Dispersive Liquid Research Articles

Solution Processable Metal-Organic Frameworks: Synthesis Strategy and Applications.

Metal-organic frameworks (MOFs), constructed by inorganic secondary building units with organic linkers via reticular chemistry, inherently suffer from poor solution processability due to their insoluble nature, resulting from their extensive crystalline networks and structural rigidity. The ubiquitous occurrence of precipitation and agglomeration of MOFs upon formation poses a significant obstacle to the scale-up production of MOF-based monolith, aerogels, membranes, and electronic devices, thus restricting their practical applications in various scenarios. To address the previously mentioned challenge, significant strides have been achieved over the past decade in the development of various strategies aimed at preparing solution-processable MOF systems. In this review, the latest advance in the synthetic strategies for the construction of solution-processable MOFs, including direct dispersion in ionic liquids, surface modification, controllable calcination, and bottom-up synthesis, is comprehensively summarized. The respective advantages and disadvantages of each method are discussed. Additionally, the intriguing applications of solution-processable MOF systems in the fields of liquid adsorbent, molecular capture, sensing, and separation are systematically discussed. Finally, the challenges and opportunities about the continued advancement of solution-processable MOFs and their potential applications are outlooked.

Using Rheology and Image Processing to Study the Effects of Cellulose Nanocrystal Sedimentation.

The effect of sedimentation on lyotropic liquid crystalline dispersions is both an interesting subject in colloidal science and is of practical importance for understanding changes that can occur during dispersion storage. This research explored how the seemingly subtle changes in average length resulting from a single sedimentation step affected the rheological properties and self-assembly of aqueous dispersions of sulfated cellulose nanocrystals. Sedimentation of a primarily isotropic aqueous cellulose nanocrystal dispersion for 1 month at ambient conditions resulted in an isotropic top phase and a biphasic bottom phase, which were separated for further study. Both atomic force microscopy measurements and intrinsic viscosities determined via Fedor's equation showed preferential fractionation of longer cellulose nanocrystals (CNCs) to the bottom phase. The effects of this fractionation on dispersion rheology and phase behavior were studied by preparing a range of concentrations from each phase. As expected, the concentration for the isotropic-biphasic phase transition was significantly lower for the bottom phase than for the top phase or parent dispersion. Rheological changes were generally subtle, but significant differences were seen in the storage modulus at concentrations approaching rheological gelation. Most notably, quantitative image processing showed that even this simple, single-step fractionation process had a significant impact on the relative proportion of tactoids and chiral helices with planar and homeotropic anchoring in self-assembled cellulose nanocrystal films. These results highlight the impact that changes in polydispersity due to sedimentation can have on the self-assembly of nanomaterial mesogens.

Chiral, Topological, and Knotted Colloids in Liquid Crystals

The geometric shape, symmetry, and topology of colloidal particles often allow for controlling colloidal phase behavior and physical properties of these soft matter systems. In liquid crystalline dispersions, colloidal particles with low symmetry and nontrivial topology of surface confinement are of particular interest, including surfaces shaped as handlebodies, spirals, knots, multi-component links, and so on. These types of colloidal surfaces induce topologically nontrivial three-dimensional director field configurations and topological defects. Director switching by electric fields, laser tweezing of defects, and local photo-thermal melting of the liquid crystal host medium promote transformations among many stable and metastable particle-induced director configurations that can be revealed by means of direct label-free three-dimensional nonlinear optical imaging. The interplay between topologies of colloidal surfaces, director fields, and defects is found to show a number of unexpected features, such as knotting and linking of line defects, often uniquely arising from the nonpolar nature of the nematic director field. This review article highlights fascinating examples of new physical behavior arising from the interplay of nematic molecular order and both chiral symmetry and topology of colloidal inclusions within the nematic host. Furthermore, the article concludes with a brief discussion of how these findings may lay the groundwork for new types of topology-dictated self-assembly in soft condensed matter leading to novel mesostructured composite materials, as well as for experimental insights into the pure-math aspects of low-dimensional topology.

Liquisolid Technique for Solubility Enhancement of Poorly Soluble Drug - A Brief Review.

Most of the newly discovered drug candidates are lipophilic and poorly water-soluble, making it a significant challenge for the pharmaceutical industry to formulate suitable drug delivery systems. This review gives insight into an overview of the liquisolid technique (LST) and summarizes the progress of its various applications in drug delivery. This novel technique involves converting liquid drugs or drugs in a liquid state (such as solutions, suspensions, or emulsions) into dry, nonadherent, free-flowing, and readily compressible powder mixtures by blending or spraying a liquid dispersion onto specific powder carriers and coating materials. In Liquisolid systems, the liquid medication is absorbed into the interior framework of carriers. Once the carrier's interior is saturated with liquid medication, a liquid layer forms on the surface of the carrier particles, which is instantly adsorbed by the fine coating material. As a result, a dry, free-flowing, and compressible powder mixture is formed. Compared to other solubility enhancement techniques, s.a. micronization, inclusion complexation, microencapsulation, nanosuspension, and self-nano emulsions, LST is relatively simple to prepare and may offer a cost-effective solution to enhance the solubility of poorly water-soluble drugs enhancing its bioavailability in drug formulation and delivery.

Process Intensification of Gas–Liquid Separations Using Packed Beds: A Review

The gas–liquid multiphase process plays a crucial role in the chemical industry, and the utilization of packed beds enhances separation efficiency by increasing the contact area and promoting effective gas–liquid interaction during the separation process. This paper primarily reviews the progress from fundamental research to practical application of gas–liquid multiphase processes in packed bed reactors, focusing on advancements in fluid mechanics (flow patterns, liquid holdup, and pressure drop) and the mechanisms governing gas–liquid interactions within these reactors. Firstly, we present an overview of recent developments in understanding gas–liquid flow patterns; subsequently we summarize liquid holdup and pressure drop characteristics within packed beds. Furthermore, we analyze the underlying mechanisms involved in bubble breakup and coalescence phenomena occurring during continuous flow of gas–liquid dispersions, providing insights for reactor design and operation strategies. Finally, we summarize applications of packed bed reactors in carbon dioxide absorption, chemical reactions, and wastewater treatment while offering future perspectives. These findings serve as valuable references for optimizing gas–liquid separation processes.

Bubble generation in a 3-D flow-focusing microchannel: From squeezing to jetting

Fine bubbles have been applied in many fields; however, the controllable preparation of monodispersed fine bubbles remains a challenge. In this study, a three-dimensional (3-D) flow-focusing microfluidic device was designed. Compared with bubble formation in one-dimensional (1-D) and two-dimensional (2-D) flow-focusing, the 3-D flow-focusing microchannel owns the features of making bubbles with much smaller sizes and wider operation range. Four different gas–liquid flow regimes (squeezing, squeezing-dripping transition, dripping, and jetting) and three different gas–liquid dispersion states (mono-dispersion, bi-dispersion, and poly-dispersion) were observed in the 3-D flow-focusing microchannels. Importantly, the bi-dispersion in the squeezing-dripping transition regime experimentally verified that the squeezing and viscous shearing mechanisms separately control bubble formation in the transition region based on the time sequence. The intrinsic reason for poly-dispersion in the squeezing-dripping transition and jetting regimes was revealed. Finally, a mathematical model is proposed to predict the bubble size in the flow-focusing microchannels.

Nucleobase‐Driven Wearable Ionogel Electronics for Long‐Term Human Motion Detection and Electrophysiological Signal Monitoring

AbstractIonogels are considered as ideal candidates for constructing flexible electronics due to their superior electrical conductivity, flexibility, high thermal and electrochemical stability. However, it remains a great challenge to simultaneously achieve high sensitivity, repeated adhesion, good self‐healing, and biocompatibility through a straightforward strategy. Herein, inspired by nucleobase‐tackified strategy, a multifunctional adhesive ionogel is developed through one‐step radical polymerization of acrylated adenine/uracil (Aa/Ua) and acrylic acid (AA) monomers in sodium caseinate (SC) stabilized liquid metal dispersions. As a soft conductive filler, the incorporating of liquid metal not only improves the electrical conductivity, but also enhances the mechanical strength, satisfying the stretchable sensing application. The large amount of noncovalent interactions (hydrogen bonding, metal coordination, and ion‐dipole interactions) within the networks enable the ionogels to possess excellent stretchability, skin‐like softness, good self‐healing, and strong adhesion. Based on these desirable characteristics, the ionogel is suitable for wearable strain sensors to precisely detect diverse human movements under extreme environments. Moreover, the seamless adhesion with human skin allows the ionogel to function as bioelectrode patch for long‐term and high‐quality electrophysiological signal acquisition. This research provides a promising strategy for designing ionogels with tailored functionalities for wearable electronics that satisfy diverse application requirements.

On the transition of liquid dispersion states and their physical-thermodynamic nature in the development of gas-condensate reservoirs in depletion mode

While the depletion regime for gas-condensate fields may be more cost-effective, it often results in the loss of hydrocarbon condensate, which is economically more valuable than gas, and leads to the inefficient exploitation of the field in terms of condensate production. Therefore, the development of effective exploitation systems for such fields is essential. Effective exploitation of gas-condensate fields involves achieving maximum hydrocarbon condensate production in addition to maximum gas production. From this aspect, managing the condensate factor of reservoir system during the depletion regime is a critical issue. The article experimentally and theoretically investigates the phase transitions or mutual dispersion occurrences between hydrocarbon liquid and gas mixtures that occur with a decrease in pressure at reservoir temperature during the natural depletion of gas-condensate fields. During the exploitation of gas-condensate fields, it has been observed that even at pressures higher than retrograde condensation pressure, the hydrocarbon system undergoes complex phase transitions, resulting in distinct transition points due to the mutual dispersion of hydrocarbon liquid and gas. Additionally, pVT studies conducted in the laboratory have made it possible to determine the transition points of the reservoir fluid in the “liquid in gas” and vice versa dispersion states. The research has demonstrated that dependance of gas condensate factor on pressure under given isothermal natural conditions more clearly reflects the retrograde and maximum condensation, also dispersion points of the liquid components. It was found that proportionality coefficient between condensate ratio and pressure of gas-condensate system is unique for each production facility under isothermal conditions and characterizes the stability of fluid’s dispersion state. The importance of considering such transition points when designing gas-condensate field development projects has been highlighted.

On the transition of liquid dispersion states and their physical-thermodynamic nature in the development of gas-condensate reservoirs in depletion mode

This work presents new results of physical and chemical analysis of samples from contaminated areas of the Absheron field. The advantages and disadvantages of the used and traditional methods of cleaning oil waste are shown. Modern methods have been used to determine the characteristics of oil sludge samples from the Balakhany, Ramana, Surakhany, Bibiheybet fields of the Absheron Peninsula: oil sludge composition, viscosity, density, water content, chemical composition, temperature, cutting size, toxicity, volume, pH level, turbidity, BOD (biological oxygen demand), TDS (total dissolved solids). The main properties of oil sludge from the fields of the Absheron Peninsula are analyzed and compared. Chromatographic analysis (Agilent 7820A GC) allowed us to separate the oil waste and mixtures of the studied samples into individual compounds and components. The separation and determination of the components of the waste mixture by gas chromatography consisted of three stages: 1) Introduction of the sample into the chromatograph, 2) Separation of the sample into individual components, 3) Determination of the compounds contained in the sample. An inductively coupled plasma mass spectrometer (Agilent 7500 cs) with reaction cell was used for the efficient determination of trace heavy metals in petroleum waste. The ion lens unit used in the Agilent 7500cs provided high sensitivity measurements. Thus, trace metals were detected in the samples. A vacuum distiller (Retort Oil and Water Kit RROW-50) was used to quantify liquid and solids in drilling mud. Comparison of our oil sludge analysis results with field data demonstrates the effectiveness of these methods in identifying the composition of oil sludge for obtaining target products. From the studied wastes of the oil industry, it is possible to obtain special additives and use them, for example, for asphalt concrete. The dependences of oil sludge evaporation (of the Balakhany, Ramana, Surakhany, Bibieybet deposits) on air temperature and thermal resistance of the waterproofing material of the oil storage facility have been studied. The evaporation of components also depends on the concentration of oil sludge. Based on our sample analyses, it has been shown that the combined use of physicochemical and chemical methods makes it possible to purify oil sludge to acceptable limits. The dependences of oil evaporation on air temperature and the thermal resistance of the waterproofing material of an oil tank on the concentration of oil sludge have been established.

Explicit and approximate solutions for a classical hyperbolic fragmentation equation using a hybrid projected differential transform method

Population balance equations are widely used to study the evolution of aerosols, colloids, liquid–liquid dispersion, raindrop fragmentation, and pharmaceutical granulation. However, these equations are difficult to solve due to the complexity of the kernel structures and initial conditions. The hyperbolic fragmentation equation, in particular, is further complicated by the inclusion of double integrals. These challenges hinder the analytical solutions of number density functions for basic kernel classes with exponential initial distributions. To address these issues, this study introduces a new approach combining the projected differential transform method with Laplace transform and Padé approximants to solve the hyperbolic fragmentation equation. This method aims to provide accurate and efficient explicit solutions to this challenging problem. The approach's applicability is demonstrated through rigorous mathematical derivation and convergence analysis using the Banach contraction principle. Additionally, several numerical examples illustrate the accuracy and robustness of this new method. For the first time, new analytical solutions for number density functions are presented for various fragmentation kernels with gamma and other initial distributions. This method significantly enhances solution quality over extended periods using fewer terms in the truncated series. The solutions are compared and verified against the finite volume method and the homotopy perturbation method, showing that the coupled approach not only estimates number density functions accurately but also captures integral moments with high precision. This research advances computational methods for particle breakage phenomena, offering potential applications in various industrial processes and scientific disciplines.

Tailoring refractive index dispersion in ionic liquids: The influence of charge delocalization in cations

In this work, we study the contributions that different molecular blocks have in the wavelength-dependence of the refractive index in ionic liquids. The ionic liquids chosen for this work are combinations of the bis(trifluoromethylsulfonyl)imide anion with cations based on four different heterocycles with different extents of charge delocalization. The analysis is performed in terms of the experimental electronic polarizability, which is obtained by combining measurements of refractive index curves and densities via the Lorentz-Lorenz equation. Exploiting the additivity of electronic polarizability in ionic liquids, the contribution of the anion and the heterocycles of the cations is separated from that of the alkyl chains. Our results show important differences in these contributions, revealing a key influence of the charge delocalization in the cationic rings on the behavior of the refractive index dispersion. The understanding of how different parts of ionic liquids affect their refractive index dependence on wavelength would allow to gain precise control of this magnitude, enabling the development of customized optical materials for diverse applications in photonics and sensing technologies.

Advanced ultrasound techniques for studying liquid–liquid dispersions in confined impinging jets

Advanced ultrasound techniques were used to study liquid–liquid dispersed flows formed in impinging jets confined in small channels. Ultrasound speed and attenuation coefficient spectra of the propagated sound waves were used to obtain volume fraction and drop size distributions, respectively. The results were compared against drop size distributions obtained with high-speed imaging. Experiments were conducted in a 2 mm internal diameter tube for both kerosene oil continuous and glycerol/water continuous dispersions. The overall mixture flow rate was set at 60 ml/s, and the dispersed phase fractions were 0.02, 0.05, and 0.10. The measured volume fractions were found to be very close to the input ones, indicating a very small slip between the phases in the dispersed flows. From the ultrasound measurements, the drop size distributions were found to range from 32 to 695 μm under the different conditions used. The drop sizes at the two low input volume fractions were in reasonable agreement with the results from the imaging. Imaging, however, could not be used for the 0.10 input dispersed phase fraction. These results demonstrate the applicability of the ultrasound techniques to measurements in dispersed liquid–liquid flows in small channels.

Modeling oil/water emulsion separation in batch systems with population balances in the presence of surfactant

This study introduces a simplified model for batch gravitational separation of liquid–liquid dispersions, integrating a decantation model with a high order moment conserving method of classes in population balances (PBM-HMMC). The proposed model incorporates the dynamics of surfactants and their effect on droplet size distribution, emphasizing the crucial influence of surfactants on emulsion stability. Notably, while extensive literature exists on predicting interphases in batch separation with surfactants, the application of population balance methods to predict droplet size distribution evolution is scarcely addressed, which is a primary focus of this work. The model’s accuracy is verified through comparison with independent experimental data, confirming its practical relevance. Furthermore, the research explores the impact of various parameters, including emulsion height, surfactant concentration and type, and droplet size distribution, on the separation process.

Algorithm for Reproducible Analysis of Semiconducting 2D Nanomaterials Based on UV‐VIS Spectroscopy

AbstractRapid and reliable analysis of liquid dispersions of 2D materials is essential for fully harnessing their potential, allowing size and quality validation before subsequent processing or device fabrication. Existing UV‐VIS extinction spectroscopy‐based metrics, particularly those related to thickness, have shown promise but rely on manual data processing, which can introduce irreproducibility and user errors. To address this challenge and enable uniform analysis across laboratories, a freely available program is developed for the reproducible analysis of nanosheet dispersions. Specifically, a smoothing routine is applied to the spectral data, takes the second derivative, and use integral areas to find the wavelength of exciton transitions. This program enables rapid measurement of nanosheet concentration, length, and thickness by UV‐VIS spectroscopy and thickness metrics are refined for eight common 2D nanomaterials. The program and methodology are freely available for use and allow metrics for new materials to be implemented easily in the future.

Experimental study of liquid–liquid dispersion patterns in T-inlet microchannels with different junction angles

Liquid-liquid two-phase flow in T-inlet microchannels with different junction angles (θ = 30°, 60°, 90°, 120° and 150°) was investigated experimentally. Four flow regimes of the dispersed phase were identified, i.e., parallel flow, jetting, dripping and squeezing, and the distribution of flow regimes for the dispersed phase corresponding to variations in the junction angle was plotted. The consequences of varying junction angle and flow conditions in the squeezing regime on the generated droplet size were analyzed. The results indicate that low capillary number and large flow rate ratio are conducive to the formation of large-size droplets. For constant flow conditions, junction angle θ = 90° is detrimental to the formation of squeezing microdroplets. The increase in microchannel junction angle causes the droplet size to decrease until θ > 90°, where the droplet size increases with the junction angle. On the basis of experimental results, the scaling law correlation equations containing the junction angle for predicting the droplet length and droplet volume are proposed, respectively. The predicted values match well with the experimental data. The results of this work contribute to the enhancement of the monodispersity of microdroplets and the precise control over a wide range of the generated droplet size by adjusting the junction angle.

The Preparation of Crumpled Graphene Oxide Balls and Research in Tribological Properties.

In this study, crumpled graphene oxide balls (CGBs) were prepared via capillary compression using a rapidly evaporating aerosol droplet method. The CGBs were observed using scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and Raman spectroscopy. The size distributions of crumpled particles were obtained using a laser nanometer particle size analyzer (DLS). The dispersibility of the water and the ionic liquid (IL) was tested by ultrasonic dispersion. The tribological properties of water or ionic liquids containing crumpled graphene oxide ball additives (W/IL-CGB) were tested by a reciprocating friction tester and compared with water/ionic liquids with graphene oxide. The morphology of the wear scar was observed by a three-dimensional optical microscope and its lubrication mechanism was analyzed. The results show that the CGBs were successfully prepared by rapid evaporation of aerosol droplets, and the obtained CGBs were crumpled paper spheres. The CGBs had good water dispersion and ionic liquid dispersion, and IL-CGB has excellent anti-friction and anti-wear effects on steel-steel friction pairs. During the friction process, the CGB was adsorbed at the interface of the steel-steel friction pair to form a protective layer, which avoids the direct contact of the friction pair, thereby reducing friction and wear.

NMR Relaxation Dispersion of Liquids Adsorbed on Modified Surfaces of SBA-15 Mesoporous Silica

NMR Relaxation Dispersion of Liquids Adsorbed on Modified Surfaces of SBA-15 Mesoporous Silica

Multi-phase shear thickening fluid based on ionic liquid dispersion medium for impact resistance and wear protection

Shear thickening fluids (STFs) have attracted increasing attention as smart materials with unique rheological properties. However, the preparation of STFs usually relies on a composite system of spherical nanoparticles with polyethylene glycol. In this work, novel multi-phase STFs (ILSTFs) were prepared in an ionic liquid by incorporating nanosized SiO2 and rod-shaped calcium metasilicate (CaSiO3) particles as a dispersed phase. Compared to traditional STFs, ILSTFs demonstrate excellent thermal stability. Rheological tests indicate that ILSTFs exhibit continuous shear thickening behavior, resulting in excellent energy absorption and impact wear resistance. In addition, ILSTFs can serve as a new type of lubricant. The tribological properties and impact resistance of ILSTFs were highly correlated with the shear thickening effect, with the multi-phase ILSTF system with CaSiO3 demonstrating superior impact wear resistance compared to the single-phase system. In this study, finite element analysis (FEA) is further utilized to investigate the local damage evolution and energy absorption rate of STF under impact loading, providing insights into the underlying mechanism. This ionic liquid-based STF holds promise for applications as a flexible filling component in the fields of lubrication technology and impact protection structures.

Gas–Liquid Microchemical Oxidation for Continuous Synthesis Processes: A Short Review

AbstractGas–liquid oxidation processes, despite their wide application in the chemical industry, still pose considerable safety concerns. Microchemical technology has received high recognition for its intrinsic safety performance and process-intensification capability in hazardous reactions. This Short Review offers a comprehensive summary on how microchemical technology can be employed to achieve gas–liquid oxidation processes for continuous synthesis of chemicals in a safe, efficient, and controlled manner. Herein, we discuss the key aspects of gas–liquid dispersion and hydrodynamics, as well as mass transfer characteristics on microscale, and present representative gas–liquid oxidation cases in microflow reactors. Finally, the current challenges in industrial applications and potential academic research directions are presented.1 Introduction2 Microbubble Generation Technology for Gas–Liquid Oxidation Reactions3 Hydrodynamic and Mass-Transfer Characteristics of Gas–Liquid Oxidation Microreactors4 Gas–Liquid Oxidation Reactions in Microreactors5 Conclusion and Outlook

Comparison through a CFD approach of static mixers in an emulsification process

Emulsions, characterized by droplet dispersions of immiscible liquids in a continuous phase, are often found in many diverse fields of the chemical industry. The energy needed to break these droplets can be sourced from mechanical agitators in stirred tanks, active mixers like pulse-flow mixers, and ultrasonic mixers. However, static mixers serve as a convenient alternative due to their typically lower maintenance costs and increased resistance to failures. Static mixers are available in diverse shapes and dimensions, with two widely used types being the Kenics Static Mixers and the Sulzer Static Mixers. While these two static mixers have been extensively studied in the literature in terms of pressure drop and mixing efficiency, to the best of the authors’ knowledge there is no study comparing the two in emulsification processes. This work aims to compare the performance of these static mixers in the production of emulsions by employing a Computational Fluid Dynamics approach. Results showed that the Sulzer Static Mixers allow to obtain higher values of turbulent energy dissipation, which in turn leads to smaller droplet diameters.