Smooth Pore Research Articles

Polyvinyl alcohol and alginate bio-composite film containing titanium dioxide nanotubes for skin injury repair

This study explores the potential of polyvinyl alcohol (PVA) and alginate (SA) blend polymer films with embedded titanium dioxide nanotubes (TiO2NT) for wound healing applications. The nanocomposite film (PVA+SA@TiO2NT) was fabricated via a simple solvent casting process. The synergistic interaction between PVA and alginate significantly enhanced the film's stability in aqueous environments without compromising its weight. After 24 hours of immersion, the film exhibited a substantial swelling capacity (836±6%) and good WVTR ((282±4%). Scanning electron microscopy (SEM) revealed the formation of a smooth and random pore structure within the film. Fourier-transform infrared spectroscopy (FTIR) confirmed the successful formation of hydrogen bonds between PVA and alginate, along with the presence of Ti-O bonds, indicating successful incorporation of TiO2NT into the PVA+SA matrix. X-ray diffraction (XRD) analysis further corroborated the presence of TiO2NT. In vitro biocompatibility studies demonstrated the non-cytotoxic nature of the PVA+SA@TiO2NT bio-composite film. Additionally, in vitro wound healing studies suggest its potential as a promising biomaterial for wound dressing applications. These findings warrant further investigation to elucidate the complete mechanisms of action and optimize the nanocomposite's properties for clinical translation.

Brittle Damage Processes Around Equi‐Dimensional Pores or Cavities in Rocks: Implications for the Brittle‐Ductile Transition

AbstractIn the Earth's upper crust, rocks deform mostly by means of brittle fracturing processes. At the micro‐scale these processes involve the formation and growth of microcracks in the vicinity of defects such as open fissures, pores and other cavities. Large defects can produce strong enough perturbations of the stress field to activate and/or intensify brittle damage around them. Here we considered the ideal cases of smooth cylindrical and spherical pores inside an infinite solid body subjected to remote triaxial compressive stresses (i.e., the intermediate and minimum principal stresses are assumed equal). We first established the resulting local stress field around one of those large pores and then verified whether certain brittle damage processes could be activated in these conditions. We mainly considered the formation of tensile microcracks and micro shear bands. The former requires the presence of tensile stresses in some regions around the pore, while the latter needs sufficiently large shear stresses on pre‐existing optimally inclined microcracks to overcome their frictional resistance to sliding. We find that shear driven deformation remains localized in the vicinity of the pore. On the other hand, dilatational, tensile cracks can propagate large distances away from the pore but cannot form at and above some threshold ratio of the least to the largest principal stresses. Faulting associated with interacting tensile cracks is therefore suppressed with increasing depth. Our analysis leads to conclusions generally consistent with published experimental observations and provides some clues to discuss the physical cause of the brittle‐ductile transition in rocks.

Experimental and statistical study on sound absorption coefficient of porous asphalt concrete considering mesoscopic pore parameters

Porous asphalt concrete (PAC) has attracted significant attention in the road industry due to its excellent noise reduction capabilities. However, clogging in PAC decreases its sound absorption performance, as mesoscopic pore parameters play a crucial role in influencing PAC’s sound absorption abilities. To further investigate the influence of mesoscopic pore parameters on the sound absorption performance of PAC, CT scanning and digital image processing technology were employed. The principal component analysis method was employed to determine the weighting of the influence of mesoscopic pore parameters on the sound absorption coefficient. The correlation between different pore parameters and the sound absorption coefficient of PAC specimens was analyzed. The results showed that the minimum Feret diameter has the most significant effect on the sound absorption performance of PAC, while the concavity and the length-short axis ratio have the least impact. The correlation between mesoscopic pore parameters and sound absorption coefficients was found to be inconsistent before and after clogging. Mesoscopic pore parameters that were positively correlated with sound absorption coefficients before clogging turned negatively correlated after clogging. Connected large pores and smooth regular pore structure enhance the sound absorption performance of PAC, but clogging disrupts this structure, resulting in a decrease in sound absorption performance.

Effect of contact angle on the pressure needed for a liquid to permeate a cylindrical pore

Effective separation of two immiscible liquids with filters requires a difference in the pressures to permeate between the two liquids, and setting the applied pressure between these two pressures. To help design such filters, we present an equation that enables the calculation of the pressure for a liquid phase to permeate through a smooth pore in the shape of a truncated cone as a function of (a) the contact angle of the liquid on the filters and (b) the angle of the pore wall. The equation was derived by considering the interfacial energy required to push a liquid meniscus from the top of the pore to the bottom, and then to exceed the maximum curvature required at the exit. This equation was tested experimentally by adding a hydrostatic head with water on the 3D-printed filters of acrylate polymer while systematically varying the pore radii and contact angle with water. Experimental results showed an increased pressure to permeate with higher contact angles while the equation predicted the opposite. We hypothesized that the reason for the disagreement was the assumption of a smooth pore. For a liquid on a rough pore wall, the curvature of the meniscus is not solely determined from the microscopic contact angle and the pore wall angle, but the liquid would adopt a lower curvature meniscus. Therefore, the developed equation was modified after reflecting the lower curvature, which showed much better agreement with the experimental results. The remaining discrepancy from the theory was attributed to the pressure fluctuation from the fluid flow occurring while adding water.

Green superabsorbent hydrogel derived from activated charcoal and glycerol with maleic acid as a cross-linker

Superabsorbent hydrogels characterize a set of polymeric materials with three-dimensional structures capable of absorbing large amounts of water due to their hydrophilic functional groups on their surface. Their application in industries, agriculture, and the environment is of primary significance. This study reports the synthesis and characterization of green superabsorbent hydrogels derived from activated charcoal. The process involved a polymerization reaction between activated charcoal (AC) with glycerol (G) using sodium hydroxide as an initiator in the absence and presence of maleic acid as a crosslinker to synthesize HCG-1 and HCG-2 superabsorbent hydrogel respectively. Characterization of the hydrogels was done using Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscope (SEM), and X-ray diffraction (XRD). Optimization conditions were done by synthesizing hydrogel with varying dosages of both activated carbon and maleic acid as well as swelling time. The FT-IR results showed the appearance of strong sharp peaks at 1591.34 cm-1 and 1400.28 cm-1 in HCG-1 associated with -COO¯ symmetric stretching and asymmetric bending vibrations, indicating interlink between reacting monomers. A new absorption band at 1639.48 cm-1 associated with -COO¯ bending in non-conjugated ester indicates ester-crosslink in HCG-2 hydrogel. XRD analysis showed a phase shift from semi-crystalline to crystalline structure upon crosslinking. SEM analysis showed a crystalline intact, rigid structure without voids and pores on its surface in HCG-1 compared to the smooth irregular pores and lamina structure observed in HCG-2 hydrogel. The dosage ratio of AC: G: maleic acid of 8:5:1 produced hydrogel with an optimal water absorption capacity of 1255.80±0.70%. Maleic acid was found to improve the water absorption capacity of the superabsorbent. The study is an eye opener towards the application of biodegradable hydrogels in agriculture, especially in semi and arid regions.

Effect of surface roughness and morphology on the adsorption and transport of CH4/CO2 mixtures in nanoporous carbons

We report here molecular simulations of the adsorption and transport behaviour of CH4/CO2 mixtures in two types of non-ideal carbon nanopores. One model decorates an otherwise slit pore with surface imperfections which disrupt the smooth walls; a second model considers a disordered media, formed of randomly arranged coronene flakes, resulting in significant tortuosity. Boundary-Driven Non-Equilibrium Molecular Dynamics (BD-NEMD) and External Force Non-Equilibrium Molecular Dynamics (EF-NEMD) are used to study adsorption and transport properties in both types of pores with varying degrees of rugosity and tortuosity. Intermolecular interactions and bulk fluid properties are described by the statistical associating fluid theory (SAFT) coarse-grained Mie potential and equation of state respectively. Strong CO2 adsorption and fast CH4 transport are observed in smooth slit pores. Small instances of surface rugosity change the dynamics significantly, reducing the transport diffusivity by over an order of magnitude. The fast plug-like flow reported in slit pores dissipates with increasing rugosity, indicating a fundamental change in the flow pattern. Furthermore, rugose pores exhibit a lower capacity for CO2 adsorption, suggesting the performance of CO2 -enhanced oil recovery may be overestimated by the smooth pore models. A pore characteristic factor is shown to be appropriate to correlate the transport diffusivities in nano-pores.

Effects of Lycium barbarum polysaccharide on gelatinization properties of potato starch

AbstractIn this research, the influences of Lycium barbarum polysaccharide (LBP) on gelatinization properties of potato starch (POS) were evaluated. The swelling power of POS was inhibited, and the leaching of amylose declined. The LBP increased the peak temperature (Tp), while decreased the enthalpy (ΔH) of gel from 6.62 to 4.87 J g−1. Compared with pure POS gel, the hardness of POS gel added with 0.6% LBP decreased by 13% after storage for 20 days. The syneresis of gels that exposed to four freeze–thaw cycles was significantly reduced from 65.8% to 41.2%. Rheological measurements revealed that the viscoelasticity of composites was enhanced. The addition of LBP can enlarge the particle size of composite gels, and make the microstructure of composite gels become smooth, compact, and thicker pore wall. Fourier‐transform infrared spectroscopy (FTIR) and interaction force test showed that the hydrophobic bond was likely to be the main force.Practical applicationsThe incorporation of LBP could improve the gelling characteristics of POS‐based gel by delaying the change on gel hardness of POS composites during storage, and reducing the undesirable impact of freeze‐thawing treatment on POS gel system. The research outcome of the gelling characteristics of POS‐based gel can be used for frozen food, low‐temperature refrigerated food, and soft food. And the results of rheological behavior on POS‐based gel can be used in sauces, thickeners, and puddings.

Direct solar-driven thermochemical CO2-to-fuel conversion with efficiency over 39 % employing hierarchical triply periodic minimal surfaces biomimetic foam reactors

Solar-driven CO2 reforming of CH4 is considered a promising approach for achieving CO2 emission reduction and clean energy utilization simultaneously. However, reactors suffer from uneven temperature distribution and severe carbon deposition, leading to low solar-to-fuel efficiency. This study introduces a novel strategy for highly efficient solar-driven thermochemical CO2-to-fuel conversion based on hierarchical triply periodic minimal surfaces (TPMS) biomimetic foam reactors. The biomimetic hierarchical foam reactor exhibits a remarkably high light-to-fuel efficiency of 39.14 %, with CH4 and CO2 conversion rates reaching 72.6 % and 83.9 %, respectively, along with no obvious attenuation over 50 h. A 73.7 % reduction in temperature non-uniformity and a 96.9 % decrease in the carbon deposition rate are also demonstrated. The underlying mechanism is attributed to unique highly interconnected and smooth hierarchical pores, for which large pores promote the penetration of sunlight while small pores enhance fluid-solid energy transfer. Effects of solar irradiation conditions and foam thermal conductivity are investigated numerically, providing guides for further reactor optimization under different operating scenarios. This work presents a new approach for designing and manufacturing efficient direct solar-driven thermochemical CO2-to-fuel conversion reactors using hierarchical TPMS biomimetic foams.

Morphological and molecular characterisation of two free-living bacterivorous nematodes belonging to Rhabditida from South Africa

AbstractA new population of Pseudacrobeles (Pseudacrobeles) macrocystis and Poikilolaimus oxycercus is described from South Africa. Poikilolaimus oxycercus was collected from soil covered by a natural grass in South Africa, which is morphologically similar to the original description. The South African population of P. oxycercus is characterised by having a small size (807–818 µm in males and 703–779 µm in males), female tail cupola-shaped (24–35 µm), and spicule length (27–35 µm). The South African population of P. (P.) macrocystis, collected from natural grass, is characterised by having a small size (611–786 µm), a lateral field with three incisures, lip region with lips bearing seta-like processes and blunt conoid labial probolae, primary and secondary axils smooth, nerve ring and excretory pore at the posterior part of the pharyngeal corpus, spermatheca well developed, postvulval uterine sac poorly developed, female tail conoid-elongate, male tail conoid with thin acute mucro and spicules small (31–36 µm). Measurements and line illustrations of the species are given. In addition, LM, SEM photographs and the phylogenetic position of P. (P.) macrocyctis are provided. The 18S and 28S rDNA analyses show that P. macrocystis is closely related to other species of the genus Pseudacrobeles having lips with seta-like processes. This is the first report of P. (P.) macrocystis from South Africa.

Capillary rise behavior of lubricant in micropores with spiral bulge structures.

The highly efficient exudation of lubricant in porous self-lubricating materials significantly influences the formation of self-lubricating films. In this paper, micropores with inner spiral bulge structures are considered, and their influence on the capillary behaviors of the lubricant is discussed to reveal the capillary rising mechanism. The results show that the Taylor capillary lift phenomenon is produced in the spiral bulge structure of the micropore, and the capillary lift force is enhanced. The spiral structure decreases the effective diameter of micropores. The magnitudes of the pressure and velocity in the spiral structure pores are larger than those in smooth pores. The liquid in the upper part of the micropores forms a velocity vortex during its upward rotation along the spiral channel, which promotes the capillary rising behavior. For smaller pitches, the velocity vortex increases, and the rising speed of the lubricant grows. The inner spiral bulge structure gives the micropores an excellent capillary rising ability. The quantitative characterization and mechanism reveal that the capillary rising behavior can be used to guide the bionic designs of pores in self-lubricating materials.

Unraveling the relationship between molecular properties and rapid diffusion in smooth nanopores

Synthetic materials designed to enable rapid and finely tuned diffusion through semi-permeable nano and microscale pores have generally fallen short when compared to their biological counterparts. As a result, applications such as hemodialysis, drug delivery, and biomolecule purifications often require extensive run times and produce imperfect permeate solutions. Towards bridging this gap, we have recently demonstrated that, under a concentration gradient, a wide range of ions diffuse through atomically smooth carbon nanotube pores at rates more than an order of magnitude above those seen in bulk. This observation comes in a pore/molecule size regime where hindered diffusion was previously thought to apply. Here, we extend these results to include more complex and biologically relevant molecules and study how transport rates driven by diffusion depend on molecular properties such as size and flexibility. Further, we work to understand how the unique nanofluidic phenomena occurring in our pores may enable improved performance in dialysis applications by impacting selectivity, permeability, and molecular cutoff profiles. These results help to shed light on mechanisms governing diffusive transport in certain nanoscale pores that remain only partially understood and bring us closer to harnessing them in future separation technologies.

Effect of Authigenic Chlorite on the Pore Structure of Tight Clastic Reservoir in Songliao Basin.

Authigenic chlorite is a common clay mineral in clastic rock reservoirs, and it has an important influence on the pore structure of tight clastic rock reservoirs. In this paper, the tight clastic reservoirs in the Lower Cretaceous Yingcheng Formation in the Longfengshan subsag in the Changling fault depression in the Songliao Basin were investigated. Polarized light microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), high-pressure mercury injection (HPMI), and low temperature nitrogen adsorption (LTNA) were used to study the influence of authigenic chlorite on the pore structure of tight clastic reservoirs. The results show that the authigenic chlorite in the study area was mainly generated in the form of pore linings. The formation of the authigenic chlorite was mainly controlled by the parent rock type and the sedimentary microfacies in the provenance area. The hydrolysis and dissolution of the iron- and magnesium-rich intermediate-mafic magmatic rocks and the high-energy, open, weakly alkaline reducing environment in the delta-front underwater distributary channel were the key factors controlling the formation of the authigenic chlorite in the study area. The pore-lining chlorite slowed down compaction and inhibited quartz overgrowth, protecting the original pores. Moreover, there are a large number of intercrystalline pores in the chlorite, which provided channels for the flow of acidic water and thus the formation of secondary pores, playing a positive role in the physical properties of the tight clastic rock reservoirs. However, the pore-filling chlorite also blocked the pore throats, playing a negative role in the physical properties of the tight clastic rock reservoirs. The tight clastic rock reservoirs with pore-lining chlorite generally had low displacement pressures and large pore throat radii. The morphology of the nano-scale pores was mainly parallel plate-shaped slit pores. There were many primary pores and a small number of secondary pores in the reservoir. Some of the pores were connected by narrow-necked or curved sheet-like throats, and the pore structure was relatively good. A higher relative content of chlorite led to a larger nano-scale pore throat radius, a smaller specific surface area, a smoother pore surface, and stronger homogeneity. Authigenic chlorite played a positive role in the formation of the tight clastic reservoirs in the study area.

Effect of Supercritical Carbon Dioxide Fracturing on Shale Pore Structure

Supercritical carbon dioxide (SC-CO2) fracturing technology has the potential for shale reservoir stimulation. Most studies have predominantly focused on the fracture morphology of shales after SC-CO2 fracturing, while the alterations in shale pore structure have rarely been investigated. Here, CO2 adsorption, liquid nitrogen (N2) adsorption, and mercury intrusion porosimetry (MIP) tests were used to quantitatively characterize the changes in the pore shape, volume, and area as well as fractal characteristics of shales fractured by water and SC-CO2. The results show that the changes in micro-, meso-, and macropores are controlled by the injection pressure, axial-confining pressure, and infiltration range of SC-CO2 and water. However, both hydraulic fracturing and SC-CO2 fracturing do not alter the dominance of the plate-shaped and slit-type pores in the shales. For samples away from the induced fracture, the extent of SC-CO2 infiltration is greater than that of water, which is documented by the increase in total CO2 adsorption, cumulative intrusion, incremental/cumulative pore volumes of macropores, and porosity. After hydraulic/SC-CO2 fracturing, the proportions of micropores and mesopores reduce sharply, while the proportion of macropores increases significantly, reaching above 70%. Both hydraulic/SC-CO2 fracturing operations result in more regular pore structures and smoother pore surfaces for meso- and macropores near the induced fractures. However, by comparing the average fractal dimension of the samples near the induced fractures after hydraulic/SC-CO2 fracturing, it is found that the treatment of SC-CO2 makes the mesopores structure more complex and the pore surface of mesopores and macropores rougher.

Effect of the Pore Geometry on the Driving Pressure across a Bubble Penetrating a Single Pore

The passage of a bubble and the required energy for its motion through a confining pore can potentially be affected by the surface roughness and geometry of the pore. The motion of an isolated bubble passing through four different pore geometries (three circular pores, a smooth pore and 2 with different roughness, and a sharp triangular pore) is investigated. The shape of the deformed bubble passing these geometries was evaluated to determine the pressure drop across the bubble and hence the driving force to cause motion. The results of investigating the motion of the bubbles and the change in the pressure and velocity of the bubbles showed that the pore shape and surface roughness have a significant effect on the passage of the isolated phase. The motion of the bubble entering the entrance of the circular pores was similar for all circular cases. On exiting, however, a clear difference between the cases due to the presence of the peaks of the roughness was observed. These results indicate that, in addition to the critical pressure at the entrance of the pore, extra resistance will be introduced due to bubble phase pinning at the exit caused by roughness of the pore.

Storage stability of scallop (Patinopecten yessoensis) male gonad hydrolysates/κ-carrageenan composite hydrogels embeded curcumin

The combination of scallop male gonads hydrolysates (SMGHs) and κ-carrageenan (KC) was applied for curcumin (Cur) embedment and preservation, the corresponding Cur retention rate as well as gelation and microstructural properties were investigated during storage subjected to various pH (8 and 6) and temperature (25 °C and 4 °C). SMGHs-based gels could well protect Cur from degradation during 4 °C storage, with retention rate ranging from 95% to 97% after 30 day storage. At 25 °C, Cur could still be well preserved in SMGHs-based gels under pH 6 with Cur retention rate above 90%, while pH 8 led to rapid Cur degradation to around 75%. In addition, at pH 8 and 25 °C, the gel strength of SMGHs-Cur deteriorated significantly while evidently enhanced in SMGHs/KC-Cur due to synergistic combination within SMGHs and KC in couple with dehydration effect. Moreover, the water migration and distribution of SMGHs-based Cur-loaded vehicles were relatively stable at 4 °C while revealed apparent deterioration at 25 °C during storage. Furthermore, the microstructures of SMGHs/KC-Cur gradually transformed from homogeneous network with dense and smooth pores to tattered network with large and fragmentary pores, especially at 25 °C, promoting more Cur degradation. This study demonstrated that SMGHs/KC-Cur exhibited better than SMGHs-Cur in Cur preservation, potentially performing as excellent and sustainable protein hydrolysate/polysaccharide soft materials in food and biomedical fields.

Permeability of Additive Manufactured Cellular Structures—A Parametric Study on 17-4 PH Steels, Inconel 718, and Ti-6Al-4V Alloys

Cellular structures of metallic alloys are often made for various industrial applications by additive manufacturing. The permeability for fluid flow in these cellular structures is important. The current investigated the gas fluidity of cellular structures made by selective laser melting (SLM). The porosity and permeability of the SLM cellular structures were measured for 17-4 PH stainless steel, Inconel 718, and Ti-6Al-4V alloys. The relations between porosity and energy density are expressed using the power law. The characteristic molar energies were 1.07 × 105, 9.02 × 104, and 7.11 × 104 J/mole for 17-4 PH steel, Ti-6Al-4V, and Inconel 718 alloys, respectively. 17-4 PH steel gave rise to higher porosity at the same energy density when compared with Ti-6Al-4V and Inconel 718 alloy. The values of these molar energy density are related to the heat needed to melt the alloys, viscosity, and thermal conductivity. It was further shown that air permeability is not only concerned with the percentage of porosity in the cellular materials, but it also relates to the tortuosity of pore pathways formed in the cellular materials. At the same porosity, Inconel 718 demonstrates higher air permeability in comparison with that of Ti-6Al-4V and 17-4 PH alloys due to its smoother pore pathways. Ti-6Al-4V, on the other hand, demonstrates the highest specific surface areas due to powder sticking along the pore pathways and led to the lowest permeability among the three alloys.

Efficient oxidative cleavage of lignin C-C model compound using MOF-derived Cobalt/Nickel sulfide heterostructures

Producing fine chemicals by electrooxidation to replace sluggish oxygen evolution reaction (OER) provides a new opportunity and challenge for the high-value utilization of biomass. The oxidative breakage of the Cα-Cβ bond is an essential part of lignin depolymerization to platform chemicals and is largely dependent on electrocatalysts. Herein, a synthesis strategy is proposed using metal-organic framework (MOF) encapsulation and sulfuration on the nickel foam (NF) substrate. The robust bimetallic sulfides heterostructures, named Co3S4/(α,β)-NiS, showed selectively and efficiently oxidize Cα-Cβ in 2-phenoxy-1-phenylethanol (PPE), a typical β-O-4 model. An ultralow potential of 0.954 V vs RHE is exhibited by NF@Co3S4/(α,β)-NiS for 10 mA cm−2 in alkaline solutions containing PPE, owing to the multiphase active interface and smooth pore channels. A PPE conversion of 93.6% and benzoate yield of 83.8% were reached from the electrooxidation of PPE at 1.414 V vs RHE. Meanwhile, lignin can be effectively cleaved to the main product vanillin. This study develops an inexpensive and stabilized transition metal-based electrocatalyst for lignin upgrading to afford value-added products in the anode side and lower electricity consumption of water splitting.

Research on the early fracture behavior of fly ash-based geopolymers modified by molybdenum tailings

Due to the existence of abundant broken silicon-oxygen bonds on the surface, metal tailings have been successfully applied to produce novel green cementitious materials. In this paper, research on the damage mechanism of modifying fly ash-based geopolymers by molybdenum tailings is proposed, which not only realizes the reutilization of metal tailings but also reveals the damage mechanism of fly ash-based geopolymers. The effects of molybdenum tailings content on the compressive strength , flexural strength and deflection of fly ash-based geopolymers were researched by mechanical testing and digital image correlation technology (DIC). The early fracture behavior was analyzed by using acoustic emission (AE) technology for fly ash-based geopolymers that were modified with three different contents of molybdenum tailings. Finally, the micromorphology characteristics were analyzed by scanning electron microscopy (SEM), and the toughening mechanism induced by molybdenum tailings was elucidated. The results show that introducing 20% molybdenum tailings leads to significant enhancements of 79% in flexural strength and 145% in deflection in comparison to the pristine fly ash-based geopolymers. Molybdenum tailings can be dissolved in alkali activators, which are then adhered and grown as nanorods on the inner wall of the smooth pore structure. The molybdenum tailings finally fill in the pores and densify the microstructure, thus reducing the formation of macrocracks and corresponding structural damage of the fly ash-based geopolymer specimens during loading, and significantly improving the fracture-resistance. • Molybdenum tailings can be dissolved by the alkali activator. • Molybdenum tailings fill in the pores and densify the microstructure of fly ash-based geopolymers. • The fracture-resistance of fly ash based-geopolymers is significantly improved with the addition of molybdenum tailings.

Significant Effect of Rugosity on Transport of Hydrocarbon Liquids in Carbonaceous Nanopores

We report the results of modeling the transport of n-octane and n-hexadecane and their mixtures through carbonaceous nanopores at high-pressure conditions. Pores are modeled as smooth slit sheets with perturbations added as ridges and steps and a version of the statistical associating fluid theory (SAFT-γ Mie) is used both as equation of state and as a coarse-grained force field to account for fluid–fluid and fluid–solid molecular interactions. Molecular simulation allowed the description of transport diffusivities in terms of molecular flow, using boundary driven nonequilibrium molecular dynamics (BD-NEMD). Transport diffusivities are also independently calculated using equilibrium and external force nonequilibrium molecular dynamics (EF-NEMD) simulations, after accounting for the adsorption on the pores. We show consistency between the approaches for quantifying transport in terms of permeabilities (Darcy flows) and transport diffusivities. We find that smooth slit carbon pore models, which are commonly employed in the literature as surrogates for kerogen regions in shale, are an inadequate representation of ultraconfined natural pores. For slit pores, the flow patterns are characterized by a fully mutualized pluglike flow and fast transport. However, by incorporating even a small amount of rugosity (roughness) into the solid walls, the diffusion coefficients decrease dramatically, with surface roughness significantly affecting the characteristic transport and velocity profiles inside the pores. In all cases, it is seen that there are important cross-correlation effects, influencing the way components of the mixture flow together. Calculated self-diffusivities are orders of magnitude smaller than the observed transport diffusivities for liquid mixtures. This work has a direct impact on the understanding and modeling of unconventional hydrocarbon recovery and flow in organic shale rocks.

Flotation specificity of coal gasification fine slag based on release analysis

Coal gasification fine slag is a solid waste of difficult-to-separate nature . In this study, the residual carbon was enriched from fine slag by conventional flotation. The optimal flotation results in the concentrates yield of 59.01%, the concentrates ash content of 37.64%, and the flotation perfect index of 41.12%, respectively. Under the identical conditions, step release flotation exhibits abnormal results, i.e., the lowest ash content is concentrates 3 (C 3 ) corresponding to 29.21%. The particle distribution analysis of concentrates 1 (C 1 ) to concentrates 5 (C 5 ) and tailings (T) shows that particles of the highest carbon content transfer to C 3 , while dominated by ash are enriched in T. Additionally , the particle structure characteristics (with SEM , BET surface area, BJH pore volume/average pore width, FHH fractal characteristics) demonstrate that the particles differ in pore's volume, average width, and interior smoothness. This concludes that it is the larger pore volume, the wider average pore width, and the smoother pore interior that contributes to the greater amount of diesel adsorption and therefore easier release of carbon-content particles in flotation. Such regularities of particle transfer in flotation and release mechanism manifest the flotation specificities of gasification fine slag, which may provide a scientific reference for effectively enriching residual carbon in coal gasification fine slag. • Conventional flotation upgrades coal gasification fine slag with η as 41.12%. • Concentrates 3 (C 3 ) abnormally contains the lowest ash content of 29.21%. • Analysis of particle distribution reveals regularities of particle transfer. • Particle structure study learned the release mechanisms of particles. • Flotation specificities of coal gasification fine slag were clarified.