Influence Of Specific Surface Area Research Articles

Enhancing chemical heat storage performance of nanocarbon porous particle based MgO/Mg(OH)2 composite by calcination method

The application of MgO/Mg(OH)2 in heat storage technology has been limited due to slow hydration rate and easy agglomeration. In this paper, nanoporous carbon particle (NCP) as a carrier was used to prepare NCP/MgO chemical heat storage composite materials by impregnation and calcination methods, respectively. The microstructure characterization, hydration reaction, and simultaneous thermogravimetric analysis experiments were carried out on the prepared composite materials. The results showed that the internal distribution of MgO in the composite material prepared by calcination method was more uniform, and the particle size of MgO was smaller. Under the conditions of 110 ℃ hydration temperature and 57.8 kPa water vapor partial pressure, the hydration conversion ratio of the composite material prepared by calcination method after 120 min of hydration conversion ratio reached 93 %, which was 17.7 % higher than that of the impregnated composite material and 50 % higher than that of pure MgO. Under the comprehensive influence of specific surface area, pore structure, and active component particle size, compared with pure materials and impregnated composite materials, the dehydration rate of the composite material prepared by calcination method at 300 ℃ was twice that of impregnated method and 6 times that of pure MgO, and the heat storage density reached 1039kJ/kg. After 10 cycles, the heat storage density still maintained an initial state of 95.8 %. Compared with pure materials and impregnated composite materials, NCP/MgO composite materials prepared by calcination method had better heat storage performance and higher cyclic stability.

Influence of Specific Surface Area of Magnetite Concentrate on Moisture and Yield of Quality Raw Pellets

Influence of Specific Surface Area of Magnetite Concentrate on Moisture and Yield of Quality Raw Pellets

ИССЛЕДОВАНИЕ АДСОРБЦИИ МОЛЕКУЛ ВОДЫ НА КАЛЬЦИЙСОДЕРЖАЩИХ МАТЕРИАЛАХ МЕТОДАМИ ФИЗИКО-ХИМИЧЕСКОГО АНАЛИЗА

Physico-chemical methods of analysis were used to study calcium-containing materials - water systems. Samples of calcium-containing materials - micromarble of RIF, Koelga, OMUA grades, as well as silicate glass - were studied. The structural characteristics of the studied materials were determined on the basis of the analysis of experimental isotherms of water vapour adsorption obtained by the isopiestic method at 298 K. It was found that the adsorption isotherms of water vapour adsorption on the studied materials have a shape intermediate between II and III type according to Brunauer's classification, which is characteristic of adsorption on non-porous and macroporous adsorbents. The analysis of adsorption isotherms showed that they are practically parallel to each other in a wide range (p/ps=0.05-0.85), in the region of high relative pressures of adsorbent a rise of adsorption isotherm for silicate glass is observed. The identical type of isotherms for micromarbles is explained by the similarity of chemical structure of samples, small differences in the values of adsorption indicate a small difference in the values of specific surface area and particle size of materials. It is shown that adsorption of water vapour on the surface of the samples occurs with the formation of complexes - clusters consisting of calcium carbonate molecules surrounded by adsorbate molecules due to the formation of hydrogen bonds between the surface oxygen and sorbed water molecules. In the framework of theoretical models, sorption and structural parameters of adsorbent and adsorbate were determined from linearised forms of Langmuir and BET equations linking sorption values and relative vapour pressures of adsorbate. NMR-relaxation parameters of sorbed water protons were measured on a spectrometer with a working frequency of 20 MHz. According to NMR data, the relationship between spin-spin and spin-lattice relaxation times and the state of adsorbed water molecules was established. The character of dependences of spin-spin (T2) and spin-lattice (T1) relaxation times of adsorbed water on the value of water sorption (W) indicates the influence of specific surface area and size of adsorbent particles on the mobility of adsorbed water molecules and confirms the mechanism of cluster formation during adsorption of water vapour on calcium-containing materials.

Tribocatalysis effect based on ZnO with various specific surface areas for dye degradation

Degradation of dyes by the tribocatalysis effect has attracted widespread interest due to its unique advantages of scalability and recyclability. Still, the influence of specific surface area on the tribocatalysis effect has not been investigated. In order to investigate the effect of specific surface area on the friction catalytic efficiency, we designed and prepared a variety of ZnO nanomaterials with different morphologies. The experimental results showed that the ZnO nanostars could efficiently degrade the organic dyes under magnetic stirring under dark conditions with a degradation rate of 95% at the 12th hour. This is due to the fact that ZnO nanostars with larger specific surface area have more active sites, which play a key role in enhancing the degradation of organic compounds. In addition, the efficiency of friction catalysis can be greatly improved by increasing the friction between the stirring rod and the vessel and by increasing the interfacial area between the stirring rod and the vessel. Degradation experiments of rhodamine, methyl orange, and methylene blue confirm excellent universality and stability of the tribocatalysis effect based on ZnO nanostars. Our research results not only provide a basis and reference for the selection of nanomaterials for the tribocatalysis effect but also propose a new path for developing novel high-efficiency wastewater treatment systems.

Biochar-activated persulfate oxidation of arsenic(III): Nonnegligible roles of environmentally persistent free radicals

The water ecosystem and public health are often threatened by Arsenic (As). The primary type of As in paddy field and ground water is As(III), which is more toxic and mobile than As(V). In this research, biochar prepared from sewage sludge (SBC) through hydrothermal technique was used to activate persulfate (PS) to oxidate As(III), making it less toxic As(V). The developed SBC/PS system could oxidate As(III) effectively in the wide pH values (2−10). Excluding the influence of specific surface area and functional groups, the concentration of environmental persistent free radicals (EPFRs) had a good linear relationship with the oxidation of As(III), reaching above 0.96. According to a mechanism analysis, EPFRs on SBC could transfer electrons to directly activate PS to produce SO4−·, ·OH, O2−·, and 1O2 to improve the oxidation of As(III). These results not only indicated that the biochar/PS system’s application scope can be successfully increased by adjusting the preparation conditions, but also revealed the invaluable role of EPFRs in As(III) oxidation process.

Gas template mediated exfoliation of polymeric graphitic carbon nitride; what contributes more to hydrogen production, a higher specific surface area, or defect sites?

Polymeric graphitic carbon nitride (g-C3N4) has emerged as a promising photocatalyst for various applications; however, the optimization of its performance remains a challenge. In this study, we investigate the influence of specific surface area and nitrogen content on the photocatalytic activity of g-C3N4. Our findings reveal that a highly nitrogen-deficient g-C3N4 demonstrates superior photocatalytic activity in the absence of a co-catalyst. Conversely, a g-C3N4 sample with a higher surface area and reduced nitrogen deficiency performs better when coupled with a co-catalyst such as platinum. We attribute these differences to the concurrent introduction of nitrogen defects and oxygen species, which modify the conduction band position and improve the separation efficiency of photogenerated charge carriers. These outcomes suggest that the optimization of specific surface area and nitrogen defects could be a promising strategy for tailoring g-C3N4 performance in photocatalytic applications. Such an approach holds significant implications for developing highly efficient photocatalytic systems.

Reactive adsorption desulfurization of FCC gasoline over self-sulfidation adsorbent

NiSO4/ZnO-Al2O3-SiO2 adsorbent, as a novel reactive adsorption desulfurization (RADS)adsorbent, has self-sulfidation ability and high desulfurization performance when treating model fuel. However, the RADS performance of the adsorbent under FCC gasoline feedstock is not well understood. Here, we compare the performance of the adsorbent under FCC gasoline with model fuel to test the effect of the hydrocarbon composition of the feedstock. The complex composition of FCC gasoline makes it sensitive to the nickel loading amount of the adsorbent. Under the influence of specific surface area and pore structure, the adsorbent loaded with 3 wt% nickel shows better desulfurization activity when treating FCC gasoline. As hydrocarbons in FCC gasoline compete with sulfur compounds for active Ni sites, the reaction conditions have been tested and optimized to achieve deep desulfurization while maintaining low olefin loss to ensure the octane number of the product. By experimental tests and characterization, it has been proved that NiSx and NiO acted as active Ni sites of the adsorbent. Based on these observations, the mechanism of RADS of FCC gasoline over NiSO4/ZnO-Al2O3-SiO2 adsorbent has been proposed, which provides theoretical support for the development of new adsorbents and the optimization of RADS process.

Influence of Specific Surface Area on the Strength of Iron Oxidized Pellets

Blaine specific surface area (SSA) is an essential physical property of iron concentrate and is availably improved by a high-pressure grinding roller (HPGR) to enhance the pelletability and the qualities of oxidized pellets. In this study, the four concentrates with various SSA were obtained by HPGR treatment to produce the oxidized pellets. The results show that the high degree of lattice deformation corresponds to high SSA which is beneficial for improving the quality of green, preheated, and fired pellets. The compressive strength increases from 600 to 1870 N·pellet−1 for preheated pellets and increases from 2530 to 4270 N·pellet−1 for fired pellets when SSA increased from 849 cm2/g to 1601 cm2/g, under the optimal condition of preheating at 1050 °C for 12 min and firing at 1250 °C for 15 min. The oxidation of magnetite is accelerated. Low porosity and microphotographs with integrated hematite joined crystallization support the strength enhancement by high SSA.

Influence of specific surface area on sulfate attack–induced expansion of cement-treated aggregates

Sulfate attack–induced expansion of cement-treated aggregates is a well-known problem to be addressed causing remarkable heave in road and railway subgrades. The specific surface area (SSA) of the materials influences chemical reactions significantly. In this study, cement, sodium sulfate, and basalt powder were ground in a ball mill for 0 (without grinding), 5, 10, 30, and 60 min respectively to achieve different SSA gradients. Under the curing condition of a constant temperature of 10 °C and humidity of 70%, with 5% cement, the effects of sodium sulfate contents and SSA gradients on the expansion of sulfate attack in cement-treated aggregate (SACA) were investigated during 60 days in laboratory. Based on nitrogen absorption methods, microscopic tests, and swelling tests, the results show that, grinding within 60 min, the respective peak value of SSAs of cement, mixture of 3% (or 8%) sodium sulfate and basalt powder, and mixture of 3% (or 8%) sodium sulfate, cement, and basalt powder was 1.867 m2/g, 1.109 m2/g (or 1.393 m2/g), and 1.128 m2/g (or 1.404 m2/g), respectively. The SSAs increase as the aggregates refined, then decrease as the aggregates gathered. The strain variation can be generally divided into four stages with 3% sodium sulfate attack in cement-treated aggregate (3% SACA): rapid strain increase, short stagnation, continuous heave, and constant strain. Two stages of strain variation have been observed with 8% sodium sulfate attack in cement-treated aggregate (8% SACA): rapid strain increase, and a constant strain. Finer needle-like ettringite crystals (average length: 0.5–1 μm) filling in the smaller holes produce the greater expansion induced by SACA. Based on grey incidence analysis, the SSAs of cement, mixture of sodium sulfate and basalt powder (S+B), and the whole mixture of cement, sodium sulfate, and basalt powder (C+S+B) have a significant effect on strain. This work provides theoretical support for amending SACA at the SSA level.

Demonstration of the Influence of Specific Surface Area on Reaction Rate in Heterogeneous Catalysis

Heterogeneous catalysis plays an important role in many chemical reactions, especially those applied in industrial processes, and therefore, its theoretical foundations are introduced not only to students majoring in chemical engineering or catalysis but also as part of general chemistry courses. The consideration of catalytic activity of various solids and mechanisms of catalytic reactions requires the introduction of the concept of an active site, which together with the catalyst specific surface area are discussed as key parameters controlling the reaction rate. There are many known demonstrations of heterogeneous catalysis phenomena that can be performed live in a lecture hall, but all of them focus only on the general idea of catalytic processes and are not suitable for quantitative analysis. Therefore, herein we present a simple demonstration of the influence of the specific surface area of a catalyst on the rate of a catalytic reaction. This demonstration is based on a model reaction of hydrogen peroxide decomposition catalyzed by cobalt spinel (Co3O4) calcined at various temperatures. The differences in reaction rates can be monitored visually, and the obtained data can be used directly for a simple kinetic analysis, including comparison of numerical values of the reaction rate constants.

Physical Properties of Furfural Resin-Based Active Carbon for Improved Electric Double Layer Capacitor

Specific surface area, pore size distribution and surface functional group of carbonaceous material for electric double layer capacitor (EDLC) are controlling factors to improve energy density. High specific surface area would lead to high specific capacitance, however some micropores (smaller than 2 nm) may be inaccessible to electrolyte ions due to the narrow pore gate effect at the pore entrance, thereby resulting in specific capacity reduction. Surface functional groups also affect the wettability of the activated carbon electrode and pseudo-capacity was yielded due to redox reaction. The relationships between capacity and multiple factors (i.e., specific surface area, pore size distribution, and surface functional groups) are still unclear. In this study, the specific surface area was fixed at 1200 ± 100 m2/g to eliminate the influence of specific surface area on specific capacity. The influences of pore size distribution and surface functional groups on specific capacity were then evaluated.Furfural resin-based particles (1 µm in diameter) were carburized in a nitrogen atmosphere for 3 h at a temperature ramping rate of 1°C/min to 400°C. The carbonized particles were mixed with KOH at a KOH:carbonized particles ratio of 4:1; the mixture was then activated at 700–800°C for the prescribed holding time, ranging from 0 to 0.5 h, under flowing nitrogen gas at a temperature ramping rate of 10°C/min. After heat treatment had been performed, the active carbon was cooled to room temperature, washed with 1 M HCl, rinsed with distilled water, and dried in an oven at 150ºC for 24 h. Specific surface area/pore size distribution was evaluated by N2 adsorption method. Surface functional groups were evaluated by Boehm method. Active carbon, carbon black and polytetrafluoroethylene were mixed at a mass ratio of 8: 1: 1, then pellets (14 mm in diameter and 2 mm in thickness) were prepared and dried at 115ºC for 24 hours to obtain activated carbon electrodes. Constant current charge/discharge test (potential width: 0-1.0 V, current density: 20-500 mA/g) and was performed at room temperature by two-electrode cell using KOH aqueous solution (6 M) as an electrolytic solution.Table 1 shows the pore structure of 1-μm-diameter active carbon particles treated at 700–800°C for different holding times to set SBET at ca. 1200 m2/g, allowing elucidation of the factor controlling the specific capacity. For a holding time of 0.5 h, the specific surface area (SBET) and total pore volume (Vtot) increased with increasing activation temperature. We found that increasing the holding time led to higher Vmicro and lower Vmeso. The three experimental conditions (700°C-0.5 h, 750°C-0 h, and 800°C-0 h) yielded active carbons with an SBET of 1200 ± 100 m2/g; these are indicated by the orange squares in Table 1. Active carbon by 750°C-0 h or 800°C-0 h had 2 to 3 times larger Vmeso and 1.9 times larger mesopore ratio than the one with 700°C-0.5 h. Specific capacity per weight increases in the order of 750ºC-0 h (148 F/g), 800ºC-0 h (111 F/g), and 700ºC-0.5 h (66 F/g). Figure 1 shows pore size distribution of these active carbons. Although 750ºC-0 h, 800ºC-0 h have similar pore size distributions, specific capacity per weight are very different. This indicates that factors other than pore structure may have a great influence on specific capacity per weight.Figure 2 shows the quantitative results of acid-base surface functional group by acid-base back titration (Boehm method). The total amount of acidic groups increased from 700°C-0.5 h (2.48 mmol/g), 800°C-0 h (2.45 mmol/g) to 750°C-0 h (2.21 mmol/g) and correlates with the large of the capacity. The fractional order of carboxyl groups increased from 750°C-0 h (18.1%), 800°C-0 h (23.0%) to 700°C-0.5 h (31.4%). The increase of carboxyl would be one possible reason for better specific capacity. Carboxyl groups cause pseudo-capacity due to redox reaction and improve wettability, and contribute to high capacity. From these relationships, we assumed that the amount of surface functional groups has a larger influence on the capacity than the pore structure. Figure 1

Modeling and Optimization of Pollutants Removal during Simultaneous Adsorption onto Activated Carbon with Advanced Oxidation in Aqueous Environment.

The paper presents the results of studies on the modeling and optimization of organic pollutant removal from an aqueous solution in the course of simultaneous adsorption onto activated carbons with varied physical characteristics and oxidation using H2O2. The methodology for determining the models used for predicting the sorption and catalytic parameters in the process was presented. The analysis of the influence of the sorption and catalytic parameters of activated carbons as well as the oxidizer dose on the removal dynamics of organic dyes-phenol red and crystal violet-was carried out based on the designated empirical models. The obtained results confirm the influence of specific surface area (S) of the activated carbon and oxidizer dose on the values of the reaction rate constants related to the removal of pollutants from the solution in a simultaneous process. It was observed that the lower the specific surface area of carbon (S), the greater the influence of the oxidizer on the removal of pollutants from the solution. The proposed model, used for optimization of parameters in a simultaneous process, enables to analyze the effect of selected sorbents as well as the type and dose of the applied oxidizer on the pollutant removal efficiency. The practical application of models will enable to optimize the selection of a sorbent and oxidizer used simultaneously for a given group of pollutants and thus reduce the process costs.

Numerical simulation of DPF thermal regeneration process based on an improved dynamic model

ABSTRACT In this paper, an improved kinetics model of soot oxidation based on the traditional B-K model is employed to characterize the thermal regeneration process of diesel particulate filters (DPF). Considering the influence of specific surface area and inhibition factor on soot oxidation, the regeneration process is simulated and analyzed using the commercial FLUENT software combined with UDF method. The results show that soot particles react from the middle of the filter to both ends, and the temporal profile of soot mass in the thermal regeneration process could be divided into three sections: smooth reaction, rapid reaction, and late reaction. The regeneration time decreases with the increasing of the incoming oxygen volume fraction. When the thickness of the deposited soot layer is less than 0.1 mm, the regeneration time is prolonged as the thickness of the deposited layer decreases. When the thickness is more than 0.1 mm, the regeneration time shows the opposite trend with the thickness of the deposited layer. Meanwhile, the curve of maximum wall temperature changing with time is divided into heating, rapid-burning, and slow-burning regimes. The maximum wall temperature increases as the volume fraction of oxygen flow increases, and as the deposited layer thickness increases.

Modeling reactive flow on carbonates with realistic porosity and permeability fields

CO2 reinjection in petroleum reservoirs brings advantages in oil production but may cause dissolution in carbonate reservoirs. Two-scale continuum models have been successfully used to simulate acidification. However, the use of realistic porosity and permeability fields in mesh simulations is still a challenge, in such a way that uniform and normal distributions have been used to generate these fields in the past. The main objective of this work was to transcript the plugs heterogeneity from the micro-CT images to simulation. The porosity field was calculated directly from micro-CT images, and two methodologies are proposed to calculate the permeability field. A reactive two-scale continuum solver was implemented in OpenFOAM and used to simulate reactive flow in two carbonate samples with different intrinsic reaction rates (calcite and dolomite). The experimental permeability evolution curves, as well as wormholes shapes and paths, are reproduced in the simulations. We observed a critical influence of specific surface area, reaction rate constant, and initial permeability field for the simulations of acidification processes.

Tailoring the protonic conductivity of porous yttria-stabilized zirconia thin films by surface modification.

Porous yttria-stabilized zirconia (YSZ) thin films were prepared by pulsed laser deposition to investigate the influence of specific surface area on the electronic, oxygen ion, and protonic transport properties. Electrochemical impedance spectroscopy was carried out as a function of temperature, oxygen activity and humidity of the surrounding atmosphere. At high humidity, protons on the surface of the porous YSZ thin films lead to increased conductivity, even for temperatures up to 700 °C. With increasing relative humidity, the activation energy of proton transport decreases because of changes in the transport mechanism from Grotthuss-type to vehicle-type transport. By coating the porous YSZ films with an amorphous titania (TiO2) layer of only a few nanometer thickness using atomic layer deposition, the protonic contribution to conductivity is significantly reduced. Depositing an 18 nm-thick anatase TiO2 surface layer, the protonic conductivity contribution increases again, which can be attributed to enhanced capillary condensation because of the lower pore size. Interestingly, the filling of pores is accompanied by a decrease in proton mobility. Theses results demonstrate the significant effect that the porosity and the surface properties have on the protonic transport and further provide new design principles for developing nanostructured proton-conducting oxides.

Dihydrogen H2 steady state in α-radiolysis of water adsorbed on PuO2 surface

Radiolysis of water adsorbed on PuO2 surface has been the subject of several studies but still remains poorly understood. The present study brings new experimental results helping to further understand the phenomena occurring at PuO2 surface. Radiolysis of adsorbed water on PuO2 surface leads to the reach of a steady state in hydrogen content when relative humidity is kept constant implying an equilibrium between generation and consumption of hydrogen. The influences of specific surface area, relative humidity, PuO2 dose rate and composition of the atmosphere (Ar vs air) on hydrogen generation were investigated. A significant evolution of the hydrogen generation kinetics was observed upon PuO2 surface aging. This result might be related to an evolution of the surface physicochemical state induced by a long-term storage in H2O/H2/O2 atmosphere. The surface evolution modifies the equilibrium between generation and consumption of hydrogen. Several annealing thermal treatment were necessary to retrieve H2 accumulations kinetics similar to the ones obtained with the same sample as freshly prepared. This indicates an important evolution of PuO2 surface and subsurface. A mechanism is described to explain the surface evolution and its effect on H2 accumulation through radiolysis of adsorbed water.

Carbohydrate concentrations and enzyme activities as influenced by exchangeable cations, mineralogy and clay content

Abstract Enzymes can exist in bound or free form within the soil, but the impact of interactions between extracellular enzymes with the amount and type of clay minerals and exchangeable cations on the activities of enzymes and decomposition or retention of carbohydrates in soil is still poorly understood. Appropriate amounts of homoionic Na-, Ca- and Al-clay minerals from Georgia kaolinite, Illinois illite and Wyoming montmorillonite were mixed with pure sand to prepare artificial soils with different clay contents, exchange cations and clay types to examine the effects of exchangeable cations, mineralogy and clay content on the concentrations of hot water and dilute acid extractable carbohydrates and activities of acid and alkaline phosphatases and CM-cellulase. There was a significant effect of clay content on the concentrations of carbohydrates and activities of enzymes. The concentrations of carbohydrates increased when the clay contents of soils increased from 0 to 5 and 10%, respectively, showing that the clay contents influence the capacity of soils for stabilization of carbohydrates. But opposite trends were found in enzyme activities. The enzyme activities decreased significantly as the clay contents of the artificial soils increased. The concentrations of carbohydrates and activities of enzymes were significantly affected by exchangeable cations. In soils with 5 and 10% clay, the concentrations of carbohydrates were maximum in Al-soils and minimum in Ca-soils, in contrast, the activities of enzymes were maximum in Ca-soils and minimum in Al-soils. There was a significant effect of clay mineralogy on the concentrations of carbohydrates and activities of enzymes. The concentrations of carbohydrates were highest in soils with Wyoming montmorillonite clay mineral and lowest in soils with Georgia kaolinite clay mineral. But the activities of enzymes were lower in soils with Wyoming montmorillonite clay mineral than soils with Georgia kaolinite and Illinois illite clay minerals, indicating the influence of specific surface area (SSA) and cation exchange capacity (CEC) of clay minerals on carbohydrate retention and enzyme activities. The results of this study indicate that carbohydrates are stabilized in soils through the interaction with clay minerals and a small amount of clay (5%) significantly increases carbohydrate retention and reduces enzyme activities in soils. Exchangeable cations exert their influence on enzyme activities and hence carbohydrate dynamics by controlling the activities of enzymes through modifying the physicochemical characteristics of soils.

Influence of porosity parameters and electrolyte chemical composition on the power densities of non-aqueous and ionic liquid based supercapacitors

Influence of specific surface area (SDFT), total pore volume (Vtot) and other porosity characteristics on the electrochemical parameters and power density of two electrode electric double layer capacitors based on 1 M 3-ethyl-methylammonium tetrafluoroborate (Et3MeNBF4) solution in acetonitrile and on 1-ethyl-3-methylimidazolium tetrafluoroborate (EtMeImBF4) has been analysed. The pore size distribution data calculated from nitrogen, CO2 and Ar adsorption isotherms using mainly Carbon 2D non-local density functional theory for heterogeneous surface (2D-NLDFT-HS) model have been compared with crystallographic characteristics obtained by Raman, X-ray diffraction, photoelectron spectroscopy, etc. methods. It was shown that, chemical composition and crystallographic structure of precursor material, synthesis and activation conditions have decisive influence on the shape (spherical, cylindrical or slit-shape pores) and hierarchical porous structure and electrical conductivity of the carbon materials. Noticeable increase in series and parallel capacitances from 50 to 138 F g−1 in 1 M Et3MeNBF4 and up to 155 F g−1 in EtMeImBF4, gravimetric power density (up to 35 kW kg−1) and volumetric power density (up to 25 kW dm−3, both at discharge time 3.6 s in 1 M Et3MeNBF4 + AN electrolyte) for optimised EDLC has been demonstrated. For EtMeImBF4 based cells lower gravimetric (25 kW kg−1) and volumetric (10 kW dm−3) power densities have been achieved. For completing the EDLCs with high power and energy densities, highly micro-and mesoporous materials with optimum specific surface area (1200–1500 m2 g−1) but maximum (meso) pore volume (Vtot > 1.5 cm3 g−1) should be applied. Only for optimised EDLCs the very short characteristic charging/discharging times (lower than 0.3 s in Et3MeNBF4 + AN and 1.0 s in EtMeImBF4) can be achieved.

Influence of specific surface area on coal dust explosibility using the 20-L chamber

The relationship between the explosion inerting effectiveness of rock dusts on coal dusts, as a function of the specific surface area (cm2/g) of each component is examined through the use of 20-L explosion chamber testing. More specifically, a linear relationship is demonstrated for the rock dust to coal dust (or incombustible to combustible) content of such inerted mixtures with the specific surface area of the coal and the inverse of that area of the rock dust. Hence, the inerting effectiveness, defined as above, is more generally linearly dependent on the ratio of the two surface areas. The focus on specific surface areas, particularly of the rock dust, provide supporting data for minimum surface area requirements in addition to the 70% less than 200 mesh requirement specified in 30 CFR 75.2.

Specific polarizability of sand-clay mixtures with varying ethanol concentration.

We utilise a concept of specific polarizability (c s ), represented as the ratio of mineral-fluid interface polarization per pore-normalised surface area S p , to demonstrate the influence of clay-organic interaction on complex conductivity measurements. Complex conductivity measurements were performed on kaolinite- and illite-sand mixtures as a function of varying ethanol (EtOH) concentration (10% and 20% v/v). The specific surface area of each clay type and Ottawa sand was determined by nitrogen-gas-adsorption Brunauer-Emmett-Teller method. We also calculated the porosity and saturation of each mixture based on weight loss of dried samples. Debye decomposition, a phenomenological model, was applied to the complex conductivity data to determine normalised chargeability (m n ). Specific polarizability estimates from previous complex conductivity measurements for bentonite-sand mixtures were compared with our dataset. The c s for all sand-clay mixtures decreased as the EtOH concentration increased from 0% to 10% to 20% v/v. We observe similar c s responses to EtOH concentration for all sand-clay mixtures. Analysis of variance with a level of significance α = 0.05 suggests that the suppression in c s responses with increasing EtOH concentration was statistically significant for all sand-clay mixtures. On the other hand, real conductivity showed only 10% to 20% v/v changes with increasing EtOH concentration. The c s estimates reflect the sensitivity of complex conductivity measurements to alteration in surface chemistry at available surface adsorption sites for different clay types, likely resulting from ion exchange at the clay surface and associated with kinetic reactions in the electrical double layer of the clay-water-EtOH media. Our results indicate a much larger influence of specific surface area and ethanol concentration on clay-driven polarization relative to changes in clay mineralogy.