Immiscible Liquid Phases Research Articles

Metal Nanoparticles Stabilized in Ionic Liquids for Catalytic Multiphase Reactions

Metal nanoparticles (MNPs) have attracted widespread interest as catalytic materials due to their small size and high surface to volume ratio, which lead to a greater catalytic activity. To preserve such features however, agglomeration of MPNs must be prevented by the use of stabilizing agents of which ionic liquids (ILs) are probably the best ever reported compounds. ILs offer unique environments suitable for both the synthesis, the stabilization, and the segregration of highly dispersed MNPs. Such dispersions have been successfully tested for catalysis in a number of different processes mostly including hydrogenations, hydroformylations, and C-C bond forming reactions (Heck, Suzuki, Sonogashira, and Ullman couplings). In this review, an introductory section is focused on major aspects accounting for the stabilizing effects of ILs on MNPs. Then, model examples of catalytic applications are given for Pd-, Rh-, and Ru- NPs in multiphase systems composed of binary and ternary immiscible liquid phases which are able not only to improve the catalytic performance of NPs, but to allow also the recycling of nanocatalysts and the easy separation of reaction products. Keywords: Metal nanoparticles, multiphase organic reactions, catalysis, ionic liquids, catalyst recycling, products separation.

Capillary Structured Suspensions from In Situ Hydrophobized Calcium Carbonate Particles Suspended in a Polar Liquid Media.

We demonstrate that capillary suspensions can be formed from hydrophilic calcium carbonate particles suspended in a polar continuous media and connected by capillary bridges formed of minute amounts of an immiscible secondary liquid phase. This was achieved in two different polar continuous phases, water and glycerol, and three different oils, oleic acid, isopropyl myristate, and peppermint oil as a secondary liquid phase. The capillary structuring of the suspension was made possible through local in situ hydrophobization of the calcium carbonate particles dispersed in the polar media by adding very small amounts of oleic acid to the secondary liquid phase. We observed a strong increase in the viscosity of the calcium carbonate suspension by several orders of magnitude upon addition of the secondary oil phase compared with the same suspension without secondary liquid phase or without oleic acid. The stability and the rheological properties of the obtained capillary structured materials were studied in relation to the physical properties of the system such as the particle size, interfacial tension between the primary and secondary liquid phases, as well as the particle contact angle at this liquid-liquid interface. We also determined the minimal concentrations of the secondary liquid phase at fixed particle concentration as well as the minimal particle concentration at fixed secondary phase concentration needed to form a capillary suspension. Capillary suspensions formed by this method can find application in structuring pharmaceutical and food formulations as well as a variety of home and personal care products.

Mechanisms and Control of Self-Emulsification upon Freezing and Melting of Dispersed Alkane Drops.

Emulsification requires drop breakage and creation of a large interfacial area between immiscible liquid phases. Usually, high-shear or high-pressure emulsification devices that generate heat and increase the emulsion temperature are used to obtain emulsions with micrometer and submicrometer droplets. Recently, we reported a new, efficient procedure of self-emulsification (Tcholakova et al. Nat. Commun. 2017, 8, 15012), which consists of one to several cycles of freezing and melting of predispersed alkane drops in a coarse oil-in-water emulsion. Within these freeze-thaw cycles of the dispersed drops, the latter burst spontaneously into hundreds and thousands of smaller droplets without using any mechanical agitation. Here, we clarify the main factors and mechanisms, which drive this self-emulsification process, by exploring systematically the effects of the oil and surfactant types, the cooling rate, and the initial drop size. We show that the typical size of the droplets, generated by this method, is controlled by the size of the structural domains formed in the cooling-freezing stage of the procedure. Depending on the leading mechanism, these could be the diameter of the fibers formed upon drop self-shaping or the size of the crystal domains formed at the moment of drop-freezing. Generally, surfactant tails that are 0-2 carbon atoms longer than the oil molecules are most appropriate to observe efficient self-emulsification. The specific requirements for the realization of different mechanisms are clarified and discussed. The relative efficiencies of the three different mechanisms, as a function of the droplet size and cooling procedure, are compared in controlled experiments to provide guidance for understanding and further optimization and scale-up of this self-emulsification process.

Characterization of liquid–liquid mass transfer performance in a capillary microreactor system

Liquid–liquid mass transfer performance in a capillary microreactor system was studied with an improved experimental method. Proper sampling modes were chosen to eliminate the effect of the sampling zone on the mass transfer characterization in capillary microreactor systems. The overall volumetric mass transfer coefficients in the T‐micromixer and the capillary microreactor system were found to smoothly increase and then significantly increase with increasing the Reynolds number of two immiscible liquid phases. Other factors such as the inlet mode and inner diameter of T‐micromixer, the capillary length, and the volumetric flux ratio of the aqueous phase to the organic phase affected the mass transfer performance in the T‐micromixer and the capillary microreactor system. Furthermore, the contribution of the mass transfer in the T‐micromixer zone to the capillary microreactor system was found to be in a range of 34–78% under the involved experimental conditions, which was emphasized in the proposed empirical correlations. © 2017 American Institute of Chemical Engineers AIChE J, 64: 1106–1116, 2018

Experimental Investigation of Gas/Slag/Matte/Tridymite Equilibria in the Cu-Fe-O-S-Si System in Controlled Atmospheres: Development of Technique

The majority of primary pyrometallurgical copper making processes involve the formation of two immiscible liquid phases, i.e., matte product and the slag phase. There are significant gaps and discrepancies in the phase equilibria data of the slag and the matte systems due to issues and difficulties in performing the experiments and phase analysis. The present study aims to develop an improved experimental methodology for accurate characterisation of gas/slag/matte/tridymite equilibria in the Cu-Fe-O-S-Si system under controlled atmospheres. The experiments involve high-temperature equilibration of synthetic mixtures on silica substrates in CO/CO2/SO2/Ar atmospheres, rapid quenching of samples into water, and direct composition measurement of the equilibrium phases using Electron Probe X-ray Microanalysis (EPMA). A four-point-test procedure was applied to ensure the achievement of equilibrium, which included the following: (i) investigation of equilibration as a function of time, (ii) assessment of phase homogeneity, (iii) confirmation of equilibrium by approaching from different starting conditions, and (iv) systematic analysis of the reactions specific to the system. An iterative improved experimental methodology was developed using this four-point-test approach to characterize the complex multi-component, multi-phase equilibria with high accuracy and precision. The present study is a part of a broader overall research program on the characterisation of the multi-component (Cu-Fe-O-S-Si-Al-Ca-Mg), multi-phase (gas/slag/matte/metal/solids) systems with minor elements (Pb, Zn, As, Bi, Sn, Sb, Ag, and Au).

A novel simplified multivariate PBE solution method for mass transfer problems

Interphase mass transfer estimation may require not only the accurate knowledge of the interfacial area, which depends on the information about the size of each dispersed element, but also on the driving force, that can be different if the elements of the disperse phase have different chemical composition. To take into account such polydispersity, bivariate (or multivariate) population balance model (PBM) are formulated according to physical phenomena occurring in the investigated mass transfer problem. This often includes aggregation, breakage, advection, mass transfer of the chemical species and chemical reactions of the transferring components. In this work we propose a novel and simplified method to solve the bivariate/multivariate population balance equation for a mass transfer problem, based on the high-order moment-conserving method of classes (HMMC) (Alopaeus et al., 2006). The proposed method is based on the idea of deriving additional material balance equations for the concentration of the droplets belonging to each size class, reducing significantly the total number of unknown variables with respect to true bivariate/multivariate method of classes. This modeling approach is compared with two other possible solution methods for a test case in which mass transfer and chemical reactions occur in a system with two immiscible liquid phases. In the first the traditional approach is used, where a single material balance is formulated for the disperse phase along with PBM, while in the second a true bivariate/multivariate solution method is used. The results of this comparison show that the proposed method is robust and accurate, capable of properly describing the multidimensional droplet size-composition distribution needed to evaluate the mass transfer rates, in a fraction of the computational time compared with more accurate methods.

Synthesis and Characterisation of Novel Additives for Use in the Hybrid ZnBr2 Flow Battery

The zinc-bromine hybrid redox flow battery (RFB) is one of the few flow battery systems that have been commercially implemented for medium-to-large scale energy storage applications. One of the issues identified with this flow battery is bromine crossover from the positive electrolyte to the zinc side, leading to a loss of energy efficiency. This problem can be overcome through the use of inorganic-based complexing agents that bind the bromine in an immiscible liquid phase which is pumped from the electrode surface and stored in an external reservoir. This bromine-rich phase is recirculated back to the positive electrode during discharge of the battery. Currently, N-methyl-N-ethylpyrrolidinium bromide (MEP) is the choice complexing agent for industrial batteries. However, interest lies in developing a complexing agent that will bind with the electrogenerated bromine but remain in the aqueous phase of the solution. This would improve the charged materials ability to disperse throughout the solution and reduce the complexity of the pumping requirements currently used. A number of novel additives (based on specific quaternary ammonium salts, QBr) have been synthesized and characterized by focusing on both their impact on the Br2/Br− electrochemical kinetics and on their physical properties. Initial observations indicate that the amount of the immiscible liquid phase had been drastically reduced with the novel additives. Electrochemical techniques (including AC impedance spectroscopy and potentiodynamic polarisation) show that MEP and QBr have similar R CT values with a depressed semi circular profile (Figure 1). However, cyclic voltammetry shows a reduced reversibility of the Br2/Br− reaction with QBr present compared to MEP. The data from Tafel extrapolation show a 10-fold reduction in the exchange current density (j 0) between QBr and MEP. However, for the various solutions containing the QBr, MEP and no additive, the same Tafel slope was evaluated (B a ≈ 88 mV) as well as the same equilibrium potential (E 0 ≈ 0.88 V vs. SCE). This difference in the electrochemical kinetics between no additive/QBr and MEP from the CV is arguably due to the fact that the MEP can capture the electrogenerated bromine at the electrode surface better than QBr. These uncertainties led to the testing of the physical properties to determine how well the bromine is binding with the additives in question. The physical properties were found to be quite similar for all the additives (including MEP). The Br2 vapour pressure measured using an isoteniscope resulted in similar enthalpies of vaporization (ΔH ≈ 30 kJ mol− 1) and the quantity of Br2 remaining within the aqueous phase from iodometric titrations. Therefore, it can be assumed that the complex additives used bind similar concentrations of Br2 in the immiscible phase. This ability to capture (and release) larger amounts of bromine, was investigated using Raman spectroscopy and the presence of Br3 − and Br5 − species could be identified. By normalizing to the peak assigned to Br3 − the effectiveness of the novel additives can be compared to MEP based on the Br5 − content (Figure 2). The concentration ratios have an apparent effect on the intensity of the complexed peaks. However, this also shows that the new QBr salt has a similar effect on the physical properties of the electrolyte as MEP. From this series of synthesised QBr compounds, the objective to reduce the immiscible liquid phase has been achieved. This is evident from both visual inspections and the effect that QBr had on the physical properties. MEP still proves to be the better additive in terms of electrochemical kinetics. This serves as a strong starting point for finding a potential candidate that is as effective as MEP with the absence of the immiscible liquid. Figure 1

Intrinsically Disordered Domains, Amyloids and Protein Liquid Phases: Evolving Concepts and Open Questions.

Enzymes and structural proteins dominated thinking about protein structure and function for most of the twentieth century. In recent decades, however, we have begun to appreciate the significant physiological and pathological roles of nonglobular proteins. Amyloids first gained infamy from their implications in a score of human mortal diseases. However, they have recently been discovered to play vital physiological roles, such as memory consolidation in humans. This raises an important question: Can we inhibit pathological amyloids without affecting functional amyloids? Intrinsically disordered proteins (IDPs), many of which are prone to form amyloids, perform many essential functions, yet their importance has only been recognized in the last quarter century. A subclass of IDPs can form, under certain conditions, water immiscible liquid phases which serve to process, regulate, store or transport RNA. Perturbation of these remarkable liquid phases can lead to aggregates, such as those formed by the proteins TDP-43 and FUS, which are linked to ALS and other dementia. Here, we summarize our changing view of intrinsically disordered, liquid phase forming and amyloidogenic proteins and the uncertainties that will drive future research.

Centrifugal partition chromatography - A review of recent applications and some classic references.

Countercurrent chromatography, based on liquid-liquid partitioning, has many technological variants. One of them is centrifugal partition chromatography, introduced by Wataru Murayama and Kanichi Nunogaki in 1982. This technique, like other countercurrent chromatography techniques, is based on the phenomenon of liquid-liquid partitioning between two immiscible liquid phases that stay at equilibrium. But the significant difference between this technique and others is the retention mechanism of stationary phase. In the case of centrifugal partition chromatography, this mechanism is based on hydrostatic force, formed by the centrifugal field in the rotor in one-axis centrifuge. Sometimes that allows more control of stationary phase, for example, when aqueous two-phase and other difficult solvent systems are used. However, the efficiency of the separation in centrifugal partition chromatography is also affected by a variety of parameters dependent on the sample properties in the solvent system, physical properties of the solvent system, parameters of the instrument, and the method. This article includes also recent ideas for improvements to the technique and broadening its application (e.g., (multiple) dual-mode or elution-extrusion procedure, pH-zone-refining centrifugal partition chromatography, ion-exchange centrifugal partition chromatography, online and offline coupling of centrifugal partition chromatography).

Experimental Study and Thermodynamic Modelling of High Temperature Interactions Between Molten Miscanthus Ashes and Bed Particles in Fluidized Bed Reactors

This paper presents an experimental and thermodynamic contribution about the role of inorganics in ash-bed material interactions during thermal conversion of miscanthus in fluidized bed. The objectives are (1) to describe the transformation of inorganics at high temperature, (2) to reveal their role in the agglomeration and (3) to provide recommendations for miscanthus gasification in fluidized bed. The main ash forming elements in miscanthus are K, Si, Ca, Mg, P, S and Cl. The ashes are composed of silica, carbonates and salts. The carbonates and salts decompose and volatilise at 700 °C. At elevated temperature, the dominant solid phases are Ca and Mg silicates. The liquid phase is composed of SiO2, K2O, CaO, MgO regardless of the atmosphere. The accuracy of thermodynamic prediction tool is evaluated with the experimental results. The ash-bed interactions show that the wetting of bed material by molten ashes is one of the key parameters of the agglomeration. The adhesion of particles increases in the order of silica sand, olivine, calcined olivine. There is no significant difference in the agglomeration mechanism in oxidizing or reductive atmosphere. However, in reductive atmosphere, two immiscible liquid phases can occur. The parametric investigation shows that the operating temperature has a significant effect on the agglomeration ratio and the addition of kaolin or dolomite is the most effective tool to reduce agglomeration risks.

Properties of lithium under hydrothermal conditions revealed by in situ Raman spectroscopic characterization of Li2O-SO3-H2O (D2O) systems at temperatures up to 420 °C

Lithium (Li) is an important component of hydrothermal fluids, especially submarine hydrothermal fluids. Investigation of the species and ion complexation of Li+ at elevated temperature and pressure can improve our knowledge on the behavior of Li under hydrothermal conditions. In this study, in situ optical and Raman spectroscopic experiments were conducted on the Li2SO4-H2SO4-H2O system and its D2O analogue at temperatures≤420°C. An unexpected liquid-liquid phase separation (immiscibility) was observed at temperatures above 336.5°C; the aqueous phase was separated into a sulfate-rich heavy liquid phase and a sulfate-poor light liquid phase at vapor-saturation pressures. The liquid-liquid phase separation temperature decreased as the Li2SO4 concentration increased in dilute solutions (≤1.25 m), increased as the Li2SO4 concentration increased in concentrated solutions (>1.25 m), and exhibited a lower critical solution temperature (LCST) at ~336.5°C. The presence of excess H2SO4 (or D2SO4) increased the liquid-liquid phase separation temperature at a constant Li2SO4 concentration. Liquid-liquid phase separation is common in organic-bearing solutions, and LCST is considered to be a macro-scale property of polymer solutions, indicating complicated ion pairing between Li+ and SO42− at high temperature. In situ Raman spectra of the v1(SO42−) band indicated the presence of “free” SO42−, LiSO4−, possible Li2SO40 and other poly-ion associations. The Li+-SO42− association increased with increasing temperature at a constant Li2SO4 concentration. These results indicate that Li+ can form contact ion pairs with ligands despite its strong hydration tendency.In submarine hydrothermal systems, various contact ion pairs should be important Li species during the high-temperature leaching of Li from basalts (e.g., >200°C). The formation of strong and various Li+-SO42− pairs can enhance the leaching of Li because the mobility and diffusion of the Li+-SO42− complex has been reported to be stronger than that of “free” ions. During the low-temperature (e.g., <150°C) uptake of Li+ into secondary minerals (e.g., clays), free Li+ and outer-sphere ion pairs are the dominant Li+ species. Contact ion pairs are also important Li species during the hydrothermal alteration/precipitation of Li-rich minerals in pegmatite systems. Moreover, liquid-liquid phase separation was found to play important roles in the formation of low-temperature minerals (e.g., calcite). However, similar crystallization pathways have rarely been documented for inorganic systems under high temperatures. Anhydrous Li2SO4 was observed to precipitate within the dense liquid phase at ≥360°C in 1.5 m Li2SO4, confirming that the immiscible dense liquid phase can serve as a precursor for the crystallization of sulfates and other minerals under hydrothermal conditions. The possible processes for the dense-liquid-based crystallization by particle attachment can be summarized as (1) strong and reversible ion association induces liquid-liquid phase separation, (2) nucleation and crystallization within the dense liquid phase, and (3) continued growth on the surface of early formed solid phase. Submarine hydrothermal fluids often contain low-dielectric components such as methane and other organic components, which lower the dielectric constant of hydrothermal fluids and promote ion association. Therefore, liquid-liquid phase separation may occur in submarine hydrothermal fluids and can play important roles in the precipitation of sulfates and other minerals.

CaCO3 thin-film formation mediated by a synthetic protein-lysozyme coacervate

A thin film was formed through in vitro CaCO3 crystallization in the presence of complex coacervates, which was expected to be planar and poorly crystalline CaCO3 guided at the interface of two immiscible liquid phases upon complex coacervation.

Hydrophobic silica nanoparticle-stabilized invert emulsion as drilling fluid for deep drilling

An oil-based drilling fluid should be stable and tolerant to high temperatures for use in deep drilling. An invert emulsion of water in oil is a good choice as an oil-based drilling fluid which is a mixture of a solid phase and two immiscible liquid phases stabilized by a polymeric surfactant. In deep drilling, due to high temperatures, the polymeric surfactant degrades and a phase separation occurs. Here, octadecyltrimethoxysilane-modified silica nanoparticles were used to form a stable invert emulsion of water in oil for the drilling fluid model which resulted in a milky fluid with the formation of 60 µm water droplets. In addition, rheological study showed that using hydrophobic silica nanoparticles resulted in a stable water in oil invert emulsion with desired properties for a drilling fluid that can be modified by adjusting the nanoparticle nature and content. Aging experiments at 120 °C indicated that they also have good stability at high temperatures for challenging drilling operations.

Liquid/liquid phase separation heat transfer at the microscale

An experimental study of liquid/liquid phase separation heat transfer at the microscale using triethylamine (TEA)/water solvent mixture is reported here. The mixture, 32.1% mass fraction of TEA, was introduced into a 22mm long, 2mm wide, and 0.4mm deep microchannel. When heated above the critical temperature, the mixture separated into distinct immiscible liquid phases. Through flow visualization, the two-phase flow patterns were determined to be predominantly mist flow, elongated droplet flow, and annular flow. Increased heat transfer coefficients of up to about 250% and reduced pressure drop were observed between cases of phase separation flow and single phase mixture flow, demonstrating the potential for applying this type of solvent mixture to miniature heat sinks. A first-order computational fluid dynamics (CFD) model was used to reveal the mechanisms controlling the hydrodynamics and thermodynamics processes. It was determined that the latent heat of mixing associated with the phase separation process contributed to the enhanced heat transfer. The self-propelled motion of components driven by chemical potential gradient further boosted the heat transport. Reduced viscosities of both phases led to the reduced pressure drop.

Effect of Si and Cu additions on the phase composition, microstructure and properties of Al-Sn alloys

The phase transformations in Al-Cu-Si-Sn alloys were studied using both thermodynamic calculations and experimental methods. The calculated isothermal and vertical sections confirm the presence of fields of liquid phase immiscibility and monotectic reactions. It is shown that annealing at 500 °C, followed by quenching, significantly modifies the morphology of the Sn phase, with the particles acquiring a globular shape due to local melting. The influence of Si and Cu on hardness, density, specific electrical conductivity and manufacturability of the base model alloys, Al-20 wt% Sn and Al-6 wt% Sn, is investigated. It is shown that the Al6Sn4Cu5Si alloy is not inferior to antifriction bronze Cu4Sn4Zn17Pb in terms of tribological characteristics and it significantly exceeds it with regard to density, hardness and thermal conductivity.

Three orthogonal ultrasounds fabricate uniform ternary Al-Sn-Cu immiscible alloy.

The production of Al based monotectic alloys with uniform microstructure is usually difficult due to the large density difference between the two immiscible liquid phases, which limits the application of such alloys. Here, we apply three orthogonal ultrasounds during the liquid phase separation process of ternary Al71.9Sn20.4Cu7.7 immiscible alloy. A uniform microstructure consisting of fine secondary (Sn) phase dispersed on Al-rich matrix is fabricated in the whole alloy sample with a large size of 30 × 30 × 100 mm. The numerical calculation results indicate that the coupled effect of three ultrasounds promotes the sound pressure level and consequently enlarges the cavitation zone within the alloy melt. The strong shockwaves produced by cavitation prevent the (Sn) droplets from coalescence, and keep them suspended in the parent Al-rich liquid phase. This accounts for the formation of homogeneous composite structures. Thus the introduction of three orthogonal ultrasounds is an effective way to suppress the macrosegregation caused by liquid phase separation and produce bulk immiscible alloys with uniform structures.

An Activity-Based Dissolution Model for Solute-Containing Microdroplets.

When a solute is present in an aqueous droplet, the water activity in the droplet and the rate of droplet dissolution are both decreased (as compared to a pure water droplet). One of the main parameters that controls this effect is the dynamically changing solute concentration, and therefore water activity and chemical potential, at the droplet interface. This work addresses the importance of understanding how water activity changes during solution droplet dissolution. A model for dissolution rate is presented that accounts for the kinetic effects of changing water activity at the droplet interface during the dissolution of an aqueous salt solution microdroplet into a second immiscible liquid phase. The important underlying question in this model is whether the dissolving component can be considered in local equilibrium on both sides of the droplet interface and whether this assumption is sufficient to account for the kinetics of dissolution. The dissolution model is based on the Epstein-Plesset equation, which has previously been applied to pure gas (bubble) and liquid (droplet) dissolution into liquid phases, but not to salt solutions. The model is tested by using the micropipet technique to form and observe the dehydration of single NaCl solution microdroplets in octanol or butyl acetate. The model successfully predicts the droplet diameter as a function of time in both organic solvents. The NaCl concentration in water is measured well into the supersaturated area >5.4 M, and the supersaturation limit at which NaCl nucleation happens is reported to be 10.24 ± 0.31 M.

Asymmetric synthesis of chiral amine in organic solvent and in-situ product recovery for process intensification: A case study

Membrane assisted extraction in a contactor, which allows for the separation of the reaction components between two immiscible liquid phases, was applied for transamination. The reaction was conducted in an organic solvent which resulted in two benefits: higher solubility of the poorly water soluble substrate benzyl acetone, and the possibility of product removal in an aqueous phase. The aqueous phase was circulated across the shell of a hollow fiber membrane module and the organic phase (n-heptane) through the lumen. Approaches to extract the product amine, 1-methyl-3-phenylpropylamine proved beneficial to reduce its inhibitory effects, while providing an equilibrium shift aiding in higher product formation. After 72h of operation in membrane contactor, 99% substrate conversion was observed.

One-Step Generation of Cell-Encapsulating Compartments via Polyelectrolyte Complexation in an Aqueous Two Phase System.

Diverse fields including drug and gene delivery and live cell encapsulation require biologically compatible encapsulation systems. One widely adopted means of forming capsules exploits cargo-filled microdroplets in an external, immiscible liquid phase that are encapsulated by a membrane that forms by trapping of molecules or particles at the drop surface, facilitated by the interfacial tension. To eliminate the potentially deleterious oil phase often present in such processes, we exploit the aqueous two phase system of poly(ethylene glycol) (PEG) and dextran. We form capsules by placing dextran-rich microdroplets in an external PEG-rich phase. Strong polyelectrolytes present in either phase form complexes at the drop interface, thereby forming a membrane encapsulating the fluid interior. This process requires considerable finesse as both polyelectrolytes are soluble in either the drop or external phase, and the extremely low interfacial tension is too weak to provide a strong adsorption site for these molecules. The key to obtaining microcapsules is to tune the relative fluxes of the two polyelectrolytes so that they meet and complex at the interface. We identify conditions for which complexation can occur inside or outside of the drop phase, resulting in microparticles or poor encapsulation, respectively, or when properly balanced, at the interface, resulting in microcapsules. The resulting microcapsules respond to the stimuli of added salts or changes in osmotic pressure, allowing perturbation of capsule permeability or triggered release of capsule contents. We demonstrate that living cells can be sequestered and interrogated by encapsulating Pseudomonas aeruginosa PAO1 and using a Live/Dead assay to assess their viability. This method paves the way to the formation of a broad variety of versatile functional membranes around all aqueous capsules; by tuning the fluxes of complexing species to interact at the interface, membranes comprising other complexing functional moieties can be formed.

Application of the e-KT-UNIFAC Model for the Improved and Innovative Design of Biphasic Reacting Systems

Biphasic reacting systems contain effectively immiscible aqueous and organic liquid phases in which reactants, products, and catalysts can partition. These conditions allow novel synthesis paths, higher yields, and faster reactions, as well as facilitate product(s) separation. A systematic modeling framework of three modules has been developed to describe phase equilibria, reactions, mass transfer, and material balances of such processes. The recently developed group-contribution electrolyte model, e-KT-UNIFAC, is used to predict the partitioning and equilibria of electrolyte and nonelectrolyte species for a wide variety of reacting substances. Reaction kinetics and mass transfer are described by nonelementary reaction rate laws. Extents of reaction are used to calculate the species material balances. The resulting mathematical model contains only a few rate parameters to be regressed to a minimum of time-dependent data. In addition to describing the behavior of such systems, predictions can be made of th...