Liquid Research Articles

Melting Temperature Hidden Behind Liquid-Liquid Phase Transition in Glycerol.

Liquid-liquid phase transitions play a pivotal role in various scientific disciplines and technological applications, ranging from biology to materials science and geophysics. Understanding the behavior of materials undergoing these transitions provides valuable insights into complex systems and their dynamic properties. This review explores the implications of liquid-liquid phase transitions, particularly focusing on the transition between low-density liquid (LDL) and high-density liquid (HDL) phases. We investigate the thermodynamic, structural, and mechanistic aspects of these transitions, emphasizing their relevance in diverse fields. The creation of dynamic heterogeneities and critical fluctuations during liquid-liquid phase transitions is discussed, highlighting their role in shaping the phase behavior and dynamics of complex fluids. Experimental observations, including the use of dielectric spectroscopy and nonlinear methods, shed light on the intricate nature of these transitions. Our findings suggest a connection between liquid-liquid phase transitions and critical phenomena, with implications for understanding the supercooled state and phase behavior of hydrogen-bonded liquids such as glycerol. Overall, this review underscores the importance of interdisciplinary approaches in unraveling the complexities of liquid-liquid phase behavior and addressing fundamental questions.

Mixing behaviour of Al–Ga–Mg alloys in liquid state at different temperatures

ABSTRACT In the framework of Redlich–Kister (R–K) polynomials, both linear and exponential temperature-dependent energy interaction parameters for constituent binary subsystems of liquid Al–Ga–Mg alloys were optimised. These parameters were then used to estimate the excess Gibbs free energy of mixing, enthalpy of mixing and activity of the ternary system at 923 K, 973 K, 1023 K, 1073 K and 1123 K employing General Solution Model (GSM), Toop and Kohler models. The surface tensions of binary systems were calculated using Butler’s equations. The viscosity of binary subsystems was calculated employing Kaptay’s equations with the aid of exponentially optimised coefficients of R–K polynomials. Furthermore, the surface tension and viscosity of the ternary mixing were computed using aforementioned frameworks within the temperature range 923 K–1123 K. Theoretical investigation showed that the excess Gibbs free energy of mixing for the Al–Ga–Mg system was found to be negative, indicating a compound forming tendency.

Simulation of a liquid drop on a soft substrate.

A liquid drop resting on a soft substrate is numerically simulated as an energy minimization problem. The elastic substrate is modeled as a cubic lattice of mass-springs, to which an energy term controlling the change of volume is associated. The interfacial energy between three phases of solid, liquid, and vapor is also introduced. Under the constant volume constraint of the liquid drop, the total energy of the system is subjected to a numerical minimization process by which profiles of both substrate and drop are obtained. The numerical simulation enables the modeling of the wetting setup with various parameters associated with solid and liquid phases, including the Young's modulus and Poisson's ratio of the solid, the surface tension of the three phases, and geometrical parameters such as the contact radius or thickness of the solid. The direct outputs of the minimization process are the displacements of the solid lattice and boundary points of the liquid, by which the behavior of all relevant quantities, such as contact angles in the three phases, as well as the effective surface tension of the solid, can be quantitatively studied. The resulting displacements of the solid are compared with the exact solution of the elasticity equation under the assumption of no tangential traction, and a quite satisfactory agreement is observed. However, at larger Young's modulus or lower Poisson's ratios the agreement between the numerical results and the analytical solutions is lost in the vicinity of the contact points. Interestingly, a non-zero tangential traction in the vicinity of contact points is calculated by the numerical outputs, indicating that the assumption of zero tangential traction is not valid generally around the contact points. The effective surface tension at the contact points is calculated for an incompressible solid substrate, showing a linear increase with respect to the Young's modulus of the solid, as .

Molten Sn solvent expands liquid metal catalysis

Regulating favorable assemblies of metallic atoms in the liquid state provides promise for catalyzing various chemical reactions. Expanding the selection of metallic solvents, especially those with unique properties and low cost, enables access to distinctive fluidic atomic structures on the surface of liquid alloys and offers economic feasibility. Here, Sn solvent, as a low-cost commodity, supports unique atomic assemblies at the interface of molten SnIn0.1034Cu0.0094, which are highly selective for H2 synthesis from hydrocarbons. Atomistic simulations reveal that distinctive adsorption patterns with hexadecane can be established with Cu transiently reaching the interfacial layer, ensuring an energy-favorable route for H2 generation. Experiments with a natural oil as feedstock underscore this approach’s performance, producing 1.2 × 10−4 mol/min of H2 with 5.0 g of catalyst at ~93.0% selectivity while offering reliable scalability and durability at 260 °C. This work presents an alternative avenue of tuning fluidic atomic structures, broadening the applications of liquid metals.

Removal of Di (2-ethylhexyl) phthalate from groundwater by sodium persulfate activated by hollow micron zero-valent iron: Reaction mechanism and degradation path.

In this study, hollow micron zero-valent iron (H-mZVI) was prepared using the ethylenediamine liquid phase reduction method. The microstructures were characterized by SEM, XRD, BET and FTIR. The results showed that H-mZVI possessed a spherical hollow structure with a particle size of approximately 1 μm. The density of H-mZVI was notably lower compared to solid micron zero-valent iron (S-mZVI). Furthermore, with an increase in ethylenediamine addition, the density initially decreased before stabilizing. Results demonstrated that the degradation efficiency of H-mZVI/PS for DEHP was 2.96 times higher than that of S-mZVI/PS. The charge density of H-mZVI/PS degradation DEHP system was higher than that of S-mZVI/PS system, and H-mZVI exhibited a fast electron migration rate and strong electron transport ability between the solution and the interface material. The degradation of DEHP by H-mZVI/PS system was carried out jointly by the surface reaction on the surface of H-mZVI particles and the homolytic reaction led by Fe2+ ions in the solution. Additionally, the contribution rate of free radicals in the degradation process of DEHP was in the order SO4-· > ·OH > 1O2. There were three degradation pathways of DEHP in H-mZVI/PS system, and the toxicity of DEHP degradation products was significantly lower than that of the parent.

Interfacial Rheology as a Tool to Characterize the Dynamics of Spontaneous Emulsification.

Water-in-oil emulsions are critical in various fields, including food, agriculture, personal care, and pharmaceuticals. In some situations, spontaneous emulsification occurs in emulsions with high concentrations of oil-soluble surfactants, in which the parent water drops fragment into finer droplets, forming a network near the interface, which exhibits interfacial elasticity. This study investigates this phenomenon using a water/Span 80-paraffin oil system. We measured interfacial shear elasticity and used microscopy to capture the dynamics. The time of onset of the network depends on the contact time between the two liquid phases and the Span 80 concentration, scaling inversely with the square of the bulk concentration of Span 80. Beyond the time of onset of network formation, different trends are observed, depending on the concentration of Span 80. At higher concentrations, the interfacial elasticity shows a maximum, followed by a minimum. This oscillatory trend in the interfacial elasticity is an outcome of the formation of multiple layers of water droplets at the interface. The existence of multiple layers is also observed through an optical microscope. In a more viscous paraffin oil, both the emulsification rate and the elasticity peak are reduced. No spontaneous emulsification is observed when the paraffin oil is replaced with silicone oil. Moreover, spontaneous emulsification is suppressed by the addition of a salt. On the contrary, the addition of Tween 80 in water increases the rate of spontaneous emulsion, resulting in larger droplets and a denser emulsion layer. However, the drops form a very weak network, as indicated by a negligibly small interfacial elasticity.

The Synthesis, Crystal Structure, Modification, and Cytotoxic Activity of α-Hydroxy-Alkylphosphonates.

A series of α-hydroxy-alkylphosphonates and α-hydroxy-alkylphosphine oxides were synthesized by the Pudovik reaction of acetaldehyde and acetone with dialkyl phosphites or diarylphosphine oxides. The additions were performed in three different ways: in liquid phase using triethylamine as the catalyst (1), on the surface of Al2O3/KF solid catalyst (2), or by a MW-assisted Na2CO3-catalyzed procedure (3). In most of the cases, our methods were more efficient and more robust than those applied in the literature. Two of the α-hydroxy-alkylphosphonates were subjected to single-crystal X-ray analysis, suggesting a dimeric and a chain supramolecular buildup in their respective crystals. Four α-hydroxy-alkylphosphonates and one α-hydroxy-ethylphosphine oxide were reacted with different acid chlorides to afford ten α-acyloxyphosphonates. Diethyl α-hydroxy-ethylphosphonate was transformed to the methanesulfonyloxy derivative that was useful in the Michaelis-Arbuzov reaction with triethyl phosphite and ethyl diphenylphosphinite to afford tetraethyl ethylidenebisphosphonate and diethyl α-(diphenylphosphinoyl)-ethylphosphonate, respectively. The α-hydroxyphosphonates and α-hydroxyphosphine oxides prepared were subjected to bioactivity studies, and the compounds tested exhibited limited cytotoxic effects on U266 cells with modest reductions in viability at a concentration of 100 μM.

Janus Protein Nanoparticles Tailoring Bicontinuous Aerogels for Efficient Heavy Metal Ion Absorption.

Bicontinuous structures are exquisite interpenetrating constructs with an optimal balance between connectivity and surface area. Such unique geometry favors exceptional mechanical properties and efficient inward mass diffusion essential for an absorbent material. Although bicontinuous structures are found across many length scales in nature, synthesizing artificial analogs using biological building blocks remains largely unexplored. In this study, it is shown that manipulation of the surface chemistry of rapeseed cruciferin nanoparticles (≈50nm) leads to the formation of a highly amphiphilic stabilizer, ensuring equal wetting of water and oil phases in a demixed system, thereby enabling the formation of bicontinuous emulsions. By further eliminating both volatile liquid phases (water and toluene) through freeze-drying, bicontinuous emulsions are transformed into bicontinuous aerogels featuring highly interpenetrating networks with uniform domain size. These materials, characterized by high surface area (224 m2g-1) and mechanical robustness, can efficiently absorb various heavy metal ions multiple times displaying excellent absorption capacity (up to 200mgg-1) and efficiency (less than 30min). This study is at the forefront of constructing biomacromolecular bicontinuous structures, potentially expanding their applications in diverse fields such as food, cosmetics, and medicine.

Effect of the presence or absence of a gas–liquid interface on the initiation of liquid phase hydrocarbon oxidation

Effect of the presence or absence of a gas–liquid interface on the initiation of liquid phase hydrocarbon oxidation

Thermodynamic Properties of γ- and δ-Lactones: Exploring Alkyl Chain Length Effect and Ring-Opening Reactions for Green Chemistry Applications.

An extensive thermochemical study of γ-undecanolactone and δ-undecanolactone has been developed using two complementary calorimetric techniques. The combustion energy of each compound was determined by static-bomb combustion calorimetry, and the corresponding enthalpy of vaporization was determined by high-temperature Calvet microcalorimetry, in which both properties of each compound are reported at T = 298.15 K. The standard molar enthalpy of formation in the gas phase of each lactone was derived by the combination of the experimental results. Additionally, high-level computational calculations were carried out, using composite ab initio G4 and G4(MP2) methods, as well as DFT M06-2X/6-311++G(d,p) approach, to estimate the corresponding enthalpy of formation in the gas phase. The experimental and computational results are in good agreement. The G4 and G4(MP2) methods show the best accordance with experimentally determined gas phase enthalpies of formation. The experimental results are discussed in terms of structural contributions to the energetic properties of the lactones studied, as well as to other alkylated γ- and δ-lactones, and empirical correlations are suggested for the estimation of the standard molar enthalpies of formation, at T = 298.15 K, for other alkylated γ- and δ-lactones, both in the liquid and gaseous phases, as well as for the respective enthalpies of vaporization. Finally, the thermochemistry of individual steps of lactone ring opening and successive decarboxylation mechanism, including the identification of transition states, was studied using the M06-2X/6-311++G(d,p) approach.

Robust quantum spin liquid state in the presence of giant magnetic isotope effect in D3LiIr2O6

The deuterium isotope effect on the honeycomb iridate H3LiIr2O6, a quantum spin-orbit-entangled liquid, was examined by synthesizing D3LiIr2O6. The structural refinements indicate the different character of the interlayer OH and OD bonds, which results in a giant isotope effect on the magnetic interactions; the antiferromagnetic Curie-Weiss temperature |θCW| of D3LiIr2O6 increases to ~ 170 K from ~ 100 K of H3LiIr2O6. Nevertheless, the quantum liquid state is robust against the deuterium isotope exchange in contrast to the theoretical prediction that the Kitaev spin liquid is stable only for a limited phase space of magnetic interactions. The bond- and site disorders associated with disordered OD(H) bonds, in combination with Kitaev physics, may play a role in realizing the quantum liquid state.

Sustainable liquid nitrogen fertilizer production via air plasma bubbles: insights into plasma-enabled N2 fixation chemistry

Abstract Liquid nitrogen fertilizers, such as potassium nitrate (KNO3) have been commonly used in modern agriculture, playing a crucial role in agricultural production. However, its production involves energy-intensive and environmentally unfriendly processes such as the Haber-Bosch process. This study demonstrated a new strategy for the sustainable and distributed production of liquid KNO3 fertilizer via air plasma bubbles. We investigated the effects of solution characteristics (initial liquid conductivity, pH) and discharge power on the nitrogen fixation performance of the air plasma bubble system. Using a strongly alkaline solution can induce the increase of vibrational temperature (Tvib) during air plasma discharges, thereby enhancing NOx yield together with favoring the NOx adsorption process. Moreover, through electrical characteristics and a simplified circuit diagram, we found a highly conductive liquid phase is not conducive to NOx generation due to the significant energy dissipation in the liquid before discharge. By further adjusting discharge power parameters and coupling the introduction of O3, the highest energy efficiency (58.5 mmol/kWh) of NOx production, with an excellent production rate (1687.4 μmol/h) is achieved. These findings provide an overall understanding of the effects of solution characteristics on gas-liquid plasma chemistry and pave the way for the optimized production of liquid nitrogen fertilizers.

Thermosetting Resin for Plug and Abandonment of Oil Wells with Reduced Environmental Impact.

Plug and abandonment of offshore oil wells is a costly and time-consuming process, yet it is necessary for the ever-increasing number of mature fields in the region of the Danish North Sea, as well as globally. Current practices ensuring durable solutions for the complete zonal isolation of oil wells have a large environmental impact. This paper proposes a novel resin that could be mixed on the platform and pumped into the tubing in a liquid state. The increased temperature inside the oil well initiates the cross-linking reaction of the liquid resin, creating a solid and impermeable barrier. The liquid resin is thermally stable up to 180 °C and can be handled for up to 20 h at room temperature, preventing setting before intended while decreasing environmental impact. The solid resin has a compressive strength of 54 MPa and a steel adhesion strength of 6.27 MPa, highlighting its ability to withstand extreme downhole conditions.

Impact of Solid Particle Concentration and Liquid Circulation on Gas Holdup in Counter-Current Slurry Bubble Columns

In this study, in a three-phase reactor with a rectangular cross-section, the effects of liquid circulation rates and solid particle concentration on gas holdup and bubble size distribution (BSD) were investigated. Air, water, and glass beads were used as the gas, liquid, and solid phases, respectively. Different liquid circulation velocities and different solid loads were applied. The results demonstrate that increasing solid content from 0% to 6% can decrease gas holdup by 50% (due to increased slurry phase viscosity and promotion of bubble coalescence). Also, increasing the liquid circulation rate showed a weak effect on gas holdup, although a slight incremental effect was observed due to the promotion of bubble breakup and the extension of bubble residence time. The gas holdup in counter-current slurry bubble columns (CCSBCs) was predicted using a novel correlation that took into account the combined effects of solid concentration and liquid circulation rate. These findings are crucial for the design and optimization of the three-phase reactors used in industries such as mining and wastewater treatment.

First-principles molecular-dynamics equation of state of liquid to dense plasma iron

First-principles molecular-dynamics equation of state of liquid to dense plasma iron

Damage due to ice crystallization

The freezing of water is one of the major causes of mechanical damage in materials during wintertime; surprisingly this happens even in situations where water only partially saturates the material so that the ice has room to grow. Here we perform freezing experiments in cylindrical glass vials of various sizes and wettability properties, using a dye that exclusively colors the liquid phase; this allows precise observation of the freezing front. The visualization reveals that damage occurs in partially water-saturated media when a closed liquid inclusion forms within the ice due to the freezing of the air/water meniscus. When this water inclusion subsequently freezes, the volume expansion leads to very high pressures leading to the fracture of both the surrounding ice and the glass vial. The pressure can be understood quantitatively based on thermodynamics which correctly predicts that the crystallization pressure on the inclusion boundary is independent of the volume of the liquid pocket. Finally, our results also reveal that by changing the wetting properties of the confining walls, the formation of the liquid pockets that cause the mechanical damage can be avoided.

Effect of hydrogenated tail oil on liquid phase carbonization performance of medium- and low-temperature coal tar pitch

Effect of hydrogenated tail oil on liquid phase carbonization performance of medium- and low-temperature coal tar pitch

Cross-Linked Self-Standing Graphene Oxide Membranes: A Pathway to Scalable Applications in Separation Technologies.

The large-scale implementation of 2D material-based membranes is hindered by mechanical stability and mass transport control challenges. This work describes the fabrication, characterisation, and testing of self-standing graphene oxide (GO) membranes cross-linked with oxides such as Fe2O3, Al2O3, CaSO4, Nb2O5, and a carbide, SiC. These cross-linking agents enhance the mechanical stability of the membranes and modulate their mass transport properties. The membranes were prepared by casting aqueous suspensions of GO and SiC or oxide powders onto substrates, followed by drying and detachment to yield self-standing films. This method enabled precise control over membrane thickness and the formation of laminated microstructures with interlayer spacings ranging from 0.8 to 1.2 nm. The resulting self-standing membranes, with areas between 0.002 m2 and 0.090 m2 and thicknesses from 0.6 μm to 20 μm, exhibit excellent flexibility and retain their chemical and physical integrity during prolonged testing in direct contact with ethanol/water and methanol/water mixtures in both liquid and vapour phases, with stability demonstrated over 24 h and up to three months. Gas permeation and chemical characterisation tests evidence their suitability for gas separation applications. The interactions promoted by the oxides and carbide with the functional groups of GO confer great stability and unique mass transport properties-the Nb2O5 cross-linked membranes present distinct performance characteristics-creating the potential for scalable advancements in cross-linked 2D material membranes for separation technologies.

Viscoelastic Behavior of Aqueous Hydroxypropyl Cellulose Solutions Due to Entanglements.

Hydroxypropyl cellulose (HpC) forms a liquid crystalline phase and is thought to have a rod-like shape in aqueous solution. The viscoelastic behaviors of aqueous solutions of HpC samples with average molar substitution numbers (MS ∼ 3.8) and weight-average molar masses (Mw = 36-740 kg mol-1) were examined over a wide concentration (c) range, and the results were discussed based on a concept of rod particle suspension rheology. The c and Mw dependencies of viscoelastic parameters determined in the frequency range showing flow behavior, such as the zero-shear viscosity, the average relaxation time, and the steady-state compliance in the c range for HpC molecules to fully entangle, were considered by using the number density (ν = cNA/Mw, where NA is the Avogadro constant), the intrinsic viscosity, and the average rod particle length of HpC molecules determined via dilute solution properties. The obtained relationships were successfully understood with the rod particle suspension rheology.

Liquid Crystal Polycaprolactone Copolymer Elastomer With Low Autonomous Driving Temperature

ABSTRACTLiquid crystal elastomers (LCEs) are liquid crystal polymers with moderate crosslinking that exhibit elasticity in both their isotropic and liquid crystal states. These materials can be programmed through chemical design and geometric configuration to achieve autonomous actuation at specific temperatures. Typically, the autonomous actuation temperature of LCEs exceeds the phase transition temperature of their isotropic states, with most reported LCEs requiring temperatures above 100°C. Such high temperatures pose challenges for use in soft robotics due to increased energy consumption and limited operational flexibility. In this study, we introduce a small amount of polycaprolactone (PCL) into the main chain of LCEs, effectively lowering their phase transition temperature while maintaining over 90% of the reversible shrinkage strain characteristic of pure LCEs. By adjusting the PCL content, the number of twists, and the helix density, we successfully obtained an LCE‐PCL actuator with improved autonomous actuation performance at temperatures ranging from 45°C to 105°C. Moreover, by modulating the degree of torsion and the operating temperature, the LCE‐PCL autonomous actuator demonstrates the ability to perform complex motions, such as reversing and parking. This work offers new insights into the design and application of LCEs with reduced phase transition temperatures and enhanced self‐driving capabilities.