Mercury Porosimetry Research Articles

A rapid hydrophilization of porous poly(tetrafluoroethylene) film via co-deposition of phenol derivatives and polyethyleneimine

A series of hydrophilized porous polytetrafluoroethylene (PTFE) membranes were prepared by a mussel-inspired coating method. Various types of phenol derivatives possessing different number of hydroxide groups at different position such as hydroquinone, pyrogallol, hydroxyhydroquinone were applied along with polyethyleneimine (PEI) to seek for the fast and stable surface modification. The co-deposition kinetics of phenol/PEI pair on the porous PTFE membranes was examined using the ultraviolet spectroscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. Surface morphology and pore diameter were analyzed by the field emission scanning electron microscopy and mercury porosimetry. To confirm the complete surface hydrophilicity, water contact angle was measured as a function of time for different co-deposition pairs. Among several phenol derivatives paired with PEI, hydroxyhydroquinone showed the fastest deposition rate (in about 40 min) for excellent hydrophilicity and stability. The chemical modification method applied in this study showed the long-term stability in commonly used and harsh solvents including acidic and basic solutions compared to the other physical and chemical methods previously reported.

Fabrication and properties of novel porous ceramic membrane supports from the (Sig) diatomite and alumina mixtures

In this paper, the manufacturing of macro-porous tubular ceramic supports for membranes is described. The novel supports are fabricated from natural diatomite and alumina raw materials using the extrusion method. The structure was analyzed by X-ray diffraction (XRD) and mercury porosimetry techniques; the presence of possible defects was investigated by scanning electron microscopy (SEM). The permeability has been measured from water flux in standard experiments. Experimental results show that the open porosity, the average pore size (APS), the pore size distribution, the strength, and the permeability of sintered supports, have been found to depend, mainly on the concentration of alumina (Al2O3) additive. Supports prepared with the addition of 10wt.% of alumina and sintered at 1200°C, can be considered as the most optimized; they have a porosity ratio of about 46%, an APS is around 7.7μm, a flexural strength value of about 28MPa, and water permeability of around 15m3h−1m−2bar−1. Such materials could be of great interest in the supports fabrication for membrane application, for instance, water filtration.

Manufacturing of Low-Carbon Binders Using Waste Glass and Dredged Sediments: Formulation and Performance Assessment at Laboratory Scale

Few studies focus on the co-valorization of river dredging sediments (DS) and residual waste glass (RWG) in alkali-activated binders. This study investigates the use of DS as an aluminosilicate source by substituting a natural resource (metakaolin (MK)), while using RWG as an activator (sodium silicate source). Suitable treatments are selected to increase the potential reactivity of each residue. The DS is thermally treated at 750 °C to promote limestone and aluminosilicate clays’ activation. The RWG (amorphous, rich in silicon, and containing sodium) is used as an alkaline activator after treatment in 10 M NaOH. Structural monitoring using nuclear magnetic resonance (29NMR and 27NMR), X-ray diffraction, and leaching is conducted to achieve processing optimization. In the second stage, mortars were prepared and characterized by determining compressive strength, water absorption, mercury porosimetry and Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS). Results obtained show the great advantage of combining RWG and DS in an alkali-activation binder. The treated RWG offers advantages when used as sodium silicate activating solution, while the substitution of MK by calcined sediments (DS-750 °C) at 10%, 20%, and 30% leads to improvements in the properties of the matrix such as an increase in compressive strength and a refinement and reduction of the pore size within the matrix.

Synthetic nanostructured wollastonite: Composition, structure and “in vitro” biocompatibility investigation

This article describes an original sol-gel (template) method for the synthesis of a dispersed form of nanostructured wollastonite (CaSiO3), its gold nanoparticles (40–60 nm) functionalized form CaSiO3/Au-NPs, and its composite in the composition with 20 mass% of hydroxyapatite CaSiO3/HAp and synthetic hydroxyapatite, that are widely used in medicine for the reconstruction and regeneration of bone defects. The method provides the formation of porous silica carcass in samples with an average pore size of 100–160 nm due to the application of polymer siloxane-acrylate as a pore-forming template. The authors studied the processes of template destruction and phase formation in the composition of samples using TGA/DTA/DSC (thermogravimetric analysis/differential thermal analysis/differential scanning calorimetry), and XRD (X-ray diffraction analysis). The methods of SEM (scanning electron microscopy), low-temperature nitrogen adsorption, and mercury porosimetry were used to identify the morphology and study the structural characteristics (Sspec and Vpor, pore size distribution) for dispersed nanostructured samples based on wollastonite and hydroxyapatite. An “in vitro” model was used to study the functional activity (metabolism and cytokine production) of innate immune cells (neutrophils and macrophages) in contact with the obtained samples and to evaluate the viability of cells, the activity of ATPase activity, the number of cationic proteins, and apoptosis of cells. The study is novel for these systems and contributes to the existing knowledge on the biocompatibility for “in vivo” model, which provides a complex evaluation of the quality of wollastonite biomaterials used as grafts.

Hardening Slurries with Fluidized-Bed Combustion By-Products and Their Potential Significance in Terms of Circular Economy.

Hardening slurries (water-bentonite-binder mixtures) constitute a well-established material used broadly, i.a., for cut-off walls in civil and water engineering. Although they usually contain Portland cement, similar to common concrete, their properties differ greatly, mostly due to a much higher water content. This characteristic of hardening slurries creates unique opportunities for the utilization of significant quantities of industrial by-products that are deemed problematic in the concrete industry. This article investigates the effect of the addition of by-products of fluidized-bed combustion of hard, brown coal and municipal sewage sludge, as well as ground granulated blast furnace slag, on the properties of slurries. Unconfined compressive strength tests, as well as mercury porosimetry, scanning electron microscopy, and X-ray diffraction analyses were performed. The results suggest that it is possible to design hardening slurry mixes of desired properties, both in liquid and solid state, containing at least 100–300 kg/m3 of industrial waste. This includes cement-free slurries based entirely on industrial by-products as binders. In addition, the analyzed slurries exhibited good chemical resistance to landfill eluates, at the same time effectively immobilizing heavy metals. It was concluded that hardening slurry technology can ensure the safe deposition of significant amounts of waste that would be otherwise difficult to manage, thus contributing to the circular economy concept.

Influence of Substrate Removal Method on the Properties of Free-Standing YSZ Coatings

Thermally sprayed ceramic coatings are often tested as free-standing layers to investigate different properties such as thermal expansion coefficient, thermal conductivity, sintering, mechanical behavior, corrosion resistance, gas tightness, or electrical properties. In this paper, four different substrate removal methods were used to obtain free-standing YSZ coatings. At first, spraying on a steel substrate and subsequent dissolution of the substrate-coating interface by hydrochloric acid (HCl) was used. Second, the steel substrate was removed by applying an electrical field via electrochemical corrosion of the surface of the substrate. In a third method, the coating was sprayed on a salt (NaCI) interlayer, which was removed later by dissolution in water. At last, the coating was sprayed on a graphite substrate and the substrate was removed by heat treatment. After the preparation of free-standing coatings, these were characterized using scanning electron microscopy, mercury porosimetry, indentation tests, and room temperature three-point bending tests, which allowed the determination of Young’s modulus and viscosity. The results revealed measurable differences in coating properties as a result of the substrate removal methods, i.e., HCl method led to higher porosity and lower modulus in the YSZ coating.

Effects of ratio variation in substrate and micro porous layer penetration on polymer exchange membrane fuel cell performance

A gas diffusion layer (GDL) facilitates the diffusion of reactant gas and the discharge of the generated water. The GDL performs various functions, such as conducting heat and electrons generated by electrochemical reactions and providing mechanical support for the catalyst layer. In this study, the effects of ratio variation in the substrate and microporous layer (MPL) penetration region on the proton exchange membrane fuel cell (PEMFC) performance were investigated. Furthermore, the reasons for these performance tendencies are explained based on the thermogravimetric analysis, contact angle, scanning electron microscopy, mercury porosimetry, electrical resistance, electrochemical impedance spectroscopy, and capillary pressure gradient. The experimental results indicate that the MPL penetration ratio within 15–20% of the total GDL thickness and the combined ratio of the MPL and MPL penetration within 35–40% is the best for the overall PEMFC performance. In addition, when the substrate ratio is excessively low, water flooding substantially occurs in the substrate, and this accumulated water functions as a back pressure, causing severe capillary condensation in the MPL penetration region and thus depriving the supply of the reactant gas.

Synthesis and characterization of hexagonal BN-based aerogels for absorbing oils

Porous oil absorbents have been extensively studied in recent years. Boron nitride (BN) is an ideal inorganic material to withstand severe absorption conditions due to its excellent inertness and high-temperature resistance. A large challenge of BN aerogels is their high preparation costs due to requiring high temperatures and dangerous atmospheres. A facial synthesis of h-BN-based aerogels by the cast-freezing method is reported here, which has the advantages of producing a light and recyclable material (~0.035 g/ml) at a low cost and with low energy consumption. In this work, carboxymethylcellulose (CMC) is used as the compounder to interact with BN and form an aerogel that has controllable porosity (38–86 μm) and hydrophobicity (~140°). The porous structure, components, and reaction mechanisms are analyzed by SEM, XRD, mercury porosimetry, etc.. The pore distributions can be controlled by the concentrations of CMC and crosslinking agents. The intercalation effect on BN is carried out by CMC, which increases the specific surface area. Finally, the oil absorption performances are measured. The oil absorption capacity is up to 31.55 g/g (~97% ml/ml) because of the high specific surface area of the prepared material; additionally, the capacity of this material shows no obvious decrease after 6 cycles. Therefore, h-BN-based aerogels are expected to be applied in the oil absorption field and have the potential to be applied in the biochemical and nuclear fields.

Characterization of Nanoporous Materials.

Detailed analysis of textural properties, e.g., pore size and connectivity, of nanoporous materials is essential to identify correlations of these properties with the performance of gas storage, separation, and catalysis processes. The advances in developing nanoporous materials with uniform, tailor-made pore structures, including the introduction of hierarchical pore systems, offer huge potential for these applications. Within this context, major progress has been made in understanding the adsorption and phase behavior of confined fluids and consequently in physisorption characterization. This enables reliable pore size, volume, and network connectivity analysis using advanced, high-resolution experimental protocols coupled with advanced methods based on statistical mechanics, such as methods based on density functional theory and molecular simulation. If macro-pores are present, a combination of adsorption and mercury porosimetry can be useful. Hence, some important recent advances in understanding the mercury intrusion/extrusion mechanism are discussed. Additionally, some promising complementary techniques for characterization of porous materials immersed in a liquid phase are introduced.

Densification of A3-3 matrix graphite to inhibit the infiltration of liquid FLiBe salt in molten salt reactors

In this study, a novel graphite was prepared by adding MCMBs (mesocarbon microbeads) to densify matrix graphite A3−3, a typical fuel element and moderator material in high-temperature gas-cooled reactors. The densified graphite was evaluated as a potential fuel element material for molten salt reactors (MSRs). In particular, the effects of MCMB loading on physical properties and the corresponding effects on the infiltration of liquid fluoride salt in MSRs were studied, as molten salt infiltration can impact safe reactor operation. MCMBs with a mean particle size of approximately 3 μm were added to matrix graphite A3−3 at loading levels of 1 wt%, 5 wt%, 10 wt%, and 15 wt%, and samples were prepared by a quasi-isostatic pressing process at 250 MPa. Mercury porosimetry data showed that MCMB-densified graphite (MDGs) had lower porosity (approximately 15 vol%) and median pore diameters (ranging from 105 to 306 nm) compared to A3−3 itself (22.9 vol% porosity and 573 nm median pore diameter). Importantly, the MDGs exhibited greatly reduced infiltration by FLiBe molten salt compared to unmodified A3−3. For instance, A3−3 modified with 1 wt% MCMB exhibited a 2.1 % weight increase after treatment at 1 MPa for 20 h, while unmodified A3−3 exhibited a weight increase of 11.6 %. This study revealed that MDGs could be promising candidate materials for the graphite matrix of fuel elements as well as a neutron moderator and reflector in MSRs.

Lightweight concretes based on wheat husk and hemp hurd as bio-aggregates and modified magnesium oxysulfate binder: Microstructure and technological performances

Using lightweight building materials from ecological resources reduces the environmental impact of buildings. Most attention has been paid to lime-based agro-concretes, but low binder-aggregate compatibility as well as slow strength gain are drawbacks. The use of magnesia-based binders has the potential to mitigate these problems. Here, a modified magnesium oxysulfate (MOS) cement was used to manufacture lightweight concretes using wheat husk, a highly available and unexploited resource, and hemp hurd as bio-aggregate. A combined microstructural-technological study was performed, filling gaps in existing literature. Through microstructural observations made by X-ray Powder Diffraction, microscopy imaging (optical, electron) and mercury porosimetry, mechanical and thermal properties in the different concretes were elucidated. It will be shown that the developed lightweight concretes are technologically competitive with lime-based ones, having the advantage of possessing high early strength.

The Effect of Various Graphite Additives on Positive Active Mass Utilization of the Lead-Acid Battery

Various graphite additives were incorporated into the positive paste in a range of amounts to study and compare their effects on the positive active mass utilization of lead-acid batteries. Four types of graphite—two anisotropic, one globular, and one fibrous—were investigated by SEM, XRD, and Raman spectroscopy. Their physico-chemical properties were correlated to the electrochemical performances of 2 V test batteries under a wide range of conditions. This works presents the influence of graphite additives’ structural order, phase composition, particle size, morphology, and surface area on the formation, initial cycling, and electrochemical utilization of the positive plate. The effects of various graphite on electrochemical performance were investigated using SEM, mercury porosimetry, and TGA/DSC to correlate the function of graphite on the positive active mass utilization of the lead-acid battery.

PTFE Content in Catalyst Layers and Microporous Layers: Effect on Performance and Water Distribution in Polymer Electrolyte Membrane Fuel Cells

This work describes the effects of catalyst layers (CLs) consisting of hydrophobic PTFE on the performance and water management of PEM fuel cells. Catalyst inks with various PTFE contents were coated on Nafion membranes and characterized using contact angle measurements, SEX-EDX, and mercury porosimetry. Fuel cell tests and electrochemical impedance spectroscopy (EIS) were conducted under varying operating conditions for the prepared materials. At dry conditions, CLs with 5 wt.% PTFE were advantageous for cell performance due to improved membrane hydration, whereas under humid conditions and high air flow rates CLs with 10 wt.% PTFE improved the performance in high current density region. Higher PTFE contents (≥20 wt.%) increased the mass transport resistance due to reduced porosity of the CLs structure. Operando neutron radiography was utilized to study the effects of hydrophobicity gradients within CLs and cathode microporous layer (MPLC) on liquid water distribution. More hydrophobic CLs increased the water content in adjacent layers and improved performance, especially at dry conditions. MPLC with higher PTFE contents increased the overall liquid water within the CLs and GDLs and escalated the water transfer to the anode side. Furthermore, the role of back-diffusion transport mechanism on water distribution was identified for the investigated cells.

Comparative Evaluation of LMR-NCM and NCA Cathode Active Materials in Multilayer Lithium-Ion Pouch Cells: Part I. Production, Electrode Characterization, and Formation

A lithium- and manganese-rich layered transition metal oxide (LMR-NCM) cathode active material (CAM) is processed on a pilot production line and assembled with graphite anodes to ≈7 Ah multilayer pouch cells. Each production step is outlined in detail and compared to NCA/graphite reference cells. Using laboratory coin cell data for different CAM loadings and cathode porosities, a simple calculation tool to extrapolate and optimize the energy density of multilayer pouch cells is presented and validated. Scanning electron microscopy and mercury porosimetry measurements of the cathodes elucidate the effect of the CAM morphology on the calendering process and explain the difficulty of achieving commonly used cathode porosities with LMR-NCM cathodes. Since LMR-NCMs exhibit strong gassing during the first cycles, a modified formation procedure based on on-line electrochemical mass spectroscopy is developed that allows stable cycling of LMR-NCM in multilayer pouch cells. After formation and degassing, LMR-NCM/graphite pouch cells have a 30% higher CAM-specific capacity and a ≈5%–10% higher cell-level energy density at a rate of C/10 compared to NCA/graphite cells. Rate capability, long-term cycling, and thermal behavior of the pouch cells in comparison with laboratory coin cells are investigated in Part II of this work.

Deposition, Diagenesis, and Sequence Stratigraphy of the Pennsylvanian Morrowan and Atokan Intervals at Farnsworth Unit

Farnsworth Field Unit (FWU), a mature oilfield currently undergoing CO2-enhanced oil recovery (EOR) in the northeastern Texas panhandle, is the study area for an extensive project undertaken by the Southwest Regional Partnership on Carbon Sequestration (SWP). SWP is characterizing the field and monitoring and modeling injection and fluid flow processes with the intent of verifying storage of CO2 in a timeframe of 100–1000 years. Collection of a large set of data including logs, core, and 3D geophysical data has allowed us to build a detailed reservoir model that is well-grounded in observations from the field. This paper presents a geological description of the rocks comprising the reservoir that is a target for both oil production and CO2 storage, as well as the overlying units that make up the primary and secondary seals. Core descriptions and petrographic analyses were used to determine depositional setting, general lithofacies, and a diagenetic sequence for reservoir and caprock at FWU. The reservoir is in the Pennsylvanian-aged Morrow B sandstone, an incised valley fluvial deposit that is encased within marine shales. The Morrow B exhibits several lithofacies with distinct appearance as well as petrophysical characteristics. The lithofacies are typical of incised valley fluvial sequences and vary from a relatively coarse conglomerate base to an upper fine sandstone that grades into the overlying marine-dominated shales and mudstone/limestone cyclical sequences of the Thirteen Finger limestone. Observations ranging from field scale (seismic surveys, well logs) to microscopic (mercury porosimetry, petrographic microscopy, microprobe and isotope data) provide a rich set of data on which we have built our geological and reservoir models.

Porosity Pattern of 3D Chitosan/Bioactive Glass Tissue Engineering Scaffolds Prepared for Bone Regeneration

Aim: The study was conducted to investigate the obtained external and internal porosity and the pore-interconnectivity of specific fabricated bioactive composite tissue engineering scaffolds for bone regeneration in dental applications. Materials and Methods: In this study, the bioactive glass [M] was elaborated as a quaternary system to be incorporated into the chitosan [C] scaffold preparation on a magnetic stirrer to provide bioactivity and better strength properties for the attempted composite scaffolds [C/ M] of variable compositions. The homogenous chitosan/bioactive glass mix was poured into tailor-made cylindrical molds [10cm×10cm]; a freeze-dryer program was used for the creation of uniform and interconnected macropores for all prepared chitosan-based scaffolds. The morphology of fabricated chitosan [C] and chitosan-bioactive glass [C/ M] composite scaffolds was studied by a scanning electron microscope [SEM] and a mercury porosimeter. In addition, the in-vitro biodegradation rate of all elaborated scaffolds was reported after immersing the prepared scaffolds in a simulated body fluid [SBF] solution. Furthermore, for every prepared scaffold composition, characterization was performed for phase identification, microstructure, porosity, bioactivity, and mechanical properties using an X-ray diffraction analysis [XRD], an X-ray Fourier transfer infrared spectroscopy [FTIR], a mercury porosimetry, a scanning electron microscopy [SEM] coupled to an energy-dispersive X-ray spectrometry [EDS] and a universal testing machine, respectively. Results: All the prepared porous chitosan-based composite materials showed pore sizes suitable for osteoblasts seeding, with relatively larger pore sizes for the C scaffolds. Conclusion: The smart blending of the prepared bioactive glass [M] with the chitosan matrix offered some advantages, such as the formation of an apatite layer for cell adhesion upon the scaffold surfaces, the reasonable decrease in scaffold pore size, and the relative increase in compressive strength that were enhanced by the incorporation of [M]. Therefore, the morphology, microstructure, and mechanical behavior of the elaborated stress loaded biocomposite tissue engineering scaffolds seem highly dependent on their critical contented bioactive glass.

Processing study of gel-cast tubular porous NiO/SDC composite materials from gel-combustion synthesized nanopowder

In the present research, NiO–SDC (Samarium doped Ceria) nanopowder was synthesized through sol–gel combustion method using citric acid as a reducing agent (fuel) and metal nitrates as an oxidant. The characteristics of the synthesized powder were thoroughly analyzed by DTA/TG, XRD, BET and FESEM/EDX. Tubular gel-casted porous specimens of NiO–SDC (50:50 wt%) composite materials were produced after stabilizing suspensions of composite powder in an aqueous environment by addition of 3 wt% dispersant and 2.5 wt% agar as the gel builder. The effect of Dolapix CE64 as a dispersant, agar as a gel-builder and the amount of solid loadings on the processing and properties of porous ceramics was investigated. Viscosity measurements, zeta potentials of suspensions with and without dispersant and sedimentation measurement were used to determine the optimum dispersant concentration and solid concentration needed to prepare a stable slurry. The phase composition and microstructure of sintered samples were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Moreover, the distribution and porosity of the samples were determined through mercury porosimetry method. Results confirmed that stable NiO–SDC slurries with high solid loading (60 %) were achieved with Dolapix CE64, which also met the requirements to reach porous tubular samples with up to 60% porosity.

Porous PTFE reinforced SPEEK proton exchange membranes for enhanced mechanical, dimensional, and electrochemical stability

The pores of polytetrafluoroethylene (PTFE) film were filled with the sulfonated poly (ether ketone) (SPEEK) electrolyte molecules to prepare the proton exchange membrane with the enhanced mechanical, dimensional and electrochemical stability for fuel cell application. Catechol/polyethyleneimine was co-deposited on the PTFE pore surface as an adhesive mediator for the feasible impregnation of SPEEK. The chemical composition, morphology, and wettability of the porous PTFE film were investigated by electron spectroscopy for chemical analysis, scanning electron microscope, mercury porosimetry, and water contact angle measurements. After pore filling with SPEEK electrolytes, several essential properties of membranes (e.g. water uptake, proton conductivity, mechanical property) and wet/dry cyclic cell performance were examined. The prepared pore-filled electrolyte membranes showed the superior mechanical and dimensional stability at the reduced water uptake to the pristine SPEEK membrane. Those excellent properties of the electrolyte membranes are reflected in the stable electrochemical cell performance over the repeated wet/dry cycles with suppression of crack/void formation and edge breakdown.

Characterization of Hierarchically Ordered Porous Materials by Physisorption and Mercury Porosimetry—A Tutorial Review

AbstractThis paper is devoted to the textural characterization of nanoporous materials with a focus on hierarchically ordered materials such as mesoporous zeolites, which exhibit an interconnected pore network consisting of micro‐, meso‐, and often macropores. Hierarchically ordered zeolites have the potential to improve various industrial applications for instance in the areas of heterogeneous catalysis, separation, gas, and energy storage. Detailed insights into the pore architecture are important, because they control transport phenomena, diffusional rates, and govern selectivity, e.g. in catalyzed reactions. However, a reliable characterization of such complex pore structures is still a major challenge. Within this context, the application of advanced physisorption methodologies for micro‐mesopore analysis is discussed but also the characterization of macroporosity by mercury porosimetry is addressed. Fundamental concepts and recent major advances in understanding the underlying mechanisms are highlighted. In conjunction with selected case studies, it is illustrated how the application of advanced physisorption methodologies allows i) for the determination of reliable surface areas, pore volumes, and pore size distributions and ii) for obtaining information about pore network characteristics. This tutorial offers guidance for an advanced characterization of nanoporous materials by physisorption and mercury intrusion/extrusion.

The single freezing episode of early-age cementitious composites: Threshold properties of cement matrix ensuring the frost resistance

The freezing is recognized as one of the most dangerous phenomena jeopardizing the durability of cement-based materials. In this work, the cementitious material exposed to a single freezing event after 1, 2, 3, 7, 14, 21, and 28 days of hydration was investigated. The change of mechanical parameters, e.g. compressive strength and Young’s modulus, due to individual water crystallization was determined. Water freezing in cement paste proceeds at depressed temperature, which can be calculated using Gibbs-Thomson equation. The change of the in-pore ice content profile in temperature domain along with hydration was calculated using differential scanning calorimetry and was related with the degradation of mechanical properties. The two dominant mechanisms inducing water freezing can be recognized in cement paste: gradual ice penetration and ice nucleation. The change of microstructure along with hydration was monitored using mercury porosimetry. These observations allowed to determine the threshold properties which provide the resistance of cementitious materials to the single freezing at early age. The research was supplemented with isothermal calorimetry and XRD data of the applied binder.