Pore Size Distribution Research Articles

Multi-method characterization of 50-year-old mass concrete from the nuclear power plant Unterweser in Germany: A forensic approach

Concrete core samples extracted from the base of the 50-year-old reactor building at the Unterweser nuclear power plant in Germany were analyzed using contemporary and complementary experimental techniques. The analysis focused on qualitative and quantitative assessments of the mineralogical composition of ingredients, mixture composition, aggregate size distribution, presence of cracks, porosity, and compressive strength. Optical microscopy revealed insignificant micro-cracking in the concrete matrix, while the presence of blast furnace slag was clearly visible. Petrographic analysis of polished and thin sections has enabled the estimation of the concrete mixture composition and the grain size characteristics of the aggregates. The aggregates consist of quartz, silt, and volcanic rock with minor amounts of fossil-bearing grains. Pore size distribution obtained from mercury intrusion porosimetry (MIP) reveals that the concrete has a relatively refined pore structure. Hydration products in the matrix, i.e., hardened paste, were analyzed using powder X-ray diffraction (p-XRD) and thermogravimetry (TGA). Furthermore, backscattered electron (BSE SEM) image analysis was conducted to quantify the original mixture composition, including cement and slag contents, and water/binder ratio. This study emphasizes strategic and practical aspects of conducting in-depth analysis on hardened concrete samples that are several decades old and may serve as a general guideline for similar inquiries in diverse concrete structures.

Extent of As(III) versus As(V) adsorption on iron (oxyhydr) oxides depends on the presence of vacancy cluster-like micropore sites: Insights into a seesaw effect

Iron (oxyhydr)oxides are ubiquitous in terrestrial environments and play a crucial role in controling the fate of arsenic in sediments and groundwater. Although there is evidence that different iron (oxyhydr)oxides have different affinities towards As(III) and As(V), it is still unclear why As(V) adsorption on some iron (oxyhydr)oxides is larger than As(III) adsorption, while it is opposite for other ones. In this study, six typical iron (oxyhydr)oxides are selected to evaluate their adsorption capacities for As(III) and As(V). The characteristics of these iron minerals such as morphology, arsenic adsorption species, and pore size distribution are carefully examined using transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), positron annihilation lifetime (PAL) spectroscopy, and X-ray absorption spectroscopy (XAS). We confirm a seesaw effect occurred in different iron minerals for As(III) and As(V) immobilization, i.e., at pH 6.0, adsorption of As(V) on hematite (0.73 μmol m−2) and magnetite (0.33 μmol m−2) is higher than for As(III) (0.61 μmol m−2 and 0.27 μmol m−2, respectively), for goethite and lepidocrocite it is almost equal, while As(III) sorption on ferrihydrite (5.77 μmol m−2) and schwertmannite (28.41 μmol m−2) showed higher sorption than As(V) (1.53 μmol m−2 and 12.99 μmol m−2, respectively). PAL analysis demonstrates that ferrihydrite and schwertmannite have a large concentration of vacancy cluster-like micropores, significantly more than goethite and lepidocrocite, followed by hematite and magnetite. The difference of adsorption of As(III) and As(V) to different iron (oxyhydr)oxides is due to differences in the abundance of vacancy cluster-like micropore sites, which are conducive for smaller size As(III) immobilization but not for larger size of As(V). The findings of this study provide novel insights into a seesaw effect for As(III) and As(V) immobilization on naturally occurring iron mineral.

D-BJH: The Intrinsic Model for Characterizing the Pore Size Distribution of Porous Materials.

A novel approach, the differential Barrett-Joyner-Halenda model (D-BJH), is proposed to address the limitations of the traditional BJH model in determining the pore size distribution (PSD). This method integrates multilayer adsorption and capillary condensation processes using advanced numerical techniques, notably, a Galerkin-based framework for solving the differential BJH equations. The D-BJH model offers a precise analytical framework, establishing itself as a benchmark in adsorption theory. It enables accurate PSD calculations and provides robust theoretical support for interpreting adsorption isotherms. Additionally, a simplified D-BJH method allows for direct point-by-point PSD calculation, reducing computational complexity and eliminating cumulative errors inherent in traditional methods like BJH, DH, CI, and VBS. The D-BJH model demonstrates that PSD is directly related to the differential function of the isotherm and pore size concerning relative pressure. Comparative analyses with BJH, DH, and NLDFT models show that D-BJH effectively explains fundamental adsorption mechanisms, such as the "spurious peak" observed in desorption branches. This work expands the applicability of the BJH model, proving that both the D-BJH model and its simplified method are accurate and comprehensive for characterizing the pore structures of microporous and mesoporous materials.

Thermoporometry measurements of human hair via differential scanning calorimetry.

Hair fibres possess an inherently porous structure, which is affected by physical and chemical agents from the environment, as well as those from cosmetic treatments. The present work aims to investigate the potential of a calorimetric method for evaluating the changes of hair porosity, in terms of pore size and size distribution. The temperature of the phase transition from solid to liquid is known to be depressed if the liquid is confined within a pore. This shift in temperature can be measured by a calorimetric method like differential scanning calorimetry, DSC. This method is termed thermoporometry and it is the tool used for investigating hair porosity in this work. Virgin and bleached hair fibres are measured by DSC and, by using the equations developed for water behaviour confined in pores of a solid, the size and size distribution of the hair pores are evaluated, and the influence of the cosmetic treatment on the pores is discussed. Thermoporometry measurements of hair produced results in good agreement with those obtained by other methods for measuring hair porosity. The analysis of the data suggests that the fibre pores are mostly of a radius of 4 nm, and that the bleaching process increases the total volume of pores through the addition of smaller pores. A prolonged bleaching process appears to reduce the amount of fine pores produced by the first short process, resulting in fewer, but larger, cavities, most likely through a process of pore-merging.

A statistical physics-based physicochemical study of L-phenylalanine adsorption on activated carbon.

In this comparative study of the adsorption of L-phenylalanine (L-Phe) on two modified low-activated carbons (ACK and ACZ) at four temperatures (293-313K), steric and energetic characteristics of adsorption were investigated. An advanced statistical physics multilayer model involving single-layer and double-layer adsorption scenarios was developed to interpret the L-Phe adsorption phenomenon. Modeling results indicate that two and three L-Phe layers were arranged depending on the tested adsorption systems. The estimated number of L-Phe molecules per leading adsorption site varied from 1.71 to 2.09 and from 1.76 to 1.86 for systems L-Phe-ACK and L-Phe-ACZ, respectively. The results show that a multimolecular adsorption mechanism might connect this amino acid molecule on ACZ and ACK surfaces in a non-parallel location. These parameters changed as follows, according to the adsorbed quantity at saturation analysis: Qasat (L-Phe-ACK) ˃ Qasat (L-Phe-ACZ). This indicates that ACK material was more efficient and valuable for L-Phe adsorption than ACZ. It was also shown that the adsorption capacity decreases as the temperature increases, proving the exothermicity of the adsorption process. This analytical substantiation is confirmed by calculating the binding energies, suggesting the occurrence of physical bonds between L-Phe amino acid molecules and ACK/ACZ binding sites and among L-Phe-L-Phe molecules. Pore size distribution was interpreted and calculated by applying the Kelvin theory to data from single adsorption isotherms. All used temperatures depicted a distribution of pores below 2nm. The docking analysis involving L-Phe and the ACZ and ACK adsorbents reveal a significant resemblance in how receptors detect ligands. Consequently, the findings from the docking process confirm that the calculated binding affinities fall within the spectrum of adsorption energy. This study analyzed the adsorption capacity of the L-Phe through a model proposed by statistical physics formalism. Molecular docking was used to determine the various types of interactions between the two activated carbons. Two aspects, including orientation of L-Phe on the site, number of molecules per site n, interaction energy, density of receptor site, and adsorption capacity, were discussed to elucidate the influence of activation on the two adsorbents.

Manufacturing of heavy tungsten alloys from nano-sized metal oxides via simultaneous reduction-sintering powder treatments

Heavy tungsten alloys are of great importance in the engineering and mining industries as well as the military and medical applications because of their stability at high temperatures, high strength and dense structures. The present study develops a novel technology for the production of heavy tungsten alloys via thermal treatment of nano-sized metal oxides based on simultaneous reduction and sintering processes. Heavy tungsten alloy (95W-3Ni-2Fe) was produced from the reduction of mixed nano-sized metal oxides precursor in H2 at 1000 o C followed by sintering at 1350–1450 o C for 30–90 min. The reduced and sintered samples were characterized by XRD to follow up the crystallinity, total porosity measurement was used to find out the densification properties, the grain structure and morphology were examined by RLM and SEM attached with EDAX. Micro-hardness tester was also used to investigate the influence of sintering conditions on the grain densification. A fundamental study on the kinetics of reduction of mixed nano-sized metal oxides precursor was performed by isothermal and non-isothermal techniques. Both results from isothermal and non-isothermal tests were used to calculate the activation energy which was correlated with macro- and micro-structures to predict the corresponding reduction mechanism. However, the influence of sintering temperature and time on the crystallinity of the produced phases, grain structure, morphology, total porosity, pore-size distribution, bulk and apparent densities, and the hardness of sintered compacts was extensively investigated. The results revealed that the presence of NiO and/or Fe2O3 in the mixed metal oxides precursor was very important to ease the reducibility of WO3 as the metallic phases of Ni and/or Fe act as a catalyst for the reduction of WO3. The rate of reduction proceeds faster in the following order: NiO > Fe2O3 > mixed oxide > WO3. In non-isothermal experiments, it was found that the heating rate has a considerable effect on the reduction of precursor, i.e., the lower the heating rate, the higher the degree of reduction. It might be reported that the use of nano-sized metal oxides particles in the fabrication of heavy tungsten alloys greatly affects the main properties of the produced alloy. With the increase in sintering time, larger sizes of dense grains were developed, and the matrix became denser as a result of sintering and re-crystallization effects. The higher the sintering time, the higher the grain densification and the less pores formed in the matrix. On the other hand, with the increase in the sintering temperature, the grain boundaries were well defined in which the grains were composed of tungsten metal and surrounded by inter-metallics. The higher the temperature, the higher the XRD peak intensities of metallic tungsten and intermetallics as a result of sintering and re-crystallization.

Determining pore size distribution in rocks using shear‐thinning fluids: Utilisation of the method in geomorphology

AbstractThe pore space characteristics of geological materials are closely related to their mechanical, transport and hydraulic properties. In geomorphology, pore size distribution (PSD) is an important characteristic in rock weathering, evaporation and other studies. In an effort to find novel methods to determine the PSD, perhaps to bypass the disadvantages of the current techniques, there has been a growing interest in the use of non‐Newtonian fluids. In this contribution, we are particularly interested in the method recently introduced by Abou Najm and Atallah (the ANA method), which exploits the way in which the flow of different shear‐thinning fluids distributes differently in the pore space to compute the functional PSD estimation. We performed a set of saturated flow experiments with aqueous xanthan gum solutions of different concentrations, using as simple as possible laboratory settings, and we implemented a modified version of the previously introduced numerical model to obtain the PSDs of four sandstone and one tuff samples. The results are compared with conventional mercury intrusion porosimetry, showing a good agreement regarding the dominant pore size and a notable similarity in the distributions. Several limitations were identified as well, such as the lack of information on relatively small pores (<5–10 μm for the samples studied) and the potential issues in obtaining a more detailed distribution. We conclude that the ANA method is promising for geomorphological evaporation and rock durability studies, particularly for coarser materials such as sandstone, but it also encounters challenges for certain applications, especially for fine‐grained rocks. It must be acknowledged that the ANA method has been tested on a limited range of materials and further investigation is required to fully explore its capabilities and limitations.

An empirical model for predicting saturation pressure of pure hydrocarbons in nanopores

Due to the confinement and strong adsorption to the pore wall in meso‑ and nano pores, fluid phase behavior in the confined media, such as the tight and shale reservoirs, can be significantly different from that in the bulk phase. A large amount of work has been done on the theoretical modeling of the phase behavior of hydrocarbons in the confined media. However, there are still inconsistencies in the theoretical models developed and validations of those models against experimental data are inadequate.In this study, we conducted a comprehensive review of experimental work on the phase behavior of hydrocarbons under confinement and analyzed various theoretical phase-behavior models. Emphasis was given to the modifications to the Peng-Robinson equation of state (PR EoS). Through the comparative analysis, we developed a modified alpha-function in PR EoS for accurate prediction of the saturation pressures of hydrocarbons in porous media. This modified alpha-function accounts for the pore size and was derived based on the regression results through minimizing the deviation between the experimentally measured and numerically calculated saturation pressure data. Meanwhile, the thermodynamic properties of propane were calculated in the bulk phase and in the nanopores. Finally, we validated the newly developed model using the experimental data in synthesized mesoporous materials and real reservoir rocks.By applying the modified PR EoS, a more accurate representation of the experimentally measured saturation pressure data in confined nanopores was achieved. This newly developed model not only enhanced the accuracy of the predictions but also provided valuable insights into the confinement effects on the phase behavior of hydrocarbons in nanopores. Notably, we observed significant changes in the properties of propane within confined nanopores, including suppressed saturation pressure and fugacity, indicating a greater tendency for the gas to remain in the liquid phase. Enthalpy of vaporization was found to increase highlighting increased difficulty in transitioning from liquid to gas phase under confinement. Additionally, the new model predicts an increased gas compressibility factor in the nanopores suggesting a close resemblance of ideal gas due to the counterbalance between the attractive and repulsive forces. To validate the model, new datasets containing saturation pressures of propane and ethane under a wide range of temperatures and pore sizes were employed. The newly developed model was further applied to the experimental data obtained in real rock samples (sandstones, limestones, and shales). Interestingly, it was observed that the phase change in these samples predominantly occurred in the smallest pores. This finding highlights the importance of considering the pore size distribution when studying the phase behavior of hydrocarbons in a capillary medium even if the rock has high permeability.This study provided a simple and easy-to-implement modification to the PR EoS for accurate prediction of the phase behavior of petroleum fluids under confinement. The newly developed model for calculating saturation pressures of hydrocarbons demonstrates improved accuracy in representing experimental data compared to the previous models, while offering a more straightforward and simplified approach.

Magnesium nitrate-tricine nanoparticles: Temperature impact to enhancing third order optical nonlinearity

Nano-hybrid promoted as materials with improved optical properties. The aim of this study was to analyze differences in optical properties at micro-scale. This research focuses on the impact of reaction temperature during the creation of magnesium nitrate-tricine nanoparticles through chemical vapor deposition. The study investigates how temperatures of 200°C and 300°C affect the particle size, crystallinity, and morphology of the nanoparticles. Optimizing these properties is essential for achieving the desired third-order NLO effect. By understanding the influence of temperature on nanoparticle characteristics, researchers can develop more effective NLO materials for future photonic devices. This study explores the chemical and structural differences between MNT 300 and MNT 400 materials using various techniques. Spectroscopic analysis reveals similarities in both materials with a shared peak at 1400 cm−1. However, MNT 400 exhibits additional peaks suggesting the presence of aromatic rings, nitro compounds, or variations in N–H bonds. Both MNT 300 and MNT 400 exhibit micro porous behaviour with a narrow pore size distribution around 14 nm to 15 nm, indicating tightly packed structures. Transmission Electron Microscopy analysis shows a wide particle size range (2 nm to 200 nm) in both materials, suggesting the presence of atomic clusters, individual molecules, and potentially agglomerated structures. FT-Raman spectroscopy reveals higher intensity peaks in MNT 400, which could be due to a higher concentration of specific bonds, a more ordered structure, or enhanced Raman scattering. This suggests greater crystallinity or molecular uniformity in MNT 400 compared to MNT 300.

Electrical conductivity model for reactive porous media under partially saturated conditions with hysteresis effects

The electrical conductivity of a porous medium is strongly controlled by the structure of the medium at the microscale as the pore configuration governs the distribution of the conductive fluid. The pore structure thus plays a key role since different geometries translate in variations of the fluid distribution, causing different behaviors measurable at the macroscale. In this study, we present a new physically-based analytical model derived under the assumption that the pore structure can be represented by a bundle of tortuous capillary tubes with periodic variations of their radius and a fractal distribution of pore sizes. By upscaling the microscale properties of the porous medium, we obtain expressions to estimate the total and relative electrical conductivity. The proposed pore geometry allows us to include the hysteresis phenomenon in the electrical conductivity estimates. The variations on these estimates caused by pore structure changes due to reactive processes are accounted by assuming a uniform dissolution of the pores. Under this hypothesis, we describe the evolution of the electrical conductivity during reactive processes. The expressions of the proposed model have been tested with published data from different soil textures, showing a satisfactory agreement with the experimental data. Hysteretic behavior and mineral dissolution are also successfully addressed. By including hysteresis and mineral dissolution/precipitation in the estimates of the electrical conductivity, this new analytical model presents an improvement as it relates those macroscopic physical phenomena to its origins at the microscale. This opens up exciting possibilities for studies involving electrical conductivity measurements to monitor water movement, and hysteretic and reactive processes in porous media.

The effect of pyrolysis heating rate on the mesoporosity of Pluronic F-127 templated carbon xerogels

This study explored the impact of pyrolysis heating rates ranging from 1 to 20 K min−1 (final temperature 500 °C) on the porosity of resorcinol-formaldehyde based carbonaceous xerogels soft-templated with Pluronic F-127. We primarily utilized thermoporometry (differential scanning calorimetry technique) and, to a lesser extent, conventional nitrogen adsorption at −196 °C to analyze the porosity of the resulting carbons. Additionally, we examined the effects of particle size and the scale of the pyrolysis experiment, comparing a laboratory furnace with a thermal analyzer. At lower heating rates, particularly in a thermal analyzer, mesopores approximately 7–8 nm in size were observed. An increase in the heating rate resulted in larger mesopores, from 7 to 17 nm, widened pore size distribution (PSD), and a rise in mesopore volume from 0.21 to 0.53 cm3g−1. Higher heating rates (> 5 K min-1) also accelerated the decomposition of the Pluronic F-127, leading to fast gas release, which subsequently caused cracking of the carbon skeleton and widening of the pores. Pyrolysis heating rate had no significant effect on the degree of graphitization in the pyrolyzed samples. Particle size showed minimal influence on porosity when xerogels were pyrolyzed at either the minimal or maximal heating rates in the thermal analyzer. However, experiments conducted in a laboratory furnace at the lowest heating rate demonstrated that imprecise temperature control and fluctuations can lead to the formation of larger mesopores.

Efficient separation of HEPES and CO2-derived fructose by nanofiltration: Optimizing pH for improved separation and proposing a potential mechanism

Utilization of an in vitro multi-enzyme catalytic system for the synthesis of fructose from carbon dioxide is a promising approach towards achieving carbon neutrality. However, the lack of effective separation methods for the buffer HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) and the product fructose within the system has hindered the industrialization of in vitro multi-enzyme catalytic synthesis systems. This study aimed to separate and recover HEPES and fructose using nanofiltration technology. We investigated the influence of various parameters, including total solution concentration, solute concentration ratio, pH, and temperature, on the nanofiltration separation performance. Experimental results revealed that increasing the pH to 9.0 significantly decreased the fructose retention rate while maintaining a nearly complete HEPES retention rate. The HEPES-fructose mixed solution was further subjected to diafiltration using a spiral-wound membrane, ultimately yielding fructose and HEPES solutions with purities of 90.22 % and 92.93 %, respectively. Combining separation test results with models such as DSPM-DE, and using characterization methods such as ATR-FTIR and pore size distribution analysis, we observed pore swelling during nanofiltration of the HEPES-fructose solution at pH 9.0. A mechanism for this pore swelling, induced by the dissociation of HEPES under the influence of pH, was proposed: Dissociated HEPES in the solution interacts with the membrane surface at the liquid-membrane interface, causing reversible swelling of the membrane pores at the membrane surface, thereby reducing the retention rate of fructose. The nanofiltration process developed in this study effectively separates HEPES and fructose, enabling resource recycling and cost reduction. Furthermore, this study provides theoretical foundations and practical guidance for the design of nanofiltration separation strategies for similar systems using HEPES as a buffer, holding significant scientific and practical value.

Design and fabrication of MnCo2O4@MnCo2S4 Core@Shell nanostructured arrays decorated over the rGO sheets for high-performance asymmetric supercapacitor

In order to create reliable and effective energy storage systems, it is crucial to choose electrode materials that exhibit high stability and energy density. In this work, MnCo2S4@MnCo2O4 core@shell nanoneedle-like nanostructures (MCS@MCO/rGO) are synthesised over a rGO sheet using an innovative and easy hydrothermal technique. Electrolyte transport and sulphur incorporation during charge-discharge reactions are both made easier by the core@shell nanostructured arrays' large active surface area. With an appropriate pore size distribution centred at 13.4 nm and a high surface area of 125.4 m2g-1, the ternary electrodes composed of MCS@MCO and rGO have a rich mesoporous structure. A specific capacitance of 1346 Fg-1 at 1 Ag-1 demonstrates the exceptional performance of the MCS@MCO/rGO ternary electrode. The MCS@MCO/rGO ternary electrodes show a remarkable cyclic stability of 88.9 % capacity retention over 10,000 cycles, according to the cycling stability studies. With an impressive power density of 1010 Wkg-1 and remarkable cycling stability (95.5 % retention of the original capacitance after 10,000 cycles), the manufactured MCS@MCO/rGO//AC ACS displays an impressive energy density of 57.5 Whkg-1. The mesoporous structure is excellent for increasing the characteristics of supercapacitor electrodes, as these astounding results can demonstrate.

Mechanism of one-step hydrothermal nitric acid treatment for producing high adsorption capacity porous materials from coal gasification fine slag

The increasing amount of coal gasification fine slag (CGFS) necessitates its resource utilization. CGFS, mainly composed of porous carbonaceous particles and partially fused spherical or agglomerated ash particles, is an inexpensive and high-quality raw material for preparing adsorbent materials. However, the challenge remains in developing a simple, low-cost, and environmentally friendly method to produce high-performance porous materials from CGFS. In this study, a one-step treatment method using 2 mol/L nitric acid under hydrothermal conditions was proposed for CGFS. The adsorbent material (CGFS-2 M) prepared under a solid–liquid ratio of 2:5 and an initial concentration of 200 mg/L methylene blue (MB) exhibited an equilibrium adsorption capacity as high as 210.20 mg/g. The excellent adsorption performance of CGFS-2 M can be attributed to several factors: acid leaching for mineral removal and pore formation, resulting in a specific surface area and total pore volume 2.2 and 1.6 times that of untreated CGFS, respectively, and an optimized mesoporous pore size distribution favorable for MB adsorption; optimal mineral removal and a well-defined carbon microcrystal structure providing more space for MB adsorption; nitric acid treatment increasing the surface oxygen content and hydrophilicity, enhancing its ability to remove MB. The synergistic effect of pore structure improvement and surface modification indicates a feasible research direction for enhancing the performance of CGFS-based adsorbent materials. These results provide theoretical support for the development of efficient CGFS-based adsorbents.

Electrical resistivity imaging of crude oil contaminant in coastal soils – A laboratory sandbox study

Characterizing the subsurface distribution of crude oil after a spill in a coastal environment is challenging due to variations in the soil and fluid properties. In situ sampling is limited in capturing the lateral and vertical migration of the crude oil within the vadose and saturated zones. This study presents a laboratory sandbox framework used to assess the effectiveness of electrical resistivity imaging for investigating the spatiotemporal distribution of crude oil in coastal sandy soils. A sandbox with dimensions L = 240 cm, W = 60 cm, and H = 60 cm was constructed using a 10 mm plexiglass and filled to a 40 cm height with 2 mm medium to fine-grained sand. At each stage of the experiment, 20 kg of sand was mixed with 1 l of water to create moist sand, after which the mixture was flushed over 12 h to remove suspended fine particles. Both saturated and unsaturated conditions were simulated by setting the water table at 10 cm and draining a fully saturated system overnight. Two liters of crude oil were spilled and monitored for 30 h. A surface array of 98 electrodes, with a unit electrode spacing of 2 cm, was installed along two transects 12 cm apart. Resistivity measurements were collected using a dipole-dipole array before, during, and after the simulated crude oil spill. The time-lapse electrical resistivity results revealed an initial gravity-induced vertical migration under both saturated and unsaturated conditions; over time, lateral migration of crude oil became apparent. In the saturated zone, there was a noticeable reduction in the percentage difference in resistivity from 700 % to 400 % after 24 h, depicting a spatial and temporal redistribution of the crude oil attributed to variation in pore geometry. This highlights the sensitivity of electrical resistivity measurements to subtle but measurable anisotropy in the distribution of soil pores. Overall, electrical resistivity proved successful in imaging the non-ideal behavior of crude oil pollutants and the associated spatial changes in the pore-size distribution of subsurface sediments.

An Engineering Porous Spherical Carbon Cathode for High-Energy Sodium-Ion Capacitor.

Sodium-ion hybrid capacitors (SICs) are emerging as promising devices that can balance energy and power output. However, the lack of a high-capacity cathode that can match the anode has limited its further application. In this work, we develop an efficient method to prepare spherical porous carbons (SPCs) with great specific surface area and narrow pore size distribution from coal-based humic acid via spray drying and a subsequent chemical activation process. Thanks to this unique porous structure, the SPC cathode has a superb capacity of 223 F g-1 at 0.05 A g-1, as well as splendid rate performance and cycling stability. SICs constructed by an SPC cathode and hard carbon anode can exhibit a high energy density of 179.8 Wh kg-1 at 155 W kg-1 and achieved 89.4% capacity retention after 10 000 cycles at 0.5 A g-1. This outcome presents a viable approach to attaining high-capacity cathodes for constructing outstanding performance hybrid capacitors.

Re-Calibrating the Mercury-Intrusion-Porosimetry-Measured Pore Size Distribution of Coals: A Novel Method for Calculating the Matrix Compression Coefficient

Accurate measurement of the pore size distribution (PSD) in coals is crucial for guiding subsequent coalbed methane (CBM) engineering practice. Currently, mercury intrusion porosimetry (MIP) measurement has been widely used as a PSD testing method due to its effectiveness and convenience. Nevertheless, it is worth noting that the elevated pressure during the MIP experiments can lead to matrix compressibility, potentially causing inaccurate estimations of PSD in coals. Therefore, correction methods are used to modify the PSD in the high-pressure segment to improve the accuracy of MIP data. This study proposed a novel method with higher accuracy and convenience for calculating the matrix compressibility coefficient compared to the traditional calculation methods. Firstly, the matrix compressibility coefficients of six coal samples were calculated by using low-temperature nitrogen adsorption (LTNA) data. Subsequently, by utilizing the mathematical correlation between Kc (the compressibility coefficient of the coal matrix) and Ro,max (the maximum vitrinite reflectance) from prior research, a novel statistical method was designed to determine the matrix compressibility coefficient of the samples. Finally, the statistical matrix compressibility coefficient determination method was used to examine the fractal characteristics of the actual PSD. The results indicate that when the pressure exceeds 24 MPa, the volume obtained from mercury intrusion exceeds the pore volume measurement. The Kc calculated using the traditional correction method is in the range of 0.876–1.184 × 10−10 m2/N, while the Kc values of our proposed statistical correction method range from 0.898 × 10−10 to 1.233 × 10−10 m2/N, with a comparison error rate of ~0.11–5.25%. The MIP data greater than 24 MPa were effectively corrected using the statistical correction method, thus reducing the mercury intrusion volume error by 91.75–96.40%. Additionally, the corrected pore fractal dimension (D2) values fall within the range of 2.792 to 2.975, which are closer to the actual values than the pore fractal dimension range of 3.186 to 3.339.

Impact of PCLNPG Nanopolymeric Additive on the Surface and Structural Properties of PPSU Ultrafiltration Membranes for Enhanced Protein Rejection

This research explored the use of a partially cross-linked graft copolymer (PCLNPG) as an innovative nanopolymer pore-forming agent to enhance polyphenylsulfone (PPSU) membranes for protein separation applications. The study systematically examined the impact of incorporating PCLNPG at varying concentrations on the morphological and surface properties of PPSU membranes. A thorough characterization of the resulting PPSU-PCLNPG membranes was performed, focusing on changes in morphology, water affinity, porosity, pore size, and pore size distribution. The experimental findings demonstrated that the use of PCLNPG led to a significantly more porous structure, as confirmed by SEM analysis, with notable increases in porosity and pore size (nearly double). Additionally, the hydrophilicity of the PPSU membrane was remarkably enhanced. Performance evaluations revealed a substantial improvement in pure water flux, with the flux nearly tripling. The BSA retention was directly correlated with the concentration of the PCLNPG pore former for a loading range of 0.25–0.75 wt.%. The incorporation of PCLNPG also reduced the membrane fouling propensity by reducing both cake layer resistance (Rc) and pore plugging resistance (Rp). These results underscore the potential of PCLNPG-PPSU membranes for wastewater reclamation and nutrient recovery applications.

New porous adsorbents based on natural polymers for treatment of motor oil contaminated wastewaters

AbstractThis study aims to develop efficient adsorptive materials for retaining used 5w40 motor oil using xanthan (XG), xanthan esterified with acrylic acid (XGAC), Lignoboost lignin (LB), and LB esterified with oleic and stearic acids. The adsorption capacities of these materials were systematically evaluated, revealing a hierarchical efficacy with XG exhibiting the highest performance (60.16 g/g), followed by XGAC/LB (59.92 g/g) and XGAC (55.79 g/g). These capacities were correlated with the materials' surface area and morphology. Additionally, accelerated weathering studies assessed the degradation process of the adsorptive materials over time, revealing that all of them undergo significant structural changes, which suggests potential pathways for environmentally friendly disposal. Kinetic studies indicated that the experimental data fit well with the pseudo‐second‐order (PSO) model. The high correlation coefficient values for the PSO model (0.9318–0.9998) confirmed its suitability for describing the kinetics of oil sorption. FTIR spectra of the used motor oil‐loaded materials confirmed the physical nature of the adsorption process, involving interactions such as hydrogen bonding, van der Waals forces, and π–π interactions. SEM analysis demonstrated that materials with larger pore sizes showed less efficient oil adsorption despite having high porosity, highlighting the importance of optimal pore size distribution for effective adsorption.

Wetting mechanism and alteration of nano-sized shale pores: Insights from contrast variation small angle neutron scattering

Wettability of tight shale is crucial for fluid flow and mass transport process in energy geosciences. However, understanding the interfacial chemistry and wetting mechanisms at sub-nano-pore scales remains a formidable challenge. In this study, the Contrast Variation technique of Small Angle Neutron Scattering (CV-SANS) is employed to investigate shale’s interfacial chemistry using reagents that possess a range of different polarities, including water, n-decane, toluene, and dimethyl methanamide. Through five different experimental strategies, we have demonstrated a successful modification of shale wettability, ranging from enhancement, weakening, to reversal. Delving into the mechanisms, we illustrated the crucial role of pre-existing liquid films in these changes, where the uniquely co-existing polar and non-polar functional groups in dimethyl methanamide acted as a conduit for interfacial chemistry adjustments. Furthermore, a solvent immersion led to matrix dilation as well as liberation of residual oil-occupied pores, resulting in altered pore size distributions, with hydrogen bonding playing a significant role in the polar groups. Interestingly, despite shale exhibiting a stronger affinity for oil over water, hydrophilic solvents induced more substantial dilation than lipophilic ones. Collectively, this work elucidates the dynamic change of interfacial chemistry via the configuration of polarity using chemical reagents, and the CV-SANS technique underscores its invaluable utilities in decoding the interfacial wettability traits in nanopore space of shale.