Pore Size Distribution Analysis Research Articles

Wood based biochar supported MnO2 nanorods for high energy asymmetric supercapacitor applications

Eco-friendly Acacia leucophloea wood sawdust based Biochar (BC) is used as a substrate material to support nanorod-like MnO2 through an easy-to-operate in-situ redox reaction between the biochar and KMnO4. The physical and chemical properties of the prepared materials are characterized by using X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) with EDAX, X-ray Photoelectron Spectroscopy (XPS), BET surface area with BJH pore size distribution and bio-logic electrochemical analyzer. The XRD result reveals the bare manganese oxide has tetragonal phase group with the space group of I4/m. FESEM image of BC and BC@MnO2 materials exhibits highly porous nature and bundle of nanorod like morphologies respectively. The XPS result reveals the chemical bonding and oxidation state of BC@MnO2 nanocomposite material. The N2 adsorption and desorption result reveals that the prepared materials BC, MnO2 and BC@MnO2 exhibit high surface area of 550, 152.3 and 613.8 m2 /g respectively. Electrochemical properties are characterized by three and two electrode set-up. The BC@MnO2 composite electrode exhibits high specific capacitance of 512 Fg−1 at 0.5 Ag−1 and cyclic stability of 93% after 10,000 cycles. The assembled ASC cell BC@MnO2//AC delivers high specific capacitance of 209 Fg−1 at 0.5Ag−1and cyclic stability of 97.1% after 10,000 cycles. Further, ASC cell exhibits huge energy density of 74.3 Whkg−1 and power density of 1996.4 Wkg−1 at 0.5 Ag−1.

Use of Stevia and inulin in combination with bovine plasma proteins as sugar substitute for the development of a sugar-free and low-fat muffins formulation.

This study analyzes the effectivity of a freeze-dried additive formulated with inulin (I), Stevia (St), and ultrafiltered bovine plasma proteins (P) as a sugar substitute on the final properties of a sugar-free and low-fat muffins formulation. The following analysis were performed: shape factor, moisture loss, lamella thickness, final volume, aeration, pore size distribution and textural analysis. The addition of the binary combination 50%(P + St + I) + 50%(Sucralose) generated a synergistic effect: increasing the shape factor, final volume and aeration, and improving the pore size distribution and moisture loss. Given the success, the concentration of (P + St + I) was adjusted. A 12.5% concentration of (P + St + I) generated a hardness decrease during the studied period and did not exhibit statistical significant differences when compared to the control sample. Therefore this study demonstrated the effectiveness of the combination of Stevia, inulin, and bovine plasma proteins as sugar substitute.

Application of A∗ algorithm for microstructure and transport properties characterization from 3D rock images

Thorough comprehension of flow behavior in underground porous media is fundamental for several applications such as oil and gas production, Underground Gas Storage, CO2 storage, and Enhanced Geothermal Systems. Macroscale petrophysical parameters, as well as hydraulic parameters, are strongly linked to the microstructure of the rock.In this paper, we present a methodology for the geometric analysis and characterization of the pore structure of 3D binary images of rocks. The geometric analysis is based on the A∗ pathfinding algorithm extended to 3D domains and on the measurement of the pore radius along the identified paths. The analysis is carried out for the main flow directions to obtain a tensorial representation of tortuosity, effective porosity, and representative pore radius, to provide permeability estimation and effective characterization of anisotropy. Moreover, the approach provides the analysis of pore size distribution and constriction.The methodology was applied to synthetic but realistic rock samples, generated through the QSGS algorithm. Two case studies, representative of an isotropic and an anisotropic porous media, are presented. Validation was carried out through comparison with FVM hydrodynamic modeling. Analysis of the results shows that the presented geometric approach can provide thorough and reliable characterization of the porous media.

Elucidation of Detailed Pore Structure of (NH4)4SiW12O40 Sponge Crystal

Abstract Pore structure of (NH4)4SiW12O40 sponge crystal was successfully elucidated by means of Ar adsorption isotherm analysis combined with molecular probe method and molecular modeling. The pores consist of spherical voids or “cages” with diameter of ca. 12 Å and these are connected by smaller “windows”. These “cages” and “windows” are clearly resolved in the pore size distribution analysis for the first time. Molecular probe method elucidated the diameter of the “windows” is larger than 8.5 Å and smaller than 10.2 Å, being consistent with molecular modeling.

Study on Adsorption Behavior of Nickel Ions Using Silica-Based Sandwich Layered Zirconium-Titanium Phosphate Prepared by Layer-by-Layer Grafting Method.

In this study, the composite of silica-based sandwich-layered zirconium-titanium phosphate was prepared by a layer-by-layer grafting method and its adsorption properties in a diluted solution of Ni ions were specifically researched by the bath experiment method. The field-emission scanning electron microscope (FESEM) results presented the smooth surface morphology of the pristine adsorbent and a rough surface morphology of the adsorbed adsorbent and the energy dispersive analysis (EDS) results ensured the presence of the original metal element (Si, O, Ti, P, Zr) and the captured nickel element on the adsorbent. The Fourier transformed infrared spectroscopy (FTIR) revealed the new band formation of -Si-Ti-O-, -Si-Ti-O-P-, and -Si-Ti-O-P-Zr-O-, which ensured the successful modification of the silica substrate by zirconium-titanium phosphate. The specific surface area and pore size distribution analysis indicated that the pore structure was changed from type-Ⅳ to H2-type and the specific surface area (BET) of the modified composite was 337.881 m2/g. In the bath experiment, the optimal pH for adsorbing Ni ions on the composite was ~8 with the equilibrium time 30 min at room temperature and the maximum sorption amount was 50.1 mg/g. The adsorption kinetics of the sorption process were corresponded to the pseudo-second-order kinetic equation and the isothermal adsorption data were fitted well to the Redlich-Peterson Model. Thermodynamic simulation results revealed the species of Ni ions and provided a reasonable pH scope for better removal of the Ni element in wastewater.

The Effect of Reclaimed Asphalt Pavement (RAP) Aggregates on the Reaction, Mechanical Properties and Microstructure of Alkali-Activated Slag

Reclaimed asphalt pavement (RAP) is a recyclable aggregate produced during the demolition of old flexible pavements and consists of natural aggregates (NA) coated with aged bitumen. The detrimental effect caused by the bitumen coating on strength and porosity has limited the use of RAP on traditional cementitious systems. This study investigates the potential use of fine RAP to substitute NA in the production of alkali-activated slag mortars (AAM). The effect of different activator dosages was assessed, i.e., either 4% or 6% Na2O (wt. slag) combined with a modulus of silica equal to 0, 0.5 and 1.0. The characterisation of 100% RAP-AAM consisted of hydration kinetics (Isothermal Calorimetry), pore size distribution (Mercury Intrusion Porosimetry), mechanical performance (Compressive and Flexural strength), and microstructure analysis (Scanning Electron Microscopy and Confocal Laser Scanning Microscopy). The results show that RAP aggregates do not compromise the reaction of the matrices; however, it causes a significant strength loss (compressive strength of RAP-mortars 54% lower than reference NA-mortar at 28 days). The higher porosity at the interface transition zone of RAP-AAM is the main responsible for the lower strength performance. Increasing silicate dosages improves alkaline activation, but it has little impact on the adhesion between aggregate and bitumen. Despite the poorer mechanical performance, 100% RAP-AAM still yields enough strength to promote this recycled material in engineering applications.

Ultra-thin and highly porous PVDF-filters prepared via phase inversion for potential medical (COVID-19) and industrial use

The COVID-19 pandemic has resulted in an increased demand for air-filtration based personal protective equipment. Existing filter masks are mostly based on melt-blow fabrics, which had production upscaling issues because of long lead-times for additional production equipment and the limited number of polymer materials that can be used. Phase inversion is a readily scalable technique for the production of porous films and is compatible with a large number of polymers. As such, the potential for phase inversion to produce comparable air-filtration masks, and filters in general, was herein investigated. Polymer solutions based on various PVDF-types, solvents and additives were prepared and cast onto a widely available industrial type of supporting fabric. From the various solvents and additives tested, only DMF and Tamisolve® NxG-based solutions with LiCl as an additive resulted in filters with suitable pore size and acceptable pore size distribution. The effects of polymer and additive concentration were investigated through SEM-based observation of the pore size and pore size distribution analysis via porometry. As expected, phase inversion proved to be a versatile tool to tune and control the pore size. Porometry-based comparison of the produced filters with a commercial surgical and FFP2-mask showed that comparable pore sizes could be easily obtained. The best membranes were tested for aerosol retention, proving them to be highly promising alternative materials for current masks and air filters in more general.

Effect of activated carbon’s pore size distribution on oxygen induced heel build-up

Thermal desorption of volatile organic compounds (VOCs) from activated carbon (AC) is negatively impacted by oxygen. Oxygen reacts with the adsorbed VOCs, resulting in heel buildup in the porous structure of AC and reducing its adsorption capacity. This study investigated the contribution of physical properties of AC (specific surface area, micropore volume, and total pore volume) to this type of heel. Three different ACs with different micro/mesopore structures were tested through cyclic adsorption/desorption of 1,2,4-trimethylbenzene (TMB) using ultra-pure nitrogen (≤5 ppmv O2) as the purge gas during thermal desorption. Each set of experiments was repeated with dry air (21% O2) to evaluate the effect of O2 on heel build-up. Pore size distribution (PSD) analysis on the adsorbents cycled in dry air suggested a correlation between the amount of heel and the microporosity of adsorbents. Differential thermogravimetric (DTG) analysis was used to distinguish between the physically adsorbed and chemically formed heel. X-ray photoelectron spectroscopy (XPS) analysis showed a noticeable increase in surface oxygen content of the ACs desorbed in air. Finally, Boehm titration confirmed the presence of different surface oxygen functional groups on these adsorbents, suggesting oxidation reactions as the main mechanism of heel build-up.

Pressurized physical activation: A simple production method for activated carbon with a highly developed pore structure

Activated carbon (AC) is produced by a physical or chemical activation process. Physical activation methods are commonly adopted in industry because of their low production costs, but the insufficiency of activating agent diffusibility into core parts of the particles and microdomains of carbon materials causes a lower activation yield and degree of pore development, compared with chemical activation methods. To increase the activating agent diffusibility and corresponding degree of pore development, we propose a novel pressurized physical activation method. Pressurization afforded remarkable increases in specific surface area and total pore volume of the prepared AC, compared with atmospheric pressure. Additionally, in AC prepared by this method, pore size distribution analysis revealed characteristic development of micropores of about 1.6 nm; such micropores did not appear in AC under conventional atmospheric physical activation. Furthermore, observations of particles and their microdomains showed that pressurization increased the activating agent diffusibility in carbon particles, but not at the microdomain level. This innovative pressurized physical activation can produce AC with highly developed pores (specific surface area >2600 m2/g) and a unique pore size distribution due to the improved activating agent diffusibility in carbon particles.

Preparation of Cysteine‐Functionalized Fe3O4 Magnetic Nanoparticles for Determination of Cu2+

AbstractCysteine‐functionalized Fe3O4 magnetic nanoparticles were synthesized by thiol‐ene click reaction and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier‐transform infrared spectroscopy (FT‐IR), X‐ray diffraction spectrometry (XRD), thermal gravimetric analysis (TGA), vibrating sample magnetometer (VSM), X‐ray photoelectron spectroscopy (XPS), specific surface area (BET) analysis and pore size distribution analysis. The obtained magnetic materials were employed as a magnetic solid phase extraction adsorbent combined with inductively coupled plasma‐atomic emission spectrometry (ICP‐AES) for determination of Cu2+. Several parameters affecting extraction efficiency, including eluent concentration, adsorption time, adsorbent amounts, and sample pH were investigated. Under the optimized conditions, the method was validated. Within the concentration range of 0.01–20 μg mL−1, The limit of detection (LOD) and the limit of quantification (LOQ) were determined to be 0.002 μg mL−1 and 0.007 μg mL−1, respectively. The adsorption percentage of Cu2+ ions remained above 87.0 % when the adsorption‐desorption data of Cu2+ ions through three cycles of the successive adsorption and desorption process. The results show that a reliable and rapid method was established for determination of Cu2+ ions.

Long-term effects of inorganic fertilizers and organic manures on the structure of a paddy soil

Inorganic fertilizers and organic manures have been widely used to maintain crop yields. Leguminous green manures are usually used in the paddy fields in southern China. But the effect of green manures or combination of green manures with other fertilizers on soil physical properties, especially soil pore structure, is unclear. Based on a 34-year field experiment, we investigated the effects of different fertilization strategies on soil structural properties of a paddy soil. Four treatments were selected: no amendment as a control (CK), inorganic fertilization of N, P and K (NPK), combined application of inorganic fertilizers and green manure (GM), and combined application of inorganic fertilizers, green manure and swine manure (GSM). Results showed that relative to the CK treatment, the NPK, GM and GSM treatments increased SOC content by 7.9 %, 17.8 % and 25.7 %, respectively (P < 0.05). The increase of SOC content led to increased aggregate water stability in the GSM treatment (P < 0.05) but not in the GM and NPK treatments (P > 0.05). Consistent with SOC, soil bulk density was reduced by 5.6 %, 7.4 % and 17.6 %, respectively, for the NPK, GM and GSM treatments (P < 0.05). Total porosity was significantly increased in all the fertilized treatments (P < 0.05). Detailed pore size distribution analysis revealed that the NPK treatment mainly increased < 25 μm pores (total porosity minus porosity of pores that are > 25 μm), while the GM and GSM treatments mainly increased > 25 μm pores. The GSM treatment also significantly increased the connectivity and fractal dimension of macropores (P < 0.05). The penetration resistance of the paddy soil was not affected by the different fertilization strategies, with a low (< 0.4 MPa) value at the plough layer (0−15 cm) and a high value (up to 1.6 MPa) at the plough pan (15−25 cm). Overall, this study indicated that inorganic fertilizers had beneficial, but limited effects on paddy soil structure. Green manure and swine manure can further improve soil pore structure and soil aggregation.

Facile synthesis of spray pyrolysis-derived CuCl/γ-Al2O3 microspheres and their properties for CO adsorption and CO/CO2 separation

In this study, we developed a facile and scalable preparation method of [email protected]γ-Al2O3 composite microspheres for CO storage and separation by combining sol-gel and spray pyrolysis methods, followed by metal salt impregnation. γ-Al2O3 microspheres were first prepared by spray pyrolysis of a mixture containing various ratios of boehmite sol and citric acid (CA). Pore-size distribution analyses indicated that the mesopores that are generated inside of the γ-Al2O3 microspheres and their pore volumes could be fine-tuned by adjusting the CA/boehmite ratio. Importantly, the newly formed pore structures have been identified to accelerate the thermal dispersion of CuCl species into the γ-Al2O3 matrix, resulting in improved CO sorption. Gas-adsorption experiments showed that CO-adsorption capacity and CO/CO2 selectivity were strongly affected by the CA/boehmite ratio, CuCl-dispersion temperature, and CuCl-loading amount. The optimized adsorbent exhibited a maximum CO-adsorption capacity of 1.69 mmol g−1 and CO/CO2 selectivity of 84 (at 25 °C and 100 kPa), exceeding the benchmarks for CO-selective adsorbents. Moreover, the spherical [email protected]γ-Al2O3 adsorbent showed good regenerative ability after a number of adsorption–desorption cycles. This study provided facile and scalable synthesis method for low-cost CO-selective material with high CO performance.

Multiscale Smoothed Particle Hydrodynamics Model Development for Simulating Preferential Flow Dynamics in Fractured Porous Media

AbstractWe present our new multiscale pairwise‐force smoothed particle hydrodynamics (PF‐SPH) model for the characterization of flow in fractured porous media. The fully coupled multiscale PF‐SPH model is able to simulate flow dynamics in a porous and permeable matrix and in adjacent fractures. Porous medium flow is governed by the volume‐effective Richards equation, while the flow in fractures is governed by the Navier‐Stokes equation. Flow from a fracture to the porous matrix is modeled by an efficient particle removal algorithm and a virtual water redistribution formulation to enforce mass and momentum conservation. The model is validated by (1) comparison to a finite‐element model (FEM) COMSOL for Richards‐based flow dynamics in a partially saturated medium and (2) laboratory experiments to cover more complex cases of free‐surface flow dynamics and imbibition into the porous matrix. For the laboratory experiments, Seeberger sandstone is used because of its well‐known homogeneous pore space properties. The saturated hydraulic conductivity of the permeable matrix is estimated from a pore size and grain size distribution analysis. The developed PF‐SPH model shows good correlation with the COMSOL model and all types of laboratory experiments. We employ the proposed model to study preferential flow dynamics for different infiltration rates. Here, flow in the fracture is associated with the term “preferential flow,” providing rapid water transmission, while flow within the adjacent porous matrix enables only slow and diffuse water transmission. Depending on the infiltration rate and water inlet location, two cases can be distinguished: (1) immediate preferential/fracture flow or (2) delayed preferential flow. In the latter case, water accumulates at the surface first (ponding), then the fracture rapidly transmits water to the bottom system outlet. For the immediate fracture flow response, ponding only occurs once the fracture is fully saturated with water. In all cases, preferential flow is much more rapid than diffuse flow even under saturated porous medium conditions. Furthermore, infiltration dynamics in rough fractures adjacent to an impermeable or permeable matrix for different infiltration rates are studied as well. The simulation results show a significant lag in arrival times for small infiltration rates when a permeable porous matrix is employed, rather than an impermeable one. For higher infiltration rates, water rapidly flows through the fracture to the system outlet without any significant delay in arrival times even in the presence of the permeable matrix. The analysis of the amount of water stored in permeable fracture walls and in a fracture void space shows that for small infiltration rates, most of the injected water is retarded within the porous matrix. Flow velocity is higher for large infiltration rates, such that most of the water flows rapidly to the bottom of the fracture with very little influence of matrix imbibition processes.

Analysis of the effect of particle-wall collision process in DPF on the spatial structure of smoke cake layer.

Based on the rebound model of particle-wall collision, the influence of adhesion force on the deposition process of particles on the smoke cake wall was studied by using atomic force microscopy (AFM) and automatic specific surface area (BET) and pore size distribution analyzer. The interaction between the deposition process and the spatial structure of smoke cake was analyzed. The results show that with the increase of diesel engine speed, Young's modulus of particles decreases and the average particle size increases; the kinetic energy of particles impacting on the surface of smoke cake layer in diesel particle filter (DPF) increases; when the velocity of particles with the same particle size entering the wall increases, the maximum compression distance between particles and the surface of the smoke cake layer increases; and the adhesion force and adhesion energy increase. With the increase of diesel engine speed, the box counting dimension of smoke cake layer in DPF increases from 1.9478 to 1.996, the characteristic radius of pores decreases from 15.32 nm to 7.53 nm, the average pore diameter decreases, and the average pore volume increases. When the fractal dimension increases from 2.633 to 2.732, the deformation degree of particles increases, the smoke cake layer becomes more compact and dense, the internal structure of pores becomes more complex, the surface of pores is rougher, and particle adhesion requires overcoming larger adhesion barriers when particles adhere.

Magnetic sorbents based on hypercrosslinked copolymers of styrene and divinylbenzene with immobilized iron oxides

Magnetic sorbents were obtained by the immobilization of iron oxides into the pores of hypercrosslinked polystyrene sorbents via chemical precipitation. Various types of industrial Macronet and Amberlite adsorbents and the synthesized hypercrosslinked styrene-divinylbenzene copolymer were used as a porous polymer matrix. The volume fraction of the inorganic phase in the composites was 2.2–8.3 vol%. According to X-ray phase analysis and transmission electron microscopy, the inorganic phase in the sorbents was magnetite and the size of magnetite nanocrystallites was 3–16 nm. The structural studies of the composite sorbents by scanning electron microscopy/energy-dispersive X-ray spectrometry demonstrated a uniform distribution of nanodispersed iron oxides over the volume of sorbent granules. Investigation of the porous structure of magnetic sorbents by the low-temperature nitrogen sorption showed that the composites have a well-developed system of pores with a specific pore area of up to 1400 m2 g−1 and the volume of micropores (<3 nm) up to 0.6 cm3 g−1. The sorbent porosity parameters were calculated using methods based on the capillary condensation theory and the quenched solid density functional theory. Analysis of pore size distributions revealed that several specific pore “fractions” are present in the porous system of the magnetic sorbents. Micropores up to 2.5 nm in size were characteristic of all the studied sorbents; for some sorbent types, two to three additional “fractions” of mesopores up to 10 nm in size and macropores with sizes above 50 nm were detected. In the magnetic sorbents, the total pore volume was 0.4–1.0 cm3 g−1 and the mesopore volume was 0.2–0.6 cm3 g−1. It was found that the magnetic sorbents can adsorb toxic organic compounds of various classes: alcohols, ethers, and aliphatic, aromatic, and chlorine-containing hydrocarbons (from 0.4 to 1.0 mL cm−3). The obtained composite sorbents show promise for the purification of liquid, gaseous, and solid media by the magnetic separation method.

How the Solid/Liquid Ratio Affects the Cation Exchange Process and Porosity in the Case of Dioctahedral Smectite: Structural Analysis?

The performance of a clay mineral geomembrane used in the context of a geological barrier for industrial and radioactive waste confinement must pass through the understanding of its hydrous response as well as the limits of the cation exchange process which are closely related to the solid/liquid ratio constraint. The Na-rich montmorillonite is used, as starting material, to evaluate the link between the applied external constraint (variable solid/liquid ratio) and the structural response of the material. The geochemical constraint is realized at the laboratory scale, and the possible effects are investigated in the cases of Ba2+ and Ni2+ heavy metal cations. The structural analysis is achieved using the XRD profile modeling approach to quantify the interlayer space (IS) deformation. The quantitative XRD analysis, which consists of the comparison of experimental 001 reflections with the calculated ones deduced from structural models, allowed us to determine the optimal structural parameters describing IS configuration along the [Formula: see text] axis. The obtained result showed an interstratified hydration character, for both studied exchangeable cations, regardless of the solid/liquid ratio being described probably by a partial cation exchange process. The theoretical mixed layer structure (MLS) suggests the coexistence of more one cristallite species saturated by more than one exchangeable cations, indicating a partial saturation of all exchangeable sites. The optimum structural parameter values, from the theoretical model, allowed us to follow the evolution of several intrinsic properties versus the applied constraint strength. The variable solid/liquid ratio effect on the material porosity is examined by the BET-specific surface area and BJH pore size distribution (PSD) analyses. The adsorption measurement outcomes confirm XRD results concerning mainly the link between several intrinsic clay properties and the constraint strength.

Membrane distillation process application using a novel ceramic membrane for Brackish water desalination

Membrane distillation (MD) is a useful technology for water desalination possible at low temperatures using inexpensive membranes offering high salt rejection. Therefore, in the present study, economically and eco-friendly Saudi red clay, tetraethyl orthosilicate, ammonia, and sodium alginate powder as a binder were used to fabricate a ceramic membrane for membrane distillation using an extrusion technique. The prepared membrane was tested using a vacuum membrane distillation (VMD) process and showed promising permeate flux and salt rejection results. The membrane was characterised by SEM, mechanical testing, contact angle, pore size distribution analysis, and VMD tests were performed using deionized water, magnesium sulphate solution, sodium chloride solutions, and hot raw well water. An average flux of 13.10 kg/(m2·h) with 98.96% rejection was obtained using raw well water. During continuous well water desalination tests, the membrane exhibited a stable performance for 4 h. The average flux decreased by 16.5% after 10 h, possibly owing to fouling because of salts and suspended solids. The membrane performance was recovered after the salt water tests by applying a known cleaning procedure.

Pore size distribution of high volatile bituminous coal of the southern Junggar Basin: a full-scale characterization applying multiple methods

Studying on the pore size distribution of coal is vital for determining reasonable coalbed methane development strategies. The coalbed methane project is in progress in the southern Junggar Basin of northwestern China, where high volatile bituminous coal is reserved. In this study, with the purpose of accurately characterizing the full-scale pore size distribution of the high volatile bituminous coal of the southern Junggar Basin, two grouped coal samples were applied for mercury intrusion porosimetry, low-temperature nitrogen adsorption, low-field nuclear magnetic resonance, rate-controlled mercury penetration, scanning electron microscopy, and nano-CT measurements. A comprehensive pore size distribution was proposed by combining the corrected mercury intrusion porosimetry data and low-temperature nitrogen adsorption data. The relationship between transverse relaxation time (T2, ms) and the pore diameter was determined by comparing the T2 spectrum with the comprehensive pore size distribution. The macro-pore and throat size distributions derived from nano-CT and rate-controlled mercury penetration were distinguishingly analyzed. The results showed that: 1) comprehensive pore size distribution analysis can be regarded as an accurate method to characterize the pore size distribution of high volatile bituminous coal; 2) for the high volatile bituminous coal of the southern Junggar Basin, the meso-pore volume was the greatest, followed by the transition pore volume or macro-pore volume, and the micro-pore volume was the lowest; 3) the relationship between T2 and the pore diameter varied for different samples, even for samples with close maturities; 4) the throat size distribution derived from nano-CT was close to that derived from rate-controlled mercury penetration, while the macro-pore size distributions derived from those two methods were very different. This work can deepen the knowledge of the pore size distribution characterization techniques of coal and provide new insight for accurate pore size distribution characterization of high volatile bituminous coal.

Potential Applications in Relation to the Various Physicochemical Characteristics of Al-Hasa Oasis Clays in Saudi Arabia

In this work, various physicochemical characteristics, e.g., surface properties and mineralogical compositions, of five clays collected from different sites in the Al-Hasa oasis in Saudi Arabia have been investigated. Analysis of the mineralogical compositions of the clays in the study by X-ray diffraction indicated the coexistence of palygorskite, montmorillonite, illite, kaolinite, chlorite, calcite and quartz in different percentages. Thermogravimetric analysis indicated that all studied clays exhibited dehydroxylation temperatures higher than 470 °C. On the other hand, pore size distribution analysis of clays from N2 adsorption indicated the presence of micro- and narrow mesopores (of 1.3–2.8 nm). Furthermore, the capability of the different clays for removal of Pb (II) from aqueous solution has been studied. The adsorption process was described through the Langmuir, Freundlich, Temkin and Dubinin–Radushkevich models. The Langmuir model was the most suitable compared to the other models in the case of palygorskite- and montmorillonite-rich clays. However, the Temkin model better represented the adsorption process of Pb (II) on calcite-rich clay. The clay sample with 61.0 wt% of palygorskite was found to be the most effective at removing Pb (II), with a maximum removal capacity of 74.07 mg/g at pH 6, with a contact time of 6 h and at 25 °C. Generally, the adsorption mechanism of lead over all the studied clays followed the pseudo-second-order kinetics. On the other hand, the catalytic activity of clays in the study has been tested in methanol conversion. The acidic clays, those containing high amounts of montmorillonite, showed higher selectivity to ethylene, viz., 78.9%, with a methanol conversion of 39.1% at 350 ° C and 0.1 MPa.

Thermodynamics of liquids in capillary medium

Abstract