Liquid Intrusion Research Articles

Biomimetic Colored Coating toward Robust Display under Hostile Conditions.

Structural colors particularly of the angle-independent category stemming from wavelength-dependent light scattering have aroused increasing interest due to their considerable applications spanning displays and sensors to detection. Nevertheless, these colors would be heavily altered and even disappear during practical applications, which is related with the variation of refractive index mismatch by liquid wetting/infiltrating. Inspired by bird feathers, we propose a simple deposition toward the coating with angle-independent structural color and superamphiphobicity. The coating is composed of ∼200 nm-sized channel-type structures between hollow silica and air nanostructures, exhibiting a robust sapphire blue color independent of intense liquid intrusion, which duplicates the characteristics of the back feather of Eastern Bluebird. A high color saturation and superamphiphobicity of the biomimetic coating are optimized by manipulating the coating parameters or adding black substances. Excellent durability under harsh conditions endows the coating with long-term service life in various extreme environments.

Assessment of Hydrophilicity/Hydrophobicity in Mesoporous Silica by Combining Adsorption, Liquid Intrusion, and Solid-State NMR Spectroscopy.

We have developed a comprehensive strategy for quantitatively assessing the hydrophilicity/hydrophobicity of nanoporous materials by combining advanced adsorption studies, novel liquid intrusion techniques, and solid-state NMR spectroscopy. For this, we have chosen a well-defined system of model materials, i.e., the highly ordered mesoporous silica molecular sieve SBA-15 in its pristine state and functionalized with different amounts of trimethylsilyl (TMS) groups, allowing one to accurately tailor the surface chemistry while maintaining the well-defined pore structure. For an absolute quantification of the trimethylsilyl group density, quantitative 1H solid-state NMR spectroscopy under magic angle spinning was employed. A full textural characterization of the materials was obtained by high-resolution argon 87 K adsorption, coupled with the application of dedicated methods based on nonlocal-density functional theory (NLDFT). Based on the known texture of the model materials, we developed a novel methodology allowing one to determine the effective contact angle of water adsorbed on the pore surfaces from complete wetting to nonwetting, constituting a powerful parameter for the characterization of the surface chemistry inside porous materials. The surface chemistry was found to vary from hydrophilic to hydrophobic as the TMS functionalization content was increased. For wetting and partially wetting surfaces, pore condensation of water is observed at pressures P smaller than the bulk saturation pressure p0 (i.e., at p/p0 < 1) and the effective contact angle of water on the pore walls could be derived from the water sorption isotherms. However, for nonwetting surfaces, pore condensation occurs at pressures above the saturation pressure (i.e., at p/p0 > 1). In this case, we investigated the pore filling of water (i.e., the vapor-liquid phase transition) by the application of a novel, liquid water intrusion/extrusion methodology, allowing one to derive the effective contact angle of water on the pore walls even in the case of nonwetting. Complementary molecular simulations provide density profiles of water on pristine and TMS-grafted silica surfaces (mimicking the tailored, functionalized experimental silica surfaces), which allow for a molecular view on the water adsorbate structure. Summarizing, we present a comprehensive and reliable methodology for quantitatively assessing the hydrophilicity/hydrophobicity of siliceous nanoporous materials, which has the potential to optimize applications in heterogeneous catalysis and separation (e.g., chromatography).

Modeling pore wetting in direct contact membrane distillation—effect of interfacial capillary pressure

In this study, we aimed to develop a model for computing direct contact membrane distillation (DCMD) performance, taking into account capillary pressure effects at the liquid–gas interface within membrane pores. We developed a simulation model to investigate how factors such as pore radius, feed/permeate temperature, pressure, and contact angle influenced the distance of liquid intrusion into the pore, the weight flow rate in a single pore, and the temperature at the liquid–gas interface. The model predicted that the permeation rate would decrease with an increase in the feed pressure when the permeate pressure was kept constant and also when the pressure difference between the feed and permeate was kept constant. It also predicted that the permeation rate would increase with an increase in the permeate pressure when the feed pressure was kept constant. The model also indicated that partial pore wetting would be enhanced with an increase in feed pressure when the pore size was as large as 1 μm but would diminish when the pore size was as small as 0.1 μm. According to the model, partial pore wetting diminished with a decrease in the permeate pressure. The model’s predictions were in line with the trends observed in the experimental DCMD flux data by many authors, particularly those regarding the effects of feed and permeate temperature and the effect of contact angle. The model’s predictions were compared with the experimental data recorded in the literature, validating the model’s accuracy.

Nano-scale corrosion mechanism of T91 steel in static lead-bismuth eutectic: A combined APT, EBSD, and STEM investigation

T91 steel is a candidate material for structural components in lead-bismuth-eutectic (LBE) cooled systems, for example fast reactors and solar power plants [1]. However, the corrosion mechanisms of T91 in LBE remain poorly understood. In this study, we have analysed the static corrosion of T91 in liquid LBE using a range of characterisation techniques at increasingly smaller scales. A unique pattern of liquid metal intrusion was observed that does not appear to correlate with the grain boundary network. Upon closer inspection, electron backscatter diffraction (EBSD) reveals a change in the morphology of grains at the LBE-exposed surface, suggesting a local phase transition. Energy dispersive X-ray (EDX) maps show that Cr is depleted in the T91 material near the LBE interface. Furthermore, we observed the dissolution of all Cr-enriched precipitates in this region. Although the corrosion is conducted in an oxygen deficient environment, both scanning transmission electron microscopy (STEM) and atom probe tomography (APT) reveal a thin surface oxide layer (presumably wüstite) at the LBE-steel interface. Using electron energy loss spectroscopy (EELS) in the STEM, as well as APT, the atomic scale elemental redistribution and 3D morphology of the corrosion interface is investigated. By combining results from these different techniques, several types of oxide phases and structures can be identified. Based on this detailed nano-scale information, we propose potential mechanisms of T91 corrosion in LBE.

Performance Evaluation of Nigeria Railway Track Ballast Under Simulated Operational Conditions

Over time, most research on railway track performance has focused mainly on rail and track geometry, with a few considering the damage or degradation occurring at the substructure level. This paper presents a step‐by‐step comprehensive study on the performance evaluation of selected uncontaminated ballast under simulated operational conditions and contaminated ballast (i.e., fouled) based on a series of laboratory tests. Tested parameters included granulometry, strength, durability and drainability and were compared with the recognised railway ballast requirements. The topsoil used as one of the fouling agents is classified into the ML group as inorganic silt with median compressibility. The initial gradation of the ballast indicates that the clean ballast samples are typically uniformly graded and generally strong and suitable for use following relevant recommendations. The abrasion tolerance of the uncontaminated ballast samples from both test locations increased as the cyclic/repeated loading induced by the train increased. The ballast gradation curves for each mix after the fouling process in the worst case of degradation by abrasion and contaminant shifted to broad‐graded classification due to the presence of finer‐sized particles. Generally, the higher the content of the fouling agent as ballast contamination, the lower the hydraulic conductivity. However, the inclusion of diesel as liquid intrusion does not seem to have any significant effect on the hydraulic conductivity. The study further presents an empirical model capable of predicting the hydraulic conductivity of ballast. The study concluded with admissible ballast contamination for cleaning and maintenance works.

Study on the difference of high frequency dielectric properties of biological tissues measured by air and packed coaxial probe

In this paper, the differences between air probe and filled probe for measuring high-frequency dielectric properties of biological tissues are investigated based on the equivalent circuit model to provide a reference for the methodology of high-frequency measurement of biological tissue dielectric properties. Two types of probes were used to measure different concentrations of NaCl solution in the frequency band of 100 MHz-2 GHz. The results showed that the accuracy and reliability of the calculated results of the air probe were lower than that of the filled probe, especially the dielectric coefficient of the measured material, and the higher the concentration of NaCl solution, the higher the error. By laminating the probe terminal, liquid intrusion could be prevented, to a certain extent, to improve the accuracy of measurement. However, as the frequency decreased, the influence of the film on the measurement increased and the measurement accuracy decreased. The results of the study show that the air probe, despite its simple dimensional design and easy calibration, differs from the conventional equivalent circuit model in actual measurements, and the model needs to be re-corrected for actual use. The filled probe matches the equivalent circuit model better, and therefore has better measurement accuracy and reliability.

Investigation on coal floatability and pore characteristics using acidification method

This paper investigated the relationship between coal floatability and pore characteristics from the perspective of froth flotation. Three types of coal samples with different ash contents were pretreated with HCl and acetic acid solutions to alter the pore features. The X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) measurements were conducted to specify the reactions that happened in acidification. The batch flotation and contact angle measurements were conducted to evaluate the floatability of the coal samples. The liquid nitrogen adsorption and mercury intrusion porosimetry (MIP) measurements were applied to measure the pore characteristics of the coal. The acidification treatment partially dissolved mineral components and organic functional groups on the coal surface but did not change the types of the major functional groups. The sedimentation of liberated fine minerals on coal pores caused the decrease in pore volume. The BET specific surface area of the three coal samples after acidification was found to have consistent negative relations with the flotation recovery and combustible recovery rate. This indicated the adverse impact of porosity in coal flotation. The floatability of coal is mainly influenced by the pores at the size fraction of 1–20 μm by pore volume. The nano-scale size pore and fine mineral inside the micron pore increased the water-wettability and resulted in the low floatability of coal.

Theoretical and Numerical Constant Mean Curvature Surface and Liquid Entry Pressure Calculations for a Combined Pillar–Pore Structure

Modern microfabrication techniques have led to a growing interest in micropillars and pillar–pore structures. Therefore, in this paper a study of the liquid entry pressure of a hydrophobic pillar–pore structure and the corresponding liquid–gas interface shape for the pressurized liquid is presented. We theoretically analysed the constant mean curvature problem for the rotationally symmetric case and determined an analytical expression for the liquid entry pressure of a hydrophobic pillar–pore structure. Furthermore, the shape of the liquid–gas interface as well as a formula for the location of the minimum were derived. The results are useful for designing geometries with specific properties, such as preventing or facilitating liquid intrusion into rough structures. We compared these results to multiphase lattice Boltzmann simulations where equilibrium contact angles in the range of 157∘ to 102∘ were tested. In our further analysis, we compared theoretical findings from previous works to our lattice Boltzmann simulations. The presented cases can serve as a benchmark for the development and validation of numerical multiphase models.

Fine characterization of pore structure of acidified anthracite based on liquid intrusion method and Micro-CT

Acidification erosion can seriously affect the pore structure characteristics of anthracite. In this paper, the low-temperature nitrogen adsorption method, mercury intrusion method, and Micro-CT scanning are used to analyze the pore structure of coal samples. The microscopic morphology and spatial distribution of coal pores are characterized by fractal dimension calculation and three-dimensional reconstruction. The results show that HCl has the highest removal efficiency of minerals in the Yuwu coal sample, which reduces the mass of coal samples by about 4%. HNO3 increases the proportion of micropore volume by 4.93%. HCl increases the proportion of mesoporous pore volume by 11.4%. Through the 3D reconstruction of coal, it is found that the mineral content in coal decreased by 48.14% after HCl dissolution, and the maximum diameter of mineral particles decreased from 173.588 μm to 57.449 μm. The spatial distribution of minerals is uneven, and the mineral content of coal samples decreases significantly along the direction of strong fluidity. At the same time, HCl increases the pore connectivity of coal samples, the pore roar increases by 56.72%, the isolated pores decrease, and the peak frequency of pore coordination number increases by 4 units, which greatly improves the transport capacity of fluid in coal matrix.

Triangulation of pore structural characterisation of disordered mesoporous silica using novel hybrid methods involving dual-probe porosimetries

The key issue, in applying indirect pore structure characterisation methods to disordered materials, is that usually some physical assumptions are necessary to probe pore size, such as concerning the mode of the phase transition used, which determines meniscus geometry or kernel type. This issue often undermines the relative advantages of indirect methods, over direct methods like imaging, from both the wider range of pores sizes that can be probed in a single experiment and the much better statistical representativeness of the data, which are essential for highly heterogeneous disordered materials. Further, parameter calibrations provided using supposedly the same model ordered porous materials are often conflictual. However, this work introduces dual-liquid thermoporometry, and also dual-probe, serial water sorption and mercury intrusion, to complement multi-adsorbate, serial gas sorption, to overcome this issue by triangulating the data for three key probe molecules used in three different porosimetries, namely liquid intrusion, gas sorption, and thermoporometry. It has been found that augmenting one porosimetry, using just one probe molecule, to a dual-probe experiment removes the aforementioned, key drawback of indirect methods. The alternative, complementary dual-probe porosimetries can also cross-validate this approach for each other. This allows indirect methods to stand alone, without the need for direct imaging methods to inform or validate prior assumptions. Further, the dual-probe experiments allow additional information on pore structure to be obtained beyond that provided by single-probe experiments. For example, dual-liquid thermoporometry also allows the probing for the presence and nature of the advanced melting effect, and serial water adsorption and mercury porosimetry delivers information on network filling mechanisms during adsorption in disordered media.

Differential Reservoir-Forming Mechanisms of the Lower Paleozoic Wufeng-Longmaxi and Niutitang Marine Gas Shales in Northern Guizhou Province, SW China: Theories and Models

Fine dissection of microscopic pore structure variations between the Niutitang Formation and the Wufeng-Longmaxi Formation will help to improve the understanding of the underlying geological theory of shale gas in northern Guizhou Province. The stratigraphic, geochemical, physical, and tectonic properties of the two formations vary greatly, resulting in differential development of the microscopic pore structure among reservoirs and, as a result, major variances in gas concentration. To explore the mechanism of differential pore evolution, experimental techniques and instruments such as gas adsorption, liquid intrusion, SEM, XRD, and organic geochemical tests were utilized. The results indicate that the Wufeng-Longmaxi Formation is in a high-maturity stage, while the Niutitang Formation is in an over-mature stage. The latter has a higher TOC content. Both petrographic phases are siliceous shale petrographic phases, and the former has more developed dissolution pores with better pore volume, throat radius, and macropore pore diameters than the latter, as well as organic matter pores, intergranular pores, and microfracture structural parameters, whereas the specific surface area is the opposite. The differences in reservoir pore formation between the two formations were analyzed, and the results showed that the petrographic type, thermal evolution, and tectonic preservation conditions were the primary controlling elements of differential shale gas reservoir formation. A differential reservoir-forming model of the Wufeng-Longmaxi Formation and the Niutitang Formation was constructed, providing a geological and theoretical basis for shale gas geological exploration in northern Guizhou Province.

Intrusion of liquids into liquid-infused surfaces with nanoscale roughness.

We present a theoretical study of the intrusion of an ambient liquid into the pores of a nanocorrugated wall w. The pores are prefilled with a liquid lubricant that adheres to the walls of the pores more strongly than the ambient liquid does. The two liquids are modeled as a binary liquid mixture of two species of particles, A and B. The mixture can decompose into a liquid rich in A particles, representing the ambient liquid, and another one rich in B particles, representing the liquid lubricant. The wall is taken to attract the B particles more strongly than the A particles. The ratio w-A/w-B of these interaction strengths is changed in order to tune the contact angle θ_{AB} formed by the A-rich/B-rich liquid interface between the two fluids and a planar wall, composed of the same material as the one forming the pores. We use classical density functional theory in order to capture the effects of microscopic details on the intrusion transition, which occurs as the concentration of the minority component or the pressure in the bulk of the ambient liquid is varied, moving away from bulk liquid-liquid coexistence within the single-phase domain of the A-rich bulk ambient liquid. These liquid structures have been studied as a function of the contact angle θ_{AB} and for various widths and depths of the pores. We also studied the reverse process in which a pore initially filled with the ambient liquid is refilled with the liquid lubricant. The location of the intrusion transition, with respect to its dependence on the contact angle θ_{AB} and the width of the pore, qualitatively follows the corresponding shift of the capillary-coexistence line away from the bulk liquid-liquid coexistence line, as predicted by a macroscopic capillarity model. Quantitatively, the transition found in the microscopic approach occurs somewhat closer to the bulk liquid-liquid coexistence line than predicted by the macroscopic capillarity model. The quantitative discrepancies become larger for narrower cavities. In cases in which the wall is completely wetted by the lubricant (θ_{AB}=0) and for small contact angles, the reverse transition follows the same path as for intrusion; there is no hysteresis. For larger contact angles, hysteresis is observed. The width of the hysteresis increases with increasing contact angle. A reverse transition is not found inside the domain within which the ambient liquid forms a single phase in the bulk once θ_{AB} exceeds a geometry-dependent threshold value. According to the macroscopic capillarity theory, for the considered geometry, this is the case for θ_{AB}>54.7^{∘}. Our computations show, however, that nanoscale effects shift this threshold value to much higher values. This shift increases strongly if the widths of the pores become smaller (below about ten times the diameter of the A and B particles).

A Trilayered Composite Fabric with Directional Water Transport and Resistance to Blood Penetration for Medical Protective Clothing.

Functional textiles with enhanced moisture management can facilitate sweat transport away from the skin to improve personal comfort. However, porous materials exhibit low capability of preventing the intrusion of external liquids, becoming a bottleneck in the design of medical protective clothing. Herein, a trilayered composite fabric based on a gradient wettability structure is demonstrated for directional water transport and resistance to blood penetration. The proposed fabric shows distinct advantages, including a high water breakthrough pressure of 2.43 kPa from the external side, an outstanding positive water transport index (1522%), and an antiblood penetration resistance of 2.71 kPa. Moreover, the fabric shows improved comfort with a high moisture transmission (320 g m-2 h-1) and desired water evaporation rate (0.36 g h-1). This work addressed the concern of directional water transport and resistance to blood penetration while providing a comfortable wearing microenvironment, leading to a promising research direction for multifunctional medical textiles.

Advanced developments in low-toxic and environmentally friendly shale inhibitor: A review

The hydration and swelling caused by the contact of shale with water during oil and gas drilling have caused many difficulties in drilling operations. Water-based drilling fluids (WBDFs) are considered to be more environmentally friendly and economical than oil-based drilling fluids (OBDFs). However, shale inhibitors are needed to solve the problems of shale hydration swelling caused by water. Reducing water content and liquid intrusion are effective ways to prevent the interaction between water and shale. Extensive researches have been conducted to develop highly effective shale inhibitors that inhibit shale swelling and reduce drilling costs and environmental impact. Especially in recent years, environmentally friendly shale inhibitors with low toxicity have become the main research object. A good shale inhibitor should not only have the ability to efficiently reduce shale hydration swelling, but also need to be compatible with other components of the drilling fluid to develop an effective high-performance WBDF. Besides, the requirements of environmental regulations should be met. Only biodegradable environmentally friendly inhibitors can develop the green and sustainable oil and gas industry. Some researchers have published some reviews about shale inhibitors, but there has been no review about low toxic and environmentally friendly shale inhibitors considered as the trend of the oil and gas industry. The purpose of this paper is to provide a detailed review of inhibitors with low toxicity and environmentally-friendly in recent years, aiming to fully understand the current methods of shale hydration inhibition and provide new ideas for the subsequent research on shale inhibitors.

Fine Characterization of Pore Structure of Acidified Anthracite Based on Liquid Intrusion Method and Micro-Ct

Fine Characterization of Pore Structure of Acidified Anthracite Based on Liquid Intrusion Method and Micro-Ct

Anomalous solid-like necking of confined water outflow in hydrophobic nanopores

<h2>Summary</h2> Intrusion of liquid into hydrophobic nanopores has yielded unusual fluid and transport properties that classical theories cannot fully describe, and its extrusion yet remains largely mysterious. Here, we report that the outflow of confined water from hydrophobic nanopores exhibits an anomalous necking phenomenon followed by its breaks, similar to that of solid metal nanowires under uniaxial tension. Molecular dynamics simulations reveal that this solid-like behavior attributes to strong cohesions of water molecules and nanoporous confinements associated with hydrogen-bonding networks and dipole alignments. The extracted elastic modulus and failure strength are quantitatively described by establishing solid-like mechanics scaling laws of outflow deformation and strength. Quasistatic experiments on hydrophobic nanopores/water systems were performed and confirmed the scaling laws of both outflow deformation and strength in remarkable agreement with theoretical predictions. This study offers a facile route for probing mechanical and structural properties of nanoconfined liquid by leveraging its unprecedented solid-like outflow behavior.

Study on the Critical Value of Residual Gas Content Based on the Difference of Adsorption Structure between Soft and Hard Coal.

In view of the difference of the adsorption structure between soft and hard coal, there is a big difference in the critical value of the inspection index for the regional outburst risk caused by the gas content. For the coal seams with soft and hard coal stratification, the model of gas content in the equilibrium state was established first, and the microscopic parameters of different rank coals were determined by the low-temperature liquid nitrogen adsorption test and mercury intrusion test. Then, the adsorption capacity of coal samples was determined by the adsorption test. Finally, the residual gas content of the coal seam in the equilibrium state was calculated based on the adsorbed gas content, and the critical value of prediction indexes of regional outburst based on the residual gas content was studied. The results show that for the same metamorphic degree, the specific surface area of soft coal is larger than that of hard coal. However, under the same gas pressure, the residual gas content of hard coal of anthracite and lean coal is greater than that of soft coal with the same metamorphic degree, while that of meager-lean coal and gas-fat coal is opposite. It is suggested to adopt the small value (rounded) of the measured gas content of soft and hard coal at 0.74 MPa as the critical value of the residual gas content in the regional effect test from the economic perspective. It is of great significance to determine the critical standard of the residual gas content in the regional effect test according to local conditions for reducing the cost of outburst prevention work.

The Effect of Surface Entropy on the Heat of Non-Wetting Liquid Intrusion into Nanopores.

On-demand access to renewable and environmentally friendly energy sources is critical to address current and future energy needs. To achieve this, the development of new mechanisms of efficient thermal energy storage (TES) is important to improve the overall energy storage capacity. Demonstrated here is the ideal concept that the thermal effect of developing a solid–liquid interface between a non-wetting liquid and hydrophobic nanoporous material can store heat to supplement current TES technologies. The fundamental macroscopic property of a liquid’s surface entropy and its relationship to its solid surface are one of the keys to predict the magnitude of the thermal effect by the development of the liquid–solid interface in a nanoscale environment—driven through applied pressure. Demonstrated here is this correlation of these properties with the direct measurement of the thermal effect of non-wetting liquids intruding into hydrophobic nanoporous materials. It is shown that the model can resonably predict the heat of intrusion into rigid mesoporous silica and some microporous zeolite when the temperature dependence of the contact angle is applied. Conversely, intrusion into flexible microporous metal–organic frameworks requires further improvement. The reported results with further development have the potential to lead to the development of a new supplementary method and mechanim for TES.

Giant Negative Compressibility by Liquid Intrusion into Superhydrophobic Flexible Nanoporous Frameworks.

Materials or systems demonstrating negative linear compressibility (NLC), whose size increases (decreases) in at least one of their dimensions upon compression (decompression) are very rare. Materials demonstrating this effect in all their dimensions, negative volumetric compressibility (NVC), are exceptional. Here, by liquid porosimetry and in situ neutron diffraction, we show that one can achieve exceptional NLC and NVC values by nonwetting liquid intrusion in flexible porous media, namely in the ZIF-8 metal-organic framework (MOF). Atomistic simulations show that the volumetric expansion is due to the presence of liquid in the windows connecting the cavities of ZIF-8. This discovery paves the way for designing novel materials with exceptional NLC and NVC at reasonable pressures suitable for a wide range of applications.

High In Situ Stress Anisotropy Lead to Formation of Complex Fracture Patterns

During the process of water injection, due to solid particle deposition and foreign liquid intrusion, the formation near the wellbore was contaminated and blocked. As a result, water injection rate reduced and failed to meet the injection requirements. In order to improve water injection rate and improve oil recovery of offshore oilfields, hydraulic injection tests were carried out in controlled laboratory conditions. In general, the formation of complex fracture patterns is an ideal outcome of the hydraulic fracturing stimulation seeks to achieve. In situ stress condition is an inherited geological condition one can only adopt to. By comparing test results of different experiments that had varied stress and hydraulic injection conditions imposed, we can investigate their impact on the fracture patterns created. This paper presents laboratory evidences to support that if the hydraulic injection condition is managed properly, a complex fracture pattern is possible even under a high in situ stress anisotropy. Even if the in situ stress condition has a large anisotropy, proper hydraulic stimulation operations can still cause complex fracture patterns and thus provide good stimulation efficiency.