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This study presents a structural analysis of the physical phenomena involved in the processes of oil emulsion separation. Various aspects of adsorption layer formation on droplet surfaces by asphaltene-resin compounds are discussed, along with models for calculating the mass and thickness of the layer. It is demonstrated that the formation of adsorption films on the surface of water droplets provides a significant resistance to their merging at collision, resulting in aggregatively stable emulsions. Emulsion separation occurs in subsequent stages following the destruction of these films using various reagents. The mechanism of adsorption film destruction involves the diffusive transfer of demulsifiers to the film surface, followed by their adsorption and penetration into the film's volume. Equations describing coalescence during the collision of a high-viscosity droplet with an ordinary one are proposed, and expressions for calculating droplet collision frequency are derived. Experimental studies on oil emulsion separation processes have been conducted. It is established that in the experimental study many physical phenomena (convective diffusion transfer, formation of intermediate layer, etc.) can be neglected, which significantly simplifies the description of the process. The description of the experimental process in the form of a model is based on the equations of convective diffusion transfer of water mass from the bulk of oil as a function of demulsifier flow rate and temperature. Comparison curves of experimental and calculated values are given to validate the model. [ABSTRACT FROM AUTHOR]

The practical application of aqueous zinc‐ion batteries (ZIBs) indeed faces challenges primarily attributed to the inherent side reactions and dendrite growth associated with the Zn anode. In the present work, N‐Methylmethanesulfonamide (NMS) is introduced to optimize the transfer, desolvation, and reduction of Zn2+, achieving highly stable and reversible Zn plating/stripping. The NMS molecule can substitute one H2O molecule in the solvation structure of hydrated Zn2+ and be preferentially chemisorbed on the Zn surface to protect Zn anode against corrosion and hydrogen evolution reaction (HER), thereby suppressing byproducts formation. Additionally, a robust N‐rich organic and inorganic (ZnS and ZnCO3) hybrid solid electrolyte interphase is in situ generated on Zn anode due to the decomposition of NMS, resulting in enhanced Zn2+ transport kinetics and uniform Zn2+ deposition. Consequently, aqueous cells with the NMS achieve a long lifespan of 2300 h at 1 mA cm−2 and 1 mAh cm−2, high cumulative plated capacity of 3.25 Ah cm−2, and excellent reversibility with an average coulombic efficiency (CE) of 99.7 % over 800 cycles. [ABSTRACT FROM AUTHOR]

Context: Industrial production and humans cannot exist without energy, but the low efficiency of the heat transfer in the excessive use of energy is the most significant aspect of energy saving and emission reduction. Molecular dynamics simulation methods are devoted to simulate the heat transfer efficiency of a nanofluid system with different particle sizes, and the heat transfer enhancement mechanism of the nanofluid is simulated and studied from a microscopic perspective. The analysis showed that as nanoparticle size increases, the thermal conductivity of the Al–Ar nanofluid tends to decrease, but all of them are still higher than the thermal conductivity of the liquid argon system. According to the findings of the density and radial distribution function analyses, it can be seen that the microstructure of the system changes after putting solid nanoparticles to the original fluid. This alteration in the system's microstructure is the primary component responsible for the increased heat transfer efficiency of nanofluids. Methods: In this paper, based on the theory of molecular dynamics, the simulation calculations were mainly performed using LAMMPS software, which is a commonly used open source computational program in the field of MD simulation research. VMD is used for visualization and analysis. The Lennard–Jones potential function was used in the simulation to accurately describe the forces acting between the atoms. [ABSTRACT FROM AUTHOR]

Within the framework of the thermodynamic theory of equilibrium two-component adsorption from a liquid on a flat solid surface, taking into account its deformation and the presence of an electric charge on it, two equations of the isotherm of such adsorption are derived at small deformations containing two unknown functions independent of the electric potential of the solid phase. It is shown that the problem of finding the conditions for the single-phase nature of the adsorption layer is reduced to the same problem, but posed for an undeformed surface. [ABSTRACT FROM AUTHOR]

The occurrence characteristics of shale oil in the pores of shale nano organic matter are studied by molecular dynamics simulation. The adsorption characteristics of n-octane on graphene wall at 353 K and 30.7 MPa are simulated under OPLS all atomic force field, and the effects of different pores size, temperature, pressure, carbon chains length and alkane polarity on the adsorption of n-octane on organic matter wall are analyzed. The results show that n-octane has four adsorption layers on the pores wall of organic matter, the peak density of the adsorption layer decreases gradually, and the thickness of the adsorption layer is 0.4-0.5 nm. The vertical diffusion coefficient and parallel diffusion coefficient increase gradually along the z direction and reach stability at the center of the pores. And the parallel diffusion coefficient is greater than the vertical diffusion coefficient. The pressure has little effect on the adsorption capacity of alkane molecules. The larger the pores size, the higher the temperature, the shorter the carbon chains and the lower the molecular polarity, the smaller the adsorption volume fraction of alkane molecules in the pores of nano organic matter. [ABSTRACT FROM AUTHOR]

Dynamic dilational viscoelasticity is an important physical characteristic of interfacial layers because it influences the dynamics and stability of multiphase systems, such as thin liquid films, foams and emulsions. Dilational viscoelasticity depends on many factors. Less studied, but very important, factors are the solubility of the solution components in two contacting liquids, the simultaneous presence of two solution components within a mixed adsorption layer and the curvature of the interface. In this review, we considered several new developments of previously proposed models, which can be used for the analysis of new experimental data. In the presence of such effects, the behaviour of the dilational viscoelasticity becomes more complicated and requires more parameters for its description. An alternative way is to use phenomenological models, which do not identify the particular relaxation processes but propose a description of the dilational viscoelasticity in general terms. [Display omitted] [ABSTRACT FROM AUTHOR]

• Secondary liquid bridging forms when adsorbed layers grow faster than meniscus moves. • Cavitation, an activation process during desorption, intensifies, increasing cavity numbers. • Stability of liquid bridge is disrupted by converging cavities, leading to its rupture and subsequent disappearance. To explore the internal transport mechanisms and evolutionary processes within nanopore, molecular dynamic simulations were employed to explore the formation of liquid bridges and the evolution of menisci. The adsorption–desorption isotherms were obtained, and the dynamic behavior of the adsorbate was analyzed. Results revealed two distinct processes governing the behavior of the adsorbate within nanopore. At low pressure ratios, a molecular adsorption layer initially grows continuously on the pore surface. As the pressure ratio increases, an additional mechanism emerges, characterized by the formation of a liquid bridge near the nanopore mouth. This leads to pore filling as the liquid bridge expands and retreats towards the pore's closed end. During desorption, cavitation occurs, which can be characterized as an activation process. Once initiated, cavitation intensifies, progressively increasing the number of cavities. The convergence of these cavities undermines the stability of the liquid bridge, ultimately resulting in its collapse and the rapid evaporation of the adsorbate molecules. Additionally, we further calculated the contact angle at the vapor–liquid interface using the Kelvin equation. The results indicated a deviation of less than 5 % compared to our simulations, suggesting that the Kelvin equation is applicable for materials with pore sizes of at least 3.6 nm. [ABSTRACT FROM AUTHOR]

Rocks generated from tunnel construction projects for roads and railways throughout Japan have often leached out hazardous trace elements, such as arsenic (As) and selenium (Se). In nature, the oxyanionic species of As and Se have a variety of chemical species, so speciation is one of the crucial factors in their migration through natural geologic media. In this study, column experiments consisting of four types of crushed rock samples containing As and Se, and a river sediment (RS) as an adsorbent obtained near the tunnel construction site were conducted to evaluate the leaching and adsorption behavior of arsenite (As (III) ), arsenate (As (V) ), selenite (Se (IV) ), and selenate (Se (VI) ). The results showed that the dominant speciation of As and Se in the effluent from the rock layer was As (V) and Se (VI), and that the addition of a bottom RS adsorption layer or the mixing of RS with the rock layer decreased the leaching concentrations of As (III), As (V), Se (IV), and Se (VI). Cumulative leachability (CL) for each speciation through the column experiments was calculated to evaluate the amounts of As and Se retained in RS. The calculated CL showed that the bottom RS layer or mixing of RS with the rock reduced the CL of As (III), As (V), Se (IV), and Se (IV) ranging from 60 to 89%, 73 to 89%, 9 to 75%, and 36 to 60%, respectively; however, mixing of RS with the rock layer was ineffective in decreasing CL of Se (VI). The reduction of CL may be due to adsorption and/or coprecipitation by iron and/or aluminum oxides contained in RS. These results indicated that utilization of RS for the bottom adsorption layer was effective in reducing As and Se concentrations irrespective of their speciation, although that of mixed with rock layer was effective only in reducing As concentrations irrespective of their speciation.

The flow of shale gas in nano scale pores is affected by multiple physical phenomena. At present, the influence of multiple physical phenomena on the transport mechanism of gas in nano-pores is not clear, and a unified mathematical model to describe these multiple physical phenomena is still not available. In this paper, an apparent permeability model was established, after comprehensively considering three gas flow mechanisms in shale matrix organic pores, including viscous slippage Flow, Knudsen diffusion and surface diffusion of adsorbed gas, and real gas effect and confinement effect, and at the same time considering the effects of matrix shrinkage, stress sensitivity, adsorption layer thinning, confinement effect and real gas effect on pore radius. The contribution of three flow mechanisms to apparent permeability under different pore pressure and pore size is analyzed. The effects of adsorption layer thinning, stress sensitivity, matrix shrinkage effect, real gas effect and confinement effect on apparent permeability were also systematically analyzed. The results show that the apparent permeability first decreases and then increases with the decrease of pore pressure. With the decrease of pore pressure, matrix shrinkage, Knudsen diffusion, slippage effect and surface diffusion effect increase gradually. These four effects will not only make up for the permeability loss caused by stress sensitivity and adsorption layer, but also significantly increase the permeability. With the decrease of pore radius, the contribution of slippage flow decreases, and the contributions of Knudsen diffusion and surface diffusion increase gradually. With the decrease of pore radius and the increase of pore pressure, the influence of real gas effect and confinement effect on permeability increases significantly. Considering real gas and confinement effect, the apparent permeability of pores with radius of 5 nm is increased by 13.2%, and the apparent permeability of pores with radius of 1 nm is increased by 61.3%. The apparent permeability model obtained in this paper can provide a theoretical basis for more accurate measurement of permeability of shale matrix and accurate evaluation of productivity of shale gas horizontal wells.

The adsorption layer system has shown great potential as a cost-effective and practical strategy for the recycling and management of excavated rocks containing potentially toxic elements (PTEs). Although this system has been employed in various civil engineering projects throughout Japan, its long-term performance to immobilize PTEs has rarely been investigated. This study aims to evaluate the effectiveness of the adsorption layer system applied in an actual road embankment approximately 11 years after construction. The embankment system is comprised of a layer of excavated arsenic (As)-bearing mudstone built on top of a bottom adsorption layer mixed with an iron (Fe)-based adsorbent. Collection of undisturbed sample was carried out by implementing borehole drilling surveys on the embankment. Batch leaching experiments using deionized water and hydrochloric acid were conducted to evaluate the water-soluble and acid-leachable concentrations of As, Fe, and other coexisting ions. The leaching of As from the mudstone layer was likely induced by As desorption from Fe-oxides/oxyhydroxides naturally present under alkaline conditions, including the oxidation of framboidal pyrite, which was identified as a potential source of As. This was supported by electron probe microanalyzer (EPMA) observations showing the presence of trace amounts of As in framboidal pyrite crystals. Arsenic leached from the mudstone layer was then immobilized by Fe oxyhydroxides found in the adsorption layer. Based on geochemical modeling and X-ray photoelectron spectroscopy (XPS) results, leached As predominantly existed as the negatively charged HAsO 4 2− oxyanion, which is readily sequestered by Fe oxyhydroxides. Moreover, the effectiveness of the adsorption layer was assessed and its lifetime was estimated, and the results revealed it still possessed enough capacity to adsorb As released from mudstone in the foreseeable future. This prediction utilized the maximum potential amount of As that could leach from the excavated rock layer with time. [Display omitted] • Arsenic-bearing excavated rocks were repurposed using the adsorption layer system. • The effectiveness of the adsorption layer in a real road embankment was investigated. • Arsenic leaching from the rock layer was induced under alkaline conditions. • The adsorption layer could adsorb As leached from the rock layer. • Leachable As will continuously be adsorbed by the adsorption layer in the future. [ABSTRACT FROM AUTHOR]

Adsorption of cationic 1-hexadecylpyridinium bromide (HDPB) and non-ionic p-(1,1,3,3-tetramethylbutyl)-phenoxypolyoxyethylene glycols surfactants of the Triton X series (Triton X-45, Triton X-100 and Triton X-305) from their single and mixed aqueous solutions at thermally graphitized carbon black (CB) was studied. It was shown that the adsorption of the non-ionic surfactant from its individual solution decreased when a number of ethylene oxide units in the surfactant molecule increased. Addition of the non-ionic surfactants increased the amount of HDPB adsorbed from HDPB/Triton X mixtures. At low solution concentrations it was found that in HDPB/Triton X mixtures, the experimental values of total surfactants adsorption are higher than the adsorption values calculated for the ideal surfactant mixtures. The composition of the mixed HDPB/Triton X adsorption layer and the parameters of the intermolecular interaction (βs), between the components in this layer, were calculated using the Rubingh-Rosen approach. It was shown that βs parameters have negative values, which indicate notable interactions between Triton X molecules and HDPB ions in the mixed adsorption layer. It was found that the composition of the mixed adsorption layer at CB surface is notably different from the surfactants composition in the bulk solution. The mixed HDPB/Triton X adsorption layer is enriched with Triton X surfactant and the mole fraction of Triton X increases with decreasing of ethoxylation degree of its molecules.

Physicochemical characteristics of silver nanoparticles with known sizes are studied, depending on the concentration of nonionic surfactants and the concentration of the metal. Surfactants are used that form micelles of different sizes and different intensities of light scattering. It is shown that the surface tension and adhesion properties of solutions of nonionic surfactants are determined by the solvent in ranges of concentration lower than 1 mol/L. An approach based on spectrophotometry and viscosimetry is proposed that allows determination of the most likely reasons for discrepancies in the hydrodynamic diameter of nanoparticles in solutions of nonionic surfactants and the actual diameter of the nanoparticles. [ABSTRACT FROM AUTHOR]

A set of rheological experiments is performed for interphase adsorption layers at a water/butyl methacrylate interface formed by high molecular weight surfactants (HMWSs) (polyvinyl alcohol with various acetylated groups (PVA) and copolymer 2-acrylamido-2-methylpropanesulfonic acid with methyl methacrylate (AMPSA-MMA) having different contents of MMA links). It is shown there is an increase in the content of acetylated groups and MMA units in the studied HMWSs produces structures at the interface that differ in higher values of the viscosity and elastic modulus of the adsorption layer. The aggregate stability of dispersion during the suspension polymerization of acrylic monomers grows along with the content of hydrophobic units in the HMWS polymer chain. [ABSTRACT FROM AUTHOR]

Coal porosity prediction is normally based on the matrix deformation caused by effective stress and adsorption/desorption effect. However, the gas adsorption layer attached to the coal pore surface occupies the pore volume and ultimately reduces the coal porosity. Therefore, the porosity dynamic evolution is the result of the matrix deformation and gas adsorption layer variation. According to the basic definition of porosity and the porous media effective stress theory, a dynamic porosity model was developed to explicitly consider the influence of gas adsorption layer. Furthermore, the effects of temperature, gas pressure, adsorption swelling effect, and adsorption layer on coal porosity were analyzed. The model was verified with the field data under the different buried depth conditions. [ABSTRACT FROM AUTHOR]

The possibilities of optimizing the initial structure of the solid-liquid interface for in-situ neutron reflectometry experiments to maximize slight changes in the reflectometry curves associated with small changes in the interface configuration are considered. The interface was modeled as a base layer on a substrate which is in contact with a solution. An adsorption layer (with a thickness of up to 2000 Å) is deposited on this layer from the solution. The proposed optimization procedure was tested for the initial configuration of an electrochemical interface: when the electrical circuit is closed, an adsorption solid-electrolyte interphase is deposited onto a metal electrode on a silicon substrate from a liquid electrolyte with lithium ions. The study of this specific system allows the introduction of restrictions on the variation in the interface parameters, which significantly simplifies solving the optimization problem. [ABSTRACT FROM AUTHOR]

The surface properties of mixed solutions containing an anionic polyelectrolyte, carboxymethylchitosan (CMCH), and a cationic gemini surfactant, 1,2-bis(dodecyldimethlyammonio)hexane dibromide (C12C6C12), were studied by measuring the surface tension and the dynamic surface elasticity. The association behaviors in the solutions were also measured by fluorescence probe technique. The results showed that the adsorption layer transformed from pure elastic 2D layer to visco-elastic 3D layer with increase in surfactant concentration. The microparticles in the 3D layer were adsorbed from the adjacent bulk to the surface but not formed directly in the surface layer as it was sometimes assumed in other polyelectrolyte/surfactant systems. The stress relaxation mechanism were supposed to be the mass exchange between the unstructured thinner film surrounding the microparticles and the adjacent bulk during the surface compression or expansion. These surface properties of CMCH/C12C6C12 solutions were influenced strongly by the association in the bulk solution. The adsorption layers of mixed solutions of an anionic polyelectrolyte, Carboxymethylchitosan, and a cationic gemini surfactants, 1,2-bis(dodecyldimethlyammonio)hexane dibromide, have various structures at a given polyelectrolyte concentration and different surfactant concentrations. Association in the bulk solution influences strongly the adsorption at the surface. [ABSTRACT FROM AUTHOR]

The Brownian dynamics method is employed to study the formation of an electrical double layer (EDL) on the metal nanoparticle (NP) surface in hydrosols during adsorption of electrolyte ions from the interparticle medium. Also studied is the charge accumulation by NPs in the Stern layer. To simulate the process of the formation of EDL, we took into account the effect of image forces and specific adsorption, dissipative and random forces, and the degree of hydration of adsorbed ions on the EDL structure. The employed model makes it possible to determine the charge of NPs and the structure of EDL. For the first time, the charge of both the diffuse part of EDL and the dense Stern layer has been determined. A decrease in the electrolyte concentration (below c < 0.1 mol/l) has been found to result in dramatic changes in the formation of the Stern layer. [ABSTRACT FROM AUTHOR]

Surface phase transitions in surfactant adsorption layers are known to affect the dynamic properties of foams and to induce surface nucleation in freezing emulsion drops. Recently, these transitions were found to play a role in several other phenomena, opening new opportunities for controlling foam and emulsion properties. This review presents a brief outlook of the emerging opportunities in this area. Three topics are emphasized: (1) the use of surfactant mixtures for inducing phase transitions on bubble surfaces in foams; (2) the peculiar properties of natural surfactants saponins, which form extremely viscoelastic surface layers; and (3) the main phenomena in emulsions, for which the surface phase transitions are important. The overall conclusion from the reviewed literature is that surface phase transitions could be used as a powerful tool to control many foam and emulsion properties, but we need deeper understanding of the underlying phenomena to fully explore these opportunities. Image 1 [ABSTRACT FROM AUTHOR]

The adsorption of cationic hexadecylpyridinium bromide and non-ionic oxyethylated octylphenols (TХ-45, TX-100, ТХ-305) surfactants from their mixed solutions at non-porous hydrophobic carbon sorbent such as thermal graphitized carbon black has been studied. The molar fraction of oxyethylated octylphenols in the mixtures was 0.2, 0.4, 0.6, and 0.8. The results have shown that the adsorption values of hexadecylpyridinium bromide depend on the total concentration of the surfactant and the composition of mixtures. It has been found that the molar fraction of nonionic surfactants in the mixed adsorption layers at carbon black surface decreases in the series: ТХ-45 > ТХ-100 > ТХ-305. The regularities of the change in the surface activity of the surfactant mixtures at the solution-solid sorbent interface with an increase in the total surfactant concentration in the solution correlate with those for the solution-air system, but are more pronounced. The areas per hexadecylpyridinium bromide and the oxyethylated octylphenols molecules in the adsorption layer while adsorbing from their binary solutions are lesser than ones for the surfactants adsorption from their individual solutions, and smaller than the corresponding areas at the solution-air interface. These findings indicate the consolidation of the adsorption layer at the solid surface and confirm that the surfactants adsorb at carbon black surface as associates. [ABSTRACT FROM AUTHOR]

When droplets impact on a heated wall, they can levitate owing to the vapor stream generated by the droplet evaporation. This phenomenon is called the Leidenfrost effect, and the vapor layer prevents heat transfer between the droplet and heated wall. In this study, we investigated the influence of the intermolecular force between liquid and solid molecules on the levitating phenomenon, which is caused by heat transfer, for nanodroplets. We used a molecular dynamics (MD) simulation to evaluate the detailed behavior of droplet levitation and investigated the temperature field of the impacting droplet. We found that the droplet levitation was likely to occur at lower temperature when the intermolecular force was stronger. In addition, when the intermolecular force was strong enough, the liquid molecules stayed on the heated wall and an adsorption layer was formed. This adsorption layer exceeded the critical temperature of the liquid molecules, and the existence of the adsorption layer significantly affected the onset of the droplet levitation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Improving Mg metal battery performance in conventional electrolyte by porphyrin. • The analysis reveals the mechanism of how porphyrin enhances the battery performance. • The porphyrin molecules adsorbed on anode to alleviate the passivation of Mg metal. • The porphyrin additive reorganizes the Mg2+ solvation sheath near the interface. The viability of Mg metal batteries is severely threatened by the passivating instinct of Mg metal in Cl-free conventional electrolytes. To realize the reversible Mg stripping/plating in the conventional electrolyte, 5,10,15,20-tetraphenylporphyrin (TPP) with planar structure and strong adsorption ability is added into electrolyte to optimize the interfacial process by constructing a dynamic molecular adsorption layer on Mg anode, which is different from the method of tailoring artificial solid electrolyte interphases to facilitate Mg2+ transport. On one side, TPP molecules served as a protective layer to avoid the direct contact between Mg anode and passivation-inducing factors from electrolyte, alleviating passivation effectively. On the other side, a locally high concentration of TPP is created near the Mg surface for Mg2+ solvation sheath reorganization. Theoretical calculations verify that [MgTPP(DME) 2 ] in TPP-containing electrolyte possesses higher stability and a lower energy barrier than [Mg(DME) 3 ]2+ during desolvation, further alleviating passivation and reducing the overpotential of Mg metal. Consequently, the Mg symmetrical battery exhibits a reduced polarization voltage of 0.6 V from ∼ 2 V and a longer cycling life of over 500 h. With TPP-containing electrolyte, the Mg||V 2 O 5 full battery presents a higher initial capacity of 186.5 mAh/g, which confirms the practicability of this additive strategy. [ABSTRACT FROM AUTHOR]

• The thickness of the adsorption layer for the three production stages is calculated. • The interaction energy between the fluid and the wall is studied. • The adsorption ratio of the components in the three production stages is analyzed. • The self-diffusion coefficients of the components in the three production stages is compared. Due to the high clay content of shale reservoirs, developing shale oil by water flooding is difficult. CO 2 is easier to inject into formations than water, significantly increasing shale oil production by reducing the viscosity of shale oil and increasing the gas-oil ratio. Moreover, CO 2 flooding can also effectively reduce emissions. However, CO 2 flooding changes the formation fluid's phase behavior and composition. This causes the fluid to redistribute in the nanopore. Based on the field data, it can be seen that the changes of formation fluid components are obvious in the three stages of CO 2 injection, the initial state of production and depressurization production. Therefore, this paper uses the molecular dynamics method to study the changes in adsorption layer thickness, adsorption ratio of components, interaction energy, and self-diffusion coefficient of fluids in organic and inorganic pores under these three stages. The results show that the adsorption layer thickness gradually increases during CO 2 flooding. After CO 2 injection, the fluid components in kerogen are significantly desorbed. The desorption of the components in the small pore size of illite, feldspar, and calcite is insignificant; the desorption of the components in the large pore size is significant, and the desorption of the components in quartz is insignificant. The interaction energy between fluid and pores decreases first and then increases during CO 2 flooding, and the types of interaction energy between pores and fluids differ. The results show that CO 2 injection can increase shale oil production. New ways to enhance oil recovery are needed to increase shale oil production in the later stage of depressurization production. [ABSTRACT FROM AUTHOR]

The theoretical description of the adsorption of proteins at liquid/fluid interfaces suffers from the inapplicability of classical formalisms, which soundly calls for the development of more complicated adsorption models. A Frumkin-type thermodynamic 2-d solution model that accounts for nonidealities of interface enthalpy and entropy was proposed about two decades ago and has been continuously developed in the course of comparisons with experimental data. In a previous paper we investigated the adsorption of the globular protein β-lactoglobulin at the water/air interface and used such a model to analyze the experimental isotherms of the surface pressure, Π(c), and the frequency-, f-, dependent surface dilational viscoelasticity modulus, E(c)f, in a wide range of protein concentrations, c, and at pH 7. However, the best fit between theory and experiment proposed in that paper appeared incompatible with new data on the surface excess, Γ, obtained from direct measurements with neutron reflectometry. Therefore, in this work, the same model is simultaneously applied to a larger set of experimental dependences, e.g., Π(c), Γ(c), E(Π)f, etc., with E-values measured strictly in the linear viscoelasticity regime. Despite this ambitious complication, a best global fit was elaborated using a single set of parameter values, which well describes all experimental dependencies, thus corroborating the validity of the chosen thermodynamic model. Furthermore, we applied the model in the same manner to experimental results obtained at pH 3 and pH 5 in order to explain the well-pronounced effect of pH on the interfacial behavior of β-lactoglobulin. The results revealed that the propensity of β-lactoglobulin globules to unfold upon adsorption and stretch at the interface decreases in the order pH 3 > pH 7 > pH 5, i.e., with decreasing protein net charge. Finally, we discuss advantages and limitations in the current state of the model.

Abstract The presence of mixed adsorption layers affects the mechanism and kinetics of irreversible Bi(III) ions electroreduction process in 2 mol·dm−3 chlorates(VII). Triton X-100 and Tween 80 change the dynamics of the catalytic activity of 6-mercaptopurine (6MP) on Bi(III) ions electroreduction with the tendency of inhibition. Above the critical micelle concentration of Triton X-100 and Tween 80, the irreversibility of Bi(III) ions electroreduction decrease to the size comparable to the irreversible reduction of Bi(III) in 2 mol·dm−3 chlorates(VII) which can be associated with the electrode surface blocking by formed hemispherical surface micelles. It was proved that the unstable complexes of Bi – 6MP or mixed Bi – 6MP – TritonX-100 and Bi – 6MP – Tween 80 intermediating in electrons transfer, play a significant role in the multi-stage mechanism of the electrode process. The hydration shell and composition of active complexes change as well. The obtained regularities indicate that in this case confirmed changes in entropy are a decisive factor. Graphical abstract Unlabelled Image Highlights • The presence of mixed adsorption layers affects mechanism and kinetics of irreversible Bi(III) ions electroreduction process. • Surfactants change dynamics of catalytic activity of 6-mercaptopurine on Bi(III) ions electroreduction. • The unstable active complexes of intermediating in electrons transfer [ABSTRACT FROM AUTHOR]

The model of pairwise elastic repulsion of contacting colloidal nanoparticles with a rigid core and deformable shell is discussed. A simple analytical equation is applied for the energy of elastic repulsion of nanoparticles with arbitrary sizes and the elasticity moduli of self-healing polymer adsorption layers. The model is based on the representation of the absorption layer as a continuous medium that is elastically deformed upon the contact of nanoparticles. The major characteristic of this medium is the elasticity modulus. The magnitude of the elasticity modulus is determined from the condition of balance of the van der Waals attractive forces of nanoparticles and the elastic repulsion of their adsorption layers in the contact area, taking into account the temperature variations. We employed the kinetic approach to describe the dependence of the elasticity modulus on both the temperature and the rate of its change. [ABSTRACT FROM AUTHOR]

Copyright of Biological Resources & Nature Management is the property of National University of Life & Environmental Sciences of Ukraine and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of China University of Petroleum is the property of China University of Petroleum and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to investigate the effect of pore geometry structure on the gas permeability, 3 permeability models with different pore shapes were constructed, considering the sorption-induced deformation, adsorption molecular layer and variable Klinkenberg’s effect. The effect of pore geometry structure on the effective pore radius, Klinkenberg’s factor and permeability was analyzed under 3 different conditions, including constant effective stress conditions, constant pore pressure conditions and constant mean stress conditions. Results showed that, under constant effective stress conditions, the spherical pores show a greater effect on the effective radius, followed by the cylindrical pores and the slit pores. Under the constant pore pressure conditions and the constant mean stress conditions, the effective pore radius is more sensitive to the slit pores, followed by the cylindrical pores and the spherical pores. Under 3 different conditions, Klinkenberg’s factor is more sensitive to the slit pores, followed by the cylindrical pores and the spherical pores. Moreover, the permeability evolution with different pore geometry structures shows similar characteristics with effective pore radius, indicating that the effective radius dominates the permeability difference in different pore geometry structures. Furthermore, a numerical model was proposed to investigate the permeability evolution in the reservoir conditions. In the initial extraction stage, the permeability is increased with the rising slit pores. However, in the later stage, the spherical pores show more notable improvement effect on the permeability. Then, the effective pore radius and Klinkenberg’s factor were analyzed to reveal the influence mechanism of different pore geometry structures, indicating that the effective pore radius dominates the permeability difference, while Klinkenberg’s effect plays more significant role for the permeability trends and shows notable improvement effect on the permeability. [ABSTRACT FROM AUTHOR]

A diffusion model of adsorption layer from asphalto-resinous substances on water drop surface is proposed and a formula for determining its thickness is given. A model of combined drop coalescence and disintegration in an isotropic turbulent flow is developed. Equations for determining evolution of the number of drops and their size with time, which depend on the frequency of disintegration and coalescence, are proposed. At low Weber numbers (We < 1) these models agree satisfactorily with the available experiment data. [ABSTRACT FROM AUTHOR]

Nanorefrigerant–oil mixture is a promising energy-efficient refrigeration working fluid with superior thermophysical properties, and the prediction for its thermophysical properties requires the actual size of the particles in refrigerant–oil mixture. Due to the competitive adsorption of different liquid molecules on particle surface, the actual particle size of refrigerant–oil mixture cannot be predicted by the existing models developed for the nanofluids with single-component base fluid. This paper presents a model for predicting the particle size evolution during nanoparticle aggregation in refrigerant–oil mixture, considering the competitive adsorption behavior and its effects on particle movement and interaction. For model validation, the time-evolution of particle size distribution and the average size are calculated and compared with the existing experimental data. The model prediction agrees with 92% of the experimental data within deviation of ±10% and the mean deviation is 3.7%. In addition, the model can reflect the influences of oil mass fraction, initial particle concentration, primary nanoparticle diameter and temperature on particle size evolution. It is found that the adsorption layer has a significant effect on the aggregation behavior and the particle size evolution. [ABSTRACT FROM AUTHOR]

The results of tests of a Zr-Al-B boundary friction detonation coating in a wide range of changes under friction conditions have been presented. A comparative analysis of the obtained characteristics of friction and wear in order to evaluate the tribotechnical properties of amorphous-crystalline coatings has been carried out. These results have been compared with parallel tests of coatings based on tungsten carbide, samples of hardened steel and bronze, and the bearing of the sliding layer. The formation of solid solutions has been established and the introduction of oxygen in zirconium that corresponds to the formation on the friction surfaces of the secondary structures of the first type, a characteristic feature of which is their surface localization, ultra-dispersed structure, and ability to minimize disruption and shield unacceptable adhesion phenomena. The use of the Auger electron microscope confirmed that oxygen completely replaces the sulfur in the surface structures. [ABSTRACT FROM AUTHOR]

Bubble Ostwald ripening (OR) leads to a gradual increase of the mean bubble size in foams with time. The rate of OR can be reduced significantly or even arrested completely using appropriate solid particles and/or surfactants as foam stabilizers. In the current paper, we show that saponins, a widespread class of natural surfactants, can reduce significantly the rate of OR in foams. To reveal the reasons for the reduced rate of OR in saponin-stabilized foams, we performed measurements of the rate of bubble diminishing, for single air bubbles placed below a solution surface, with a series of saponin bio-surfactants. These saponin surfactants form adsorption layers with surface elasticity, spanning a very wide range – from almost zero up to several thousand mN/m. The measured rate of bubble OR showed no correlation with the surface elastic modulus (dilatational or shear), as measured at 0.1 Hz frequency of surface oscillations. A reasonable correlation was observed only with the surface stress (deviation from the equilibrium surface tension), measured at very slow rate of surface deformation, which mimics much better the actual processes of bubble OR in foams – higher surface stress corresponds to lower OR rate. New theoretical expression, accounting for the out-of- equilibrium surface tension during bubble shrinkage and for the gas flux across the meniscus regions surrounding the foam films, was derived and used to calculate theoretically the rate of bubble diminishing. The comparison of the theoretical predictions with the experimental data shows clearly that the main reason for the reduced rate of OR in the studied systems is the high resistance to gas transfer of the saponin adsorption layers. The deviations from the equilibrium surface tension, although noticeable, have smaller effect. The complementary experiments with actual foams showed that the rate of OR is even lower (compared to the rate measured with single bubbles) which is explained with the thicker non-equilibrium foam films, formed between the neighboring bubbles in saponin-stabilized foams. [ABSTRACT FROM AUTHOR]

Measurements by capillary pressure tensiometry, under microgravity conditions aboard the International Space Station, supplied a consistent set of reliable results for the dynamic interfacial tension and for the interfacial dilational viscoelastic modulus, quantitatively characterizing the dynamics of Span-80 adsorbed layers at the paraffin-oil/water interface. The experiments were executed at three different temperatures, i.e., 20, 30 and 40 °C, according to a pre-established built-in time-line in the orbiting facility. The interfacial area was subjected to perturbations with various functional forms (square pulses, ramps and harmonic oscillations), at three consecutive amplitudes (5%, 10% and 20%). Each experiment was performed in three successive repetitions, in view of an advantageous telemetered data redundancy. The interfacial responses to imposed perturbations, for the studied minimal surfactant concentration of Span-80 in paraffin-oil (that is (2 ÷ 3) × 10 −5 mol/dm 3 ) revealed a diffusion-controlled adsorption mechanism, definitely matching the Lucassen & Van den Tempel model in the frequency-domain representation. The interfacial responses also showed a linearity range up to the 20% amplitude. Interfacial relaxation responses to transient interfacial perturbations substantially validated the diffusion-controlled model for the adsorption mechanism, in the time-domain representation. [ABSTRACT FROM AUTHOR]

The effect of the ester group in side chain on adsorbing behavior and dispersion of polycarboxylate superplasticizer (PC) was studied by comparing the performance of two types of PC. The fluidity of cement paste was tested to discuss the dispersing ability and dispersing retention ability of PC. The total organic carbon analyzer was used to measure the adsorption amount, and the adsorption layer was obtained by x-ray photoelectron spectroscopy. Fourier-transform infrared spectroscopy, nuclear magnetic resonance, and pH value were used to verify the stability of the ester group, and the electrokinetic properties of cement particle were confirmed using the zeta potential measurement. The results show that the ester group in side chain reduces the initial dispersing ability while it increases the dispersing retention ability. The dispersing retention ability depends on the increase of adsorption amount and adsorption layer in 5–60 minutes, and the greater increase leads to the better dispersing retention ability. The ester group can be decomposed to release carboxyl group to enhance the adsorbing ability of PC under the condition of cement hydration, which is the main reason for the greater increase of adsorption amount and adsorption layer and the improvement in dispersing retention ability. It suggests that grafting the ester group is a good way to enhance the dispersing retention ability. [ABSTRACT FROM PUBLISHER]

The kinetics of styrene microemulsion formation in the presence of cetyl alcohol, n-dodecylmercaptan (n-DDM), and mixtures of both substances under conditions close to the emulsion polymerization was investigated. It was shown that cetyl alcohol and dodecylmercaptan differently influence under similar conditions on the intensity of the microdroplet creation on the phase boundary and on the rate of polymerization. It was shown that the concentration of n-DDM in the place of the polymerization corresponds to its value in the polymerization recipe only in the case of presence of more surface-active emulsifiers than n-DDM.

The O 2 adsorptions on three low-index Pt surfaces in pure water and alkaline solution were studied using molecular dynamics (MD) and the potential of mean force methods to determine the effect of OH − coadsorption on O 2 adsorption. The MD results indicate that the adsorption configuration of O 2 molecules showed differences on various interfaces, resulting in the variation of the stability of O 2 adsorption. OH − and H 2 O coadsorption can affect the O 2 adsorption, and represent the competitive relation of adsorption. The results indicate that the coadsorption of OH − and H 2 O formed a compact H-bonding network, which not only changed the adsorption configuration of O 2 , but also hindered the migration of O 2 molecules from the solution to the adsorption layer. The results obtained in this study provide a theoretical basis for experimental research. [ABSTRACT FROM AUTHOR]

The study aimed to determine the formation of an adsorption film at elastohydrodynamic lubricated (EHL) contacts and its effects on EHL film shape and friction. Experiments were conducted on an optical EHL test rig with surfaces of different surface energies. A new type of 'abnormal' EHL film shape characterized with three dimples in the inlet of the contact was obtained in pure ball sliding experiments with long-chain polybutene. The adsorption layer was inferred to be the main cause for the 'tri-dimple' phenomenon. The 'tri-dimple' formation was examined. Under a fixed speed, a single inlet dimple gradually broke into three dimples with increasing number of ball rotation, and it happened with slight increase in friction force. Three zones, namely a central and two lateral zones, of the contact were classified and characterized with different levels of influence on the adsorption layer. [ABSTRACT FROM AUTHOR]

The adsorption layers on the surface of silicon artifacts were determined experimentally as a function of relative air humidity in the range of 0.07 < h < 0.73 using the gravimetric method. 1 kg silicon sorption artifacts were fabricated with the same surface finish and material properties, but they had a very different surface area of 507.8 cm. In this experiment, an ultra-precision mass comparator and special humidity control unit were used. We found that the sorption behavior of the silicon surface was type II by BET classification with the parameters μ = 0.017 μg/cm, and c = 9.3 from the adsorption isotherm of water vapor on the surface of silicon with R < 26.6 nm. The coefficient of water vapor adsorption in moist air was estimated as δμ/δh = 65.3 ng cm in a limited humidity range of 0.3 < h < 0.6. [ABSTRACT FROM AUTHOR]

The paper presents fundamentals of a simple physicochemical method (SPMD) and analysis of results obtained when the method was applied for detection of organic contaminations (surface-active substances SAS) in samples of environmental and industrial waters. The method is based on measurements of variations of air bubble local velocities, which can be significantly changed in presence of surface-active contaminants. Lowering of the bubble velocity is a consequence of a motion induced dynamic adsorption layer (DAL) formed over surface of the rising bubble. The DAL formation retards the surface fluidity and the bubble rising velocity can be lowered by over 50% when the bubble surface is completely immobilized. We showed that the SPMD is a very sensitive tool (detection limit even below 1 ppm) for detection of various kinds of surface-active substances (ionic, non-ionic) in water samples. On the basis of results obtained using precise laboratory set-up, an accuracy of the SPMD is discussed. Moreover, effect of inert electrolyte addition on the bubble velocity lowering and value of detection limit of the SPMD is discussed. Simple approach, enabling quantitative analysis of the surface-active contaminants in samples collected, based on "equivalent concentrations" determination, is proposed. Results obtained for industrial (Jankowice and Knurow coal processing plants, Jaslo Refinery channel) and environmental waters (Wisloka and Ropa river) are used for detailed analysis and critical discussion of advantages and limitations of the SPMD. [ABSTRACT FROM AUTHOR]

Highlights: [•] Synthetic polycations interfere with cationic starches at adsorption onto fiber. [•] The addition of synthetic polycations after cationic starch results in higher adsorption amounts. [•] The replacement of cationic starch depends on molecular properties of the starch itself and of the synthetic polycation. [Copyright &y& Elsevier]

The deterging effect and wetting capacity of some widely used commercial surfactants and demulsifiers are examined and studied from the standpoint of the oilfield treatment of crude oil. The deterging effect of surfactants of various structures is shown to be selective in washing off disperse particles of mechanical paraffin, resin, and asphaltene impurities from the surface. New methods are proposed for determining the deterging effect of surfactacts in oil-bearing disperse systems. The mechanism of breakdown of the structure of disperse particles surrounded by a hydrocarbon adsorption layer under the action of detergents is described. The studies identified a number of surfactants that have an intrinsically pronounced deterging effect. [ABSTRACT FROM AUTHOR]

Abstract: The results of kinetic measurements revealed an accelerating influence of cystine and water activity on multistep Bi(III) ion electroreduction in chlorates(VII). The magnitude of the catalytic effect of cystine was determined based on the obtained kinetic parameters, which were correlated with water activity. The multistep Bi(III) electroreduction process is controlled by the kinetics of the formation of active Bi–Hg(SR)2 complexes preceding the transfer of consecutive electrons. Cystine is a mediator in the formation of these complexes, which are located inside the adsorbate layer. A mechanism is proposed for the catalytic action of cystine on Bi(III) ion electroreduction in chlorate(VII) solutions. [Copyright &y& Elsevier]

Systems far from equilibrium are able to self-organize and often demonstrate the formation of a large variety of dissipative structures. In systems with free liquid interfaces, self-organization is frequently associated with Marangoni instability. The development of solutal Marangoni instability can have specific features depending on the properties of adsorbed surfactant monolayer. Here we discuss a general approach to describe solutal Marangoni instability and review in details the recent experimental and theoretical results for a system where the specific properties of adsorbed layers are crucial for the observed dynamic regimes. In this system, Marangoni instability is a result of surfactant transfer from a small droplet located in the bulk of water to air/water interface. Various dynamic regimes, such as quasi-steady convection with a monotonous decrease of surface tension, spontaneous oscillations of surface tension, or their combination, are predicted by numerical simulations and observed experimentally. The particular dynamic regime and oscillation characteristics depend on the surfactant properties and the system aspect ratio. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Adsorption equilibria were analyzed on the basis of general equilibrium constant expression for the development of fundamental adsorption equations (Freundlich, Langmuir, and BET) in connection with the establishment of a general approach towards physical interpretations of adsorption parameters. Theoretically it was proved that Freundlich plot analysis cannot be used to find useful parameters such as the monolayer adsorption capacity of an adsorbent. The present theory also indicated that the adsorption process with known value of monolayer adsorption capacity can be studied for finding various equilibrium constants on the basis of the Fronaeus equation, which is commonly used in the complexation process. The applications of the Langmuir equation in finding the ligand number of a complex as well as the magnitude of equilibrium constant required for the analysis of the BET equation in the multilayer liquid phase adsorption process was also discussed. It was concluded that the general approach towards exploration and physical interpretation of adsorption parameters can be developed by analyzing the adsorption equilibria on the basis of general equilibrium constant expression in accordance with the law of mass action. [ABSTRACT FROM AUTHOR]

Abstract: The properties of Pt-electrodes in 1M HClO4 solution, in air, were studied both in the resting-state and mild oxidation conditions, within the potential range of 1000mV and 1600mV. Cyclic voltammetry (CV) and cathodic stripping voltammetry (CSV) were used for coulometric determination of the amount of O-containing species adsorbed on the electrode surface during the oxidation–reduction reactions. Simultaneously, the mass of the adsorption layer was measured in situ, with the electrochemical quartz crystal microbalance (EQCM). The surface of the Pt-black electrode in the resting-state is covered with OH*-species (apparently a ML), which are spontaneously generated by immersion in the aqueous solution without any polarization potential. The surface of the Pt smooth electrode is covered uppermost by a sub-monolayer of oxygen, in similar conditions. The resting-state of the Pt-black electrode is characterized by a reproducible value of the rest potential, E r =1040±5mV (average of 10 samples) and a reduction peak in CV mode at (average of 10 samples). In anodic polarization conditions, PtOH* is oxidized to PtO*, in CV mode, and to Pt(O2)*, in the potentiostatic mode. The reduction peak of PtO* in CV mode is (average of 10 samples), indicating a stronger bond to the surface of the electrode. The yielding of Pt(O2)* is not fast enough to accommodate the increase of the oxidation potential by finite sweep rate of the CV mode at 10mVs−1. Therefore this oxidation level could not be achieved in CV mode. The prolonged oxidation in the potentiostatic mode results in the coverage of the surface of Pt-black electrode with a monolayer of (O2)*-species. [Copyright &y& Elsevier]