Multimodal Pore Size Distribution Research Articles

Manufacturing Free‐Standing, Porous Metallic Layers with Dynamic Hydrogen Bubble Templating

AbstractThe 3D structure (i.e., microstructure) of porous electrodes governs the performance of emerging electrochemical technologies such as fuel cells, electrolysis, and batteries. Sustaining electrochemical reactions and convective‐diffusive mass transport at high efficiency is complex and motivates the search for sophisticated microstructures with multimodal pore size distributions and pore size gradients. Here a new synthesis route for porous, metallic layers is presented that combines the characteristics of carbon structures (i.e., pore size, porosity) with the properties of metals (i.e., recyclability, conductivity). Building on the method of dynamic hydrogen bubble templating, a novel approach is engineered to manufacture thin, free‐standing layers using an electrochemical flow cell through the introduction of an intermediate layer and optimization of the synthesis parameters. Mechanically stable layers are created with thicknesses ranging from ≈50 to ≈200 µm comprising porous, dendritic structures, arranged to form a vascular network of larger pores with a gradient in radii from ≈5 µm at the bottom and up to ≈36 µm at the top of the material. Using X‐ray tomographic data, the morphology is analyzed, and the diffusive transport through the material as a function of liquid filling is simulated and compared to state‐of‐the‐art carbon fiber‐based electrodes, showing significantly higher mass transfer properties.

Superflexible porous PCSnf-Fe3O4/CNT-PANI BP/PCSnf-Fe3O4 sandwich composite films with excellent electromagnetic wave absorption performance based on integral assembly by electrospinning

Polycarbosilane nanofiber-ferroferric oxide (PCSnf-Fe3O4) films were assembled on both sides of carbon nanotube-polyaniline buckypaper (CNT-PANI BP) by electrospinning to obtain PCSnf-Fe3O4/CNT-PANI BP/PCSnf-Fe3O4 sandwich porous composites, with a diameter of 110–120 mm and a thickness of 150–200 µm. The Fe3O4 nanoparticles adhered on the PCS nanofibers formed a bamboo-like or plum-like structure. The PANI nanoparticles were uniformly embedded in the CNT network. Both PCSnf-Fe3O4 film skin layers were well bonded to the CNT-PANI BP core layer, with two main forms of the interlayer interface of rattan-like and root-like entanglement. The sandwich composite film (SCF) with 15.1 wt% Fe3O4 in the skin layers had a density of 0.97 g/cm3, a porosity of 61% and a total pore area of 30.1 m2/g, with a multimodal pore size distribution. The SCFs were superflexible, being tightly wound around a 4 mm diameter glass rod and repeated 100 times without damage. The absorption performance of the SCF was significantly improved by introducing Fe3O4 nanoparticles into its skin layers. The SCF with 11.8 wt% Fe3O4 in its skin layers achieved optimal dielectric and magnetic loss matching, with minimum reflection loss of − 43.54 dB and maximum effective absorption bandwidth of 6.97 GHz.

Improved predictions of permeability properties in cement-based materials: A comparative study of pore size distribution-based models

Permeability is a fundamental physical property of a cement-based material and is closely related to its pore structure. This study developed an improved model for permeability prediction of cementitious materials with a function of the pore size distribution (PSD), in which PSD is simulated from single and compound lognormal distribution functions, respectively. The efficiency of the improved model is demonstrated by calculating permeability for mortars and pastes available in the literature. It is found that, first, for cementitious materials with unimodal PSD, the single lognormal distribution function is adequate to describe the pore structures. In contrast, for cementing mixtures presenting multimodal PSD, the compounded lognormal distribution function is highly recommended to cover a wide range of pore components. Second, the permeability model based on the compound PSD can predict well permeability to gas intrusion, whereas the single PSD-based model is applicable for calculating permeability via water intrusion. Furthermore, slippage effect and water saturation degree are introduced in the PSD-based model. Results prove that the corrected gas permeability model from the compound PSD performs well in estimating the gas permeability in unsaturated states. Finally, the compound PSD-based model is extended by considering varying porosities and relative humidities, which can be used to quantitively describe permeability when cementitious materials undergoing pore structure degradation induced by durability issues.

Stress-dependent water retention behaviour of two intact aeolian soils with multi-modal pore size distributions

The water retention curve (WRC) of unsaturated soils plays a significant role in evaluating rainfall-induced geohazards in geological and geotechnical engineering, such as ground subsidence and slope failure. Stress can affect WRC because loading/unloading alters not only density but also pore size distribution (PSD). Previous studies of stress-dependent WRC focused on soils with mono- and bi-modal PSDs only. In this study, the WRCs of intact paleosol and intact loess with quadri- and tri-modal PSDs were measured using suction- and stress-controlled pressure plate tests. The full-range PSDs of tested specimens were determined by combining X-ray computed tomography (CT) and mercury intrusion porosimetry (MIP). Experimental results show that the multi-modal PSDs and hence WRCs of both soils are strongly affected by stress in a similar approach. For instance, the relationship between degree of hysteresis and suction showed a double-humped pattern, in which the Peak-I and Peak-II were identified at the relatively low (0.1–20 kPa) and high (20–400 kPa) suctions, respectively. The application of stress resulted in a decrease of hysteresis in the Peak-I (about 30%) but an increase in the Peak-II (about 31%). The increase of hysteresis in the Peak-II differs from the behaviour of soils with mono- and bi-modal PSDs, mainly because the reduction of mega- and macro-pore diameters upon loading increases pore non-uniformity in the range corresponding to the Peak-II.

Construction of 2D metal-organic precursor networks with tunable porosity: A Monte Carlo simulation approach

Two-dimensional network structures comprising functional organic building blocks have been recently recognized as promising platforms for various physio-chemical processes running in confined spaces. In this study, we present theoretical results of the self-assembly of metal-organic precursor networks on a crystalline surface and provide quantitative characteristics of these planar architectures. To that end, a coarse-grained model of the adsorbed overlayer comprising halogenated polyaromatic aromatic hydrocarbon (PAH) molecules and bivalent metal atoms was used in combination with the equilibrium Monte Carlo (MC) simulation method. Our calculations focused on the effect of molecular features, such as size, shape and distribution of halogen substituents in the PAH monomer, on the quality and morphology of the networks formed on a model (111) crystalline surface. For the simulated porous assemblies, representing the precursor stage of the surface-assisted Ullmann coupling reaction, such descriptors as the unit cell parameters, radial distribution functions, pore size distributions and structure factors were determined. The obtained results demonstrated that fine-tuning of the monomeric PAH units enables the creation of periodic and aperiodic networks having diverse porous properties, ranging from monoporous to heteroporous with bi- and multimodal pore-size distributions. The findings of our theoretical investigations, apart from the potential application in the optimization of 2D polymeric networks, can also be helpful in designing real confined nanoenvironments for selective capture and immobilization/transformation of guest species.

Hard carbon microspheres with bimodal size distribution and hierarchical porosity via hydrothermal carbonization of trehalose.

Hydrothermal carbonization (HTC) is an efficient thermochemical method for the conversion of organic feedstock to carbonaceous solids. HTC of different saccharides is known to produce microspheres (MS) with mostly Gaussian size distribution, which are utilized as functional materials in various applications, both as pristine MS and as a precursor for hard carbon MS. Although the average size of the MS can be influenced by adjusting the process parameters, there is no reliable mechanism to affect their size distribution. Our results demonstrate that HTC of trehalose, in contrast to other saccharides, results in a distinctly bimodal sphere diameter distribution consisting of small spheres with diameters of (2.1 ± 0.2) μm and of large spheres with diameters of (10.4 ± 2.6) μm. Remarkably, after pyrolytic post-carbonization at 1000 °C the MS develop a multimodal pore size distribution with abundant macropores > 100 nm, mesopores > 10 nm and micropores < 2 nm, which were examined by small-angle X-ray scattering and visualized by charge-compensated helium ion microscopy. The bimodal size distribution and hierarchical porosity provide an extraordinary set of properties and potential variables for the tailored synthesis of hierarchical porous carbons, making trehalose-derived hard carbon MS a highly promising material for applications in catalysis, filtration, and energy storage devices.

Determination of intrinsic kinetic of corncob char gasification with CO2 and steam using multipore diffusion model

Abstract The intrinsic heterogeneous reactivity of biochar in CO2 and steam gasification plays an important role in thermochemical reactor design, adjusting operating conditions, and predicting the quality of biomass gasification products, especially when the combined valorization of syngas and biochar with important textural properties is required. In the present work, the intrinsic heterogeneous kinetics of CO2 and steam gasification of corn biochar is estimated by fitting a multimodal pore size distribution (PSD) with random capillary model evolution with respect to the experimental results by thermogravimetric analysis (TGA). As novelty the independence of the initial biochar textural properties was considered, using two samples with different initial pore size distributions (PSDs): A1 sample with an initial surface area of 54.09 m2/g and A2 sample with 22.14 m2/g. The experimental intraparticle gradient effect is considered by using samples with a particle size of 149 µm conventionally larger than those reported to guarantee chemical kinetic control at 60 µm. The apparent kinetics obtained by TGA revealed a difference of 70 kJ/mol for CO2 gasification and 30 kJ/mol for steam gasification in contrast to initial PSD change. The average activation energies and pre-exponential factor obtained by parametric fitting of the model with respect to the evolution of the conversion for CO2 gasification were E = 210.2 kJ/mol and A0 = 1.13*106 g/m2s, while steam revealed E = 136.64 kJ/mol and 7.1*102 g/m2s. Furthermore, the model reduced the activation energy differences with respect to different PSDs by 5 kJ/mol for CO2 and 18 kJ/mol for steam biochar gasification.

Simultaneous Assessment of Wettability and Water Saturation Through Integration of 2D NMR and Electrical Resistivity Measurements

Summary Nuclear magnetic resonance (NMR) transverse relaxation (T2) measurements are sensitive to fluid saturations and wettability of the rocks. However, quantifying wettability index solely from NMR T2 models relies on accurate estimates of water saturation. It has been shown that integrating resistivity measurements and NMR T2 distributions enables simultaneous assessment of wettability and water saturation. Nevertheless, there still exist significant uncertainties in this approach in the presence of multiple types of fluids with overlapping transverse relaxation times or multimodal pore-size distribution. Thus, the objectives of this paper are (a) to introduce a new multiphysics workflow integrating 2D NMR with resistivity measurements to simultaneously quantify wettability index and water/hydrocarbon saturation and (b) to verify the reliability of the introduced workflow with core measurements in different rock types. The workflow starts by using 2D diffusivity-transverse relaxation (D-T2) or longitudinal-transverse relaxation (T1-T2) measurements to estimate fluid saturations. We use a nonlinear inversion algorithm to fit a multimodal Gaussian distribution to the 2D NMR measurements. We then calculate water and hydrocarbon saturations using the fluid volumes estimated from the multimodal Gaussian distribution. This estimate of water/hydrocarbon saturation is an input to our new physics-based resistivity model that explicitly incorporates the influence of wettability. The inputs to the resistivity model include water saturation, resistivity index, and pore-geometry-related parameters. In the core-scale verification step, we compare the results of wettability and fluid saturations obtained from the new workflow with gravimetrically assessed water saturation and Amott index measurements on core sample. We successfully verified the reliability of the new workflow with experimental measurements. Estimated water saturation using the introduced workflow resulted in an average relative error of less than 7% compared to the gravimetrically assessed water saturations. Wettability indices obtained from the workflow were in agreement with those estimated using Amott indices. The average absolute error between the estimated wettability indices and the Amott indices was 0.27. In conclusion, results demonstrated that integration of 2D NMR and electrical resistivity measurements enables reliable and simultaneous assessment of wettability and water saturation in different rock types. The method introduced in this paper is promising for reliable and real-time wettability assessment, both in the laboratory and in-situ condition. It provides a physics-based and robust method to accurately and simultaneously estimate water/hydrocarbon saturation and wettability in hydrocarbon-bearing rocks.

Simultaneous oxidation of aromatic compounds using Sr‐doped lanthanum manganites as catalysts

Strontium-doped lanthanum manganites, La1-xSrxMnO3 (LSMO), are promising and affordable catalysts for oxidative degradation of volatile organic compounds. LSMO catalysts (x = 0, .1, .2, and .3) were prepared by the citrate-nitrate autocombustion (CNA) and coprecipitation synthesis. The phase composition was confirmed by X-ray diffraction and Rietveld refinement analysis, while the oxygen content was determined by Mohr's salt permanganate titration. Morphology and porosity of prepared catalysts was correlated to catalytic oxidation of benzene, toluene, ethylbenzene and o-xylene. It was observed that both synthesis methods yielded catalysts of similar average pore size diameter and specific surface area, but the pore size distribution differed: CNA-prepared catalysts had a multimodal pore size distribution, while the coprecipitated ones had a single maximum at 4 nm. Catalysts prepared by the CNA method have shown a higher catalytic activity in the temperature range 373–723 K, as the presence of Mn3+/Mn4+ mixed valences increased their reducibility.

A mathematical framework for multiphase poromechanics in multiple porosity media

Unconventional geomaterials often exhibit multi-modal pore size distribution. We have developed a comprehensive framework for porous media exhibiting multiple porosity scales that are saturated with one or two types of fluids using mixture theory. Both the governing equations and constitutive laws have been clearly derived and identified, respectively. The effective stress σ′ emerged from the energy balance equation is adoptable for both elastic and elastoplastic deformations, in which pore fractions and saturations play a central role. The proposed model is general in a sense that it works for both uncoupled simulation and coupled simulation. The field equations for uncoupled flow simulation are solved using the Laplace transform and numerical Laplace inversion methods. By visualizing the dimensionless results, we can gain a quantitative insight of the different stages in the depletion process of a naturally fractured reservoir. For coupled flow and geomechanics simulation, a strip load problem and a two-phase flow in a deformable 3D reservoir problem illustrate the impacts of plasticity, multiple porosity, inter-porosity exchange, and capillary pressure on the system response.

Microfluidic construction of nucleus-like architecture

In eukaryotic cells, genes are compartmentalized in nucleus, and the surface of nucleus is porous and rough. The physiological roles of these physicochemical attributes of nucleus were rarely explored. Herein we propose that the compartmentalization and rough surface of nucleus facilitate the biosynthesis process. We report a microfluidic construction of nucleus-like microgels with controllable roughness and investigate the effects of compartmentalization and roughness of microgels on biosynthesis in a cell-free protein synthesis system. Rough microgels showed higher protein yield and initial expression rate than non-compartmentalization system and smooth microgels; moreover, protein yield increased gradually with the roughness of microgels. Mechanism investigation indicated that rough microgels with higher specific surface area and multi-modal pore-size distribution compressed more genes on the surface and enabled a closer proximity of genes, improving the enzyme turnover rate for efficient biosynthesis. This work provides possible implications to understand why nucleus shows rough surface in cells.

A general analytical expression for pore size distribution based on probability theory

The pore structure of soils and rocks plays a crucial role in geotechnical, geo-environmental and geological engineering, as it dominates the hydro-mechanical behaviour, gas- and liquid-permeability as well as material transport property of soils and rocks. A large amount of pore size distribution (PSD) data of porous materials have been experimentally determined in the past decades and are currently available in the literature. However, a general expression to parameterize these PSD curves is still missing. In this study, a general multimodal PSD model is developed based on the probability theory, which is a strong tool to quantify the complex soil microstructure precisely. The parameters in the model possess a clear physical meaning. The model is validated by reproducing the PSD curves of two clays and a sand-clay mixture having a complex pore structure. The parameterized PSD curves demonstrate a strong consistency with the measurements. In addition, the model is applied to predict the PSD evolution under hydro-mechanical processes (e.g., compaction, saturation- swelling-process), the water content – soil suction – dry density relationship of Boom clay after compaction and the time-dependent PSD evolution of MX80 Bentonite. Beside soils, the proposed general multimodal PSD relationship can describe the pore structure of any other porous and granular material, as all the underlying physics is the same for all of them. The proposed model can be incorporated into the existing effective stress parameter formulation, permeability models and constitutive models of unsaturated multimodal soils.

Carbon cryogel preparation and characterization

The carbon cryogels (CCs) show significant potential for application in a wide variety of applications, from absorbents and catalysts to supercapacitors and fuel cells, due to their high specific surface area, multimodal pore-size distribution, electrical conductivity, and thermo-mechanical stability. In the present study, the CC material was prepared by a sol-gel process from resorcinol with formaldehyde and heat treatment in an inert atmosphere. The Brunauer Emmett Teller (BET) measurements, X-ray diffraction (XRD), Raman spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), differential thermal analysis with thermogravimetric measurements (DTA-TG), scanning electron microscopy (SEM), and small-angle X-ray scattering (SAXS) analysis, as complementary techniques, were used to characterize the obtained CC. It was found that the obtained CC is a porous amorphous material with high open porosity (≈82.5%) and complex porous structure organization. Using the small-angle neutron scattering (SANS) with the contrast variation technique and the adsorption of deuterated water by carbon cryogel it was possible to separately study the structure of open and closed pores, as well as to estimate both the volume fraction of closed pores (φclose pore ≈ 1%) and the total porosity (φtotal ≈ 83.5%) of the obtained CC.

Adsorption of nickel from aqueous solutions by natural and acid-activated nano-structured bentonite

Heavy metals, such as nickel, due to their toxicity and stability, are harmful to human health. Natural bentonite and its acid-activated forms have been employed as adsorbents for the adsorption of Ni2+ ions from wastewater. In this process, natural bentonite was first activated with sulfuric acid so that its adsorption properties, such as specific surface area, cation exchange capacity, and adsorption capacity could be increased. The samples were then characterized through XRD, XRF, FTIR, and BET Analyses. The adsorption of Ni2+ was studied by pH, reaction temperature, and shaking rate experiments. BET studies showed that the activated samples had multimodal pore size distributions in micro and mesopores and the average pore diameters were around 4 nm. The XRD patterns of the acid-activated samples showed the intensity of Opal-A peaks was not significantly affected but the peaks corresponding to the calcite mineral decreased and even disappeared after the acid-activation. The result of the pH effect on the adsorption showed the low nickel adsorption in the acidic region due to the high amount of H3O+. The results showed that the concentration of acid and time were very important factors in acid activation and the uptake of Ni2+ could be successful through acid activation.

Non-Solvent Induced Phase Separation: A Versatile Synthetic Method for High Performance Redox Flow Battery Electrodes

Carbonaceous porous electrodes are ubiquitous to advanced electrochemical systems where they are responsible for multiple critical functions in the cell related to thermodynamics, kinetics, and transport, including providing surfaces for electrochemical reactions, conducting electrons and heat, and distributing fluids. Thus, their design governs the performance, durability, and consequently, the cost of these systems. However, there is limited knowledge about how to deterministically design these electrode materials which forces the repurposing of materials that have not been tailored for the specific application (e.g. the use of polymer electrolyte fuel cell gas diffusion layer as redox flow battery porous electrode1,2). Our current arsenal of materials is limited to fibrous electrodes which are manufactured using various mechanical methods (e.g. paper making, weaving, hydro-entangling) resulting in idiosyncratic structures such as papers, cloths, and felts. These fabrication methods involve multiple complex subprocessing steps impacting the final manufacturing cost and offering limited versatility to control the electrode microstructure and surface composition, which ultimately limits the performance of the electrochemical cell. Thus, there is a need to develop novel material sets with precise control over microstructure and composition while employing synthetic methods that are compatible with large scale manufacturing. In this work, we focus our efforts on designing tailored electrodes for redox flow batteries (RFBs), which are promising for grid-scale energy storage3 if their costs can be significantly reduced4.Here, we introduce the non-solvent induced phase separation (NIPS) as a simple and versatile fabrication method for carbonaceous porous electrodes for redox flow batteries5. Drawing inspiration from membrane technology, the NIPS method has been leveraged to synthesize morphologically-diverse microstructures (e.g., isoporous, macrovoids, porosity gradient) which are appealing to electrode manufacturing6. A polymer solution, containing polyacrylonitrile (PAN, carbon-containing) and polyvinylpyrrolidone (PVP, pore-forming agent) dissolved in N,N-dimethylformamide (solvent) was casted in a mold and subsequently immersed in water (non-solvent). Finally, the polymeric scaffold is carbonized under inert conditions to form a conductive network. Easily adjustable parameters, such as solvent type, polymer concentration and temperature enable control of the final electrode microstructure. To elucidate material synthesis-property-performance relationships, we vary the polymer content, polymer ratio, and solvent type and perform microscopic, spectroscopic, and electrochemical characterization techniques over the synthetized electrodes. Microstructural characterization revealed a multimodal pore size distribution composed of fine, interconnected microvoids (pore diameter 2-15μm) coupled with through plane, finger-like macrovoid channels (throat diameter > 50 μm) forming honeycomb networks. The unique microstructure, not attainable with traditional carbon-fiber manufacturing techniques, enables large surface area at the membrane-electrode interface and fast electrolyte replenishing which reduces mass transfer resistance within the electrode. We performed flow cell tests with an aqueous iron single electrolyte which revealed a considerable reduction of the charge transfer and mass transfer overpotentials of the novel electrodes compared to the commercial baseline at the expense of a slight increase in pressure drop. In the final part, we demonstrate the use of NIPS-electrodes in a full all-vanadium RFB which results in a significant improvement in power density compared to the baseline material, which can be attributed to reductions in the charge transfer and mass transport overpotentials. Although nascent, NIPS emerges as a promising platform to engineer porous electrodes for RFBs and other convection-enhanced electrochemical systems. References Mathias, M. F., Roth, J., Fleming, J. & Lehnert, W. Diffusion media materials and characterisation. Handb. Fuel Cells 3, 517–537 (2010).Forner-Cuenca, A. & Brushett, F. R. Engineering porous electrodes for next-generation redox flow batteries: recent progress and opportunities. Curr. Opin. Electrochem. 18, (2019).Weber, A. Z., Mench, M. M., Meyers, J. P., Ross, P. N., Gostick, J. T. & Liu, Q. Redox flow batteries: A review. J. Appl. Electrochem. 41, 1137–1164 (2011).Darling, R. M., Gallagher, K. G., Kowalski, J. A., Ha, S. & Brushett, F. R. Pathways to low-cost electrochemical energy storage: a comparison of aqueous and nonaqueous flow batteries. Energy Environ. Sci. 7, 3459–3477 (2014).Wan, C. T. C., Jacquemond, R. R., Chiang, Y. M., Nijmeijer, K., Brushett, F. R. & Forner-Cuenca, A. Non-Solvent Induced Phase Separation Enables Designer Redox Flow Battery Electrodes. Adv. Mater. 2006716, (2021).Young, T. H. & Chen, L. W. Pore formation mechanism of membranes from phase inversion process. Desalination 103, 233–247 (1995).

Catalytic activity and stability of sulfonic-functionalized UiO-66 and MIL-101 materials in friedel-crafts acylation reaction

Sulfonic-containing UiO-66 and MIL-101 MOF materials, prepared by direct synthesis with a sulfonic acid-including benzene dicarboxylate (SO3H-BDC) linker, have been evaluated as acid catalysts in Friedel–Crafts acylation of anisole with acetic anhydride. The catalytic activity of these materials was compared to other conventional acidic sulfonic heterogeneous catalysts, such as commercial Nafion-SAC-13 and Amberlyst-15. The catalytic performance of MOF materials was significantly dependent on their textural properties and the availability of sulphonic acid groups. MIL-101-SO3H material displayed a remarkable anisole conversion and specific activity per sulfonic acid centre due to its open structure and multimodal pore size distribution. The inherent properties of MIL-101-SO3H material allowed a more sustainable catalyst regeneration than those used for conventional heterogeneous catalysts due to the deposition of reagents and products, in particular poly-acetylated compounds. MIL-101-SO3H proved an easy recovery and reusability in successive runs without any loss of activity. These promising results evidenced the potential of MIL-101-SO3H as an alternative catalyst for acid-catalyzed reactions.

Porous Alumina Ceramics with Multimodal Pore Size Distributions.

Pore networks with multimodal pore size distributions combining advantages from isotropic and anisotropic shaped pores of different sizes are highly attractive to optimize the physical properties of porous ceramics. Multimodal porous Al2O3 ceramics were manufactured using pyrolyzed cellulose fibers (l = 150 µm, d = 8 µm) and two types of isotropic phenolic resin spheres (d = 30 and 300 µm) as sacrificial templates. The sacrificial templates were homogeneously distributed in the Al2O3 matrix, compacted by uniaxial pressing and extracted by a burnout and sintering process up to 1700 °C in air. The amount of sacrificial templates was varied up to a volume content of 67 Vol% to form pore networks with porosities of 0–60 Vol%. The mechanical and thermal properties were measured by 4-point-bending and laser flash analysis (LFA) resulting in bending strengths of 173 MPa to 14 MPa and heat conductivities of 22.5 Wm−1K−1 to 4.6 Wm−1K−1. Based on µCT-measurements, the representative volume-of-interest (VOI) of the samples digital twin was determined for further analysis. The interconnectivity, tortuosity, permeability, the local and global stress distribution as well as strut and cell size distribution were evaluated on the digital twin’s VOI. Based on the experimental and simulation results, the samples pore network can be tailored by changing the fiber to sphere ratio and the overall sacrificial template volume. The presence pore formers significantly influenced the mechanical and thermal properties, resulting in higher strengths for samples containing fibrous templates and lower heat conductivities for samples containing spherical templates.

RETRACTED ARTICLE: Coastline geological parameters and beach motion image simulation based on particle swarm optimization

This paper uses the function of neural network-based nonlinear mapping and particle group optimization algorithm to optimize the system, and then uses the particle group optimization algorithm of inertia weight, so as to achieve the goal of optimizing the weight of neural network training. By choosing to encode the geological parameters of the coastline with mpeg-4 and obtain the relevant data, the relevant data of the beach motion image can be obtained, so that the simulation experiment can be carried out. This paper introduces the process of establishing a multi-modal pore size distribution fitting model based on probability density function, and conducts an experimental analysis on the geological parameters and pore structure of two typical shale storage layer samples in China. Finally, the multi-peak opening distribution fitting model and the pore size distribution are obtained through quantitative fitting curves, and the geological parameters of the marine continental shale that affect the pore size distribution are investigated, and the pore size distribution of the shale and the geology of the shale are investigated. In-depth parameter analysis is to explore the thermal maturity of organic matter, and the relationship between its content and mineral composition. In addition, the coastal image simulation is researched focusing on the characteristics of coastal beach recreational sports, the problems existing in the development process, and future development countermeasures. Finally, it is pointed out that the future development trend of coastal beach leisure sports, through the integration of local leisure sports-related characteristics and professional development, so as to achieve the implantation of culture in sports, and the organic combination of the two promotes the economic and ecological environment.

Activated coke preparation by physical activation of coal and biomass co-carbonized chars

Activated cokes have been prepared with a two-step process: co-carbonization of bituminous coal and poplar bark biomass in nitrogen at moderate temperatures, followed by physical activation of the char residues with CO2 and steam at higher temperatures. The microstructures, pore distributions and surface chemical characteristics of the generated chars were examined by Scanning Electron Microscopy (SEM), N2 adsorption, and Fourier Transform Infrared Spectroscopy (FTIR). This study assessed the effects of the mixing ratio of bituminous and biomass feedstocks, the carbonization temperature, as well as the type and mole fraction of activation agents on the pore structure of the produced activated cokes. It was found that char obtained by co-carbonization of coal and biomass at a ratio of 2:1, at 600 °C for 30 min, had the highest micropore surface area at 200 m2/g. Subsequent activation of this char, at 800 °C for 90 min, with 40 % CO2 and 10 % steam resulted in a threefold increase of micropore surface area (607 m2/g). Steam enhanced pore broadening and, thus, it promoted the formation of mesoporous structure, while CO2 promoted additional development of microporous structure. As a result, activated coke with extensive and multimodal pore size distribution was produced.

A simple approach for predicting soil water characteristic curve of clayey soils using pore size distribution data

The soil water characteristic curve (SWCC) of soils can be derived from the measured pore size distribution (PSD) data by applying capillary models. This method is limited for clayey soils due to the PSD changes during SWCC testing. In this study, a suction-dependent multimodal PSD model based on probability theory is developed and used to derive SWCC. The model is validated by simulating the drying branches of SWCCs of four compacted Lias Clay samples with different initial states. A good consistency between the measured and predicted SWCC is shown.