Effect Of Pore Size Research Articles

Separation of molybdenum and tungsten using selective adsorption with zirconium based metal organic framework

BackgroundThe separation of tungsten and molybdenum has always been a significant challenge. Metal organic frameworks (MOFs) has potential to solve the problem. In this study, the adsorption and separation performance of UiO-66 for tungsten and molybdenum and adsorption mechanism were investigated. MethodsUiO-66 was synthesized by solvothermal method. The physical and chemical properties of UiO-66 and adsorption mechanism were characterized and analyzed by XRD, SEM-EDS, FT-IR, Zeta-potential, XPS and thermodynamic analysis, the adsorption and separation performance of Mo/W using UiO-66 were evaluated by ICP-OES. Significant findingsUiO-66 with uniform pore size could be obtained under the conditions of crystallization for 24 h at 180 °C. This study revealed superior Mo/W separation performance under acidic conditions, where the adsorption capacity for Mo (QMo) of UiO-66 was 219.4 mg⋅g−1 and the highest separation factor (βMo/W) was 52.3. It was found that the mechanism involved the effect of pore size, electrostatic attraction and the metal point Zr had stronger affinity for Mo. This material was expected to serve as an eco-friendly and reusable adsorbent for separation of tungsten and molybdenum in resource recovery, aiming for high-quality regeneration of both metals.

The pore size effect on the degradation, tensile properties and cell viability of polycaprolactone/starch scaffold: experimental study

The pore size effect on the degradation, tensile properties and cell viability of polycaprolactone/starch scaffold: experimental study

Effects of Pore Size and Surface Modification on the Alumina Microfiltration Membrane Fouling in MBR with Backwashing

Effects of Pore Size and Surface Modification on the Alumina Microfiltration Membrane Fouling in MBR with Backwashing

Effect of pore size and temperature on the behaviour of alpha-lactalbumin and the A and B genetic variants of beta-lactoglobulin during protein fractionation microfiltration

The aim of this study was to investigate the influence of membrane pore size and filtration temperature on six individual milk protein fractions (αS-CN, β- CN, κ-CN, α-LA, β-LG A, β-LG A) during the protein fractionation microfiltration process. Pasteurised skimmed milk was microfiltrated using two different pore sizes of spiral-wound membranes, with pore sizes of 0.2 μm and 0.5 μm, at temperatures of 15 °C and 45 °C respectively. The microfiltration process was carried out with a final volume reduction of 66% and a diafiltration volume of 120% (300 L) of the original feed (250 L). It was observed that neither the pore size nor the filtration temperature significantly (p<0.05) affected the permeation of the α-LA fraction. However, the permeation of the β-LG A and β-LG B fractions can be influenced by membrane pore size and filtration temperature, and the behaviour of the three whey protein fractions, A and B genetic variants of the β-LG and α-LA fractions differs significantly during the microfiltration process. The results of this study could form the basis for the development of new, unique tailor-made milk protein ingredients.

Cage-like micro-scaffolds fabricated by DLW method for cell investigation

This paper focuses on the use of direct laser writing method in fabricating three-dimensional biocompatible scaffolds that emulate the extracellular matrix. The interaction between HEK 293 cells and these cage-like scaffolds, particularly the effect of pore size on cell invasion, is explored in detail. Our study underscores the influence of scaffold architecture on cellular behavior and highlights the potential of direct laser writing technology in creating complex 3D scaffolds. The insights gleaned from this research could be invaluable in future applications such as tissue engineering, regenerative medicine, and drug delivery.

Effect of wound dressing porosity and exudate viscosity on the exudate absorption: In vitro and in silico tests with 3D printed hydrogels

Exudate absorption is a key parameter for proper wound dressing performance. Unlike standardized tests that consider exudate viscosity close to that of water, patients' exudates vary greatly in composition and, therefore, viscosity. This work aimed to investigate the effects of exudate viscosity and pore size of hydrogel-like dressings on the exudate absorption rate to establish rational criteria for the design of dressings that can meet the personalized needs of wound treatment. Computer-aided design (CAD) was used for Digital Light Processing (DLP) 3D printing of hydrogels with 0%, 30% and 60% porosity. The hydrogels were characterized in detail, and the absorption of two simulated exudate fluids (SEFs) was video-recorded. The same CAD files were used to develop in silico models to simulate exudate uptake rate. Both in vitro data and in silico modeling revealed that low-viscosity SEF penetrates faster through relatively small hydrogel pores (approx. 400 μm) compared to larger pores (approx. 1100 μm) due to capillary forces. However, in vitro vertical uptake took longer than when simulated using CAD design due to lateral fluid absorption through the pore walls in the hydrogel bulk. Distortions of hydrogel channels (micro-CT images) and lateral fluid absorption should be both considered for in silico simulation of SEF penetration. Overall, the results evidenced that porous hydrogel dressings allow rapid penetration (within a few seconds) and hosting of exudates, especially for pore size <1 mm. This information may be useful for design criteria of wound dressings with adequate fluid handling and drug release rate.

Nanoconfinement effect on the miscible behaviors of CO2/shale oil/surfactant systems in nanopores: Implications for CO2 sequestration and enhanced oil recovery

Currently, CO2 flooding is the most promising carbon capture, utilization, and storage (CCUS) technology in the energy industry. Understanding the nanoconfinement effect on the CO2-oil miscible process is crucial for accurately determining the minimum miscibility pressure (MMP) of CO2/oil in shale reservoirs. In this study, we conducted molecular dynamics (MD) simulations to investigate the effects of pore size, surfactants, and pore type on the MMP of nanoconfined CO2/shale oil/surfactant systems. Validations against experimental data show a deviation of 2.98 % in the CO2 MMP. The MMPs under nanoconfinement are found to be significantly lower than those in bulk phase conditions (up to 22.94 %). The simulation results reveal that decreasing pore size can enhance the miscibility of CO2 and oil by increasing the CO2 adsorption ratio, improving CO2-surfactant interactions, and inhibiting the tendency of CO2 molecules to self-aggregate. The enhancement of CO2-oil miscibility caused by surfactants is ranked by CFP > SF > SDS according to the mixing degrees (Dmix) and the spatial distribution of CO2 around surfactant molecules. In addition, pore type exhibits various abilities in influencing the MMP, owing to their different mineral surface properties and ability to influence CO2-surfactant interactions. Nanopores with stronger hydrophobicity and a denser CO2 distribution around surfactant molecules have lower MMPs. The results show that the order of MMP in terms of pore types is Quartz < Kaolinite < I/M clay. This study elaborates the micro-mechanisms of surfactant-assisted CO2-oil miscibility under nanoconfinement, offering valuable insights for effectively designing CO2 miscible flooding in shale oil reservoir development.

Selective hydrogenolysis of furfuryl alcohol to 1,2-pentanediol over CuMg supported on mesoporous silica: Effect of pore size and shape

Utilizing urea homogeneous precipitation method, Cu and Mg species were successfully supported on SBA-15, KIT-6, and MCM-41 respectively for furfuryl alcohol (FFA) hydrogenolysis to 1,2-pentanediol (1,2-PeD). The catalytic results showed that the yield of 1,2-PeD followed the order of CuMg/SBA-15 > CuMg/KIT-6 > CuMg/MCM-41, especially the maximum of 50.0 % over CuMg/SBA-15 surpassing that of most copper-based catalysts reported. It is found that FFA conversion dramatically increases with the raising of Cu dispersion, attributing to the high exposure of active sites. Meanwhile, the selectivity of 1,2-PeD is strongly depended on the Cu0/Cu+ ratio of catalyst and CuMg/SBA-15 with the highest value of 57.6 % is derived from the largest Cu0/Cu+ ratio. In a word, CuMg/SBA-15 shows the excellent activity along with stability owing to the synergy between large Cu0/Cu+ ratio and good Cu dispersion, providing by two-dimensional hexagonal straight channel arrangement with generous pore diameter. Innovatively, it is put forward that dual adsorption sites of both MgO and Cu species in the CuMg/SBA-15 catalyst promote the FFA ring-opening to yield 1,2-PeD based on the comparison of Cu dispersion, metal-support (M−S) interaction and the adsorption capacity for furan rings with Cu/SBA-15. This study provides a novel approach for catalyst design for this reaction, focusing on optimizing the catalytic performance by fine-tuning structure of the support.

Evaporation from thin porous Coatings: Pore size effects and predictive equation for homogeneous coatings

Evaporation of small water droplets on solids is hindered because surface tension pulls the droplet into a spherical cap that has a small perimeter. Our solution is to coat a solid with a very thin, porous layer into which the droplet flows to create a large-area disk with concomitant high rate of evaporation. We investigate evaporation by varying factors that have not been previously considered: pore size and distribution, contact angle, temperature, and relative humidity (RH).A larger pore size resulted in faster evaporation, which we explain through faster transport within the coating. Even faster evaporation occurred for a bilayer structure with small particles on the air side and larger particles on the solid side. The water advancing contact angle had an insignificant effect in the range from < 10° through to 60°.Our results for different pore sizes, temperature, humidity, and contact angle all collapse onto a single curve when appropriately normalized. This validates an equation that can be used for the evaporation from a homogeneous coating that depends only one empirical factor and the droplet volume. Since the volume is often user-controlled, we envisage that this equation can be used to predict evaporation and guide design of fast-drying coatings.

Study on the Adsorption Law of n-Pentane in Silica Slit Nanopores.

As the main components of shale, inorganic minerals are important carriers for oil and gas adsorption, whose pore structures and surface properties have significant effects on the fluid adsorption capacity. In this study, slit nanopores (SNPs) were constructed by silica. To investigate the microscopic adsorption law of n-pentane in silica, the grand canonical Monte Carlo (GCMC) method was used to simulate the adsorption behaviors of n-pentane in silica nanoparticles. The effects of different surface wettability, pore size, temperature, and pressure values on the adsorption behavior of pentane were discussed, revealing the micro adsorption mechanism of pentane in silica with different pore sizes and wettability and evaluating the degree of oil and gas utilization. The research results indicate that the adsorption capacity of pentane is greatly affected by the temperature under low-pressure conditions. With the increase of the pore size, the adsorption capacity of pentane increases linearly, and the number of adsorbed pentane molecules gradually decreases. The availability of oil and gas increases, and the oil and gas are more easily extracted. As the surface hydrophobicity of minerals increases, the van der Waals force between minerals and pentane also increases, leading to an increase in the number of adsorbed states of pentane. The stronger the hydrophilicity of the wall, the fewer the pentane molecules adsorbed on the surface, which would improve the efficiency of oil and gas extraction. This study provides potential for the development of novel surfactants based on adsorption selectivity.

Occurrence of methane in organic pores with surrounding free water: A molecular simulation study

Free water contained in shale reservoirs can influence the enrichment and transportation of shale gas. To accurately assess shale gas adsorption in shale reservoirs and improve recovery, it is crucial to understand the occurrence of gas and water. In this study, the occurrence of methane occupying the organic pores surrounded by free water is investigated using Grand Canonical Monte Carlo/Molecular Dynamics simulations, considering the effects of pressure, temperature and pore size. The center of the model represents methane adsorbed/free within the organic pores, while the regions on either side depict free water. Although water does not significantly penetrate organic pores, pressure, temperature, and pore size have a notable impact on the wettability of water on organic surfaces, resulting in variations in the concave liquid surface morphology. This results in varying degrees of competitive adsorption of water and methane near the carbonyl group. At lower pressures, although the capillary pressure decreases sharply with increasing pore size, the improved water wettability increases the extent of its intrusion along the pore surface, thereby enhancing the competitive adsorption of methane and water. At higher pressures, capillary pressure acts as a resistance, preventing water from invading the organic pores in significant quantities. Due to the weak affinity of organic pores for water, the same phenomenon was observed even after increasing the pore size and temperature to improve water wettability. In addition, high temperatures can lead to more pronounced water intrusion. Finally, it is hypothesized that competitive adsorption of methane and water is more pronounced at shallower burial depths and slightly larger pore sizes. This result is expected to provide insights for the accurate evaluation of gas adsorption in water-bearing shales.

Influence of Porosities of 3D Printed Titanium Implants on the Tensile Properties in a Rat Tendon Repair Model.

There is a desire in orthopaedics to have soft tissue, particularly tendon, grow into metallic implants. With the introduction of three-dimensional (3D) printed porous metal implants, we hypothesized that tendons could directly attach to the implants. However, the effects of the porous metal structure on tissue growth and penetration into the pores are unknown. Using a rat model, we investigated the effect of pore size on tendon repair fixation using 3D printed titanium implants. There were three experimental groups of eight Sprague Dawley rats (n = 24) plus control (n = 3). Implants had defined pore sizes of 400µm (n = 8), 700µm (n = 8), and 1000µm (n = 8). A defect was created in the Achilles tendon and the implant positioned between cut ends and secured with suture. Specimens were harvested at twelve weeks. Half the specimens underwent mechanical testing to assess tensile load to failure. The remaining specimens were fixed and processed for hard tissue histological analysis. The average load to failure was 72.6N for controls (SD 10.04), 29.95N for 400µm (SD 17.95), 55.08N for 700µm (SD 13.47), and 63.08N for 1000µm (SD 1.87). The load to failure was generally better in the larger pore sizes. The 700µm and 1000µm specimens performed similarly, while the 400µm showed significant differences vs control (p = 0.039), vs 1000µm (p = 0.010), and approached significance vs 700µm (p = 0.066). There was increasing ingrowth as pore size increased. Histology showed fibrous tendon tissue within and around the implants, with collagen fibers organized in bundles. Tendon repair utilizing implants with 700µm and 1000µm pores exhibited similar load to failure as controls. Using a defined pore structure at the attachment points of tendons to implants may allow predictable tendon ingrowth onto/into an implant at the time of revision arthroplasty.

Study on performance regulation of electro-mechanical properties 3D printed BaTiO3/HA porous structure composite ceramic

BaTiO3/Ca10(PO4)6(OH)2 composite ceramic is an outstanding representative of piezoelectric biomaterials, with excellent biocompatibility and piezoelectric effect, and has potential applications in the field of bone tissue repair. In this work, vat photopolymerization 3D printing technology was used to fabricate triply periodic minimal surface structure BaTiO3/Ca10(PO4)6(OH)2 composite ceramic bone tissue scaffolds with different pore sizes and porosity, and their mechanical and electrical properties were studied. First, the ceramic slurry configuration process was optimized to obtain a ceramic slurry with high solid content (45 vol%) and excellent rheological properties. Then the effect of sintering temperature on microstructure, relative density, mechanical properties, and electrical properties is discussed. The results show that when sintering at 1300 °C, the BaTiO3/Ca10(PO4)6(OH)2 composite ceramic has the highest relative density (99.18 %), the highest compressive strength (44 MPa), large relative dielectric constant (379–389), and low dielectric loss. The polarization electric field strength of the BaTiO3/Ca10(PO4)6(OH)2 composite ceramic was set to 15 kV/cm through the test of the hysteresis loop. Finally, based on multi-physics coupled finite element simulation, the effects of different porosity and different pore sizes on stress distribution and piezoelectric potential were analyzed, and the relationship between them was explored through experiments. The results show that as the porosity increases and the pore size decreases, the mechanical properties of the scaffold decrease significantly, and its compressive strength ranges between 1.67 and 4.26 MPa; as the porosity increases and the pore size increases, the piezoelectric coefficient (d33) of the scaffold showed a decreasing trend, and its d33 ranged between 2 and 9 pC/N. The mechanical and electrical properties of the scaffold meet the performance requirements of cancellous bone. In summary, this work provides a strategy for the application of customized BaTiO3/Ca10(PO4)6(OH)2 composite ceramic scaffolds in new-generation orthopedic implants.

Characterization of membrane pore size using statistical model by facile method of air bubbling in liquid media

Research has shown the correlation between porous membrane pore size and bubble formation including bubble size, frequency, and operating parameters. However, attempts to create a governing equation to establish this correlation have often suffered from low accuracy due to variable interactions. Therefore, it is necessary to identify the significant effects of membrane pore size on bubble formation to establish effective correlations. This study aimed to identify the significant effect of porous membrane pore size on bubble formation using analysis of variance (ANOVA) to establish a mathematical model that predicts porous membrane pore size using bubble formation. To achieve this, various porous membranes were fabricated by varying hydrophilic silica loadings. The resulting membranes were characterized regarding pore size and employed in an aeration device under variable air flow rates and inlet pressures to obtain bubble size and frequency data. JMP software developed a statistical model to characterize membrane pore sizes. The results show a significant effect of bubble formation information on pore size, with a p-value of 0.0089, R2 of 0.96, and root mean squared error (RMSE) value of 0.02. Validation of the model using three membranes demonstrated minor deviations of 0–6.5 %, emphasizing the model's effectiveness in predicting membrane pore size.

Hierarchical nanoarchitectonics of hollow hexanitrostilbene (HNS) microspheres to improve safety and combustion performance

Hollow structures have great potential in the field of energetic materials due to their excellent properties. In this study, nitrocellulose (NC) was used as a binder, and hollow-structured HNS/NC microspheres were prepared in the form of a suspension using the microjet droplet technology. The effects of spray velocity, suspension concentration, and receiving liquid temperature on the morphology, particle size, cavity structure, and pore size of the microspheres were systematically investigated. Subsequently, the effects of shell thickness and pore size on the dispersibility, specific surface area, crystal structure, thermal performance, mechanical sensitivity, and combustion performance of the microspheres were further studied. The results show that compared with the raw HNS, the hollow HNS/NC microspheres have good dispersibility, while retaining the crystal structure and chemical structure of the raw HNS, and have a lower activation energy, which is expected to achieve a rapid energy release reaction. In addition, compared with the solid HNS/NC microspheres, the hollow HNS/NC microspheres have a higher specific surface area (19.658 m2·g−1 vs 31.335 m2·g−1) and better safety performance (6 J vs 50 J). The ignition experiment results show that the hollow structure significantly enhances the combustion performance of HNS (305 ms vs 92 ms), improving the energy release efficiency. This preparation method is simple, efficient, and easy to scale up, providing a more universal and environmentally-friendly technical approach for the multi-structural design of energetic microspheres.

Effect of Pore Size on the Mechanical Properties and Deformation Behavior of Porous ZrO2 (Y2O3) Ceramics Under Axial Compression

Effect of Pore Size on the Mechanical Properties and Deformation Behavior of Porous ZrO2 (Y2O3) Ceramics Under Axial Compression

Effect of pore shape and size on energy absorption in cellular Al-Si12 manufactured by infiltration process

Effect of pore shape and size on energy absorption in cellular Al-Si12 manufactured by infiltration process

Pore engineering of Porous Materials: Effects and Applications.

Porous materials, characterized by their controllable pore size, high specific surface area, and controlled space functionality, have become cross-scale structures with microenvironment effects and multiple functions and have gained tremendous attention in the fields of catalysis, energy storage, and biomedicine. They have evolved from initial nanopores to multiscale pore-cavity designs with yolk-shell, multishells, or asymmetric structures, such as bottle-shaped, multichambered, and branching architectures. Various synthesis strategies have been developed for the interfacial engineering of porous structures, including bottom-up approaches by using liquid-liquid or liquid-solid interfaces "templating" and top-down approaches toward chemical tailoring of polymers with different cross-linking degrees, as well as interface transformation using the Oswald ripening, Kirkendall effect, or atomic diffusion and rearrangement methods. These techniques permit the design of functional porous materials with diverse microenvironment effects, such as the pore size effect, pore enrichment effect, pore isolation and synergistic effect, and pore local field enhancement effect, for enhanced applications. In this review, we delve into the bottom-up and top-down interfacial-oriented synthesis approaches of porous structures with advanced structures and microenvironment effects. We also discuss the recent progress in the applications of these collaborative effects and structure-activity relationships in the areas of catalysis, energy storage, electrochemical conversion, and biomedicine. Finally, we outline the persisting obstacles and prospective avenues in terms of controlled synthesis and functionalization of porous engineering. The perspectives proposed in this paper may contribute to promote wider applications in various interdisciplinary fields within the confined dimensions of porous structures.

The Impact of Metal Centers in the M-MOF-74 Series on Formic Acid Production.

The confinement effect of porous materials on the thermodynamical equilibrium of the CO2 hydrogenation reaction presents a cost-effective alternative to transition metal catalysts. In metal-organic frameworks, the type of metal center has a greater impact on the enhancement of formic acid production than the scale of confinement resulting from the pore size. The M-MOF-74 series enables a comprehensive study of how different metal centers affect HCOOH production, minimizing the effect of pore size. In this work, molecular simulations were used to analyze the adsorption of HCOOH and the CO2 hydrogenation reaction in M-MOF-74, where M = Ni, Cu, Co, Fe, Mn, Zn. We combine classical simulations and density functional theory calculations to gain insights into the mechanisms that govern the low coverage adsorption of HCOOH in the surrounding of the metal centers of M-MOF-74. The impact of metal centers on the HCOOH yield was assessed by Monte Carlo simulations in the grand-canonical ensemble, using gas-phase compositions of CO2, H2, and HCOOH at chemical equilibrium at 298.15-800 K, 1-60 bar. The performance of M-MOF-74 in HCOOH production follows the same order as the uptake and the heat of HCOOH adsorption: Ni > Co > Fe > Mn > Zn > Cu. Ni-MOF-74 increases the mole fraction of HCOOH by ca. 105 times compared to the gas phase at 298.15 K, 60 bar. Ni-MOF-74 has the potential to be more economically attractive for CO2 conversion than transition metal catalysts, achieving HCOOH production at concentrations comparable to the highest formate levels reported for transition metal catalysts and offering a more valuable molecular form of the product.

Effect of foam interlayer thickness and pore size on the microstructure and properties of brazed joints

Ni foam was introduced as an interlayer to improve the performance of the brazed C/C composite-TC4 titanium alloy joint, and high-quality brazed connections of c/c composites and TC4 were realized. Compared to a brazing joint without foam, the introduction of a foam Ni interlayer can achieve a more uniform bonding interface. The effects of the thickness and pore size of the foam Ni interlayer on the microstructure, mechanical properties and residual stresses of the joints were investigated. With increasing thickness and pore diameter, Ag-based solid solutions and Ti–Cu intermetallic compounds first become more dispersed and smaller at the center of the brazed joints, and then aggregate to become larger. The brazed interface microstructure with a 0.4 mm thick foam Ni interlayer with a pore size of 0.5 mm was more uniform, and the shear strength of the joint reached 21.23 MPa, representing an 85.96 % increase compared to the joint without the foam Ni interlayer. The residual stress and its distribution calculated by finite element method (FEM), and the residual stress of the brazed joint decreased from 467 MPa/-289.53 MPa to 457.96 MPa/-234.98 MPa. These results indicated that the Ni foam could act as a buffer layer to reduce the residual thermal stress, and improve the mechanical properties of C/C composite-TC4 titanium alloy joint.