Transport Properties Of Solutions Research Articles

Effects of CO2-brine-rock Fracture Interaction on Reactive Solute Transport Properties During CO2 Sequestration in Deep Saline Aquifers

Effects of CO2-brine-rock Fracture Interaction on Reactive Solute Transport Properties During CO2 Sequestration in Deep Saline Aquifers

Electroactive ferrocene-based ionic liquids: transport and electrochemical properties of their acetonitrile solutions

The increasing global demand for energy stimulates the development of advanced energy storage and conversion technologies. Modification of electrolyte with redox-active additives is a promising way to enhance the electrochemical performance of energy storage devices. In this work new electroactive ferrocene-based ionic liquids (Fc-ILs) (N-methyl-N-(ferrocenylmethyl)piperidinium bis(trifluoromethanesulfonyl)imide [PipFcMe][NTf2], N-methyl-N-(ferrocenylmethyl)pyrrolidinium bis(trifluoromethanesulfonyl)imide [PyrFcMe][NTf2], N-ethyl-N-(ferrocenylmethyl)pyrrolidinium bis(trifluoromethanesulfonyl)imide [PyrFcEt][NTf2]) were synthesized. The structure of the Fc-ILs was confirmed by NMR and XRD. [PipFcMe][NTf2] and [PyrFcMe][NTf2] demonstrated nearly similar crystal structures consisting of cation and anion columns, while alternating cation and anion layers are stacked in the [PyrFcEt][NTf2] crystal. The effects of the Fc-IL mole fraction and temperature on the transport properties of the acetonitrile solutions of the Fc-ILs have been established. The highest electrical conductivities of the [PipFcMe][NTf2], [PyrFcEt][NTf2] and [PyrFcMe][NTf2] solutions calculated using the Casteel-Amis equation were, respectively, 38.06 ± 0.63, 40.34 ± 0.93 and 41.09 ± 0.58 mS/cm at 348.15 K. The activation energies of conductivity were calculated using the Arrhenius and Vogel-Fulcher-Tamman approaches. The Fc-ILs demonstrated a high electrochemical stability range up to 4.67 V. The introduction of electron-withdrawing substituents into the cyclopentadienyl ring of Fc-ILs shifted the half-wave potential to the positive direction. The diffusion coefficients were calculated using the Randles–Ševčík equation for a quasi-reversible process.

Ethyl-dimethyl-(ferrocenylmethyl)ammonium-based ionic liquid: Structure, transport, and electrochemical properties of binary solutions in acetonitrile

Ethyl-dimethyl-(ferrocenylmethyl)ammonium-based ionic liquid: Structure, transport, and electrochemical properties of binary solutions in acetonitrile

Thermal transport of alkali halide aqueous solutions: a non-equilibrium molecular dynamics investigation

Electrolyte solutions are essential in various physical, chemical, and biological processes. Thermal fields induce ion mass fluxes in electrolyte solutions, creating stable salt concentration gradients at stationary conditions. The response of the salt to the thermal field is quite complex, as the ions move towards hot or cold regions depending on the composition of the solution. While these phenomena are well-known, the microscopic mechanism determining thermodiffusion is still poorly understood. In this study, we used non-equilibrium molecular dynamics simulations and the Madrid 2019 forcefield to investigate the thermal transport properties of several electrolyte solutions: {Li + , Na + , K + }Cl − and {Li + , Na + , K + }I − . We show that the reduction of the thermal conductivity with salt concentration is correlated with the modification of the isothermal compressibility and the molar mass of the solution. We also calculate the Soret coefficient of the solutions and compare our results with those of existing experiments. The Madrid 2019 forcefield reproduces the main experimental trends of chloride solutions and the stronger thermophilic response of lithium salts. Our results suggest a connection between the ability of cations (Na + , K + ) to disturb oxygen-oxygen correlations within the 0.35–0.5 nm inter-oxygen distance range and the thermophobicity of the solutions.

Relative contributions of mobility and partitioning to volatile fatty acid flux during electrodialysis

Economically valuable volatile fatty acids (VFAs) are sustainably produced via fermentation processes. To use VFAs downstream, they must be recovered using technologies like electrodialysis (ED). Solute transport properties (i.e., partition coefficient (K), diffusion coefficient (D), and permeability (P=KD)) govern flux in ED. Therefore, to advance understanding of VFA flux through anion exchange membranes (AEMs) in ED, we aimed to elucidate the relative contributions of VFA partitioning and mobility to their flux. Accordingly, for VFAs of different sizes (C1–C5) and inorganic anions (Cl–, Br–), we measured their fluxes during ED, permeabilities, and partition coefficients, and calculated the diffusion coefficients. We then evaluated the correlations between flux and transport properties and between transport properties and anion physicochemical properties. Results showed VFA flux had a strong correlation with permeability (R2=0.94, p<0.01), consistent with flux described by the Nernst-Planck equation. Further, while there was a negative correlation between VFA flux and partition coefficient (R2=0.46, p=0.21), there was a positive correlation between VFA flux and diffusion coefficient (R2=0.95, p<0.01) which showed VFA mobility governed VFA flux. We observed a negative correlation between VFA diffusion coefficient and carbon–chain length which was attributed to steric hindrance, and a positive correlation between partition coefficient and carbon chain-length which we attributed to hydrophobicity and polarizability. This work provides fundamental insight on interactions between VFAs and AEMs which affect anion flux during ED.

Transport Properties of Aqueous Methane Solutions and Blocking Behavior of Intelligent-Responsive Temporary Plugging Agent in a Switchable Nano-channel: A Dissipative Particle Dynamics Simulation Study.

Intelligent-responsive temporary plugging agents (TPAs) have great potential in the field of oil and gas resource extraction due to their self-adaptability to the environment. However, the transport mechanism of oil and gas molecules, such as aqueous methane solution in intelligent-responsive TPA-modified nano-channels and the blocking behavior of TPA, have not been verified yet. In this work, dissipative particle dynamics simulations (DPD) are conducted to investigate the velocity distribution and the force characteristics of aqueous methane solutions under different driving velocities, as well as the blocking effect of TPA to the flow of solution. Simulation results indicate that aqueous methane solution primarily concentrates in theuncovered area of the TPA and diffuses into the TPA-covered area when the nano-channel is closed. The velocity distribution of the flowing solution in the open nano-channel follows a subparabolic pattern. Methane molecules in the closed nano-channel show sharp oscillations in velocity and force profiles, which can be mitigated by increasing the methane concentration. The designed TPA effectively blocks fluid flow but its head and tail are vulnerable to the shear forces from the fluid. This study enhances the understanding of the nanoflows in the wellbores during the extraction of oil and natural gas resources.

Improving monitoring network design to detect leaks at hazardous facilities: Lessons from a CO2 storage site

Exploring the challenges posed by uncertainties in numerical modeling for hazardous material storage, this study introduces methodologies to improve monitoring networks for detecting subsurface leakages. The proposed approaches were applied to the Korea CO2 Storage Environmental Management (K-COSEM) test site, undergoing calibration, validation and uncertainty analysis through hydraulic and controlled-CO2 release tests. The calibration phase involved inter-well tracer and multi-well pumping tests, leveraging the Parameter ESTimation (PEST) model to determine the aquifer flow and solute transport properties of the K-COSEM site. To tackle uncertainties with limited observation data, we adopted Latin Hypercube simulation. Our uncertainty analysis confirmed model accuracy in simulating observed CO2 breakthrough curves. We also explored a probabilistic method to identify the environmental change point (EnCP) through correlation analysis with the distance from the CO2 injection well, revealing a linear trend and pinpointed potential preferential flow pathways by assessing detection probabilities. Evaluating CO2 detection capabilities was crucial for optimizing monitoring well placement, highlighting strategic well selection based on detection probabilities. This study advances managing uncertainties in hydrogeological modeling, underscoring the importance of sophisticated models in designing monitoring networks for hazardous leak detection in complex subsurface conditions.

IV‐VI/I‐V‐VI2 Thermoelectrics: Recent Progress and Perspectives

AbstractThermoelectric energy conversion technology is considered as one of the most promising solutions for recovering waste heat generated by fossil fuel combustion. As typical types of thermoelectric materials in the middle and high‐temperature range (500–900 K), binary IV‐VI (IV = Ge, Sn, Pb; VI = Se, Te) compounds are extensively studied. Lately, the obtained high‐performance thermoelectric solid solutions between IV‐VI and I‐V‐VI2 (I = Li, Na, K, Ag, Cu; V = Sb, Bi; VI = S, Se, Te) compounds have brought those complex chalcogenides back to the central point of thermoelectric community due to the emerging rich physical phenomena. Profiting from this effective approach, unveiling the underlying mechanism and understanding of alloying effect on the transport properties of these solid solutions becomes particularly significant. This review presents the latest progress in designing high‐performance IV‐VI/I‐V‐VI2 solid solutions and the underlining physical mechanisms, in which detailed discussion about the role of I‐V‐VI2 compounds play in optimizing individual properties of IV‐VI materials is made. This comprehensive review highlights the multiple effects of I‐V‐VI2 alloying on thermoelectric properties of IV‐VI compounds and will drive the related research interests aiming at developing new‐generation thermoelectric compounds in this family.

Synthesis and Transport Properties of ZnSnP2-yAsy Chalcopyrite Solid Solutions.

This work focuses on the synthesis and properties of quaternary ZnSnP2-yAsy chalcopyrite solid solutions. Full miscibility of the solid solution is achieved using ball milling followed by hot press sintering. The measured electrical conductivity increases substantially with As substitution from 0.03 S cm-1 for ZnSnP2 to 10.3 S cm-1 for ZnSnAs2 at 715 K. Band gaps calculated from the activation energies show a steady decrease with increasing As concentration from 1.4 eV for ZnSnP2 to 0.7 eV for ZnSnAs2. The Seebeck coefficient decreases significantly with As substitution from nearly 1000 μV K-1 for ZnSnP2 to -100 μV K-1 for ZnSnAs2 at 650 K. Thermal conductivity is decreased for the solid solutions due to alloy phonon scattering, compared to the end members with y = 0 and y = 2, with the y = 0.5 and y = 1.0 samples exhibiting the lowest values of 1.4 W m-1 K-1 at 825 K. Figure of merit values are increased for the undoped solid solutions at lower temperatures when compared to the end members due to the decreased thermal conductivity, with the y = 0.5 sample reaching zT = 1.6 × 10-3 and y = 1 reaching 2.1 × 10-3 at 700 K. The largest values of the figure of merit zT for the undoped series was found for y = 2 with zT = 2.8 × 10-3 at 700 K due to the increasing n-type Seebeck coefficient. Boltztrap calculations reveal that p-doping could yield zT values above unity at 800 K in case of ZnSnAs2, comparable with ZnSnP2.

Anomalous Pressure Diffusion and Deformation in Two‐ and Three‐Dimensional Heterogeneous Fractured Media

AbstractIn fractured and stress‐sensitive reservoirs and aquifers, hydromechanical coupling is important, in connection with their heat and solute transport properties, and because the fluid production or extraction leads to land subsidence and potentially to induced seismicity. Classical dual‐porosity poroelasticity (DPP) models cannot upscale pressure diffusion and deformation in fractured porous media, which are characterized by anomalous behaviors that manifest in strong tailing in the temporal evolution of flow rate and subsidence. We study these behaviors using detailed numerical simulations of fluid production in naturally fractured formations characterized by multi‐Gaussian distributions of the matrix permeability. We find that the tailing behaviors depend on the permeability contrast between fracture and matrix, on the permeability distribution in the matrix, and on the correlation length. We use a non–equilibrium, multi‐porosity model to quantify the coupled behaviors of anomalous pressure diffusion, fluid flow and deformation. The model is parameterized by medium and fluid properties, which set the characteristic pressure diffusion time scales. It allows to identify the emerging scaling regimes and scaling behaviors of flow rate and subsidence. We propose a model implementation that captures the full anomalous evolution of flow rates and displacements observed in the detailed numerical simulations in terms of the permeability distribution and matrix length scales. The presented results shed new light on the controls of medium heterogeneity and geometry on pressure diffusion, fluid production and subsidence in highly heterogeneous fractured media.

Physicochemical Properties of Lithium Bis(trifluoromethanesulfonyl)imide Solutions in Sulfolane

A study is performed of the physicochemical properties (ionic conductivity, viscosity, and density in the 30–50°C range of temperatures) and the electrochemical and thermal stability of lithium bis(trifluoromethanesulfonyl)imide solutions in sulfolane in the 0.001–1.89 M range of concentrations. It is shown that lithium bis(trifluoromethanesulfonyl)imide solutions in sulfolane exhibit high electrochemical stability (5.75 V vs. Li/Li+) and moderate ionic conductivity (2.75 × 10−3 Ω−1 cm−1 at 30°C for a 1 M solution), which are comparable to the respective parameters of sulfolane solutions of lithium hexafluorophosphate. The structure and transport properties of sulfolane solutions of lithium bis(trifluoromethanesulfonyl)imide are determined by their concentrations. In dilute solutions, lithium bis(trifluoromethanesulfonyl)imide is weakly associated. The degree of electrolytic dissociation of LiN(SO2CF3)2 initially falls and then rises upon an increase in its concentration. The electrolytic dissociation of lithium bis(trifluoromethanesulfonyl)imide rises along with its concentration, due to the formation of ion triplets and more complex ion associates. The constant of association and limit equivalent conductivity of LiN(SO2CF3)2 in sulfolane rise along with temperature, due to a drop in the degree of self-association and the degradation of the solvent’s structure. A specific feature of sulfolane solutions of lithium bis(trifluoromethanesulfonyl)imide is their tendency to form stable supercooled solutions.

Characterization of Manganese Acetate Hydrate Solutions and Their Potential Use for Energy Storage Applications

AbstractWhile there have been numerous studies on the use of manganese acetate for electrode manufacture, scarce reports exist on the utility of manganese acetate electrolytes for energy storage applications. This study provides a comprehensive understanding of the thermal, volumetric, and transport properties of manganese acetate hydrate solutions and highlights their potential for use in energy storage applications. Noteworthy thermal behaviours, phase transitions, and strong interactions between manganese cations, acetate anions, and water molecules are observed. Transport properties reveal salt concentration‘s impact (0.4–3.9 mol L−1) on viscosity and conductivity, with higher concentrations (&gt;2.5 mol L−1) indicating increased interaction. The non‐Arrhenius behaviour in conductivity is elucidated using the Vogel‐Fulcher‐Tammann model, accentuating the unique properties of these solutions compared to other aqueous electrolytes due to the role of acetate ligands. The formulated two‐electrode symmetric supercapacitors exhibit pseudocapacitive behaviour, reversible redox reactions (Mn2+/Mn3+), and salt concentration‐dependent specific capacitance. Manganese acetate as an electrolyte leads to reversible manganese dioxide deposition, with its concentration affecting redox reactions and capacitance. Molecular simulations support the observed electrochemical performance, emphasizing the Mn2+‐acetate complexation. Long‐term cycling experiments demonstrate stability over 2000 cycles, with a stable specific capacitance of 130 F g−1 and a gradual coulombic efficiency decrease (~97 %). The results of this work underscore the potential of manganese acetate hydrate solutions as a stable, effective and green electrolyte for energy storage applications.

Interfacial structure and transport properties of concentrated lithium chloride solutions under an electrostatic field

Efficient moisture exchange between liquid desiccants and air is essential for optimizing dehumidification and air-conditioning systems, with the interfacial layer playing a critical role. This work investigates the influence of electrostatic fields (E-fields) on the structural and transport properties of the liquid-vapor interface between aqueous lithium chloride solutions and air at a microscopic scale using molecular dynamics (MD) simulations. Our research reveals that negative normal E-fields deplete ions within the interfacial layer, weakening their interactions with water molecules. Conversely, positive normal E-fields enrich surface ions, attracting a higher concentration of water molecules to the interface. The E-field enhances interactions between water molecules, increasing hydrogen bonds (H-bonds) at the interface. This weakens cohesion between water molecules and the liquid phase, ultimately reducing surface tension and the associated interfacial free energy barrier, facilitating the departure of water molecules from the liquid phase. Negative normal E-fields demonstrate greater advantages due to their pronounced alteration of the interface structure and the polarization of water molecules.

Enzymatic cleaving of entangled DNA rings drives scale-dependent rheological trajectories.

DNA, which naturally occurs in linear, ring, and supercoiled topologies, frequently undergoes enzyme-driven topological conversion and fragmentation in vivo, enabling it to perform a variety of functions within the cell. In vitro, highly concentrated DNA polymers form entanglements that yield viscoelastic properties dependent on the topologies and lengths of the DNA. Enzyme-driven alterations of DNA size and shape therefore offer a means of designing active materials with programmable viscoelastic properties. Here, we incorporate multi-site restriction endonucleases into dense DNA solutions to linearize and fragment circular DNA molecules. We pair optical tweezers microrheology with differential dynamic microscopy and single-molecule tracking to measure the linear and nonlinear viscoelastic response and transport properties of entangled DNA solutions over a wide range of spatiotemporal scales throughout the course of enzymatic digestion. We show that, at short timescales, relative to the relaxation timescales of the polymers, digestion of these 'topologically-active' fluids initially causes an increase in elasticity and relaxation times followed by a gradual decrease. Conversely, for long timescales, linear viscoelastic moduli exhibit signatures of increasing elasticity. DNA diffusion, likewise, becomes increasingly slowed, in direct opposition to the short-time behavior. We hypothesize that this scale-dependent rheology arises from the population of small DNA fragments, which increases as digestion proceeds, driving self-association of larger fragments via depletion interactions, giving rise to slow relaxation modes of clusters of entangled chains, interspersed among shorter unentangled fragments. While these slow modes likely dominate at long times, they are presumably frozen out in the short-time limit, which instead probes the faster relaxation modes of the unentangled population.

Study of thermodynamic, transport and volumetric properties of nanofluids containing ZrO2 nanoparticles in polypropylene glycol, polyvinyl pyrrolidone and water.

Zirconium dioxide (ZrO2) nanofluids are used in cooling systems, solar energy, and heat exchangers, offering improved heat transfer and efficiency across a wide temperature range. The aim of this work was to study the influence of polypropylene glycol (PPG) and polyvinyl pyrrolidone (PVP) and aqueous solutions of them as a base fluid on stability, volumetric properties, and viscosity of nanofluids containing Zirconium oxide (ZrO2) nanoparticles. The stability of these nanofluids has been confirmed using UV-Vis spectroscopy, and the particle size distribution of the systems using dynamic light scattering (DLS). Among these systems ZrO2-PPG and ZrO2-H2O-PVP30% have appropriate stability. The density, speed of sound and viscosity of these nanofluids have been measured at T = (293.15 to 318.15) K. From these data, the excess molar volume (V E m) and isentropic compressibility (κ s) have been determined. The effects of ZrO2 nanoparticles and temperature have also been investigated on volumetric and transport properties of aqueous solutions of PPG and PVP. The (V E m) values were fitted to the Redlich-Kister, Ott et al., and polynomial equations. Also, the isentropic compressibility (κ s) values were correlated with the polynomial equation. The Eyring-NRTL and Eyring-mNRF models have been used for correlating of the viscosity of the nanofluids with temperature dependency. The performance of the Einstein, Brinkman, Lundgren and Batchelor models in the prediction of viscosity of the nanofluids has also been analyzed.

Effect of Lactate-Based Protic Ionic Liquids on the Thermodynamic and Transport Properties of Aqueous Lithium Bromide Solutions at Different Temperatures

Effect of Lactate-Based Protic Ionic Liquids on the Thermodynamic and Transport Properties of Aqueous Lithium Bromide Solutions at Different Temperatures

Correlations between Molecular Structure, Solvation Topology, and Transport Properties of Aqueous Organic Flow Battery Electrolyte Solutions

Correlations between Molecular Structure, Solvation Topology, and Transport Properties of Aqueous Organic Flow Battery Electrolyte Solutions

Multi-scale modelling of dilute viscoelastic liquids: Atomistic to mesoscale mapping of polymer solutions

A framework predicting the rheological (storage and loss moduli, first normal stress coefficient, and relaxation time) and transport (viscosity, diffusivity) properties of non-Newtonian dilute polymer solutions at mesoscales (e.g. ∼ns to μs) from the atomistic-scale molecular behaviour is presented. More specifically, the rheological behaviour differences of OCP and PMA polymer solutions in PAO-2 oil are simulated using both atomistic molecular dynamics (MD) and many-body dissipative particle dynamics (mDPD) within a temperature range of 313–373 K. The simulation methodology described is able to distinguish itself from the standard DPD model by accurately reproducing the shear-thinning with high sensitivity, as seen in the atomistic MD simulations at high shear rates (e.g. 108−1013 s−1). It is shown that the model is well-suited to compute properties such as first normal stress differences and relaxation times that are difficult to estimate at atomistic scales due to the low signal-to-noise ratio. Moreover, the Schmidt numbers (>103) are predicted with high accuracy when compared with the values from atomistic-scale simulations. The proposed model is able to predict relaxation times of dilute polymer mixtures that are difficult to be obtained using state-of-the-art rheometers. Finally, it is found that the terminal relaxation time of PMA polymer chain does not vary monotonically as a function of temperature, unlike in the case of OCP; this is significant for describing viscoelastic behaviour at macroscales where satisfactory constitutive equations are not available.

Structurally decoupled stiffness and solute transport in multi-arm poly(ethylene glycol) hydrogels

Synthetic hydrogels are widely used as artificial 3D environments for cell culture, facilitating the controlled study of cell-environment interactions. However, most hydrogels are limited in their ability to represent the physical properties of biological tissues because stiffness and solute transport properties in hydrogels are closely correlated. Resultingly, experimental investigations of cell-environment interactions in hydrogels are confounded by simultaneous changes in multiple physical properties. Here, we overcame this limitation by simultaneously manipulating four structural parameters to synthesize a library of multi-arm poly (ethylene glycol) (PEG) hydrogel formulations with robustly decoupled stiffness and solute transport. This structural design approach avoids chemical alterations or additions to the network that might have unanticipated effects on encapsulated cells. An algorithm created to statistically evaluate stiffness-transport decoupling within the dataset identified 46 of the 73 synthesized formulations as robustly decoupled. We show that the swollen polymer network model accurately predicts 11 out of 12 structure-property relationships, suggesting that this approach to decoupling stiffness and solute transport in hydrogels is fundamentally validated and potentially broadly applicable. Furthermore, the unprecedented control of hydrogel network structure provided by multi-arm PEG hydrogels confirmed several fundamental modeling assumptions. This study enables nuanced hydrogel design for uncompromised investigation of cell-environment interactions.

Computation of Electrical Conductivities of Aqueous Electrolyte Solutions: Two Surfaces, One Property.

In this work, we computed electrical conductivities under ambient conditions of aqueous NaCl and KCl solutions by using the Einstein-Helfand equation. Common force fields (charge q = ±1 e) do not reproduce the experimental values of electrical conductivities, viscosities, and diffusion coefficients. Recently, we proposed the idea of using different charges to describe the potential energy surface (PES) and the dipole moment surface (DMS). In this work, we implement this concept. The equilibrium trajectories required to evaluate electrical conductivities (within linear response theory) were obtained by using scaled charges (with the value q = ±0.75 e) to describe the PES. The potential parameters were those of the Madrid-Transport force field, which accurately describe viscosities and diffusion coefficients of these ionic solutions. However, integer charges were used to compute the conductivities (thus describing the DMS). The basic idea is that although the scaled charge describes the ion-water interaction better, the integer charge reflects the value of the charge that is transported due to the electric field. The agreement obtained with experiments is excellent, as for the first time electrical conductivities (and the other transport properties) of NaCl and KCl electrolyte solutions are described with high accuracy for the whole concentration range up to their solubility limit. Finally, we propose an easy way to obtain a rough estimate of the actual electrical conductivity of the potential model under consideration using the approximate Nernst-Einstein equation, which neglects correlations between different ions.