BET Theory Research Articles

Effects of O2 adsorption on secondary electron emission properties

The surface adsorption of gas molecules is a key factor limiting the secondary electron yield (SEY) of a material in many areas of applied physics. The influence of O2 adsorption on the SEY of metallic Ag is investigated in this work. To account for the particle distribution, we propose a BET theory based on multilayer O2 physisorption model. Furthermore, based on the phenomenological model of secondary electron (SE) emission and by taking into account the different scattering processes between electrons and particles in the adsorbed layer, we develop a numerical model of SEY in the adsorbed state using Monte Carlo simulations. The relationships among O2 adsorption, adsorption layer thickness, and SEY variation characteristics are then examined through a series of experiments. After 12-h exposure to O2, the clean samples increases 12%–19% of the maximum value of SEY and 2.3 nm in thickness of the adsorbed layer. Experimental results are also compared with the results from the MC model to determine whether the model is accurate.

Highlighting the Importance of Characterization Techniques Employed in Adsorption Using Metal-Organic Frameworks for Water Treatment.

The accumulation of toxic heavy metal ions continues to be a global concern due to their adverse effects on the health of human beings and animals. Adsorption technology has always been a preferred method for the removal of these pollutants from wastewater due to its cost-effectiveness and simplicity. Hence, the development of highly efficient adsorbents as a result of the advent of novel materials with interesting structural properties remains to be the ultimate objective to improve the adsorption efficiencies of this method. As such, advanced materials such as metal–organic frameworks (MOFs) that are highly porous crystalline materials have been explored as potential adsorbents for capturing metal ions. However, due to their diverse structures and tuneable surface functionalities, there is a need to find efficient characterization techniques to study their atomic arrangements for a better understanding of their adsorption capabilities on heavy metal ions. Moreover, the existence of various species of heavy metal ions and their ability to form complexes have triggered the need to qualitatively and quantitatively determine their concentrations in the environment. Hence, it is crucial to employ techniques that can provide insight into the structural arrangements in MOF composites as well as their possible interactions with heavy metal ions, to achieve high removal efficiency and adsorption capacities. Thus, this work provides an extensive review and discussion of various techniques such as X-ray diffraction, Brunauer–Emmett–Teller theory, scanning electron microscopy and transmission electron microscopy coupled with energy dispersive spectroscopy, and X-ray photoelectron spectroscopy employed for the characterization of MOF composites before and after their interaction with toxic metal ions. The review further looks into the analytical methods (i.e., inductively coupled plasma mass spectroscopy, ultraviolet-visible spectroscopy, and atomic absorption spectroscopy) used for the quantification of heavy metal ions present in wastewater treatment.

Preparation of magnesium aminoclay-carbon dots/TiO2 as photocatalysts for wastewater management

Magnesium aminoclay (MgAC) has been used to remove different harmful pollutants from the environment. In this study, MgAC was successfully converted into MgAC-carbon dots (MgAC-CDs) using microwave radiation, which was then used to prepare MgAC-CDs/TiO2 composites for use in water treatment. Pure TiO2, MgAC-CDs, and MgAC-CDs/TiO2 were investigated via X-ray powder diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller theory, and photoluminescence. Through these techniques, the presence of MgAC-CDs decreased the size of TiO2, and the interaction between TiO2 and MgAC-CDs led to the formation of vacant oxygen in TiO2. MgAC-CDs [0.20 g]/TiO2 had the best photocatalytic performance in the ultraviolet spectrum/light-emitting diode (LED, in visible spectrum) among all MgAC-CDs/TiO2 composites. Preliminary data indicate that a concentration of 1 mg/mL can inactivate an MS2 bacteriophage in 1 h of irradiation under ultraviolet light or LEDs. The high photocatalytic performances of MgAC-CDs/TiO2 can be explained by interactions between MgAC-CDs and TiO2, which forms a layer of vacant oxygen, and also by the remaining MgAC sheet, which contributes to the high specific surface area.

Post-synthetic halogen incorporation in Zr-based MOF for enhancement of the catalytic oxidation reactions

BackgroundOne way to convert hydrocarbons to processed products is to use a catalytic oxidation reaction. The oxidation process, unlike hydrogenation, has not grown much in the industry and oxidation of CH bond is important in the production of precursors in the pharmaceutical and agronomical industries. The aim of this work is the study of catalytic properties of alcohol oxidation in the case of post-synthetic modification, as MIP-202 includes large hydrogen-bonding networks that are available to replace chloride with iodide and bromide. MethodThis is the first time that iodide and bromide have been used as active sites on heterogeneous catalysts through post-synthesis modification. These compounds were characterized by X-ray powder diffraction (PXRD), thermal gravimetric analysis (TGA), infrared spectroscopy (FT-IR), N2 gas adsorption-desorption (BET theory), scanning electron microscopes (SEM), and energy dispersive X-ray (EDX) analysis. Significance of findingsUnder ambient temperature, MIP-202-Cl, MIP-202-I, and MIP-202-Br catalyzed the oxidation of alcohols, including benzyl alcohol, with TBHP as the oxidant. Halogens are commonly used in oxidation reactions as oxygen-carrying species, called active catalytic sites. MIP-202-I is introduced as the best catalyst for improving the oxidation of alcohols, and then MIP-202-Br and MIP-202-Cl were introduced as high-efficiency catalysts, respectively.

Preparation and characterization of two novel osteoinductive fishbone-derived biphasic calcium phosphate bone graft substitutes.

Many studies have reported on the conversion of natural resources into xenografts with hydroxyapatite (HA) as major component, but the extraction of biphasic calcium phosphate (HA/β-TCP) from animal bones and transformation into bone graft substitutes are rarely reported. In this research, two kinds of fish bones were made into granular porous biphasic calcium phosphate bone graft substitutes with particle sizes between 500 to 1000μm through a series of preparation procedures (Salmo salar calcined at 900°C named Sa900 and Anoplopoma fimbria calcined at 800°C named An800). The chemical composition was characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The morphology and porous structure of the scaffolds were comparatively analyzed by scanning electron microscopy (SEM) and mercury porosimeter. The specific surface area of materials was measured by the nitrogen adsorption technique based on BET theory. Cytotoxicity and ectopic osteogenesis were also carried out to investigate the biocompatibility and osteoinductive potential of these materials. The results showed that both fishbone-derived scaffolds were composed of HA and β-TCP with different proportions, and numerous interconnected pores with different sizes were observed at the surface of materials. An800 had higher total porosity reaching 74.8% with higher interconnectivity and micropores mostly distributed at 0.27μm and 0.12μm, while Sa900 had a higher specific surface area and higher intraparticle porosity with nanopores mostly distributed at 0.07μm. CCK-8 assays and Live/dead staining demonstrated excellent biocompatibility. Material-induced osteoid formation were observed on the interface of both internal pores and periphery of materials after implantation in muscle pouch of Wistar rats for 8weeks which indicated some extent of osteoinductive potential of materials. The possible mechanism of material-induced osteogenesis and the effects of chemical composition, surface topography, and spatial structure on osteogenesis were also discussed in this paper.

Microwave-assisted synthesis of novel porous organic polymers for effective selective capture of CO2

Performing carbon dioxide (CO2) capture in an environmentally benign and cost-effective way is challenging owing to several factors including selectivity. Thus, the development of polymers that provide high capacity and selectivity for the removal of CO2 gas is important. N-based porous polymers are promising for CO2 capture due to their abundant porosity, variable surface characteristics, and great stability. Herein, porous organic polymers were synthesized by microwave-assisted Freidel-Crafts alkylation of 2,2′-bipyridine and pyrrole with dimethoxymethane as a cross-linker. The synthesized polymers were characterized by Fourier transform infrared, nuclear magnetic resonance, thermogravimetric analyzers, and surface analyzers based on Brunauer–Emmett–Teller theory (BET). The porous polymers exhibited high surface areas of 580 – 930 m2/g. The polymers showed high ideal adsorbed solution theory (IAST) selectivity of 53 – 63 toward CO2 over N2 at 1 bar and 298 K under flue gas composition. Whereas the selectivity toward CO2 over CH4 at 1 bar and 298 K under natural gas composition was 12 – 18. The synthesized polymers achieved exceptional H2O adsorption capacity at P/P0 = 0.9 and 293 K of 35 – 45 mmol/g. The results reveal the polymers provide promising candidates for the CO2 capture from various mixtures, such as flue gas and natural gas.

Elaboration of porous alumina nanofibers by electrospinning and molecular layer deposition for organic pollutant removal

The development of heterogeneous nanomaterials with high surface to volume ratio is crucial for enhancing the adsorption of water pollutants, such as toxic organic dyes. Here, we describe the synthesis of polyacrylonitrile (PAN) nanofibers coated with porous alumina nanolayers, and their application for adsorption of the organic dye methylene blue (MB). First, we produced PAN nanofibers by electrospinning, and then coated them with an aluminum alkoxide hybrid films fabricated using molecular layer deposition. Finally, we used thermal annealing to obtain the final PAN nanofibers coated with porous alumina nanolayers. We characterized the obtained nanostructured materials by scanning electron microscopy, transmission electron microscopy, N 2 desorption/adsorption porosimetry (BET theory), and Fourier-transform infrared spectroscopy. The porous nanomaterials had a surface area of 631.79 m 2 /g that allowed reaching an adsorption efficiency of 88% with 10 ppm MB. The adsorption kinetics and isotherms were better described by a pseudo-first-order model and the Langmuir adsorption model, respectively, based on physical adsorption (monolayer adsorption) of the adsorbed molecules. • Alucone Hybrid polymeric thin films grown on PAN nanofibers prepared by MLD route using TMA and EG as precursors. • Hybrid alucone polymeric thin films annealed in air gives a Mesoporous structure of Al 2 O 3 with a surface area of 631.8 m 2 /g. • Adsorption efficiency of 88% for 10 ppm MB dye concentration was reached due to high porosity of the alumina structure. • The adsorption of MB onto alucone is a monolayer adsorption process confirmed by the Langmuir model.

Evolution of biomass to porous graphite carbon by catalytic graphitization

The generation of porous graphitic carbon (PGC) by catalytic graphitization of biomass has been widely studied and the growth evolution mechanism needs to be further investigated. This study investigated the direct growth of PGC through sugarcane bagasse and microcrystalline cellulose as raw materials. Structural analyses by Brunauer–Emmett–Teller theory and Raman spectroscopy showed a significant improvement in graphitic structure. The SBET of PGC derived from sugarcane bagasse at 1000 °C for 1 h with 5 mmol Fe was 311 m2 g−1, and I2D/ID ratio was 0.553. The effect of growth parameters on the qualities of PGC was investigated by transition state theory and chemical reaction rate curves, and the growth mechanism of PGC was elucidated. Results showed that the biomass carbon sources evolve first from small molecule substances to graphene oxide and then to PGC under appropriate conditions. This study provided a comprehensive strategy for the rational and effective preparation of PGC and opened a clear pathway for the low-cost synthesis of graphitic carbon materials.

Applying Neural Network Model for Adsorption Methyl Paraben (MP) dye Using Ricinus Communis-capeed Fe3O4 NPs Synthesized from Aqueous Solution.

ABSTRACT: The applicability of the synthesized Ricinus Communis-capeed Fe3O4NPs as a novel adsorbent for eliminating Methyl Paraben (MP) from aqueous media was investigated. Various techniques including Brunauer Emmett Teller theory (BET), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Energy dispersive X-ray (EDX) were used to characterize this novel adsorbent. The maximum adsorption efficiency of (MP) dye onto Ricinus Communis-capeed Fe3O4 NPs was 98.6% at optimum pH value of 7.0, adsorbent dosage of 0.01 g, (MP) dye concentration of 15 mg/L, and contact time of 12 min were considered as the ideal values for (MP) dye. The adsorption data fitted well with the Langmuir isotherm model with correlation coefficient (R2 > 0.97), whereas the adsorption kinetics followed the pseudo-second-order kinetics. The use of artificial neural network model in predicting data with Levenberg–Marquardt algorithm, purlin or a linear transfer function at output layer, and training was helpful. ANN model as a tool (mean square error) MSEANN = 0.0034, MSEFL = 0.023 and MSEANFIS = 0.0020 for removal of the (MP) dye onto Ricinus Communis-capeed Fe3O4 NPs synthesis. Thermodynamic parameters of free energy (ΔG0), enthalpy (ΔH0) and entropy (ΔS0) of adsorption were determined using isotherms. ∆H0=59.58 kJ/mol, ∆G0= -2.8324 kJ/mol and ∆S0=221.15 kJ/mol. K. The value of (ΔGo, ΔHo and ΔSo) confirmed the sorption process was endothermic reflects the affinity of Ricinus Communis-capeed Fe3O4NPs for removing (MP) dye onto Ricinus Communis-capeed Fe3O4NPs process requires heat. The maximum monolayer capacity (qmax) was observed to be 195.0 mg/g for (MP) dye at desired conditions.

Women and Matrimony: A Study of Mona Lisa Smile

This study intended to use the film Mona Lisa Smile (1993) as an example to examine how women in the traditional generation of 1950 were gender stereotyped and used to trade themselves off through marriage in consideration of a cost-and-benefit analysis. However, as the change of women’s gender consciousness from the conservative to the feminist in the USA of 1950, women began to realize their potential and subjectivity, hence questing for liberal spirit and autonomy to choose their career and husbands based on love. The researchers used the qualitative method, with both the primary and secondary data, to facilitate a latent-content analysis. After conducting a content analysis of the film and the script of Mona Lisa Smile, the researchers took notes regarding gender stereotyping and conventional gender norms in social interactions and conducted a literature review of Becker’s side bet theory and Homan’s social exchange theory to investigate how women in America in the 1950s were disciplined to meet the expectation of social norms to fit the notion of conventional matrimony, and how people, both men and women, while choosing their mates, seek the maximum interest and minimum cost. The film Mona Lisa Smile lets readers have a chance to see the transformation of a marital relationship from the old days to modern ones. With raised gender consciousness, women may now subject their choices to their own will and, hence, apply a different definition to the word “marriage.”

Micro-mesoporous TiO2/SiO2 nanocomposites: Sol-gel synthesis, characterization, and enhanced photodegradation of quinoline

Micro-mesoporous TiO2/SiO2 nanocomposite powders have been successfully synthesized by the sol-gel process with different TiO2/SiO2 molar ratios and were applied in the UV-photodegradation of quinoline (λ = 254 nm). The structural, morphological, and textural characterization of the powders showed a homogeneous distribution of TiO2 nanoparticles within a porous amorphous SiO2 matrix. Due to the micro-mesoporous character of the materials, their textural characteristics were evaluated by the N2 adsorption method, by comparing BET, DR, Langmuir, and DFT theories. Si60Ti40 powders (60%SiO2/40%TiO2) presented the highest specific surface area (SSA) obtained from BET (SSA = 363 m2g-1), DR (SSA = 482 m2g-1), and Langmuir (SSA = 492 m2g-1) due to the adequate particle size of TiO2 and its high dispersion in the porous matrix. A higher degradation of quinoline in the presence of H2O2 (66%) was achieved using Si80Ti20 powders (80%SiO2/20%TiO2), as compared to pure sol-gel TiO2 powders, (51%) under the same reaction conditions (1 UVC lamp - 250W, t = 180 min). The better performance of the Si80Ti20 nanocomposite could be attributed to the small TiO2 anatase crystallite size (<5.7 nm), high dispersion of these crystallites in the SiO2 matrix, great specific surface area (DR SSA = 342 m2 g−1), and the formation of Ti–O–Si bond, which is associated with new catalytic sites in TiO2/SiO2 composite.

Ultrasonic assisted adsorption of methylene blue dye and neural network model for adsorption of methylene blue dye by synthesised Mn-doped PbS nanoparticles

ABSTRACT In the present study, the applicability of Mn-doped PbS nanoparticle synthesis for eliminating (methylene blue [MB]) dye rapidly from aqueous solutions was investigated. Identical techniques including Brunauer–Emmett–Teller theory, Fourier transform infrared, X-ray diffraction, thermogravimetric analysis, differential thermal analysis and scanning electron microscopy have been utilised to characterise this novel material. The investigation showed the applicability of Mn-doped PbS nanoparticles as an available, suitable and low-cost adsorbent for proper deletion of (MB) dye from aqueous media. Also, the impacts of variables including initial (MB) dye (X1), pH (X2), adsorbent dosage (X3), sonication time (X4), central composite design and response surface methodology (RSM) were shown. In the current article, the values of 10 mgL−1, 0.025 g and 6.0 and 5.0 min were considered as the ideal values for (MB) dye removal, respectively. The adsorption data fitted well with the Langmuir isotherm model with correlation coefficient (R 2 > 0.999), and the maximum adsorption capacities (qmax) were observed to be 200.0 mg g−1 for (MB) dye at desired conditions. The pseudo-second-order kinetics coincides quite well with the kinetic results. The thermodynamic parameters including enthalpy, entropy and Gibbs energy were calculated for the adsorption of these (MB) dyes using Mn-doped PbS nanoparticles that are suitable, spontaneous and exothermic. The use of artificial neural network model as a tool for determining mean square error (=0.607) for (MB) dye removal by Mn-doped PbS nanoparticles. Ultrasonic power had important role in shortening the adsorption time of (MB) dye by enhancing the dispersion of adsorbent in solution. Overall, Mn-doped PbS nanoparticles could be a promising adsorbent material for (MB) dye removal from aqueous solutions in a short time.

Ethanol as a Probe for the Mechanism of Bubble Nucleation in the Diet Coke and Mentos Experiment.

The Diet Coke and Mentos experiment involves dropping Mentos candies into carbonated beverages to produce a fountain. This simple experiment has enjoyed popularity with science teachers and the general public. Studies of the physicochemical processes involved in the generation of the fountain have been largely informed by the physics of bubble nucleation. Herein, we probe the effect of ethanol addition on the Diet Coke and Mentos experiment to explore the impact that beverage surface tension and viscosity have on the heights of fountains achieved. Our results indicate that current descriptions of the effects of surface tension and viscosity are not completely understood. We also extend and apply a previously reported, simplified version of Brunauer–Emmett–Teller theory to investigate kinetic and mechanistic aspects of bubble nucleation on the surface of Mentos candies in carbonated beverages. A combination of this new theory and experiment allows for the estimation that the nucleation sites on the Mentos candy that catalyze degassing are 1–3 μm in size, and that between 50,000 and 300,000 of these sites actively nucleate bubbles on a single Mentos candy. While the methods employed are not highly sophisticated, they have potential to stimulate fresh investigations and insights into bubble nucleation in carbonated beverages.

Pore structure representations based on nitrogen adsorption experiments and an FHH fractal model: Case study of the block Z shales in the Ordos Basin, China

Shale oil/gas is a crucial development in the exploitation of unconventional reservoirs. However, owing to the small pore size and complicated structure, finding an inexpensive and accurate method of accurately representing the pore structure has become an important issue. This paper summarizes and compares the current popular shale pore structure research methods and investigates three rock samples from well Z-1 and two rock samples from well Z-2 in block Z in the Ordos Basin, China. The components of the shale were analyzed using X-ray diffraction. In addition to the Brunauer–Emmett–Teller theory, there are also the Barrett, Joyner, and Halenda theoriesfor mesopores and the Horvath and Kawazoe method for macropore. Based on these theories, the pore size distribution was analyzed using nitrogen adsorption experiments at low temperatures. According to the fractal model of Frenkel–Halsey–Hill, the characteristics of the shale pore structure were studied. The fractal dimension values of single and bilinear segments fitted by double logarithm curves were applied to describe the fractal features of the pores, and the differences were compared. The relationship between the fractal characteristics and the pore parameters was analyzed. The outcomes of the tests indicate that the shale is mainly comprised of kaolinite, illite, and quartz, and the N 2 adsorption curves are type IV. There are hysteresis loops, which indicate the occurrence of multi-layer adsorption. The fractal analysis revealed that the shales have significant fractal characteristics, which are chiefly affected by the mesopores and macropores. Otherwise, the fractal dimension values of the single line segment D and the bilinear segments D1 and D2 generally consistently represent the fractal pore features. Relationships were found between the pore parameters and the fractal dimensions. • A convenient and low-cost way is used to characterize the pore structure of shale. • The fractal characteristics of pores are described by using FHH model of fractal theory. • The relationships between pore structure parameters and fractal dimensions are found. • Similarities and differences between different fitting linear segments of double logarithmic curves are found and compared. • The boundary points of pore size which leads to the changes of pore fractal characteristics are found.

Preparation and water sorption properties of novel SiO2-LiBr microcapsules for water-retaining pavement

Novel SiO 2 -LiBr microcapsules for water-retaining pavement were prepared and firstly characterized by scanning electron microscope (SEM), particle size analysis, and Fourier transform infrared spectroscopy (FT-IR). The water vapor sorption and desorption of the formulated microcapsules was then experimentally studied using dynamic vapor sorption (DVS), with the results fitted to three kinds of adsorption kinetics models. In addition, the specific surface area (SSA) was also calculated based on BET theory; and the thermal performance was investigated by laser flash analysis (LFA). Experimental results show a change of 103% in mass of the microcapsule sample under 90% relative humidity (RH) at 30 °C after water vapor sorption. The fitting of results indicates that the adsorption process is mainly governed by the intra-particle diffusion mechanism, followed by the pseudo-first-order adsorption process. In comparison with most conventional pavement materials, it is found that the SSA of the formulated microcapsules is much larger while the thermal conductivity is lower. The unique properties of the formulated SiO 2 -LiBr microcapsules have significant potential to take the edge off the urban heat island effect and reduce rutting when applied to water-retaining pavement materials.

Prussian Blue: A Safe Pigment with Zeolitic-Like Activity.

Prussian blue (PB) and PB analogues (PBA) are coordination network materials that present important similarities with zeolites concretely with their ability of adsorbing cations. Depending on the conditions of preparation, which is cheap and easy, PB can be classified into soluble PB and insoluble PB. The zeolitic-like properties are mainly inherent to insoluble form. This form presents some defects in its cubic lattice resulting in an open structure. The vacancies make PB capable of taking up and trapping ions or molecules into the lattice. Important adsorption characteristics of PB are a high specific area (370 m2 g−1 determined according the BET theory), uniform pore diameter, and large pore width. PB has numerous applications in many scientific and technological fields. PB are assembled into nanoparticles that, due to their biosafety and biocompatibility, can be used for biomedical applications. PB and PBA have been shown to be excellent sorbents of radioactive cesium and radioactive and nonradioactive thallium. Other cations adsorbed by PB are K+, Na+, NH4+, and some divalent cations. PB can also capture gaseous molecules, hydrocarbons, and even luminescent molecules such as 2-aminoanthracene. As the main adsorptive application of PB is the selective removal of cations from the environment, it is important to easily separate the sorbent of the purified solution. To facilitate this, PB is encapsulated into a polymer or coats a support, sometimes magnetic particles. Finally, is remarkable to point out that PB can be recycled and the adsorbed material can be recovered.

A Novel Method for Evaluating the Combustion Characteristics of Carbon Materials and Mold Fluxes

The combustion characteristic of mold fluxes is extremely important for the high‐quality slabs and the smooth casting process, which is directly determined by the type and content of carbon materials. Herein, the physicochemical properties and combustion characteristics of carbon materials are investigated by field emission scanning electron microscopy, X‐ray diffraction, Brunauer–Emmett–Teller theory, and thermogravimetry (TG) and differential scanning calorimetry (DSC), followed by the influences of carbon materials on the combustion and melting behavior of mold fluxes. The results show that: 1) the fixed carbon content in single‐carbon materials and carbon‐added mold fluxes can be determined by TG curves; 2) the combustion temperature ranges and the combustion reaction time of single‐carbon materials and carbon‐added mold fluxes can be characterized by DSC curves; and 3) the combustion characteristics of carbon are influenced by mold fluxes, leading to a shorter combustion reaction time. The reduction of combustion reaction time for 1# and 2# being 7.5 and 8.2 min is much larger than that of 2.4 min for 3#. Finally, the melting behavior of mold fluxes is influenced by carbon, especially the melting temperature, flowing temperature, and the melting time, showing an increase trend. However, the softening temperature shows little change.

Sorption of Methylene Blue for Studying the Specific Surface Properties of Biomass Carbohydrates

The surface area is an important parameter in setting any biorefining technology. The aim of this study was to investigate the applicability of sorption of methylene blue to characterize the surface of the main biomass carbohydrates: α-cellulose, sigmacell cellulose, natural gum, β-glucan, and starch. The morphology of particles of the model objects was studied by scanning electron microscopy. Nitrogen adsorption isotherms demonstrate that the selected carbohydrates are macroporous adsorbents. The monolayer capacities, the energy constants of the Brunauer–Emmett–Teller (BET) equation, and specific surface areas were calculated using the BET theory, the comparative method proposed by Gregg and Sing, and the Harkins–Jura method. The method of methylene blue sorption onto biomass carbohydrates was adapted and mastered. It was demonstrated that sorption of methylene blue proceeds successfully in ethanol, thus facilitating surface characterization for carbohydrates that are either soluble in water or regain water. It was found that the methylene blue sorption values correlate with specific surface area determined by nitrogen adsorption/desorption and calculated from the granulometric data. As a result of electrostatic attraction, the presence of ion-exchanged groups on the analyte surface has a stronger effect on binding of methylene blue than the surface area does. Sorption of methylene blue can be used in addition to gas adsorption/desorption to assess the accessibility of carbohydrate surface for binding large molecules.

Cu@SB-MCM-41 composite as an efficient and recyclable nanocatalyst for the synthesis of polyhydroquinoline derivatives via unsymmetrical Hantzsch reaction

In this paper, a novel Schiff-base/copper complex containing ordered mesoporous silica (Cu@SB-MCM-41) material is synthesized, characterized and its catalytic application is investigated in the one-pot synthesis of polyhydroquinolines through the Hantzsch reaction. Cu@SB-MCM-41 nanocatalyst was characterized by using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Brunauer–Emmett–Teller theory (BET), energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA) and transmission electron microscopy (TEM). This catalyst demonstrated high performance to prepare of a set of different derivatives of polyhydroquinolines under moderate reaction conditions with short reaction times. This catalyst was effectively recovered and reused several times without an important decrease in its catalytic activity.

Sintering Kinetics of Austenitic Stainless Steel AISI 316L Modified with Nanographite Particles with Highly Developed BET Specific Surface Area.

The subject of this work was the study of processes occurring during sintering of water atomized AISI 316L austenitic stainless steel powder modified by the addition of graphite nanoparticles. The main purpose of the work was to determine the effect of modification of the AISI 316L stainless steel austenitic powder by the addition of graphite nanopowder on the sintering kinetics and oxide reduction mechanism. The phenomena occurring during the sintering process and oxide reduction mechanisms were subjected to detailed characterizations. Mixtures with two types of nanopowder with a high BET (measurement technique of the specific surface area of materials based on Brunauer–Emmett–Teller theory) specific surface area of 350 and 400 m2/g and for comparison with graphite micropowder with a poorly developed BET specific surface area of 15 m2/g were tested. The conducted thermal analysis showed that the samples made of austenitic stainless steel doped with 0.2% and 0.3% by weight graphite nanopowder with a BET specific surface area of 400 m2/g, sintered best the oxide reduction reactions, with a more intensive participation of carbon, for these samples.