Separation Of Liquid Mixtures Research Articles

Pillared graphene oxide frameworks for the adsorption and separation of polar protic and aprotic liquid solvents: The cases of pure water, methanol, dimethyl sulfoxide, and dimethyl sulfoxide-water mixtures.

Potential applications of previously synthesized pillared graphene oxide frameworks with phenyldiboronic acid linkers in the field of the adsorption and separation of polar protic and aprotic liquid solvents have been systematically explored using grand canonical Monte Carlo simulations. Particular attention was initially paid to the adsorption of pure liquid water, methanol, and dimethyl sulfoxide. The results obtained a significant increase in the isosteric heat of adsorption at low uptake in the case of dimethyl sulfoxide, which is about 17.9 and 26.8kJ/mol higher than the values corresponding to methanol and water adsorption. These findings indicated that from a thermodynamic point of view, these pillared graphene oxide frameworks could be used in the separation of dimethyl sulfoxide-water liquid mixtures. Systematic grand canonical Monte Carlo simulations were then subsequently performed for dimethyl sulfoxide-water mixtures, with a low dimethyl sulfoxide concentration. The calculated values of the separation selectivity indicate that these materials could have potential applications in the separation of these mixed liquid solvents. Molecular dynamics simulations performed for a representative adsorbed mixture have revealed a substantial slowing down of the dynamics under confinement, particularly in the case of the hydrogen bonds formed between water and dimethyl sulfoxide.

Influence of Process Parameters on the Efficiency of Pervaporation Pilot ECO-001 Plant for Raw Ethanol Dehydration.

Pervaporation is a membrane-based process used for the separation of liquid mixtures. As this membrane process is governed by the differences in the sorption and diffusivities of separated components, close boiling mixtures and azeotropic mixtures can effectively be separated. The dehydration of ethanol is the most common application of hydrophilic pervaporation. The pilot scale properties of hydrophilic composite poly(vinyl alcohol) PVA membrane (PERVAPTM 2200) in contact with wet raw bioethanol are presented. The wet raw bioethanol was composed of ethanol (82.4-89.6 wt%), water (5.9-8.5 wt%), methanol (2.3-6.9 wt%), cyclohexane (0.2-2.4 wt%), higher alcohols (0.2-1.3 wt%), and acetaldehyde (0.004-0.030 wt%). All experiments were performed using a SULZER ECO-001 plant equipped with a 1.5 m2 membrane module. The efficiency of the dehydration process (i.e., membrane selectivity, permeate flux, degree of dehydration) was discussed as a function of the following parameters: the feed temperature, the feed composition, and the feed flow rate through the module. It was found that the low feed flow rate influenced the dehydration efficiency as the enthalpy of evaporation caused a high temperature drop in the module (around 25 °C at a feed flow rate equal to 5 kg h-1). The separation coefficient during pervaporation was in the range of 600-1200, depending on the feed composition. The increase in temperature augmented the permeation flux and shortened the time needed to reach the assumed level of dehydration. It was revealed that dehydration by pervaporation using ECO-001 pilot plant is an efficient process, allowing also to investigate the influence of various parameters on the process efficiency.

A priori and a posteriori estimates for solving one evolutionary inverse problem

This article considers an initial-boundary value problem for a system of parabolic equations, which arises when studying the flow of a binary mixture in a horizontal channel with walls heated non-uniformly. The problem was reduced to a sequence of initial-boundary value problems with Dirichlet or Neumann conditions. Among them, an inverse problem with a non-local overdetermination condition was distinguished. The solution was constructed using the Fourier method and validated as classical. The behavior of the non-stationary solution at large times was discussed. It was shown that certain functions within the solution tend to their stationary analogs exponentially at large times. For some functions, only boundedness was proved. The problem and its solution are relevant for modeling the thermal modes associated with the separation of liquid mixtures.

Data-driven predictions of complex organic mixture permeation in polymer membranes

Membrane-based organic solvent separations are rapidly emerging as a promising class of technologies for enhancing the energy efficiency of existing separation and purification systems. Polymeric membranes have shown promise in the fractionation or splitting of complex mixtures of organic molecules such as crude oil. Determining the separation performance of a polymer membrane when challenged with a complex mixture has thus far occurred in an ad hoc manner, and methods to predict the performance based on mixture composition and polymer chemistry are unavailable. Here, we combine physics-informed machine learning algorithms (ML) and mass transport simulations to create an integrated predictive model for the separation of complex mixtures containing up to 400 components via any arbitrary linear polymer membrane. We experimentally demonstrate the effectiveness of the model by predicting the separation of two crude oils within 6-7% of the measurements. Integration of ML predictors of diffusion and sorption properties of molecules with transport simulators enables for the rapid screening of polymer membranes prior to physical experimentation for the separation of complex liquid mixtures.

Diversified separations of immiscible organic liquids by a modification of superwettable supramolecular framework composite on porous support

Superwetting porous materials possessing wide applicability and responsiveness are becoming highly desired for the needs of the separation of immiscible liquid mixtures with less difference in surface tension during the treatment of wastes. In targeting this purpose, we propose a strategy to regulate the wettability of a sponge by coating a supramolecular framework (SF) bearing tunable wetting states under the assistance of polycaprolactone. This SF assembly-modified porous support demonstrates the under-liquid dual lyophobicity for polar liquids under nonpolar ones and for nonpolar liquids under polar ones via a simple in-situ adjustment of intermediate fluids. Depending on the capillary force of nanopores and amphiphilic components existing in the SF assembly, the switchable surface-modified sponge connecting to a pump quickly suction lyophilic organic liquids either located on the top or bottom phase despite touching the lyophobic liquids. Moreover, in-situ modulated filtrations to the emulsions comprising polar and nonpolar liquids are achieved with high efficiency (greater than 94.8 %) and flux (up to 9261.2 L m−2 h−1). Importantly, the suction and filtration separations are also available for organic liquid pairs with a high viscosity. The reversible interconversion between nonpolar and polar liquids is achieved and can be recycled several times with undiminished performance.

Repeated Microphase Separation and Heating-free Distillation-like Behavior of Miscible Binary Liquid Mixtures Using Nanoconfined Grafted Polymer Layers.

Nanoconfinement is known to drive phase separation (often denoted as microphase separation) of two highly miscible liquids by subjecting the two liquids to disparate influences. Here, we propose a paradigm shift to this problem: we introduce the idea of "repeatability" in nanoconfinement-driven microphase separation. A drop consisting of two highly miscible liquids (A and B) is made to pass through a nanochannel grafted with a collapsed layer of polymer that is philic to A but phobic to B. Subsequently, a significant number of molecules of liquid A get imbibed into the polymer layer and the polymer layer partially swells, while the molecules of liquid B mostly remain out of the polymeric layer and are carried away, emerging as a drop on the other side of the polymer bilayer. This passage of drop (of liquids A and B) is continued, and each time liquids A and B get separated with liquid A imbibing into the polymer layer and liquid B being carried away with the drop. This scenario, therefore, points to the repeated occurrence of the microphase separation of miscible binary liquid mixtures, enabling the processing of a much larger volume of liquid, given the fact that the presence of a grafted polymer layer continues to provide a dynamically increasing space where liquid A can get localized after being separated from liquid B. We quantify such repeated microphase separation by noting the extent of separation (of liquid A) and extent of recovery (of liquid B) as functions of nanochannel height and number of passes. Interestingly, we establish that this process also leads to a distillation-like behavior (without any heat addition), where the concentration of liquid B (equivalent to the "less volatile" liquid in a standard distillation process) progressively increases inside the drop after its passage through the nanochannel.

Separation of liquid crystalline racemic mixtures obtained on the basis of (R,S)-2-hexanol on amylose tris(3-chloro-5-methylphenylcarbamate) covalently immobilised on silica in high-performance liquid chromatography

ABSTRACT The separation on the enantiomers of thirteen newly synthesised liquid crystalline racemic mixtures obtained on the basis of (R,S)-2-hexanol was studied in HPLC on a chiral column prepared by covalent immobilisation of the chiral selector, namely amylose tris(3-chloro-5-methylphenylcarbamate) on silica. The mobile phases (MPs) consisting of n-heptane/isopropanol (IPA) or acetonitrile (ACN)/water (H2O) at different volume ratios were used. All measurements were made at room temperature. The order of the elution was also determined. The chromatographic parameters such as: resolution - (R), selectivity - (α) and number of theoretical plates - (N) were determined. On the basis of the obtained results, optimal conditions were indicated for the best separation of the tested racemic mixtures.

Possibilities of Optimizing the Purity of Mannose in Continuous Chromatographic Separation

AbstractThe development of separation technology based on continuous simulated moving bed chromatography in sugar technology is described. This is a potential economic alternative method both in terms of separation efficiency and process performance, and in terms of the high purity of the resulting products. This work focuses in detail on the isolation of mannose from natural polysaccharides, such as galactomannans; however, the developed procedures and equipment can be further applied to the separation of various liquid mixtures of carbohydrates. The main aim was to find optimal operating conditions for hydrolytic and separation steps of the whole technology. The obtained results provide a basic data set for further development of the industrial application.

Liquid–Liquid Phase Separation of Two Non-Dissolving Liquids—A Mini Review

The separation of immiscible liquids is critical in many industrial processes, such as water treatment, different extraction processes, the petroleum industry, food production, and medicine. This work provides an overview of present research on the separation of liquid mixtures. A brief summary of the thermodynamic basis is provided, covering phase equilibrium, phase diagrams, and thermodynamic properties of phases. Additionally, the fundamentals of dispersion, necessary for discussing liquid–liquid separation, are presented. Subsequently, different liquid–liquid separation methods are discussed, highlighting their advantages and limitations. These methods include decanters, coalescers, centrifugal separators, membranes and electro-coalescers for liquid–liquid separation. Phase properties, dispersion formation, and time and space constraints specify the most efficient separation method. Phase recycling is also briefly discussed as a method to reduce the environmental impact of liquid–liquid extraction with subsequent phase separation. In summary, liquid–liquid separation methods are compared and future perspectives of liquid–liquid separation are discussed.

Applicability of Composite Magnetic Membranes in Separation Processes of Gaseous and Liquid Mixtures-A Review.

Recent years have shown a growing interest in the application of membranes exhibiting magnetic properties in various separation processes. The aim of this review is to provide an in-depth overview of magnetic membranes that can be successfully applied for gas separation, pervaporation, ultrafiltration, nanofiltration, adsorption, electrodialysis, and reverse osmosis. Based on the comparison of the efficiency of these separation processes using magnetic and non-magnetic membranes, it has been shown that magnetic particles used as fillers in polymer composite membranes can significantly improve the efficiency of separation of both gaseous and liquid mixtures. This observed separation enhancement is due to the variation of magnetic susceptibility of different molecules and distinct interactions with dispersed magnetic fillers. For gas separation, the most effective magnetic membrane consists of polyimide filled with MQFP-B particles, for which the separation factor (αrat O2/N2) increased by 211% when compared to the non-magnetic membrane. The same MQFP powder used as a filler in alginate membranes significantly improves water/ethanol separation via pervaporation, reaching a separation factor of 12,271.0. For other separation methods, poly(ethersulfone) nanofiltration membranes filled with ZnFe2O4@SiO2 demonstrated a more than four times increase in water flux when compared to the non-magnetic membranes for water desalination. The information gathered in this article can be used to further improve the separation efficiency of individual processes and to expand the application of magnetic membranes to other branches of industry. Furthermore, this review also highlights the need for further development and theoretical explanation of the role of magnetic forces in separation processes, as well as the potential for extending the concept of magnetic channels to other separation methods, such as pervaporation and ultrafiltration. This article provides valuable insights into the application of magnetic membranes and lays the groundwork for future research and development in this area.

State-of-the-art review of porous polymer membrane formation characterization—How numerical and experimental approaches dovetail to drive innovation

Porous polymer membranes substantially contribute to an acceleration of sustainability transformation based on the energy efficient separation of liquid and gaseous mixtures. This rapid shift toward sustainable industrial processes leads to an increased demand for specifically tailored membranes. In order to predict membrane performance factors like permeability, selectivity and durability, the membrane formation process by film casting and phase inversion needs to be understood further. In recent years, computational models of the membrane formation process have been studied intensely. Their high spatial and temporal resolution allows a detailed quantitative description of phase inversion phenomena. New experimental techniques complement this development, as they provide quantitative data, e.g., on compositional changes of the polymer solution during membrane formation as well as the kinetic progression of the phase separation process. This state-of-the-art review compiles computational and experimental approaches that characterize the phase inversion process. We discuss how this methodological pluralism is necessary for improving the tailoring of membrane parameters, but that it is unlikely to be the way to the ultimate goal of a complete description of the evolution of the membrane structure from the initial demixing to the final solidification. Alternatively, we formulate an approach that includes a database of standardized and harmonized membrane performance data based on previously publicized data, as well as the application of artificial neural networks as a new powerful tool to link membrane production parameters to membrane performance.

Molecular Simulation of Pervaporation on Polyurethane Membranes.

This article discusses a molecular simulation of membrane processes for the separation of liquid mixtures during pervaporation. A method for simulating the structure of polyurethane membranes was developed. The method was based on the known mechanisms of the formation of macromolecules from constituent monomers. For the formation of a chemical bond between the monomers, values of the parameters of the potentials of intermolecular interactions were set so that bonds were formed only between the corresponding atoms. The algorithm was validated to produce polymer films from diphenylmethane diisocyanate (MDI) and amino ethers of boric acid (AEBA). The polymer film obtained according to the developed algorithm was used to study the adsorption of ethanol and water. The concentration distributions of the components inside the polymer film were obtained for films of various thicknesses. Modifications of the DCV-GCMD method were proposed for the molecular simulation of pervaporation. The algorithm was based on maintaining a constant density of the mixture in the control volume. After the molecules were added to the control volume, thermodynamic equilibrium was established. During this process, molecules moved only in the control volume, while the rest of the molecules were fixed. The proposed algorithm was used to calculate the flows of water and ethanol through the polymer film.

Neural network modeling of flow hydrodynamics in packed bed reactors

This paper presents the results of determination of the hydrodynamic characteristics of the packed bed reactor using an artificial neural network. Experimental and model values of the pressure drop are obtained, a graphical dependence of the hydraulic resistance of the packed bed on the fictitious gas velocity is constructed. In recent years, the processes of complex separation of gas and liquid mixtures have attracted considerable attention, both in academic research and in industrial applications, since they combine the advantages of flow recirculation and cost reduction by reducing equipment units. However, the design of separation processes, especially when it comes to the packed bed reactor, is still a difficult task for chemical engineers due to the difficulties associated with obtaining process models that can reliably describe the mutually influencing processes and phenomena, including simultaneous separation reactions, heat exchange in the conditions of the hydrodynamics of the packed bed reactor. The complex behavior of the process forced to look for a very reliable and powerful tool for modeling and simulating the dynamics of the packed bed reactor. Neural networks are one of the strategies proposed for solving such problems, since they can be trained to process and describe complex phenomena. This paper presents an approach using a neural network and the laws of physics with regression analysis. The efficiency and reliability of these method are proved by numerical experiment in comparison with experimental data taking into account various initial/boundary conditions. Thus, in this paper, neural networks are developed and modeled using Wolfram Mathematica to predict the resistance of the packed bed of the column.

Thermodynamic modeling of adsorption at the liquid-solid interface

Adsorptive separation techniques are significantly energy efficient in comparison to conventional thermal separation techniques such as distillation. Despite extensive research and development activities undertaken for mixed-gas adsorption, the use of adsorption techniques for the separation of multicomponent liquid mixtures is still limited. A major barrier is the lack of accurate adsorption thermodynamic models, which form the scientific foundation of process simulation of such systems, making the translation to industrial scale challenging. In this work, we have rigorously computed the surface excess of adsorption for six binary liquid mixtures on silica gel at 303 K using the frameworks of the generalized Langmuir isotherm (gL) and the adsorbed solution theory (AST). The six binary liquid mixtures were formed by the pair-wise combinations of four components: benzene, 1,2-dichloroethane, cyclohexane, and n-heptane. We have based our calculations by considering simultaneous equilibria of three phases: saturated vapor phase, bulk liquid phase, and adsorbed phase. The composition of the corresponding saturated vapor phase was estimated by the Nonrandom Two-Liquid activity coefficient model and experimental vapor-liquid equilibria data. The activity coefficients of the adsorbed phase, the central issue of multicomponent adsorption thermodynamics, were calculated using the adsorption Nonrandom Two-Liquid activity coefficient model. Devoid of simplifying assumptions, gL and AST provide rigorous thermodynamic frameworks for adsorption equilibria of multicomponent liquid mixtures.

Dry Glass Reference Perturbation Theory Predictions of the Temperature and Pressure Dependent Separations of Complex Liquid Mixtures Using SBAD-1 Glassy Polymer Membranes.

In this work we apply dry glass reference perturbation theory (DGRPT) within the context of fully mutualized diffusion theory to predict the temperature and pressure dependent separations of complex liquid mixtures using SBAD-1 glassy polymer membranes. We demonstrate that the approach allows for the prediction of the membrane-based separation of complex liquid mixtures over a wide range of temperature and pressure, using only single-component vapor sorption isotherms measured at 25 °C to parameterize the model. The model was then applied to predict the membrane separation of a light shale crude using a structure oriented lumping (SOL) based compositional model of petroleum. It was shown that when DGRPT is applied based on SOL compositions, the combined model allows for the accurate prediction of separation performance based on the trend of both molecular weight and molecular class.

Carbon nanotube assisted highly selective separation of organic liquid mixtures

Carbon nanotubes (CNTs) are prominent candidates for the separation of various polar and non-polar liquid mixtures. Numerous studies report the application of CNTs for isolating the binary aqueous liquid mixtures, but very few demonstrate the separation of organic liquid mixtures. Here, we investigate the selective permeation of cosolvents such as ethanol, isopropanol, n-butanol, acetone, and tetrahydrofuran into the CNTs from the binary mixtures of benzene using molecular dynamics simulations. Our findings reveal that extremely small-sized (11,0) CNTs achieve almost 100% cosolvent capture selectivity in all five equimolar binary mixtures. In considerably bigger-sized CNTs such as (20,0), benzene accumulates inside along with the cosolvent, however, forms a well-distinguishable layer close to the interior wall of CNTs analogous to the second layer of a double-walled CNT. The results confirm that the liquid capture and selectivity are governed by the polarity and molecular size of the solvents as well as the CNT diameters.

A model for the separation of complex liquid mixtures with glassy polymer membranes: A thermodynamic perspective

In this work, a new model is developed to predict the separation of organic solvent mixtures with glassy polymer membranes. Particular attention is paid to thermodynamic contributions such as guest solubility and guest-induced polymer swelling, and how these contributions affect the flux in multi-component mixtures. The thermodynamic contributions are complicated by the fact that the membranes are glassy polymers. The thermodynamic aspects of the diffusion problem are calculated using DGRPT (dry glass reference perturbation theory), which extends the non-equilibrium thermodynamics of glassy polymers (NETGP) such that polymer swelling is calculated self-consistently in the theory. The diffusion model for pure fluids diffusing through the membrane is obtained through Maxwell-Stefan equations where the polymer membrane is stationary. The mixture diffusion model is then constructed using a simple diffusivity averaging scheme on this pure fluid result. The model is then shown to accurately predict binary and complex mixture separations in SBAD-1, STARMEM-240, and Torlon membranes. We highlight the ability of the model accurately predict membrane based fractionation of crude oil, using only the sorption isotherms of toluene and octane as input to the model. • A new membrane model was proposed for multicomponent liquid mixtures in glassy polymer membranes. • The role of pressure in liquid phase reverse osmosis separations is discussed. • The model correctly predicts the separation of crude oil using only two experimental sorption isotherms.

Fabrication of melamine-based hybrid organic membrane for ethanol/water pervaporation

Covalent organic frameworks recently were utilized as membrane fillers for effective liquid mixture separation due to their intriguing structure. Though a facile dipcoating-wiping method, a melamine-based hybrid membrane was prepared where Chitosan (CS) was combined with SNW-1 (Schiff base network-1) on the surface of α -Al 2 O 3 support followed by crosslinking with calcium ions, a dense SNW-1/CS layer with thickness of 550 nm was successfully fabricated for ethanol/water pervaporation. The hydrophilicity of melamine-based membranes surface was enhanced by SNW-1 incorporation with improved anti-swelling property and thermal stability. The porous structure of SNW-1 offered free volume and fast channels for water transport. Consequently, the melamine-based membranes showed long-term stability and excellent separation factor of 373 with high permeance flux of 2.8 kg/(m 2 ·h). The fabrication of the SNW-1/CS hybrid membrane by dipcoating-wiping for ethanol/water pervaporation. • Melamine-based SNW-1 was incorporated into chitosan to fabricate COF-based SNW-1/CS hybrid membranes. • SNW-1 incorporation endowed the hybrid membrane with enhanced surface hydrophilicity, thermal stability and anti-swelling property. • Improved separation factor and permeance flux was observed on the SNW-1/CS hybrid membrane with long-term stability.

Miscible organic liquid separation of superwetting membrane driven by synergistic polar/nonpolar interactions

<h2>Summary</h2> Membrane-based technologies for separation of miscible liquid mixtures have been developed as potential alternatives to energy-intensive distillation. However, these separation modalities suffer drawbacks of needing thermal phase-change processes, exhibiting low flux, or utilizing complicated membrane preparation procedures. Here, we develop a polar/nonpolar interaction-induced superwetting membrane system to separate miscible organic liquid mixtures in an energy-saving and high-flux manner. The relatively polar (or nonpolar) target liquid component can rapidly permeate the porous membrane and be selectively separated by interacting with the polar (or nonpolar) porous membrane. Meanwhile, the other relatively nonpolar (polar) liquid component is being blocked through an additive inductive agent dragging it by forming strong nonpolar (or polar) interactions. With this newly developed system, we can successfully realize the separation of miscible organic liquid mixtures with a wide range of polarity. This research points toward new ways of developing the superwetting membrane-based technologies for miscible liquid mixture separation.

Acid-reinforced ionic cross-linking of sodium alginate/polyamidoamine dendrimer blended composite membranes for isopropanol dehydration through pervaporation

Extreme swelling of hydrophilic polymer such as sodium alginate in aqueous liquid mixture separation processes has always been a problem that needs to be resolved. Herein, the ionic interactions between polyamidoamine (PAMAM) dendrimers and sodium alginate (SA) were improved by using simple aqueous acidic solution after obtaining the dense composite membranes. The zero generation PAMAM dendrimer (G0) used has four terminal primary amine reactive groups (P4). The acid-reinforced ionic cross-linked (ARIC) membranes gave an impressive water stability even at high water content in feed of 90 wt% during the separation process. The composite membranes were characterized accordingly for their chemical and physical properties. Also, the efficiency of the ARIC process was evaluated by separating alcohol/water mixtures through pervaporation at varying feed concentration and temperature. Impressively, the membranes treated with sulfuric acid resulted to a smaller free volume size compared to hydrochloric acid revealed by positron annihilation spectroscopy (PAS). This means that a lower swelling degree for the sulfuric acid-treated membranes giving better separation efficiency even at high water feed composition. The best pervaporation separation performance was observed in separating 70/30 wt% isopropanol/H2O aqueous solution at 55 °C. It has a permeation flux of 6.59 kg m−2 h−1 and a 99.97 wt% water content in permeate. The membrane, SA-P4-H2SO4/PVDF also exhibited good stability for 552 h maintaining a water concentration in permeate above 97 wt%.