Surface Hydration Research Articles

Surface Engineering for Endothelium-Mimicking Functions to Combat Infection and Thrombosis in Extracorporeal Life Support Technologies.

Blood-contacting medical devices routinely fail from the cascading effects of biofouling toward infection and thrombosis. Nitric oxide (NO) is an integral part of endothelial homeostasis, maintaining platelet quiescence and facilitating oxidative/nitrosative stress against pathogens. Recently, it is shown that the surface evolution of NO can mediate cell-surface interactions. However, this technique alone cannot prevent the biofouling inherent in device failure with dynamic blood-contacting applications. This work proposes an endothelium-mimicking surface design pairing controlled NO release with an inherently antifouling polyethylene glycol interface (NO+PEG). This simple, robust, and scalable platform develops surface-localized NO availability with surface hydration, leading to a significant reduction in protein adsorption as well as bacteria/platelet adhesion. Further in vivo thrombogenicity studies show a decrease in thrombus formation on NO+PEG interfaces, with preservation of circulating platelet and white blood cell counts, maintenance of activated clotting time, and reduced coagulation cascade activation. It is anticipated that this bio-inspired surface design will enable a facile alternative to existing surface technologies to address clinical manifestations of infection and thrombosis in dynamic blood-contacting environments.

A Numerical Hydration Model to Predict the Macro and Micro Properties of Cement–Eggshell Powder Binary Blends

This study aims to propose a hydration kinetic model for the cement–eggshell powder binary system and predict the performance development of composite concrete through this model. The specific content and results of the model are as follows. First, based on the cumulative hydration heat of the cement and eggshell powder binary system in the first seven days, the parameters of the cement hydration model and the eggshell powder nucleation parameter are calibrated. These parameters remain constant regardless of the mix ratio. Secondly, the hydration heat of the cement–eggshell powder binary system over 28 days is calculated using the hydration model. The results show that at 28 days, for specimens with 0%, 7.5%, and 15% eggshell powder substitution, the cement hydration degrees are 0.832, 0.882, and 0.923, respectively. The hydration heat per gram of cement is 402.69, 426.88, and 446.73 J/g cement, respectively, while the hydration heat per gram of binder is 402.69, 394.86, and 379.72 J/g binder, respectively. Additionally, the hydration model is used to calculate the chemically bound water and calcium hydroxide content of the cement–eggshell powder binary system. At 28 days, for samples with 0%, 7.5%, and 15% eggshell powder, the chemically bound water content is 0.191, 0.188, and 0.180 g/g binder, respectively, and the calcium hydroxide content is 0.183, 0.179, and 0.173 g/g binder, respectively. Finally, a power function is used to regress the calculated hydration heat with experimentally measured compressive strength and surface electrical resistivity. The correlation coefficients for compressive strength and surface electrical resistivity are 0.8474 and 0.9714, respectively. This is because the strength weak point effect of eggshell powder has minimal impact on hydration heat and surface electrical resistivity experiments but significantly affects the strength experiment.

External electric field effects on asphaltene adsorption on Kaolinite-water interface: A molecular dynamics study

Applying electric fields to promote water/oil recovery efficiency is gaining increasing attention in downstream of heavy oil development. In this work, molecular dynamics simulations were performed to study the motion of N-(1-Hexylheptyl)-N′-(5-carboxylicpentyl) perylene-3,4,9,10-tetracarboxylic bisimide (C5Pe) between kaolinite (Kaol) surfaces mediated by external electric field in water under different pH. Aggregation of C5Pe was mainly mediated by pH and not affected by the electric field, while adsorption responded to both pH and the electric field. In neutral and alkaline solutions, C5Pe was deprotonated, and its distribution between two Kaol surfaces was mainly mediated by the Coulombic force exerted by the electric field. In acidic solutions, C5Pe carried zero charge, and yet its distribution was still affected by the electric field. The external electric fields mediated the wettability of the two Kaol surfaces in different extents, and C5Pe preferred to adsorb on the more hydrated surface. The mediation of the electric fields on the wettability of surfaces was achieved in two stages. In the first stage, when the electric field of a low strength was applied, diffusion of water enhanced. The hydration of both Kaol surfaces became increased as water molecules formed more hydrogen bonds with the surfaces. As the electric field strength became sufficiently high, diffusion showed no further enhancement, and the re-orientation of water dipoles started dominating the hydrogen bonding with the surfaces. Carrying opposite charges, the hydrogen bond donors and acceptors of water were differently regulated by the electric field, and therefore water molecules conformed in a certain manner under the electric field of high strength. As a result, the hydrogen bonding between water and the two Kaol surfaces (placed on two sides of the simulated box under the electric field) varied with their positions. Due to the structural hindrance of the hydroxyl groups on the surface, the surface could provide more hydrogen bonding donors formed more hydrogen bonds with water, and thus became more hydrophilic and had stronger attraction to C5Pe.

Effects of a mattress cover with special airflow technology on the structure and function of the sacral and heel skin during loading: A two-arm exploratory crossover trial.

Prolonged mechanical loading of the skin and underlying soft tissue cause pressure ulceration. The use of special support surfaces are key interventions in pressure ulcer prevention. They modify the degree and duration of soft tissue deformation and have an impact on the skin microclimate. The objective of this randomized cross-over trial was to compare skin responses and comfort after lying for 2.5 h supine on a support surface with and without a coverlet that was intended to assist with heat and moisture removal at the patient/surface interface. In addition, physiological saline solution was administered to simulate an incontinence episode on the mattress next to the participants' skin surface. In total, 12 volunteers (mean age 69 years) with diabetes mellitus participated. After loading, skin surface temperature, stratum corneum hydration and skin surface pH increased, whereas erythema and structural stiffness decreased at the sacral area. At the heel skin area, temperature, erythema, and stratum corneum hydration increased. These results indicate occlusion and soft tissue deformation which was aggravated by the saline solution. The differences in skin response showed only minor differences between the support surface with or without the coverlet.

In Ukrainian

The paper discusses the results of saponite research from the Tashkiv deposit of Ukraine. X-ray structural analysis proved the necessity of preliminary cleaning of saponites from mineral impurities. The study of the morphology, nanoprofile and topography of the surface of saponite by the methods of SEM-microscopy and Atomic Force Microscopy revealed that the mineral is represented by aggregates of nano- and microparticles of a pyramidal shape. Its characteristic feature is the heterogeneity of isomorphic substitutions of ions in the tetrahedral and octahedral sheets of the structural elementary package. According to X-ray fluorescence analysis, saponite contains a significant amount of Fe3+, which isomorphically replaces magnesium Mg2+ and, accordingly, is located mastly in the octahedral sheet of the structural package with a charge from +0.37 to +0.35. The number and mechanism of isomorphic substitutions determine the presence of a total negative charge of the crystal lattice (from –0.38 to –0.3), the value of which ensures intensive interaction with water molecules of the interpacket space with the formation of surface OH groups. Accordingly, both acidic and alkaline Lewis and Brønsted centers are present on the surface with a predominance of acidic ones, so the acidity function is 5.82, and the point of zero proton charge is pH = 5.5. During dispersion in water, a part of the alkaline centers of the side surface are transformed into Brønsted acid centers as a result of their protonation, which causes an increase in the pH of the dispersion medium to pH = 8–8.6. Accordingly, the isoionic state is reached at pH = 7.5. The difference in pH values characterizing the isoionic state of the surface and the point of zero net proton charge (PZNPC) indicates the presence of weak acid-alkaline centers on the surface. The study of the adsorption of acid-alkaline dyes showed the adsorption of alkaline (pK = 1¸3) and acid (pK = 7¸14) dyes on saponites. The latter is significantly reduced due to the preliminary hydration of the solid surface - mainly the lateral edges of the particles. Acidic dyes are not adsorbed from a dispersion medium with pH < 5.5 (PZNPC), and basic dyes are adsorbed at pH > 5,5( PZNPC).

TiO2 Nanoparticles with Adjustable Phase Composition Prepared by an Inverse Microemulsion Method: Physicochemical Characterization and Photocatalytic Properties.

Titania nanoparticles (NPs) find wide application in photocatalysis, photovoltaics, gas sensing, lithium batteries, etc. One of the most important synthetic challenges is maintaining control over the polymorph composition of the prepared nanomaterial. In the present work, TiO2 NPs corresponding to anatase, rutile, or an anatase/rutile/brookite mixture were obtained at 80 °C by an inverse microemulsion method in a ternary system of water/cetyltrimethylammonium bromide/1-hexanol in a weight ratio of 17:28:55. The only synthesis variables were the preparation of the aqueous component and the nature of the Ti precursor (Ti(IV) ethoxide, isopropoxide, butoxide, or chloride). The materials were characterized with X-ray diffraction, scanning/transmission electron microscopy, N2 adsorption-desorption isotherms, FTIR and Raman vibrational spectroscopies, and diffuse reflectance spectroscopy. The synthesis products differed significantly not only in phase composition, but also in crystallinity, textural properties, and adsorption properties towards water. All TiO2 NPs were active in the photocatalytic decomposition of rhodamine B, a model dye pollutant of wastewater streams. The mixed-phase anatase/rutile/brookite nanopowders obtained from alkoxy precursors showed the best photocatalytic performance, comparable to or better than the P25 reference. The exceptionally high photoactivity was attributed to the advantageous electronic effects known to accompany multiphase titania composition, namely high specific surface area and strong surface hydration. Among the single-phase materials, anatase samples showed better photoactivity than rutile ones, and this effect was associated, primarily, with the much higher specific surface area of anatase photocatalysts.

Hydration-induced plasma surface modification of aluminum nanoparticles for power generation in oxygen deficient environments

An approach to increase the energy release rate from aluminum (Al) combustion is to modify the alumina (Al2O3) passivation shell surrounding the Al fuel core. One approach uses atmospheric plasma treatment to physically reduce the Al2O3 shell thickness while simultaneously exposing the defected surface to water vapor to promote surface hydration. Combining water-vapor with an atmospheric helium dielectric barrier discharge (DBD) plasma yields a thinner Al2O3 shell with double the surface hydration compared to as-received aluminum nanoparticles (nAl). Non-equilibrium combustion studies on plasma-treated nAl particles demonstrate increased energy release rates owing to the thinned shell and reduced diffusion barrier. Adding hydration further provides more oxidizer species in molecular scale proximity to the core such that the thinned and hydrated shell increased the initial pressurization rate by 50 % compared to as-received nAl. The results introduce a method to modify the native oxide surface and a strategy to control energy release rates from metal particle combustion.

Hydration mechanism of molybdenite affected by surface oxidation: New insights from DFT and MD simulations

The oxidation and hydration of molybdenite surfaces cannot be avoided during the crushing and flotation processes in industry, which adversely affects its clean separation and extraction. In this study, the hydration mechanism under the influence of molybdenite surface oxidation was investigated using density functional theory (DFT) and molecular dynamics (MD) simulations. The results showed that the adsorption energy of a single water molecule on the molybdenite (0 0 1) surface changed from −0.33 kcal/mol to −2.07 kcal/mol after oxidation. Dissociated O acted as a bridging link on the molybdenite (0 0 1) surface, inducing hybridization of the Hw 1 s orbitals with the Os 2p orbitals, thereby enhancing the adsorption of water molecules. The adsorption energy of a single water molecule on the molybdenite (1 1 0) surface changed from −33.97 kcal/mol to −3.37 kcal/mol after oxidation. The dissociated O hindered the hybridization of the Mo 4d and Ow 2p orbitals, thus preventing the adsorption of water molecules on the (1 1 0) surface. After oxidation, the interfacial interaction between the molybdenite (0 0 1) surface and water molecules was enhanced, while the interfacial interaction between the molybdenite (1 1 0) surface and water molecules was weakened. The water molecules near the surface of molybdenite are adsorbed through hydrogen bonding and gradually form a hydrated film consisting of three layers of water molecules with a thickness of 8–9 Å as the water coverage increases.

Evaluation of a novel paraffin wax microemulsion for improving wellbore stability in shale formations

High-performance shale stabilizers are urgently required to address the concerns of wellbore instability when drilling troublesome shale wells. Herein, a novel paraffin wax microemulsion (PM) containing cationic surfactant was prepared and evaluated for shale formations. The shale stability performance of PM was studied using shale pressure penetration test, shale swelling and dispersion test. The shale stabilization mechanism of PM was investigated by surface tension, contact angle, surface free energy, capillary tube rise and SEM tests. The experimental findings showed that the pressure penetration time in shale after treatment with PM was extended from 13 to 107 min. And PM could decrease the shale swelling rate by 41.5%, and increase the recovery rate to 89.4%. PM exhibited better sealing and inhibition properties than that of commonly used shale stabilizers. The mechanism research revealed that the nano-droplets in PM could freely penetrate into shale pores and cracks of different sizes to form an effective sealing membrane. The water contact angle reached 91.4° after treatment with PM and the surface energy was significantly reduced, effectively inhibiting surface hydration. Through decreasing the surface tension and changing the wettability, the capillary force experienced a noticeable decrease with further enhanced inhibition of shale hydration. Therefore, the application of PM for shale stabilization exhibited promising potential, suggesting its possible effective utilization in shale drilling.

Effect of interface properties between functionalized cellulose nanocrystals and tricalcium silicate on the early hydration mechanism of cement

The hydration process is a critical stage in the development of the properties of cement-based materials，however, the influence of cellulose nanocrystals (CNC) on cement during the early hydration is controversial. This study uses pure tricalcium silicate (C3S) as the object to analyze the influence of carboxyl CNC (CCNC) and sulfonic CNC (SCNC) on hydration parameters such as hydration rate, types, quality, and pore structure of hydration products during the early hydration period. The dissolution of C3S and the interaction between fluids and minerals at the C3S/CNC interface is the core mechanism of the early hydration. Ultraviolet and energy spectrum analyzed adsorption between CNC and C3S from a physical perspective, and molecular dynamics simulations deeply discussed the adsorption behavior between C3S/Water/CNC at nano-scale. The results show that CNC prolongs the hydration induction and acceleration period, delays the early hydration of C3S; CCNC exhibits a more significant effect than SCNC. Under the action of Ca-O and hydrogen bonds, CNC will adsorb on the surface of C3S and cover its surface, reducing the number of waters on the surface of C3S. Hydrophilic CNC molecules attract water molecules close to the CNC chain, and solidifying water molecules prevents it from entering the hydration surface. CNC also restricts the diffusion of Ca2+ on the surface of C3S to outside, improving the stability of Ca-O coordination, promoting the accumulation of hydration products at the C3S surface, and inhibiting the dissolution of C3S. Understanding the effect of functionalized CNCs on the diffusion and sedimentation mechanism of water molecules and Ca2+ during hydration can provide insights for guiding the design of nanomaterials with strong compatibility with cement systems and enlarging the application of functionalized nanomaterials in cement-based materials engineering fields.

Mechanically Robust Lubricating Hydrogels Beyond the Natural Cartilage as Compliant Artificial Joint Coating.

Natural cartilage exhibits superior lubricity as well as an ultra-long service lifetime, which is related to its surface hydration, load-bearing, and deformation recovery feature. Until now, it is of great challenge to develop reliable cartilage lubricating materials or coatings with persistent robustness. Inspired by the unique biochemical structure and mechanics of natural cartilage, the study reports a novel cartilage-hydrogel composed of top composite lubrication layer and bottom mechanical load-bearing layer, by covalently manufacturing thick polyelectrolyte brush phase through sub-surface of tough hydrogel matrix with multi-level crystallization phase. Due to multiple network dissipation mechanisms of matrix, this hydrogel can achieve a high compression modulus of 11.8MPa, a reversible creep recovery (creep strain: ≈2%), along with excellent anti-swelling feature in physiological medium (v/v0 < 5%). Using low-viscosity PBS as lubricant, this hydrogel demonstrates persistent lubricity (average COF: ≈0.027) under a high contact pressure of 2.06MPa with encountering 100k reciprocating sliding cycles, negligible wear and a deformation recovery of collapse pit in testing area. The extraordinary lubrication performance of this hydrogel is comparable to but beyond the natural animal cartilage, and can be used as compliant coating for implantable articular material of UHMWPE to present, offering more robust lubricity than current commercial system.

Formation and phase equilibria of gas hydrates confined in hydrophobic nanoparticles

The promotion of gas hydrate formation is of fundamental importance to facilitate its great potential applications in, for example, gas separation, transportation and energy storage. The employment of Dry Water (DW), which is a powdery Pickering system composed of macro water droplets surrounded by stabilising hydrophobic nanoparticles, is considered an effective method for enhancing hydrate formation. The promotion mechanism underlying this observation, however, has yet to be well understood. In this work, the effect of DW on both formation kinetics and thermodynamic stability of gas hydrates was investigated using a micro differential scanning calorimetry (µDSC) in CH4 and CO2 hydrate systems, using two different hydrophobic nanoparticles. Distinctly shorter induction times and higher conversion ratios were observed for DW compared to bulk water. The DW system stabilised by more hydrophobic nanoparticles showed benefits in accelerating nucleation, while the other system, which consisted of smaller DW droplets, led to a superior enhancement of hydrate growth. Besides the effect on formation kinetics, it was also noted that DW influenced the µDSC hydrate dissociation peak characteristics, including melting points and melting peak shapes. This phenomenon suggested that the centre- and surface-droplet hydrates in DW may have different structures, due to the “hydrophobic effect” of the nanoparticles structuring the near-surface water, so exhibiting melting points corresponding to bulk hydrate or to a more structured surface hydrate (with raised melting point), respectively. To support this “hydrophobic effect” hypothesis, a series of hydrate and ice formation experiments were conducted in porous media having different hydrophobicity, the results of which demonstrated that hydrates adjoining confined hydrophobized surfaces, in other systems similar to DW, also displayed higher melting temperatures.

EVALUATION OF THE EFFECT OF AIR ON THE HYDRATION SYSTEM OF THE AXIAL PISTONS

This study investigates the effect of air exposure on the hydration system of axial pistons, critical components in various hydraulic systems. The hydration process, which is integral to the functionality and longevity of axial pistons, is potentially sensitive to environmental factors such as air. This research aims to elucidate the effect of air on the hydration kinetics, surface properties and performance of axial pistons. Experimental studies were conducted using controlled environments to analyze the hydration behavior of piston samples under varying degrees of air exposure. Techniques such as surface microscopy, chemical analysis and mechanical testing were used to comprehensively evaluate the effects. Preliminary findings indicate that exposure to air significantly affects the hydration kinetics of axial pistons, affecting the rate and extent of hydration. Surface analysis reveals changes in surface morphology and chemical composition indicating changes in the air-induced hydration process. Moreover, mechanical testing reveals notable differences in the performance characteristics, including wear resistance and friction properties, of pistons exposed to varying weather environments. Overall, this study underlines the importance of considering air exposure in understanding and optimizing the hydration system of axial pistons and provides valuable information for improving hydraulic system efficiency and reliability. Keywords: axial pistons, hydration system, piston, hydraulic machine, rotor.

Calcium-sensing receptor (CaSR) modulates ocular surface chloride transport and its inhibition promotes ocular surface hydration

PurposeOcular surface hydration is critical for eye health and its impairment can lead to dry eye disease. Extracellular calcium-sensing receptor (CaSR) is regulator of ion transport in epithelial cells expressing cystic fibrosis transmembrane conductance regulator (CFTR) Cl− channel. CFTR is also a major ion channel in ocular surface epithelia, however the roles of CaSR in ocular surface are not well studied. This study aims to investigate expression and functional roles of CaSR in ocular surface. MethodsCaSR immunostaining was performed in mouse and human cornea and conjunctiva. Ocular surface potential difference (OSPD) and tear fluid volume measurements were performed in mice with topically applied cinacalcet (CaSR activator) and NPS-2143 (CaSR inhibitor). ResultsCaSR is expressed in corneal and conjunctival epithelia of mice and humans. Topically administered CaSR activator cinacalcet inhibits cAMP agonist forskolin-induced Cl− secretion and CFTR activity up to 90 %. CaSR inhibitor NPS-2143 stimulates CFTR-mediated Cl− secretion in mouse ocular surface, after which cAMP agonist forskolin had minimal additional secretory effects. Single dose NPS-2143 treatment (as an eye drop) increases tear fluid volume in mice by ∼60 % compared to vehicle treatment. NPS-2143 effect on tear volume lasts at least 8 h after single dose. ConclusionsCaSR is a key regulator of ocular surface ion transport and CaSR inhibition promotes Cl− and tear secretion in the ocular surface. If they are found to be effective in in dry eye models, CaSR inhibitors (currently in clinical development) can potentially be repurposed as novel prosecretory treatments for dry eye disease.

Bioinspired Dopamine and N-Oxide-Based Zwitterionic Polymer Brushes for Fouling Resistance Surfaces.

Biofouling is a great challenge for engineering material in medical-, marine-, and pharmaceutical-related applications. In this study, a novel trimethylamine N-oxide (TMAO)-analog monomer, 3-(2-methylacrylamido)-N,N-dimethylpropylamine N-oxide (MADMPAO), was synthesized and applied for the grafting of poly(MADMPAO) (pMPAO) brushes on quartz crystal microbalance (QCM) chips by the combination of bio-inspired poly-dopamine (pDA) and surface-initiated atom transfer radical polymerization technology. The result of ion adsorption exhibited that a sequential pDA and pMPAO arrangement from the chip surface had different characteristics from a simple pDA layer. Ion adsorption on pMPAO-grafted chips was greatly inhibited at low salt concentrations of 1 and 10 mmol/L due to strong surface hydration in the presence of charged N+ and O- of zwitterionic pMPAO brushes on the outer layer on the chip surface, well known as the "anti-polyelectrolyte" effect. During BSA adsorption, pMPAO grafting also led to a marked decrease in frequency shift, indicating great inhibition of protein adsorption. It was attributed to weaker BSA-pMPAO interaction. In this study, the Au@pDA-4-pMPAO chip with the highest coating concentration of DA kept stable dissipation in BSA adsorption, signifying that the chip had a good antifouling property. The research provided a novel monomer for zwitterionic polymer and demonstrated the potential of pMPAO brushes in the development and modification of antifouling materials.

Quantitative skin surface hydration measurement by visible optical image processing: A pilot study.

Skin barrier function is significantly impacted by skin moisture. Most non-invasive evaluation techniques to measure skin surface hydration relying on its electrical properties, which are limited in scope and have unstable operations. Applying image processing for skin hydration assessment is uncommon, with an emphasis on skin-capacitive pictures and near-infrared images in general, which demand a certain spectrum. As a result, there is an increasing need for wide-area skin hydration evaluation and mapping. Thestudy aimsto propose a quantitative evaluation algorithmforskin surface hydrationfrom visible-light images. Threedeviceswere applied tomeasureskin hydration:skin image capturedevice and tworecognizedcommercialskindevices.A digital image processing system creates a new index, called GVR, to symbolize skin surface moisture. TheCLAHE algorithmwas appliedto enhance the contrast of skin image, andafter calculating it with the monochrome image,the skin reflectance imagewas segmented.The GVR was estimated using the values of the individual sites and the entire skin. The correlation coefficient between the three methods was examined using statistical analysis to assess the performance of GVR. Skin hydrationestimated from visible-light imagesis influenced by the entire facial structure in addition to specific areas.The electrical and visible image evaluations showed a strong association with a significant difference. It was discovered that reflecting measures from visible images provide a quick and efficient way to quantify the moisture of the skin's surface.

Novel cesium immobilization by alkali activation and cold consolidation of waste pharmaceutical glass

A new method of cesium immobilization has been successfully developed by combining alkali activation of boro-alumino-silicate glass and viscous flow sintering. Powdered glass from discarded pharmaceutical vials, suspended in a 2.5 M CsOH aqueous solution, underwent surface hydration as well as partial dissolution. Condensation reactions occurring at hydrated surface layers upon drying at 40 °C over 7 days resulted in welding of adjacent particles, forming a network that trapped newly formed gel and crystal phases. The newly formed phases including crystalline boro-pollucite (CsBSi2O6), were derived mostly from Cs+ ions reacting with the products of glass dissolution and exhibited a high chemical stability. Further stabilization was achieved through viscous flow sintering at 700 °C, resulting in the incorporation of Cs+ ions in a glass matrix. The effectiveness of the immobilization was confirmed by leaching test using the Materials Characterization Center-1 Standard (MCC-1). This innovative approach not only enhances the chemical stability of cesium waste forms, but also aligns with principles of cleaner production by repurposing pharmaceutical glass waste, promoting sustainable materials management.

Insights into the adsorption behavior of ions at the calcite/brine interface: Charge preferences and energetic analysis via DFT calculations

A comprehensive investigation into the intricate dynamics at the interface of brines and calcite is imperative for effectively tackling challenges in enhanced oil recovery (EOR). Utilizing Density Functional Theory (DFT) calculations, we scrutinized the adsorption behavior of NaCl and Na2SO4 brines on the calcite surface, aiming to glean atomistic insights into their physicochemical characteristics. Our structural analysis reveals distinctive features: NaCl brine forms an electrical double layer atop the calcite surface, while Na2SO4 brine demonstrates a predilection for the wetting layer, facilitated by electrostatic interactions of sulfate ions through the first hydration layer to the calcite surface. This preference is ascribed to the enhanced electronic potential of sulfate ions, which aids in their penetration to the surface and concurrent hydration by water molecules through non-covalent interactions. Calculations of adsorption energy unveil a decrease in calcite hydrophilicity upon ion interaction, with Na+/Cl− ions forming a comparatively less stable interface in contrast to Na+/SO42− ions. Furthermore, analysis of charge redistribution highlights electron transfer from the calcite surface to interfacial water, with sulfate ions exhibiting a capability to interact with surface sites non-covalently and exchange charge. These findings underscore the significant influence of sulfate ions in altering the wetting characteristics of calcite, carrying implications for ion-modified waterflooding techniques in EOR strategies targeting carbonate reservoirs.

An in-situ study of the interaction mechanism between xanthate and unactivated/Cu-activated sphalerite surfaces at solid–liquid interfaces

The mechanism of surface hydration and xanthate adsorption in the flotation of unactivated/Cu-activated sphalerite is still controversial. Therefore, a study combining in-situ measurement and quantum simulation is employed to investigate the interaction mechanism of ethyl xanthate (EX) and butyl xanthate (BX) on the fully hydrated, unactivated/Cu-activated sphalerite surfaces at solid–liquid interfaces. Density functional based on tight-binding (DFTB+) and molecular dynamics (MD) results suggest that the Cu-activated surface is hydrophobic with the first layer of water being distributed more disorderly on it. This is due to the difficulty of the lone pair electrons of water to interact with Cu. On the unactivated surface, water adsorption is more favorable than xanthates, hence, water molecules are physically adsorbed on it. Whereas the interaction of EX/BX with the hydrated, activated surface is chemisorption. The higher reactivity of Cu+ d orbitals to form π-backbonds with xanthate and the orbital symmetry matching of the Cu dyz orbitals and xanthate pz orbitals contribute to these results. Microcalorimetric results also demonstrate that copper activation enhances the exothermic heat and reaction rate, facilitating the interaction of EX/BX with sphalerite. These are consistent with the flotation and quartz crystal microbalance with dissipation (QCM-D) results.

Preparation and Mechanism of Low-Molecular-Weight Amine-Based Inhibitor that Completely Inhibits Surface Hydration of Clay Minerals

Preparation and Mechanism of Low-Molecular-Weight Amine-Based Inhibitor that Completely Inhibits Surface Hydration of Clay Minerals