Search

To reinforce natural rubber latex foam, fumed silica and precipitated silica are introduced into latex foam prepared using the Dunlop process as fillers. Four types of silica, including Aerosil 200 (hydrophilic fumed silica), Reolosil DM30, Aerosil R972 (hydrophobic fumed silica), and Sipernat 22S (precipitated silica), are investigated. The latex foam with added silica presents better mechanical and physical properties compared with the non-silica foam. The hydrophobic nature of the fumed silica has better dispersion in natural rubber compared to hydrophilic silica. The specific surface area of silica particles (BET) also significantly influences the properties of the latex foam, with larger specific surface areas resulting in better dispersity in the rubber matrix. It was observed that exceeding 2 phr led to difficulties in the foaming process (bulking). Furthermore, higher loading of silica also affected the rubber foam, resulting in an increased shrinkage percentage, hardness, compression set, and crosslink density. The crosslink density increased from 11.0 ± 0.2 mol/cm3 for non-silica rubber to 11.6 ± 0.6 mol/cm3 for Reolosil DM30. Reolosil DM30 also had the highest hardness, with a hardness value of 52.0 ± 2.1 IRHD, compared to 45.0 ± 1.3 IRHD for non-silica foam rubber and 48 ± 2.4 IRHD for hydrophilic fumed silica Aerosil 200. Hydrophobic fumed silica also had the highest ability to return to its original shape, with a recovery percentage of 88.0% ± 3.5% compared to the other fumed silica. Overall, hydrophobic fumed silica had better results than hydrophilic silica in both fumed and precipitated silica. [ABSTRACT FROM AUTHOR]

The study demonstrates a new method to create high‐purity mesoporous silica from coal fly ash without using structure‐directing agents. Divided into two stages, the process involves pre‐treating the ash with Na2CO3, calcination, cooling, washing, and drying to yield a dehydrated sample. Subsequently, silica synthesis occurs through an acid refluxing technique using thermally activated coal fly ash with Na2CO3. Key factors impacting synthesis include acid content and liquid‐to‐solid ratio. The study extensively employs various characterization methods like XRF, XRD, FTIR, and BET analysis, revealing a 99.1 % purity in silica content, a surface area of 793.51 m2/g, and a pore size of 3.9 nm. Optimal conditions for this synthesis involve 80 °C temperature, 2‐hour reaction time, 25 % hydrochloric acid concentration, and a 10 : 1 liquid‐to‐solid ratio. FTIR spectra demonstrate similarities between the obtained silica and commercial Sigma Aldrich silica. This innovative approach presents a promising avenue for generating top‐quality silica from coal fly ash, potentially diversifying applications across industries reliant on high‐performance silica materials. [ABSTRACT FROM AUTHOR]

Electrospun nanofibres can be used in nanosensors, nanofilters, catalysts, tissue scaffolds, batteries, solar cells, protective clothing and so on. The major improvement in various applications is brought about by the enhanced surface area of the electrospun nanofibres. We employed a statistical approach to optimize electrospinning process parameters to produce cellulose acetate (CA) nanofibre mat with Brunauer–Emmett–Teller (BET) surface area as the response variable. The selected variables (applied voltage, distance between needle and collector, and flow rate of solution) were optimized by response surface methodology (Central Composite Design–CCD) to capture the linear and quadratic influence to maximize specific surface area (SSA) of electrospun fibre mat measured by BET analyzer. The predicted model was significant with R2 value of 0.91 and adjusted R2 value of 0.83. This model predicted the SSA of 2.34 m2 g−1 for the optimized parameters 24.8 kV voltage, 12 cm distance between needle and collector and 0.04 ml min−1 flow rate. The difference between the predicted value and the experimental result at the same parameters setting was less than 5%. The obtained results confirmed that the selected CCD model appropriately presented the performance of selected parameters in the prediction of SSA of CA nanofibre mat. [ABSTRACT FROM AUTHOR]

[Display omitted] • Recycled quartz fiber with coating was tested for solar thermal evaporation. • Hydrothermal carbonization at 200 °C for 4 h created hydrochar on quartz wool. • Carbon coating thickness varied, enhancing solar absorption and water transport. • Carbon-coated quartz wool evaporated water 2.5 times faster than uncoated wool. Hydrothermal carbon derived from D-glucose was deposited on quartz fiber wool to enhance solar thermal evaporation. Thermogravimetric analysis (TGA) indicated 46 % weight loss for the coated wool above 500 °C. The BET surface area of the coated wool was 6.8581 m2/g. The carbon at the outer surface fibers of the quartz wool was thicker. The steady-state solar thermal evaporation rate of the carbon-coated quartz wool was found to be 3.1831 kg/m2∙h, which is 2.5 times higher than that of the uncoated one (0.8785 kg/m2∙h). [ABSTRACT FROM AUTHOR]

The aim of this work has been to examine the effect of intensive ball milling of sphalerite in the wet and dry modes on the microstructural changes and the subsequent effect on its dissolution rate. Sample characterization showed that the BET surface area and the amorphization degree were obtained to 18.2 m2/g and 78.92% in the wet mode and 7.72 m2/g and 90.35% in the dry mode milling after 180 min, respectively. The maximum extraction of Zn obtained 23.7, 67.12 and 85% in the unmilled, wet and dry milled samples, respectively. The ratio of kinetic rate constant has been increased by 37 and 67 times, respectively. Also, the activation energy was decreased with increasing of milling time. Selectivity of sphalerite leaching versus surface area was obtained higher than that of the wet milling. Leaching experiments indicated that structural disordering had a drastic effect on the reactivity of mechanically activated sphalerite. [Display omitted] • Dry mechanical activation led to more structural changes and increased sphalerite reactivity. • Maximum BET surface area of 18.20 and 7.71 m2/g were measured in the wet and dry modes. • Structural changes are more effective than BET surface area on sphalerite reactivity. • Leaching efficiency enhanced by 85% in dry mode compared with 67% in wet mode milling. • Selectivity of sphalerite leaching (Zn/Fe) increased by surface disordering. [ABSTRACT FROM AUTHOR]

Fine activated carbon (FAC) is prepared from rubber fruit shells (RFS) using two chemical activating agents (ZnCl2 and KOH) and three impregnation ratios (1:3, 1:4, and 1:5). The Brunauer–Emmett–Teller (BET) results show that for a constant impregnation ratio, the ZnCl2 activating agent yields a higher specific surface area than the KOH agent. In particular, for the maximum impregnation ratio of 1:5, the FAC prepared using ZnCl2 has a BET surface area of 456 m2/g, a nitrogen absorption capacity of 150.38 cm3/g, and an average pore size of 3.44 nm. Moreover, the FAC structure consists of 70.1% mesopores and has a carbon content of 80.05 at.%. Overall, the results confirm that RFS, activated using an appropriate quantity of ZnCl2, provides a cheap, abundant, and highly promising precursor material for the preparation of activated carbon with high carbon content and good adsorption properties [ABSTRACT FROM AUTHOR]

A hydrophilic terpolymer MOF composite is designed with high surface area and porosity to enrich mono- and multi-glycosylated peptides facilitating a bottom-up approach. Terpolymer@ZIF-8 is synthesized using free radical polymerization followed by layer by layer ZIF-8 fabrication. Subsequent surface modification was made by aminophenylboronic acid (AMBA). The enrichment ability of terpolymer@ZIF-8@BA is evaluated by using tryptic digest of IgG and HRP to exemplify mono- and multi-glycosylated protein samples. Improved selectivity of 1:200 for spiked HRP in BSA digest and sensitivity down to 1 fmol μL−1 is achieved. Batch to batch reproducibility is better 1% RSD which favors the adoption of the developed method for routine N-linked glycopeptide/protein determination. Cost-effective nature of given approach is given by regeneration of the material up to four cycles. Total 318 N-linked glycopeptides have been identified from 1 μL human serum digest after subjecting the enriched and PNGase-treated deglycosylated peptides to LC-MS. Thus, terpolymer@ZIF-8@BA holds the potential both for mono- and multi-glycosylated peptides from complex biological sample. [ABSTRACT FROM AUTHOR]

Sol gel based method assisted by Pluronic P123 has been employed to successfully synthesize mesoporous alumina (MA) with high surface area (363.4 m2 g−1), large pore volume (0.65 cm3 g−1) and narrow pore size distribution (7.42 nm). An optimization study was performed using response surface methodology (RSM) to design the experiments. The use of central composite design (CCD) allowed determination of levels of various parameters including the amount of P123, nitric acid and calcination temperature to be carried out with the interrelation between each parameters evolved simultaneously. Finally, a quadratic model has been introduced to explain the significant effect of preparation parameters on the principal feature of mesoporous alumina (SBET). The test results confirm the validity and adequacy of the developed RSM model and BET surface area obtained from the confirmation test (363.4 m2 g−1) was near to the predicted SBET from the quadratic model (431.25 m2 g−1). However, the experimental and predicted values were in a good agreement. The existence of the difference is proved that SBET is highly dependent on the variety of synthesis parameters. Additionally, the simultaneous interactions among the independent parameters were clearly demonstrated by three dimensional response surface plots. [ABSTRACT FROM AUTHOR]

Gas physisorption is an experimental technique based on equilibrium Van der Waals interactions between gas molecules and solid particles, that quantifies the specific surface area (SSA), pore size distribution (PSD), and pore volume of solids and powders. The performance of catalysts, absorbents, chromatography column materials, and polymer resins depends on these morphological properties. Here we introduce the basic principles and procedures of physical adsorption, especially nitrogen physisorption, as a guide to students and researchers unfamiliar with the field. The Brunauer‐Emmett‐Teller theory (BET) is a common approach to estimate SSA that extends the Langmuir monolayer molecular adsorption model to multilayer layers. It relies on an equilibrium adsorption isotherm, measured at the normal boiling point of the adsorbate, eg, 77 K or 87 K for N2 and Ar, respectively. Web of Science indexed 45 400 articles in 2016 and 2017 that mentioned N2 adsorption porosimetry—BET and BJH (Barrett‐Joyner‐Halenda) keywords. The VOSViewer bibliometric tool grouped these articles into four research clusters: adsorption, activated carbon in aqueous solutions for removal of heavy metal ions; synthesis of nanoparticles and composites; catalysts performance in oxidation and reduction processes; and photocatalytic degradation with TiO2. According to the literature, the accuracy of the density function theory (DFT) method is higher than with the BJH theory and it is more reliable. [ABSTRACT FROM AUTHOR]

Custard apple-shaped NaX zeolite with a large surface area was synthesized from rice husk ash without use of a templating agent via a single-step autoclave process at 90 °C/6h. The crystallinity of the particles was confirmed by XRD. An FTIR study shows the characteristic bands at 560 cm−1 for a double 6-membered ring (D6R), while a Raman shift at around 500 cm−1 indicates the bending mode of 4-membered ring fragments of NaX zeolite. The total BET surface area of the product was found to be 703 m2g−1 comprising a micrpore surface area of 623 m2g−1 and a mesopore surface area of 80 m2g−1. A hierarchical porous structure with micropores in the range of 0.72–1.76 nm and mesopores centred at 3.5 nm was obtained. FESEM and TEM images of NaX zeolite show a custard apple-like morphology (1–2 μm) of secondary particles which was formed by self-assembly of nanometer-sized (50–100 nm) primary particles. A proposed formation mechanism was illustrated. [ABSTRACT FROM AUTHOR]

Taguchi method (TM) and response surface methodology (RSM) have been employed to optimize three parameters, including the amounts of P123, the amounts of nitric acid and calcination temperature, in order to define an optimal setting for sol‐gel synthesis of high surface area mesoporous alumina powder (MA). Herein, the comparison of the both statistical approaches has been examined and discussed considering the nitrogen adsorption as the response variable because this important character for mesoporous materials is exceedingly sensitive to the synthesis parameters. The BET surface area (SBET) and pore volume of MA under Taguchi optimal condition were 323.5 m2 g−1 and 0.551 cm3 g−1, respectively, by conducting confirmation test. Furthermore, the confirmation test showed high SBET of MA (363.4 m2 g−1), which was in a good agreement with calculated SBET result (431.25 m2 g−1) by a quadratic model under RSM optimal condition. Moreover, 3D response surface plots and 2D contour plots of desirability have been discussed to visualize the influence of input factors on response variable. It is also concluded that RSM shows more appropriate (12.33% higher SBET than TM) and efficient optimal condition with determining a quadratic function as the relationship between SBET and synthesis parameters. [ABSTRACT FROM AUTHOR]

Injection of carbon dioxide into saline aquifers is one the most promising methods for mitigating the increase in atmospheric CO 2 concentrations. Reactions of CO 2 with brine and formation rocks are important in determining the ultimate fate of CO 2 . Rates of reactions of the different relevant minerals are dependent on rate constants and mineral surface area. It is important to quantify the effect of surface area on reaction rates when different types of rock samples are employed in experiments. Batch experiments with different forms of the Berea sandstone were set up and performed at high pressure (2000 psi) and reservoir temperature (60 °C) for two-week under reservoir CO 2 sequestration conditions. Experiments were performed with markedly different samples (cores, rock chips, and powdered) with progressively increased surface areas. Experiments with the different forms of sandstones showed similar trends in major minerals dissolution with increase in cation concentrations of iron, magnesium, and calcium in the effluent brine. Under realistic aquifer pressure and temperature conditions, iron chemistry plays an important role in the dissolution reactions in the Berea sandstone. Reactivities increased leading to larger cationic concentrations in brine (as determined using ICP-MS) as the surface areas increased. Morphology of the reacted volume was viewed using QEMSCAN and Micro-CT for core plug samples. These experiments helped quantity the effect of surface area (higher surface area leading to more dissolution) and revealed that reactions appear to be limited more to the surface in Berea sandstone. It was shown that the factor used to obtain geometric surface area from a core decreased when samples with higher surface areas were used. This indicated that some internal surface area became available for fragmented (fractured), and powdered samples. Mineral dissolution caused the growth and expansion of pores in Berea sandstone and surface area measurements (BET) showed that the new porosity generated was characterized by a smaller pore size distribution in comparison to the unreacted one. [ABSTRACT FROM AUTHOR]

DDR3 zeolite has been attracted by the researchers for its characteristics which are potential in various applications including CO 2 adsorption. Thus, in the current work, DDR3 zeolite synthesized via ultrasonic irradiation method reported in our previous work [14] are characterized by BET surface area and tested for CO 2 adsorption at room temperature. DDR3 sample synthesized in 10 days via hydrothermal heating and ultrasonic pre-treatment of 3 h showed the BET surface area of 297 m 2 /g with CO 2 adsorbed amount of 1.86 mmol/g (28 cm 3 /g STP). Subsequently, samples synthesized in 1 day and 0.5 day with ultrasonic pre-treatment of 1 h showed the BET surface area of 201 m 2 /g and 2.0 m 2 /g, respectively, with CO 2 adsorbed amount of 1.61 mmol/g (14 cm 3 /g STP) and 0.3 mmol/g (2 cm 3 /g STP), respectively. Subsequently, reference DDR3 sample which was synthesized in 25 days as reported in literature showed the BET surface area of 323 m 2 /g with CO 2 adsorbed amount of 1.91 mmol/g (31 cm 3 /g STP). Consequently, in the present work, it was observed that BET surface area and CO 2 adsorption decreases with decrease in synthesis duration. This result was mainly because of the effect of growth duration and ultrasonic pre-treatment. Overall, it was concluded that DDR3 zeolite synthesized in 1 day via ultrasonic irradiation coupled with hydrothermal heating method showed comparable CO 2 adsorption results with the DDR3 reference sample obtained in the present work as well as the DDR3 samples reported in the literature. [ABSTRACT FROM AUTHOR]

In this paper, the effect of synthesis parameters including temperature, pressure and volume of the synthesis solution towards the formation of ZIF-8 under microwave-assisted solvothermal synthesis was investigated. The resultant ZIF-8 samples were characterized using X-ray diffraction and nitrogen physisorption. The surface morphology was examined via scanning electron microscopy. The results exhibited that, highly crystalline ZIF-8 was successfully synthesized within 0.5 hours at 120 ̊C, with the BET surface area up to 690.75 m 2 /g and micropore volume of 0.32 cm 3 /g. It was found that, at higher temperature and pressure, the formation of ZIF-8 can be affected by the expansion of solvent, which reduced the initial concentration of the reactant ions. Hence, further increased of the temperature did not cause higher crystallinity and larger size of ZIF-8 particles. [ABSTRACT FROM AUTHOR]

The specific surface area (SSA) is a principal characteristic for the assessment of the sorption capacity of minerals. In addition to size, the accessibility of the surface area is of importance, which is primarily affected by porosity. In particular the micropore surface area of soil minerals may be inaccessible due to too small pore entrances or their clogging by organic material. In this study, SSA and micropore surface area of three minerals (Al oxide, Al hydroxide and kaolinite), acting as model materials for oxides, hydroxides and clay minerals, respectively, were measured by gas adsorption methods with both N 2 at 77.35 K or CO 2 at 273.15 K and the retention of the polar liquid ethylene glycol monoethyl ether (EGME). Moreover, porosity was assessed by 129 Xe nuclear magnetic resonance (NMR) spectroscopy. A NaY zeolite was used as microporous reference material. 129 Xe NMR spectroscopy and the determination of SSA by physisorption of N 2 (BET-N 2 SSA) were performed after sample pretreatment at various outgassing temperatures because BET-N 2 SSA and porosity are significantly affected by the outgassing temperature due to the loss of adsorbed water molecules. For all minerals investigated, the highest SSA was obtained by EGME retention. The gas adsorption methods exhibited differences in SSA and micropore surface area depending on the gas and pretreatment temperature. Thereby, increased pretreatment temperatures resulted in increased SSA and micropore surface area. 129 Xe NMR spectra revealed that this increase in surface area was mainly ascribed to an increase in porosity. It appeared that the accessibility of surface area was limited by surface hydration. This implies that at environmental conditions, partly saturated pores will yield a reduced sorption capacity compared to the one that may be expected from SSA measurements. Consequently, porosity and hydration of the mineral surfaces have to be considered for an improved assessment of the sorption capacity of minerals and soils. [ABSTRACT FROM AUTHOR]

The characterisation of sepiolite-bearing samples from five lutite associations occurring in the Cerro de los Batallones deposit has been carried out. Based on both the composition and texture of the sepiolite, two main formation patterns for this clay mineral, transformation from saponite by dissolution–precipitation and direct precipitation from solution, is proposed. From a compositional point of view, sepiolite oscillates between typical Mg-rich sepiolite and near Al-rich sepiolite, all samples showing variable swelling with ethylene glycol (up to 0.25Å). There is a relationship between mechanism of formation and crystallinity of the sepiolite mineral. Both DRX and FTIR analyses led to differentiate between low crystallinity sepiolite (LCS) and high crystallinity sepiolite (HCS). The presence of the triplet 2.61Å, 2.58Å and 2.56Å is especially useful for HCS identification. The two types of sepiolite show slightly a different thermal behaviour. In particular, coordinated water loss at 350°C in LCS is higher than in HCS. BET surface area is high in all studied samples, reaching up to 360m2/g and 328m2/g in LCS and HCS, respectively. Differences in the microporosity and mesoporosity contribution have also been recognised. The reported dissimilarities account for differences in the technological behaviour of sepiolite clays and therefore these differences must be taken into account as they constrain industrial uses. [ABSTRACT FROM AUTHOR]

[Display omitted] • A general method to achieve high surface area (SA = 45–620 m2 g−1) films for polymers exhibiting co-crystalline phases. • Application of this preparation method to industrially relevant thermoplastic polymers: PLLA, sPS, and PPO. • Fast guest-induced crystallization and fast guest extraction are required for the achievement of high SA polymer films. • High SA films when exhibit nanoporous-crystalline (NC) phases show fast and high pollutant uptakes even at low activities. • Kinetics of pollutant uptakes increase by two or three orders of magnitude, going from amorphous to high SA and NC film. A general method to achieve high surface area (SA) films (SA in the range 45–620 m2/g), based on polymer co-crystallization with low-molecular-mass guests, is presented. The method requires fast guest-induced co-crystallization of amorphous polymer films, reaching high guest equilibrium contents (typically in the range 65–90 wt%), followed by fast guest removal from guest-reach co-crystalline films. This method is effective not only for polymers that by guest removal can lead to nanoporous-crystalline phases (like poly(2,6-dimethyl-1,4-phenylene)oxide, PPO and syndiotactic polystyrene, sPS) but also for polymers that by guest removal lead to usual dense crystalline phases (like polylactic acid, PLLA). These high SA films show guest uptakes at low activities which are high or negligible if the films exhibit nanoporous-crystalline (as for PPO and sPS) or dense phases (as for PLLA), respectively. Kinetic studies show that guest diffusivity can be increased by two or three orders of magnitude, going from amorphous to high SA NC films. [ABSTRACT FROM AUTHOR]

Abstract: In the present study the dry end of the soil water characteristic curve (SWCC) was used to estimate the specific surface area (SSA) of 90 engineering soil samples, using the Tuller and Or (2005) model. The results of SSA obtained by measurements using a WP4-T dew point potentiometer were compared with those obtained by means of traditional BET (Brunauer, Emmett, and Teller) surface area and the methylene blue (MB) techniques. An analysis of the results discussed in terms of the representative literature data showed that the SWCC method could provide a reliable estimation of the specific surface area in the case of fine grained inorganic soils with a total specific surface area greater than 5m2/g. A Hamaker constant with a value of 6×10−20 J was found to be a good approximation, in the case of SSA calculations. The study also shows that karstic clay — terra rossa exhibits specific behavior which was not investigated in detail in the study, but clearly shows that further research is needed in order to modify the Tuller and Or (2005) model to a wider range of engineering soils with more complex mineralogical composition and texture. [Copyright &y& Elsevier]

Abstract: Brunauer-Emmett-Teller (BET) surface area of quartz gouge was measured before and after shearing deformation at subseismic to seismic slip rates to determine how much of frictional work and fracture energy was consumed during grain crushing. Measurement of BET surface area provides more direct data on surface-area change than grain-size measurement does. Twenty-four experiments on quartz gouge composed of Ottawa sands or crushed quartz were conducted dry (with room humidity) or wet (with added water) at slip rates of 0.006∼1.3 m/s and normal stresses of 0.76∼3.37 MPa, using a high-velocity friction apparatus and a low to high-velocity friction apparatus. About 1 mm-thick gouge was placed between cylindrical specimens of Belfast dolerite of 25 mm in diameter. Results show that grain crushing absorbed only 0.02∼0.22% of frictional work and only 0.05∼1.06% of fracture energy under dry and wet conditions. Thus, grain comminution is unlikely to be an important energy sink at least for mature faults with well-developed slip zone. Surface area of gouge decreases with deformation at seismic slip rates. This and SEM observations suggest partial sintering due to frictional heating. Thus a simple scenario of grain crushing as an energy sink does not hold for estimating the energy budget during earthquakes. [Copyright &y& Elsevier]

Abstract: A common view concerning the energetics of seismogenic fault motion is that at least part of the fracture energy is consumed in grain crushing in the fault zone, and that this part may be estimated by grain-size analysis of fault rocks. We address this problem by conducting room-dry friction experiments on Nojima fault gouge at subseismic to seismic slip rates (0.009–1.31m/s) and at normal stresses up to 3.64MPa, and by measuring the BET surface area of the gouge before and after the experiments. Where it cuts granite, the Nojima fault zone has BET surface area of about 65×106 m2 per unit fault area (1m2). Clayey and granular fault gouges, composed mainly of quartz, plagioclase, kaolinite and smectite, were collected from a granitic fault zone at a new outcrop in Funaki, Awaji Island, southwest Japan. Both clayey and granular gouges exhibit dramatic weakening at high slip rates. Specific BET surface areas of clayey and granular gouges decreased with increasing slip rate from 46.0 and 15.4m2/g before deformation to about 20 and 5m2/g after deformation (55–70% reduction), respectively. Microstructural observations revealed that grain welding within the slip zones at high slip rates reduced grain surface area. The energetics of seismic fault motion should be examined with broader views taking into account grain crushing, grain welding, decomposition and frictional melting. [Copyright &y& Elsevier]

The measured vitrinite reflectance ( Ro ), low-temperature nitrogen gas adsorption, carbon dioxide adsorption and scanning electron microscopy(SEM) analyses were carried out with 23 fresh samples from Wolonghu and Haizi Mine of Huaibei coalfield at various distances from two sills was done. Comparative analysis of the relation between micropores (micropore surface area, micropore volume and average micropore diameter) and the BET surface area of coal seams and the distance from sills was done. The results show that Ro levels of the Wolonghu coal increases from 2.74% to 5.03% near the sill. Approaching the intrusion, Ro levels of the Haizi coal increases from 2.30% to 2.78%. It is concluded that the contact-metamorphism of the sill in the Wolonghu Mine decreases the micropores and the BET surface area of coal( 0 ~5 m from sill), while the thermal evolution of sill increases it of coal (5 ~ 60 m from sill), and the thermal evolution of sill in the Haizi Mine increases it of coal (60 ~ 160 m from sill). The scanning electron microscopy found massive devolatilization vacuoles of coal in the thermal evolution zone. [ABSTRACT FROM AUTHOR]

The present article reports results of the studies on adsorptive removal of catechol and resorcinol from aqueous solution by granular activated carbon (GAC). Physico-chemical characterization including surface area, X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and Fourier transform infrared spectroscopy (FTIR) of the GAC before and after catechol and resorcinol adsorption have been done to understand the adsorption mechanism. Bulk density and heating value of GAC were found to be 725 kg/m3 and 8.26 MJ/kg, respectively. The BET surface area was 977.6 m2/g whereas the BET average pore diameter was 18.79 Å. Different experimental parameters like initial pH, initial dosage, contact time, and initial concentration were evaluated for their effect on the adsorption of catechol and resorcinol onto GAC. The kinetics of adsorption was found to be described by the pseudo-second order equation. Results of the intra-particle diffusion model show that the pore diffusion is not the only rate limiting step. The effective diffusion coefficient of catechol and resorcinol were of the order of 2.9 × 10-10 and 2.2 × 10-10 m2/s. [ABSTRACT FROM AUTHOR]

Abstract: A series of MnO x -CeO2 mixed oxides were prepared using a sol-gel method followed by calcinations at various temperatures. The soot oxidation activities were measured in different NO concentrations under loose contact conditions. A quasi-parabolic curve is observed for the apparent dependency of activity on the catalyst surface area. As the surface area is below 8m2/g, the soot oxidation is limited by the availability of NO2 due to the separation and sintering of the mixed oxides. The rate-determining step turns to be NO2 reaction with soot for the high-surface-area catalysts. [ABSTRACT FROM AUTHOR]

Abstract: It is postulated that the behavior of fine-grained soils may be explained by the relationship between surface area and other geotechnical properties. To this end, there are several studies correlating geotechnical indexes with specific surface area (SSA). However, there is no universally accepted specific surface area determining method as several methods are available. Depending on the method employed, the measured specific surface area may show variations for a given soil. This is because the predictive power of each method depends on the type of minerals and organic matter that are present in the soil. Thus, different SSA determination methods yield widely different estimates of index properties and regression equations. To examine the role of method on SSA of soils, the SSAs of 32 soils with different mineralogies were determined using BET-N2, EGME, MB-titration, and MB-spot test methods. The measured SSA of soils was correlated with their respective geotechnical index properties. Further, the data obtained in this study and those reported by previous researchers were compared. The results suggest that correlations between geotechnical index properties and SSA using different methods may not be comparable. Accurate prediction, however, is provided only if the relationship is calibrated using soils having similar physical and chemical characters. [ABSTRACT FROM AUTHOR]

Abstract: Bismuth titanate (Bi12TiO20) nanostructures with different morphologies were synthesized hydrothermally using Bi(NO3)3 and Ti(SO4)2 in the presence of polyethylene glycol (PEG). X-ray diffraction (XRD) proved that the samples were in pure cubic phase. UV–visible diffuse reflection spectra showed the band gap of Bi12TiO20 is about 2.7eV. Brunauer–Emmett–Teller (BET) analysis proved that the Bi12TiO20 samples have higher surface areas than samples prepared by methods reported previously. Photocatalytic degradation of acid orange 7 (AO7) under visible light illumination was used to evaluate the photocatalytic ability of samples. The photocatalytic results showed Bi12TiO20 could degrade AO7 very efficiently and had higher photocatalytic activity than traditional N-doped TiO2. In addition, we have also discussed factors that have major effect on reaction efficiency. BET surface area played the most important role in the photocatalytic degradation of AO7. The crystallinity of the samples is another important factor which can also influence photocatalysis results. [Copyright &y& Elsevier]

Abstract: Utilization of poultry litter as a source material for generating activated carbon is a value-added and environmentally beneficial approach to recycling organic waste. In this study, the overall quality of poultry litter-derived granular activated carbon was systematically evaluated based on its various physical and chemical properties. Granular activated carbon generated from pelletized poultry litter following a typical steam-activation procedure possessed numerous micropores in the matrix. The product exhibited a mean particle diameter of 2.59mm, an apparent density of 0.45gcm−3, a ball-pan hardness of 91.0, an iodine number of 454mgg−1, and a BET surface area of 403 m2 g−1. It contained high ash, nitrogen, phosphorus contents and the trace elements Cu, Zn, and As. Most of the nutrients and toxic elements were solidified and solution-unextractable. In general, poultry litter-based activated carbon demonstrated overall quality comparable to that of low-grade commercial activated carbon derived from coconut shell and bituminous coal. It is promising to use poultry litter as a feedstock to manufacture activated carbon for wastewater treatment. [Copyright &y& Elsevier]

Abstract: Carbonaceous materials with different hierarchical porous structures for electrorheological (ER) dispersed phase have been synthesized by carbonization of as-prepared starch/silica precurser at different temperatures. The N2 adsorption isotherms show that Cmeso-700 and Cmeso-500 particles have the BET surface areas of 1028 and 603m2 g−1, respectively. They both have the mesoporous pores with size of about 4.6nm and the microporous pores (1.1 and 1.5nm, respectively). The BET surface areas and C/O atomic ratio of porous carbon materials can be increased with the carbonization temperatures. The rheological measurements indicate that the Cmeso-700 and Cmeso-500 ERF have the better ER effect resulted from their hierarchical porous structures. The shear stress of Cmeso-700 ERF is 900Pa at 1000s−1 under 3kVmm−1, which is almost 4.5 times larger than that of Cmicro-350 ERF. The mesoporous carbon ERFs also show the better sedimentation stability than microporous carbon ERFs. The different ER effect of carbonaceous particles may derive from their different dielectric polarization property induced by the hierarchical porous structures. [Copyright &y& Elsevier]

Abstract: Graphitic nanofibres (GNFs) were successfully synthesised at low temperatures (below 400°C) using NiO powder as the catalyst precursor and a H2/C2H4 gas mixture with a high yield, around . The yield was found to vary with temperature with the optimum yield at 500°C. XRD patterns confirm that during GNF formation the NiO was reduced forming either metallic Ni and or Ni3C phase. TEM study confirmed the formation of a graphitic phase in the form of GNFs and that the diameter was dependent on the synthesis temperature, varying from 500nm to 20nm. The sample surface area was found to increase from 49 to 252m2 g−1, with lowering of the synthesis temperature. [Copyright &y& Elsevier]

Fabrication of porous materials from the standard sacrificial template method allows metal oxide nanostructures to be produced and have several applications in energy, filtration and constructing sensing devices. However, the low surface area of these nanostructures is a significant drawback for most applications. Here, we report the synthesis of ZnO/carbon composite monoliths in which carbon is used as a sacrificial template to produce zinc oxide (ZnO) porous nanostructures with a high specific surface area. The synthesized porous oxides of ZnO with a specific surface area of 78 m2/g are at least one order of magnitude higher than that of the ZnO nanotubes reported in the literature. The crucial point to achieving this remarkable result was the usage of a novel ZnO/carbon template where the carbon template was removed by simple heating in the air. As a high surface area porous nanostructured ZnO, these synthesized materials can be useful in various applications including catalysis, photocatalysis, separation, sensing, solar energy harvest and Zn-ion battery and as supercapacitors for energy storage. [ABSTRACT FROM AUTHOR]

A mixed solvent solvothermal approach was employed for the synthesis of NiO (NO) nanostructures under a low temperature route. The nanoflakes when studied for its electrochemical performance in a 3-electrode method in aqueous 2 M KOH revealed a high capacitance value of 305.0 F g−1 at a scan rate of 5 mV s−1 apart from good rate capability, cyclic stability and coulombic efficiency. The fabricated symmetrical supercapacitor device also showed good electrochemical performance of pseudocapacitive nature with a high power density of 8000.0 W kg−1. The extent of surface sites taking part in the electrochemical processes reveals the enhanced performance is due to the high surface area of NO with a mesoporous structure. The enhanced conductivity of the nanoflakes also provided an unhindered path way for the ionic transport. The promising results reveal that the synthetic technique employed could be extended to other oxides as well. Simple solvothermal synthesis of NiO nanoflakes using mixed solvent system for supercapacitor applications with high rate capability and cyclic stability. [Display omitted] • Simple solvothermal synthesis of NiO nanoflakes. • Use of unique mixed solvent system for the solvothermal synthesis. • Nanomaterial exhibits good specific capacitance and coulombic efficiency. • NiO nanoflakes show high rate capability and high cyclic stability. [ABSTRACT FROM AUTHOR]

Abstract: A simple and cost-effective method for the production of porous macro–meso structures is proposed. The approach involves using of monodispersed silica particles and in situ polymerized silica network as a removable template, and using resorcinol-sucrose derivative polymer as a carbon source. The three steps – carbon precursor, silica particles, template – are synthesized simultaneously through sol–gel reaction in one-pot system. The sample prepared by this method was characterized by scanning electron microscopy (SEM) and nitrogen adsorption and desorption, and the results present us a well long-ranged ordered structure and three-dimensionally interconnected macroporous carbon with mesoporosity. [Copyright &y& Elsevier]

Monolithic physical aerogels based on semicrystalline linear polymers are suitable for molecular separation, catalysis, and thermal insulation. These low-density materials generally exhibit thermal shrinkage in their pre-melting region. Differential Scanning Calorimetry (DSC) shows that aerogel thermal shrinkages occur with relevant step decreases of heat capacity (ΔC p < 0). For physical aerogels based on the thermodynamically stable β form of syndiotactic polystyrene (sPS), a positive heat capacity step associated with glass transition (T g) and a negative heat capacity step associated with thermal shrinkage are well separated. As for poly (2,6-dimethyl-1,4-phenylene)oxide (PPO), which exhibits the rather unique closeness of T g and T m , the two phenomena are superimposed and a regular increase of heat capacity with porosity, going from positive to progressively more negative values is observed. Negative heat capacity steps are not present for thermal shrinkage of polymer foams, which exhibit high porosity but the low surface area. On the basis of the present study, simple and fast DSC scans allow accurate evaluation of temperatures of thermal shrinkage of monolithic physical polymer aerogels. Image 1 • DSC study of monolithic physical aerogels based on semicrystalline linear polymers. • Thermal shrinkage of aerogels occur with relevant negative step decreases of heat capacity. • As for PPO, a regular change of heat capacity with porosity is described. • Negative heat capacity steps are not present for thermal shrinkage of polymer foams. • DSC scans allow accurate evaluation of temperatures of shrinkage of polymer aerogels. [ABSTRACT FROM AUTHOR]

High-specific-surface-area MgF2 was prepared by microwave-assisted solvothermal synthesis. The influences of the solvent and the magnesium precursors, and the calcination atmospheres, on the nanoparticle sizes and specific surface areas, estimated by X-Ray Powder Diffraction, N2 sorption and TEM analyses, were investigated. Nanocrystallized (~7 nm) magnesium partially hydroxylated fluorides (MgF2−x(OH)x) with significant specific surface areas between 290 and 330 m2∙g−1 were obtained. After activation under gaseous HF, MgF2−x(OH)x catalysts underwent a large decrease of both their surface area and their hydroxide, rates as shown by their 19F and 1H solid-state NMR spectra. Expect for MgF2 prepared from the acetate precursor, an activity of 30–32 mmol/h∙g was obtained which was about 40% higher compared with that of MgF2 prepared using Trifluoroacetate method (21.6 mmol/h∙g). [ABSTRACT FROM AUTHOR]

Magnesium stearate is an extremely common pharmaceutical excipient and the measurement of BET surface area via nitrogen adsorption is undertaken during pharmaceutical formulation and manufacture. In this paper, four commercial magnesium stearate materials in mono- and di-hydrated forms are analysed by nitrogen and krypton adsorption for the calculation of BET surface area. BET surface area via nitrogen adsorption is shown to be erroneously high due to a structural swelling and adsorbate encapsulation effect occurring throughout the BET range and which should preclude the use of BET theory. However, with krypton adsorption this effect commences at higher adsorption pressures and it is possible to calculate BET surface area which better represents the true surface area of the material. The disparity between nitrogen and krypton adsorption is greater for the di-hydrate form: the mean average BET surface area of 10 samples from the same di-hydrate containing batch are 23.18 m2g−1 via nitrogen adsorption and 6.78 m2g−1 via krypton. It is also shown than the standard deviation of BET surface area across 10 analyses of each of the four batches is considerably lower via krypton adsorption. Finally, an analytical protocol for krypton adsorption onto magnesium stearate for BET surface area measurement is established. [ABSTRACT FROM AUTHOR]