Specific Surface Area Of Mesopores Research Articles

Brown coal char CO2‐gasification kinetics with respect to the char structure part II: Kinetics and correlations

AbstractCoal's physical structure is known to affect high‐temperature coal conversion processes such as gasification or combustion. This paper is Part II of the study of brown coal char structural changes during gasification. Firstly, German Lusatian brown coal was gasified in a laboratory‐scale fluidized bed reactor in CO2 within a temperature range of 800–950 °C at atmospheric pressure. Then, physical structure properties were extensively evaluated by means of various techniques. Char specific surface area and its changes during gasification reaction were evaluated using N2 and CO2 physical adsorption techniques. Adsorption isotherms were also interpreted employing unconventional methods in order to obtain the specific surface areas of pores of different sizes. Gasification kinetics were evaluated employing three widely applied kinetic models: the random pore model (RPM), the volume reaction model (VM), and the shrinking core model (SCM). Finally, the instantaneous gasification reaction rate was correlated with the char structural properties at the corresponding conversion degrees. The closest linear correlation appeared between the gasification reaction rate and the specific surface area of mesopores (as determined by N2 adsorption). Furthermore, correlations of the other structural properties with char conversion are provided. Observed structural changes were compared with the assumptions of the kinetic models.

Modifying Zeolite ZSM-5 to Increase the Yield of Light Olefins in Cracking Feedstocks of Petroleum and Vegetable Origin

The effect modifying the HZSM-5 zeolite contained in a bizeolite catalyst has on the conversion of hydrotreated vacuum gas oil, vegetable oil, and a vacuum gas oil–vegetable oil mixture under conditions of catalytic cracking is investigated. It is found that modification lowers both the specific surface area and the volume of the meso- and micropores of HZSM-5 zeolite; the higher the phosphorus content, the greater the reduction in the main characteristics of the pore structure of the zeolite. A drop in the total acidity of P/HZSM-5 and a quantitative redistribution of weak and medium-strength acid sites are also observed. Catalytic tests of the zeolites in the cracking process show that phosphorus modification helps increase the total yield of propane–propylene and butane–butylene fractions with high olefin contents. Alkaline treatment of HZSM-5 zeolite with a high SiO2/Al2O3 ratio facilitates the extraction of silicon and increases the specific surface area of mesopores considerably. In addition, weakening of the strong acid sites of the zeolite and/or a change in the accessibility of these sites due to the partial removal of silicon is observed.

Preparation and Characterization of Wood-based Pre-oxidized Precursors and Activated Carbon Microspheres

Wood-based activated carbon microspheres (WACMs) were successfully prepared from Chinese fir. However, the weak thermal stability of the precursors resulted in melting at high activation temperatures, which led to a lower yield and poor adsorption properties. To promote the thermal stability of the precursors in the process without chemicals, this paper focused on the effects of the pre-oxidation before activation on the thermal stability and chemical structure of the precursors and the pore structure of the activated samples. The results showed that during the pre-oxidation process, the O/C ratio increased noticeably and the intensity of oxygen-containing functional groups, such as carbonyl, carboxyl, and ester groups, were enhanced, which contributed to the improvement of the thermal stability. Moreover, the etching effect of oxygen on the structure of the precursors was verified when the porous structure was enriched by activation. The activated sample pre-treated at pre-oxidation temperature 250 °C had the maximum micropore specific surface area and pore volume. As the temperature was raised to 280 °C, the mesopore specific surface area and pore volume increased, which indicated that the optimization of the pre-oxidation parameters contributed to the formation of the mesopore structure.

Modification of ZSM-5 Zeolite in order to Improve the Yield of Light Olefins during Cracking of Oil and Plant Materials

The influence of modifying HZSM-5 zeolite as a component of a bizeolite catalyst in transformations of hydrotreated vacuum gasoil, plant oil, and a mixture of vacuum gasoil and plant oil was studied. The modification with phosphorus was established to decrease the specific surface area and meso- and macropore volumes in HZSM-5 zeolite; the higher phosphorus content, the lower main characteristics of the zeolite porous structure. A decrease in the total acidity of P/HZSM-5 and quantitative redistribution between weak and moderate acid sites also was observed. Testing of the zeolites in catalytic cracking revealed that the phosphorus modification favored an increase in the total yield of propane-propylene and butane-butylene fractions containing olefins in high proportions. Alkali treatment of HZSM-4 zeolite with a high silicate module resulted in a higher silicon extraction and in a considerable increase in the specific surface area of mesopores. In addition, strong acid sites of the zeolite were transformed to weaker ones and/or their exposure changed due to partial silicon removal.

Pore structure characterization of low volatile bituminous coals with different particle size and tectonic deformation using low pressure gas adsorption

Low pressure N2 and CO2 adsorption experiments were performed on two low volatile bituminous coals to gain insights into mesopore and micropore characteristics and the effects of particle size, composition (mineral matter and maceral) and tectonic deformation on them. Original coal and tectonized coal were sieved into five particle size fractions, i.e., 18–35 mesh (0.50–1.00mm), 35–60 mesh (0.25–0.50mm), 60–120 mesh (0.125–0.250mm), 120–230 mesh (0.063–0.125mm) and 230–450 mesh (0.032–0.063mm). Low pressure gas adsorption analysis, proximate analysis and maceral analysis were conducted on each particle size fraction. Specific surface area of mesopore varies from 0.22m2/g to 3.06m2/g and from 1.00m2/g to 2.07m2/g in original coal and tectonized coal, and that of micropore is from 123.7m2/g to 164.6m2/g and from 100.7m2/g to 106.7m2/g, respectively. The vast majority of total specific surface area is within micropores. Mesopore specific surface area and volume are dependent on particle size. Decreasing particle size makes some inaccessible mesopores become accessible to N2 molecules, increasing mesopore specific surface area and volume. In contrast to mesopore characteristics, micropore characteristics are independent of particle size. Mineral matter contributes minimally to micropore specific surface area and volume. There is no consistent relationship between mineral matter and mesopore characteristics. Maceral composition, which is represented by the ratio of vitrinite to inertinite, has a uniformly negative correlation with mesopore characteristics, but plays a different role in micropore characteristics. The heterogeneity in composition resulting from sieving is reduced, so the effect of particle size on pore characteristics is weakened in the tectonized coal. Tectonic deformation enhances mesopore specific surface area and volume by removing constricted pore openings and increasing accessible mesopores. Moreover, tectonic deformation is likely to cause micropores collapse, which results in a significant decrease in micropore specific surface area and volume.

Direct synthesis of ordered meso/macrostructured phosphotungstic acid/SiO2 by EISA method and its catalytic performance of fuel oil

A series of ordered meso/macrostructured phosphotungstic acid (HPW)/SiO2 materials were synthesized by evaporation-induced self-assembly (EISA) method using nonionic surfactant (P123) and monodispersed polystyrene (PS) spheres as templates. SEM images displayed close-packed ordered macropores with an average pore size of 210nm. TEM, small-angle XRD and N2 adsorption-desorption isotherms confirmed the existence of two-dimensional (2D) hexagonal (p6mm) mesostructure, embedded in the wall of macropores. The wild-angle XRD and FT-IR spectra proved that the Keggin-type HPW were finely dispersed in a silica matrix. The composite materials were used as catalysts for oxidative desulfurization of model oil (ODS). Compared with the ordered meso/macroporous HPW/SiO2 catalyst and ordered macroporous HPW/SiO2 catalyst prepared by colloidal crystal template method, ordered meso/macroporous HPW/SiO2 catalysts synthesized through EISA method displayed much higher catalytic activity of thiophenol, dibenzothiophene (DBT) and its alkyl derivatives, achieving the thiophenol, BT, DBT, 4-MDBT and 4,6-DMDBT conversions of 100%, 83.3%, 99.3%, 89.1% and 86.5% within 40min under the optimum conditions. This feature may be attributed to the larger mesoporous specific surface area and peculiar hierarchically meso/macroporous structural characteristics of the catalyst. Moreover, the catalytic activity has no obviously decreased even after sixth cycle of uses.

Fractal and pore dispositions of coal seams with significance to coalbed methane plays of East Bokaro, Jharkhand, India

In India, much attention has been paid to the Gondwana coals of Permian age of Damodar valley, which comprises the major CBM producing blocks. East Bokaro Coalfield is part of Damodar valley and one of the promising potential CBM plays. In this study, the technological properties, TOC content, thermal maturity (Ro%), low pressure N2 sorption isotherm and SEM analyses were performed to find out the significance of fractal dimension, pore dispositions and associated geological influence on pore structure and fractal dimensions for better understanding of gas adsorption capacities of coal seams of East Bokaro. The micropore and mesopore specific surface area obtained through DR and multi-point BET ranges from 0.18 to 8.86 m2/g and 0.42–7.41 m2/g respectively, signifying dominance of micro and mesopores involvement in specific surface area. The BJH and DFT pore volume varying from 0.002 to 0.007 and 0.001–0.007 cc/g respectively. It is observed that the considerable pore volume contributed by mesopores of the range 3–50 nm and least fractions of macropores ranges from 50 to 278 nm. There is a tremendous increase in pore volume, when the pore size in between 4 and 16 nm, these pores are particularly more suitable for gas storage and associated with carbon rich vitrinite maceral. The pore size distribution obtained through BJH, DFT, DA, DR and average pore diameter values ranges from 2.99 to 10.20, 1.77–3.17, 1.42–2.48, 0.46–3.28 and 4.48–16.43 nm respectively. The opening of the hysteresis loop at lower pressure ∼0.2 (P/P0) and closing of hysteresis loop between 0.6 and 0.8 (P/P0) acutely connects to the adsorption branch is revealing of cavitation and irregularities in pore structures, consequently rapid decline in desorption curve due to the condensation and evaporation characteristics of micro and mesopores, often associated with combined slit and bottle neck pores and bottle-neck open ended shaped mesopores. The variations in correlation coefficients of two separate linear segments of fractal dimensions (D1 and D2), summarizes the suitability of D1, for pore structure analysis. Nevertheless, the low values of fractal dimensions (D1 = 1.1600–2.5450 and D2 = 1.5580–2.8730), signifies the pore surfaces are controlled by heterogeneity of coal composition. However, the correlations of D2 with ash, average pore diameter, specific surface area, Ro%, pore volume and depth accentuated that D2 may be considered for CBM reservoir characterization of East Bokaro Coalfield. The very good correlations between depth with D2, total pore volume and thermal maturity (Ro%) signifies the intensification of fractal dimensions as a function of reduction and variations in pore diameter with increasing degree of coalification. The effects of rank upon fractal dimensions are mainly due to structured variety of micropore and mesopore of coals. SEM studies supports the variations in surface morphology, pore structure and fractal dimension controlled by complex coal compositional parameters like carbon content, volatile matter, thermal maturity and pore size distribution.

The Influence of Porous Features on the Electrochemical Performance of Its Supported Platinum Catalyst in Porous Carbon Nanofibers

Porous carbon nanofibers (PCNFs) were prepared through electrospinning, pre-oxidation and carbonization with polyacrylonitrile (PAN) as carbon precursor and polymethyl methacrylate (PMMA), CaCO3 as pore-forming agents. The structure, morphology, specific surface area and electrochemical performance of the carbon nanofibers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption/desorption method and electrochemical tests. Compared with PCNFs without CaCO3, PCNFs(CaCO3 1%) had higher specific surface area, better dispersion of Pt nanoparticles, and the particle size become smaller, which was corresponding with the results of electrochemical performance test. It could be seen in cyclic voltammetry (CV) and linear sweep voltammetry (LSV) test, ECSA of Pt/PCNFs (CaCO3 1%) attained 82 m2?g?1, while that of JM20 and Pt/PCNFs without CaCO3 were 77 m2?g?1 and 60 m2?g?1, respectively. These results revealed that CaCO3 as the second pore-forming agent can further increase the mesoporous number and specific surface area of nanofibers, and can improve the electrochemical properties of Pt catalyst as the support.

Synthesis and properties of magnetic superhydrophobic mesoporous Fe2O3–SiO2 composites

Ways to obtain Fe2O3–SiO2 iron-containing silica composites with organized mesoporous structure (MCM-41) and large specific surface area (up to 1476 m2 g–1) were considered. The influence exerted by the method used to synthesize the materials on their structure, texture characteristics, particle size, and magnetic properties were studied. The aggregative stability of samples was examined. It was shown that treatment of the resulting composites with compounds from the chlorosilane group affects their hydrophobic properties.

Physicochemical Characteristics of Nitrogen Sorption on High-Porous Powders of Graphene-Like Boron Nitride

The porous structure of graphene-like boron nitride t-BNg powders is qualified. The material is homogenous and micro-mesoporous, with pores being distributed in the range 3.53–4.12 nm corresponding to 55% volume and 60% specific surface area of mesopores. The specific surface area of micropores calculated with the Dubinin–Kadlets method (t-method) is 28.3 m2/g and the specific surface area of mesopores calculated with the Barrett–Joyner–Halenda method is 141 m2/g. Powders of graphene-like t-BNg synthesized from carbamide contain impurities of polycondensed flat particles of boron oxonitride. Impurities as a refined sublimate (white powder) are separated out of the washed and dried t-BNg powder by subsequent vacuum heat treatment at 540 K and pressure to ≤1.0 Pa. The sublimate is identified as a heterocyclic six-membered dimer with molecular formula H(OH)[(BON)2](OH)H.

Hydrocarbons from Bio-oils: Performance of the Matrix in FCC Catalysts in the Immediate Catalytic Upgrading of Different Raw Bio-oils

Matrices of FCC catalysts with different content of alumina and the compound catalysts prepared with them including Y zeolite were used to upgrade bio-oils from pine wood sawdust and soybean shell. The biomasses were selected according to their different lignin content which results in very different proportions of phenolic compounds (coke precursors) in the respective bio-oils. The bio-oils were produced by fast pyrolysis and the vapours were immediately upgraded over a fixed bed of catalyst at 550 °C using a mass catalyst/bio-oil relationship of 3.5. In terms of hydrocarbon yield, the matrices were more effective in deoxygenating pine wood sawdust bio-oil and the compound catalysts in deoxygenating soybean shell bio-oil. These differences can be the consequence of the different compositions of the bio-oils which, in the case of pine wood sawdust, includes a significant concentration of phenolic ethers which form coke on the matrix and the external surface of the zeolite, thus preventing lighter compounds from accessing the micropore system of the compound catalysts. Pine sawdust bio-oil produced more coke than soybean shell bio-oil; in the case of compound catalysts, coke deposited preferentially on the catalyst matrix, thus decreasing its mesopore specific surface area up to 65 %.

Study on synthesis and properties of composite mesoporous TiO2/MCM-41 photocatalysts

Composite mesoporous TiO2/MCM-41 photocatalysts was prepared via a sol–gel method using an activated MCM-41 mesoporous molecular sieve as carrier. The morphology and photocatalytic activity of TiO2/MCM-41 photocatalysts were characterised by the X-ray diffraction, Brunauer–Emmett–Teller, Fourier transform infrared and TEM spectra, and the degradation experiment of Acid Red B aqueous solution was also investigated. The results showed that the TiO2 nanocrystalline could firmly combine with MCM-41 by Ti–O–Si. The results also showed that the samples were calcined at 600 °C for 2 h, and the prepared 30 wt-%TiO2/MCM-41 photocatalysts possessed highest photocatalytic activity with a clearer mesoporous structure and larger specific surface area. Furthermore, the composite mesoporous TiO2/MCM-41 photocatalysts exhibited excellent performance in the degradation of Acid Red B aqueous solution under ultraviolet irradiation, and the prepared photocatalysts were stable and could be recycled without considering loss of activity.

Pore structure characterization of different rank coals using gas adsorption and scanning electron microscopy

Eleven coal samples of different metamorphism are studied with regard to their pore structures. Both low-pressure nitrogen gas adsorption (LP-N2GA) and scanning electron microscopy (SEM) were performed. The use of these techniques allows us to gain clearer insight into the nature of the pore structure including the pore volume, specific area, pore size distribution (PSD) and pore shape. The LP-N2GA isotherms demonstrate strong differences in gas adsorption capacity between the coal samples studied, consistent with variability in specific surface area (SSA) of the samples. Pore geometry of coals with different metamorphism varies a lot, indicative of heterogeneity on coal surface, which was verified with SEM observation. Adsorption analysis revealed that mesopore size distributions are multi-modal, whereas, the micropore structure of the samples tested appears to be unimodal, with a major peak between 1.6 and 2.0 nm. The influence of coal rank on pore structure was also analyzed. The U-shape relationship between mesopore SSA and Vdaf is observed, demonstrating that the number of mesopores within the lower rank coals (Vdaf > 15%) decreases with increasing coal rank and the coalification mainly affects the mesopore structure. For the higher rank coals with Vdaf < 15%, as the coalification effect increases, the mesopore size diminishes and the number of micropores ascends. Smaller mesopores and micropores gradually become the dominant roles. This phenomenon is due to the effect of intensive compaction within the coal bulk. The combination of LP-N2GA and SEM techniques gives a better understanding of pore characteristics in coal. The research results will provide guidance for the gas control in coal mines.

Triple hierarchical micro–meso–macroporous carbonaceous foams bearing highly monodisperse macroporosity

The limited coalescence phenomenon occurring in Pickering emulsions stabilized by solid particles allows preparing monolithic silica foams with nearly monodisperse macroscopic voids and also meso- and microporosities. After soaking of these foam hard templates with a phenolic resin, partially graphitized interconnected porous carbon monoliths can be obtained easily. Like the silica templates, these carbon monoliths possess a hierarchical, triple porosity. Mercury intrusion porosimetry reports a macropore volume fraction of 45–70% with a narrow pore size distribution, while their specific surface area values lie between 700 and 900m2g−1 and their mesopore specific surface area between 200 and 500m2g−1. This approach allows preparing hierarchical porous carbon whose mesoporosity does not require using any soft template to organize the resin precursor.

Synthesis and electrochemical performance of mesoporous nickel oxide using mixed surfactant template

Nickel oxide is an environment-friendly transition metal oxide with relatively low cost and a kind of excellent electrode materials for supercapacitor. High surface area with favourable porosity can facilitate the electrochemical performance of NiO. Mesoporous nickel oxide was synthesised by a hydrothermal homogeneous precipitation method in this research, using mixed anionic/non-ionic surfactant as template. The influence of mixing ratio of the two constituents in the mixed surfactant was investigated. The prepared NiO samples were characterised by N2 adsorption–desorption, X-ray diffraction, scanning electron microscope and high-resolution transmission electron microscope measurements. Also, the electrochemical performances of the NiO electrode were determined by cyclic voltammetry at different scan rate and chronopotentiometry at different current density. The results showed that the prepared NiO had mesoporous structure and high specific surface area while the electrochemical performances exhibited high redox capacity, good cycle stability and great rate capability.

Organic matter/clay mineral intergranular pores in the Lower Cambrian Lujiaping Shale in the north-eastern part of the upper Yangtze area, China: A possible microscopic mechanism for gas preservation

Gas shales with a high gas content were encountered in the Lower Cambrian Lujiaping Formation in the northeast part of the upper Yangtze area, China. In this area, the tectonic condition is complex and the organic matter is over-matured, so conventional oil and gas exploration have not previously been considered. During a recent shale gas exploration, canister-desorbed gas contents of more than 1 m3/t were detected from 490 to 825 m depth, with a maximum value of 3.18 m3/t at 762 m. Hence to understand the mechanism of preservation of the gas is important. The gas shales have a total organic carbon (TOC) content of between 0.44% and 6.91%, and vitrinite-like macerals reflectance (Ro) between 3.3% and 4.3% with type II kerogen. The porosity of 22 gas shale samples ranges between 0.4% and 2.29%, and their permeability is between 6.9 × 10− 5 and 3.8 × 10− 1 mD. To investigate the shale's pore structure and its relation to gas storage behavior, we studied the microscopic mechanism of gas preservation using a combination of pore characterization techniques, including focused ion beam-scanning electron microscope (FIB-SEM) imaging, and comparison of gas sorption and free gas storage capacity. Folding, thrusting and subsequent rapid uplifting movements occurred after most of the dry gas had been originally generated, and the present gas is a mixture originated from the cracking of liquid hydrocarbons at high maturity and kerogen pyrolysis in the early hydrocarbon-generation phase. SEM observations, combined with low temperature gas adsorption and mercury injection capillary pressure analyses, show that pores within the organic matter or the mineral particles in the Lujiaping Shale are rare, while the nanometer-sized pores (1–4 nm) between organic matter and clay mineral particles, especially in cleavage domains, are greatly developed. Thus the gas in these shales is mainly adsorbed gas due to the limited free gas storage space. This is unlike most other shale gas reservoirs, pores within the organic matter and pores between or within mineral particles are dominant. Moreover, the desorbed gas content correlates well with TOC content and the microporous and mesoporous specific surface area determined by low temperature CO2 and N2, respectively, suggesting that the nanometer-sized pores associated with the organic matter make up the fundamental storage space for this shale. The calculations based on FIB-SEM observation showed that the nanometer-sized intergranular pores have large specific surface areas, with their small pore throat diameters resulting in high capillary pressure. These characteristics have contributed to the preservation of shale gas in this complex tectonic area.

Synthesis of Mesoporous Silica Nanoparticles for Drug Delivery

Mesoporous silica nanoparticles (MSNs) is an attractive candidate as a drug delivery carrier due to their large surface area, high pore volume and t intrinsic biocompatibility. Here, MSNs were synthesized by the hydrolysis and condensation of tetraethyl orthosilicate (TEOS) with cetyltrimethylammonium bromide (CTAB) acting as structural directing agent. A large mesopore with diameter of 3.8 to 5.5 nm of MCM-41style can be obtained via the addition of 1,3,5-trimethylbenzene. Metoprolol tartrate as a selective β1 receptor blocker was embedded on MSNs by the incipient wetness impregnation. The delivery profiles were collected in vitro in SBF at pH 7.4. A close correlation can be observed between the drug release kinetic and the mesopore size and specific surface area of MSNs.

Changing the relation between micro- and mesoporosity in porous glasses: The effect of different factors

The relation between micro- and mesoporosity in the porous glasses produced by leaching of two-phase alkali borosilicate glasses was studied by use of advanced classical nitrogen equilibrium adsorption–desorption methods and new kinetic method of diffusion diagnostics with mass spectral recording. The effect of different factors, such as chemical composition, conditions of acid and alkaline treatments on the change of morphology and pore characteristics of the micro- and mesoporous substructures in the porous glasses was revealed. The porous glasses are characterized by the polymodal size distribution of mesopores (up to 4 modes) and micropores (up to 3 modes). The shape of mesopores is not purely cylindrical; there is a contribution of conical and interglobular pores. The micropore volume decreases with the decrease of the mesopore specific surface area and increasing the globule diameters of secondary silica. The micropores in the porous glasses are generally the regions of interglobular contacts in secondary silica with 1–2 times the diameter of N2 molecules. The introducing lead oxide allows obtaining the porous glasses with the highest specific surface area, maximum micropore volume, and minimum micropore diameter. The introduction of phosphorus and fluorine in the glass matrix allows producing the porous glasses with the minimal porosity, mesopore surface area, micropore volume and with the maximal size of mesopores. When increasing the leaching concentration of hydrochloric acid from 1 to 3M and acid leaching time from 3 to 9h, the mesopore specific surface area decreases and the mesopore diameters increase. The effect of alkali leads to the monomodal pore size distribution of mesopores, significant increase in the mesopore volume, and significant reduction in the micropore volume. At this, the new micropores due to the dissolution of channel walls do not create.

Preparation, characterization and lysozyme immobilization studies on siliceous mesocellular foams: Effect of precursor chemistry on pore size, wall thickness and interpore spacing

Three homologous series of siliceous meso-cellular foams (MCFs) were synthesized using microemulsion templating by incremental variation of ratio of organic pore expander, trimethyl benzene (TMB), and silica precursor (TEOS) concentrations using Pluronic™ block co-polymer (P123) as the surfactant. The calcined materials were tested for lysozyme immobilization to relate the adsorption capacities to meso-structure. Small angle X-ray scattering (SAXS) shows a short range ordering of pores. The pore size and wall thickness were determined from Porod analysis of the SAXS data combined with gas adsorption data. The pore size and lysozyme loading both increase systematically with TMB/P123 ratio, and decrease with increasing TEOS/P123 ratio. By comparing gas adsorption and SAXS data, we show that the BET method overestimates the mesopore specific surface area and therefore leads to an underestimate of the pore size. The effective pore size determined by the BdB-FHH method on the other hand is consistent with that determined by SAXS surface area analysis. The wall thickness (4.4±0.5nm), interpore distance (23.9±1.5nm) and meso-pore volume fraction (0.82±0.04) are independent of synthesis conditions. The mean pore size (33±8nm, spherical equivalent) is generally larger than the interpore distance, which forces the system to adopt a more cylindrical pore morphology at large pore and window sizes, which is confirmed by SAXS and TEM. TEM shows worm-like pores intermixed along with the familiar cellular foam phase.

Preparation and Methylene Blue Adsorption Characteristics of Highly Mesoporous Rice Husk Active Carbon Prepared by an Alkali-Saving and Equipment-Friendly Method

Highly mesoporous active carbon for removing methylene blue (MB) from aqueous solution was prepared from pyrolyzed rice husk by combination of CO2activation and NaOH-solution boiling. The preparation method was found to be alkali-saving and equipment-friendly. The prepared active carbon exhibited high mesoporosity (79.1%), with mesopore volume and specific surface area up to 0.619 mL/g and 899 m2/g, respectively. At initial MB concentrations of 240-380 mg/L, the MB removal efficiency of the prepared active carbon ranged from 92% to more than 99%, fairly comparable to that of the highly mesoporous commercial active carbon used for reference. The adsorption of MB onto the prepared active carbon well followed the pseudo second-order kinetic model and Langmuir isotherm. This study indicated that highly mesoporous active carbon with large dye removal efficiency could be prepared from rice husk by an alkali-saving and equipment-friendly process.