and 25 °C for octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5) with soil and sediments. Approximate log KOC values at 25 °C were 4.5–5.0 for D4 and 5.5–6.1 for D5 with different sorbents, and decreased by 0.3 log units or less at 4–5 °C. Enthalpies of sorption, ΔHOC, obtained for the different sorbents ranged from +7.2 to +16 kJ mol−1, with average values of +7.9 and +13 kJ mol−1 for D4 and D5, respectively. These values differ in magnitude and direction from those reported elsewhere based on KOC values determined by a novel dynamic purge-and-trap (PnT) method, but are consistent with predictions based on their solvation properties. A new fugacity-based multimedia model incorporating sorption/desorption kinetics was developed and used to predict concentrations in the phases of BE and PnT systems during desorption of cVMS under different experimental and ideal conditions. Model simulations suggested that KOC values for cVMS compounds derived from the PnT systems could be influenced by sorption disequilibrium between water and solids controlled by desorption rates from the particle phase to water, and subsequent losses due to volatilization and degradation. This has the potential to result in overestimation of KOC values when fitting the experimental data of cVMS mass remaining in a PnT system over time, which could explain the observed differences between the methods.

Attraction from kinetic frustration in ladder systems

We analyze the formation of multiparticle bound states in ladders with frustrated kinetic energy in two-component bosonic and two-component fermionic systems. We focus on the regime of light doping relative to insulating states at half-filling, spin polarization close to 100%, and strong repulsive interactions. A special feature of these systems is that the binding energy scales with single-particle tunneling t rather than exchange interactions, since effective attraction arises from alleviating kinetic frustration. For two-component Fermi systems on a zigzag ladder we find a bound state between a hole and a flipped spin (magnon) with a binding energy that can be as large as 0.6t. We demonstrate that magnon-hole attraction leads to formation of clusters comprising several holes and magnons, and we expound on antiferromagentic correlations for the transverse spin components inside the clusters. We identify several many-body states that result from self-organization of multiparticle bound states, including a Luttinger liquid of hole-magnon pairs and a density wave state of two-hole–three-magnon composites. We establish a symmetry between the spectra of Bose and Fermi systems and use it to establish the existence of antibound states in two-component Bose mixtures with SU(2) symmetric repulsion on a zigzag ladder. We also consider Bose and Fermi systems on a square ladder with flux and demonstrate that both systems support bound states. We discuss experimental signatures of multiparticle bound states in both equilibrium and dynamical experiments. We point out intriguing connections between these systems and the quark bag model in QCD. Published by the American Physical Society 2024

Influence of biochar on the removal of Microcystin-LR and Saxitoxin from aqueous solutions

The present study assessed the effective use of biochar for the adsorption of two potent HAB toxins namely, Microcystin-LR (MCLR) and Saxitoxin (STX) through a combination of dosage, kinetic, equilibrium, initial pH, and competitive adsorption experiments. The adsorption results suggest that biochar has excellent capabilities for removing MCLR and STX, with STX reporting higher adsorption capacities (622.53–3507.46 µg/g). STX removal required a minimal dosage of 0.02 g/L, while MCLR removal needed 0.4 g/L for > 90%. Similarly, a shorter contact time was required for STX removal compared to MCLR for > 90% of toxin removed from water. Initial pH study revealed that for MCLR acidic conditions favored higher uptake while STX favored basic conditions. Kinetic studies revealed that the Elovich model to be most suitable for both toxins, while STX also showed suitable fittings for Pseudo-First Order and Pseudo-Second Order in individual toxin systems. Similarly, for the Elovich model the most suited kinetic model for both toxins in presence of each other. Isotherm studies confirmed the Langmuir–Freundlich model as the best fit for both toxins. These results suggest adsorption mechanisms including pore filling, hydrogen bonding, π–π interactions, hydrophobic interactions, electrostatic attraction, and dispersive interactions.

Carbamazepine adsorption with a series of organoclays: removal and toxicity analyses

Organoclays have been used as efficient adsorbents for pharmaceutical pollutants present in waters. Carbamazepine (CBZ) is one of the drugs most frequently found in water bodies. In this study, four organoclays were prepared by modifying bentonite with the cationic surfactants hexadecyltrimethylammonium bromide (HDTMA) and octadecyltrimethylammonium bromide. The synthesized materials were characterized by XRD, CHN, FTIR, TG, BET and SEM analyses, confirming organophilization. The surfactants were interspersed in different arrangements in the interlayer space. CBZ sorption was investigated through batch equilibrium experiments, under variation of the pH, contact time, dosage of adsorbent, and initial drug concentration. Changes in pH showed no adsorption influence. CBZ sorption by the organoclays followed a pseudo-second-order kinetics. The best sorption performance was obtained for the BCN1-HDTMA100 clay, with a capacity of 34.34 ± 1.41 mg g−1, about ten times greater than the unmodified bentonite under the same conditions. This may be attributed to the higher surfactant content. The adsorption isotherm at 25 ºC showed linear behavior. Toxicity tests of the organoclays and corresponding medium in presence of CBZ were carried out. This is a novelty report. Most of the organoclays had no toxicity against Artemia salina. The toxicity of the medium after adsorptive treatment was eliminated. Organoclay-CBZ hybrids were also characterized after adsorption. FTIR and TG analyzes confirmed the incorporation of the drug. Hydrophobic interaction was the dominant contribution evaluated to the adsorption of CBZ. The results demonstrated that organoclays can be a promising alternative adsorbent for the removal of pharmaceutical pollutants in water remediation.

Amino acids to reduce the escape of organic amines in the CO2 capture process

Carbon neutrality and carbon peaking are important strategic policies for our country. Carbon dioxide capture technology is the bottom of the realization of this strategy, in which amine escape is an important issue for the development of this technology. Herein, the proposal to utilize amino acids for reducing volatilization of organic amines was introduced for the first time. Diethylaminoethanol (DEEA), widely applied and highly volatile, was selected as the primary target for volatility reduction, while hydroxyethyl ethylenediamine (AEEA) and piperazine (PZ) were chosen as the main absorbents for absorption and desorption processes. The effects of DEEA addition on the main absorbent, different types of amino acid additives on volatility, and amino acids on absorption and desorption performance were investigated, respectively. Glutamine (Tyr) demonstrated significant potential in reducing the volatilization of organic amines; when 2% Tyr was added during gas–liquid equilibrium experiments, it resulted in a 74.5% decrease in DEEA volatilization within the absorbent system. Simulated gas–liquid entrainment escape showed that CO2 loading reduced volatilization by 42.31%, with a further reduction of 53.93% achieved when loaded with 0.5 molCO2/mol amine; this loading also had a promotional effect on absorption and desorption processes. Moreover, Tyr exhibited excellent stability without generating any degradation products, thereby prolonging absorber lifespan and minimizing economic cost losses.

Extraction, purification, and clumped isotope analysis of methane (Δ13CDH3 and Δ12CD2H2) from sources and the atmosphere

Abstract. Measurements of the clumped isotope anomalies (Δ13CDH3 and Δ12CD2H2) of methane have shown potential for constraining methane sources and sinks. At Utrecht University, we use the Thermo Scientific Ultra high-resolution isotope-ratio mass spectrometer to measure the clumped isotopic composition of methane emitted from various sources and directly from the atmosphere. We have developed an extraction system with three sections for extracting and purifying methane from high (> 1 %), medium (0.1 % to 1 %), and low-concentration (< 0.1 %) samples, including atmospheric air (∼ 2 ppm = 0.0002 %). Depending on the methane concentration, a quantity of sample gas is processed that delivers 3 ± 1 mL of pure methane, which is the quantity typically needed for one clumped isotope measurement. For atmospheric air with a methane mole fraction of 2 ppm, we currently process up to 1100 L of air. The analysis is performed on pure methane, using a dual-inlet setup. The complete measurement time for all isotope signatures is about 20 h for one sample. The mean internal precision values of sample measurements are 0.3 ± 0.1 ‰ for Δ13CDH3 and 2.4 ± 0.8 ‰ for Δ12CD2H2. The long-term reproducibility, obtained from repeated measurements of a constant target gas, over almost 3 years, is around 0.15 ‰ for Δ13CDH3 and 1.2 ‰ for Δ12CD2H2. The measured clumping anomalies are calibrated via the Δ13CDH3 and Δ12CD2H2 values of the reference CH4 used for the dual-inlet measurements. These were determined through isotope equilibration experiments at temperatures between 50 and 450 °C. We describe in detail the optimized sampling, extraction, purification, and measurement technique followed in our laboratory to measure the clumping anomalies of methane precisely and accurately. This paper highlights the extraction and one of the first global measurements of the clumping anomalies of atmospheric methane.

Electrical Resistivity and Phase Evolution of Fe–N Binary System at High Pressure and High Temperature

Partitioning experiments and the chemistry of iron meteorites indicate that the light element nitrogen could be sequestered into the metallic core of rocky planets during core–mantle differentiation. The thermal conductivity and the mineralogy of the Fe–N system under core conditions could therefore influence the planetary cooling, core crystallization, and evolution of the intrinsic magnetic field of rocky planets. Limited experiments have been conducted to study the thermal properties and phase relations of Fe–N components under planetary core conditions, such as those found in the Moon, Mercury, and Ganymede. In this study, we report results from high-pressure experiments involving electrical resistivity measurements of Fe–N phases at a pressure of 5 GPa and temperatures up to 1400 K. Four Fe–N compositions, including Fe–10%N, Fe–6.4%N, Fe–2%N, and Fe–1%N (by weight percent), were prepared and subjected to recovery experiments at 5 GPa and 1273 K. These experiments show that Fe–10%N and Fe–6.4%N form a single hexagonal close-packed phase (ɛ-nitrides), while Fe–2%N and Fe–1%N exhibit a face-centered cubic structure (γ-Fe). In separate experiments, the resistivity data were collected during the cooling after compressing the starting materials to 5 GPa and heating to ~1400 K. The resistivity of all compositions, similar to the pure γ-Fe, exhibits weak temperature dependence. We found that N has a strong effect on the resistivity of metallic Fe under rocky planetary core conditions compared to other potential light elements such as Si. The temperature-dependence of the resistivity also revealed high-pressure phase transition points in the Fe–N system. A congruent reaction, ε ⇌ γ’, occurs at ~673 K in Fe–6.4%N, which is ~280 K lower than that at ambient pressure. Furthermore, the resistivity data provided constraints on the high-pressure phase boundary of the polymorphic transition, γ ⇌ α, and an eutectoid equilibrium of γ’ ⇌ α + ε. The data, along with the recently reported phase equilibrium experiments at high pressures, enable construction of a phase diagram of the Fe–N binary system at 5 GPa.

Experimental and mechanism study on the separation of isobutyl alcohol and water azeotrope using hydrophobic deep eutectic solvents

Isobutyl alcohol with good miscibility, high octane number and energy density has been paid more and more attention in the field of new biofuels, as it is an ideal alternative fuel for gasoline. However, isobutyl alcohol and water azeotrope need a clean and efficient separation method to realize the separation in isobutyl alcohol production process and industrial wastewater. Three hydrophobic deep eutectic solvents (DESs) were used to separate isobutyl alcohol. Decanoic acid was used as hydrogen bond donor and menthol, thymol and lidocaine were used as hydrogen bond acceptors to synthesize DESs. The liquid-liquid equilibrium experiment was carried out for the system containing DESs and MSD −water at 101.3 kPa and 303.15 K, and the separation effect of different DESs was indicated using distribution coefficient (β) and selectivity (S). The σ-Profile can be a good reflection of the strength of a substance's ability to accept and provide hydrogen bonds. The interaction energy and self-diffusion coefficient of the separation system were described quantitatively by molecular dynamics simulation. The relationship between DESs and the separation system was analyzed quantitatively by radial distribution function and spatial distribution function. The separation results show that the three DESs have good separation effect on isobutyl alcohol-water system, among which the DESs synthesized by thymol and decanoic acid has the best separation effect, and the interaction of isobutyl alcohol-water separation process is controlled by van der Waals forces. DESs plays an important role in the separation and treatment of isobutyl alcohol-containing wastewater, and promotes the sustainable development of wastewater treatment projects to save costs and increase production benefits.

Last Interglacial subsurface warming on the Antarctic shelf triggered by reduced deep-ocean convection

The Antarctic ice-sheet could have contributed 3 to 5 m sea-level equivalent to the Last Interglacial sea-level highstand. Such an Antarctic ice-mass loss compared to pre-industrial requires a subsurface warming on the Antarctic shelf of ~ 3 °C according to ice-sheet modelling studies. Here we show that a substantial subsurface warming is simulated south of 60 °S in an equilibrium experiment of the Last Interglacial. It averages +1.2 °C at ~ 500 m depth from 70 °W to 160 °E, and it reaches +2.4 °C near the Lazarev Sea. Weaker deep-ocean convection due to reduced sea-ice formation is the primary driver of this warming. The associated changes in meridional density gradients and surface winds lead to a weakened Antarctic Circumpolar Current and strengthened Antarctic Slope Current, which further impact subsurface temperatures. A subsurface warming on the Antarctic shelf that could trigger ice-mass loss from the Antarctic ice-sheet can thus be obtained during warm periods from reduced sea-ice formation.

Exploring ionic liquids for the extraction separation of aromatic hydrocarbons from diesel via multiple interaction analyses coupled with experimental evaluation

The separation of aromatic hydrocarbons from petroleum fractions is of great significance for both the quality upgrading of products and value-added utilization of aromatic compounds. However, the separation of polycyclic aromatic hydrocarbons (PAHs) and their derivatives from diesel remains challenging because of their lower solubility and selectivity as compared to the monocyclic aromatic compounds. In this work, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][TF2N]) was screened from 320 ionic liquid (IL) candidates through solvent capacity predication using COSMO-RS method. Liquid-liquid equilibrium experiments were carried out using a series of tetralin/n-decane mixtures with different tetralin concentrations to evaluate the extraction performance of several solvents. The results indicate that [EMIM][TF2N] has high selectivity up to 95.73 for tetralin over n-decane, which is 4.5 and 3.9 times higher than that of dimethyl sulfoxide and sulfolane. During five regeneration cycles, the [EMIM][TF2N] exhibits consistent extraction performance and nearly complete recovery. Molecular polarity index (MPI) analysis indicates that tetralin has larger dissolving affinity to solvents as compared to n-decane. Combined analyses of interaction energy, energy decomposition, and visualization of weak interaction reveal that the crucial role of weak hydrogen bond in dominating the complex solvent–solute interactions. Compared to n-decane, tetralin shows a stronger interaction with the solvents due to the existence of C-H···π and hydrogen bond interactions. The great difference in interaction energy between {[EMIM]+ + tetralin} and {[EMIM]+ + n-decane}, therefore, endows [EMIM][TF2N] with high selectivity for tetralin. Given the dominant role of cation, a IL, [CN1 = C2SCCS2(CC = C)C1][TF2N] having both high selectivity and high solvent capacity was subsequently explored using the cation generation method based on the SeqVAE model. Furthermore, present study proposes a strategy for the design of ILs for separation and other specific application circumstances.

Improving the Teaching/Learning Process in the Binary Vapor–Liquid Equilibrium Experiment Based on the Activity Coefficient Model

Improving the Teaching/Learning Process in the Binary Vapor–Liquid Equilibrium Experiment Based on the Activity Coefficient Model

Systematic screening ionic liquid as extractant for benzene-cyclohexane separation

In the separation of aromatic-alkane systems, ionic liquids (ILs) demonstrate superior performance over organic solvents. In this work, a rational screening strategy is proposed for tailoring ILs for the benzene-cyclohexane extraction. The reliability of COSMO-RS and UNIFAC-IL for this system are first assessed by comparing experimentally reported and model-predicted ternary liquid–liquid equilibria. The key thermodynamic evaluations of ILs are predicted by COSMO-RS and UNIFAC-IL separately while their important physical properties and commercial availability are estimated by a deep learning model and prepared python program. The screened promising IL [EPY][Tf2N] is tested by liquid–liquid equilibrium experiments and the NRTL parameters are regressed. The process simulation with the chosen IL is conducted using Aspen Plus and then compared with that of a benchmark IL, affirming the exceptional efficacy of the identified [EPY][Tf2N] as a prospective solvent for the benzene-cyclohexane separation. This study can be a crucial reference for guiding screening of ILs for various separation applications.

Study on separation of acetonitrile and methanol azeotropic system using tetraethylammonium chloride-based deep eutectic solvents

Large quantities of waste streams containing mixed acetonitrile (ACN) and methanol (MeOH) are generated during pharmaceutical and chemical production. The polarity of these two substances is extremely similar, resulting in the formation of an azeotrope at room temperature and atmospheric pressure. In this study, deep eutectic solvents (DESs) were selected as extractants for the separation of ACN-MeOH binary azeotrope. To obtain suitable DESs, the σ-profiles of ACN, MeOH, DESs were calculated using the COSMO-SAC model, and the results demonstrated that the DESs synthesized when tetraethylammonium chloride (TEAC) was chosen as the hydrogen bond acceptor (HBA) and acetamide as the hydrogen bond donor (HBD) could effectively break the azeotropy of ACN and MeOH. Therefore, four DESs were synthesized with molar ratios of TEAC: acetamide = 1: n (n = 1, 2, 3, 4) for subsequent ACN-MeOH-DESs ternary vapor–liquid phase equilibrium (VLE) experiments at 101.3 kPa to determine the optimal extractant. The measured VLE data revealed the higher separation of DES TEAC-2acetamide on the ACN-MeOH binary azeotrope compared with other DESs. Afterward, the NRTL model was adopted to calculate the binary interaction parameters between ACN/MeOH and DESs. The results of the fitting indicated agreement with the experimental data. Finally, the separation mechanism was further analyzed using the interaction energy analysis, improved independent gradient model (IGMH), and the theory of atoms in molecules (AIM). The results indicated that the strong interaction between DESs and MeOH is the primary factor in the ability of DESs to break the azeotrope of the system.

479 EVALUATION OF IRAQI MONTMORILLONITE AS ADSORBENT FOR THE REMOVAL OF OXYTETRACYCLINE FROM WATER

This work is a contribution to the global interest of scientific community in the field of cleaning the environment from drug and antibiotic residues which lead to the development of new generations of bacteria with improved resistance to antibiotics. The sorption of oxytetracyclin, OTC, on an Iraqi certified clay mineral, the montmorillonite, is used as indicative for the success of the used treatments. Batch equilibration experiments were carried out to follow the sorption behavior of OTC on the clay. The concentration of OTC was determined by spectral absorption at 360 nm which presented excellent correlation with high performance liquid chromatography, HPLC, method over a wide range of concentration (R2 = 0.977). After equilibration of synthetic OTC solutions with the clay for various intervals of time and various pH values, the concentration of OTC was employed to estimate the sorption efficiency of montmorillonite. The pH of the solution has only minor effect on the sorption efficiency. The kinetic treatment of the sorption results indicated two distinctive steps for the adsorption of OTC on the clay. Montmorillonite was proved as a candidate sorption material for OTC ensuring a removal efficiency of (94-96%) even at low clay contents. Experimentally the OTC concentration could be decreased from 0.5 to 0.03 mol/L at a pH value of 5.5 by sorption onto 2.0 g clay (montmorillonite)/L.