scholarly journals Structural Study of Microporous Xerogels Prepared by Polycondensation of Pyrogallol with Formaldehyde

2010 ◽  
Vol 6 (1) ◽  
pp. 878-883 ◽  
Author(s):  
Rebeh Moussaoui ◽  
Mongi Ben Mosbah ◽  
Younes Moussaoui ◽  
Elimame Elaloui
Keyword(s):  
Specific Surface ◽  
Aqueous Medium ◽  
Surface Area ◽  
Absorption Spectra ◽  
Structural Study ◽  
Perchloric Acid ◽  
Nitrogen Adsorption ◽  
Desorption Isotherms ◽  
Adsorption Desorption ◽  
Ftir Absorption Spectra

Microporous xerogels were prepared by polycondensation of pyrogallol with formaldehyde catalyzed by perchloric acid in aqueous medium. The samples were characterized by FTIR absorption spectra. The micro-porosity and the specific surface area are characterized by nitrogen adsorption - desorption isotherms. The obtained characteristics depend on the conditions of polycondensation.

Synthesis of Novel Core-Shell Structured Hydroxyapatite/Meso-Silica for Removal of Methylene Blue from Aqueous Solutions

2012 ◽  
Vol 463-464 ◽  
pp. 543-547 ◽  
Author(s):  
Cheng Feng Li ◽  
Xiao Lu Ge ◽  
Shu Guang Liu ◽  
Fei Yu Liu
Keyword(s):  
Methylene Blue ◽  
Aqueous Solutions ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Low Cost ◽  
Nitrogen Adsorption ◽  
Precipitation Method ◽  
Core Shell ◽  
Adsorption Desorption

Core-shell structured hydroxyapatite (HA)/meso-silica was prepared and used as absorbance of methylene blue (MB). HA/meso-silica was synthesized in three steps: preparation of nano-sized HA by wet precipitation method, coating of dense silica and deposition of meso-silica shell on HA. As-received samples were characterized by Fourier transformed infare spectra, small angle X-ray diffraction, nitrogen adsorption-desorption isotherm and transmission electron microscopy. A wormhole framework mesostructure was found for HA/meso-silica. The specific surface area and pore volume were 128 m2•g-1 and 0.36 cm3•g-1, respectively. From the adsorption isotherm, HA/meso-silica with the great specific surface area exhibited a prominent adsorption capacity of MB (134.0 mg/g) in comparison with bare HA (0 mg/g). This study might shed light on surface modification of conventional low-cost adsorbents for removal of organic pollutants from aqueous solutions.

Effects of Carbonation on the Specific Surface BET of Cement Mortar Measured by Two Different Methods: Nitrogen Adsorption and Water Adsorption

2014 ◽  
Vol 931-932 ◽  
pp. 421-425 ◽  
Author(s):  
Son Tung Pham ◽  
William Prince
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Water Adsorption ◽  
Cement Mortar ◽  
Nitrogen Adsorption ◽  
Accelerated Carbonation ◽  
Molecular Sizes ◽  
The Difference ◽  
Adsorption Desorption

The objective of this work was to examine the microstructural changes caused by the carbonation of normal mortar. Samples were prepared and subjected to accelerated carbonation at 20°C, 65% relative humidity and 20% CO2concentration. The evolutions of the pore size distribution and the specific surface area during carbonation were calculated from the adsorption - desorption isotherms of water vapour and nitrogen. Conflicts observed in the results showed that the porous domains explored by these two methods are not the same due to the difference in molecular sizes of nitrogen and water. These two techniques therefore help to complementarily evaluate the effects of carbonation. The study also helped to explain why results in the literature diverge greatly on the influence of carbonation on specific surface area.

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

Coatings ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1115
Author(s):  
Tatiana Skripkina ◽  
Ekaterina Podgorbunskikh ◽  
Aleksey Bychkov ◽  
Oleg Lomovsky
Keyword(s):  
Methylene Blue ◽  
Specific Surface ◽  
Surface Area ◽  
Surface Characterization ◽  
Gas Adsorption ◽  
Comparative Method ◽  
Nitrogen Adsorption ◽  
Surface Areas ◽  
Nitrogen Adsorption Isotherms ◽  
Adsorption Desorption

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.

scholarly journals Surface Structure Engineering of Nanosheet-Assembled NiFe2O4 Fluffy Flowers for Gas Sensing

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 297
Author(s):  
Xiaofeng Wang ◽  
Xu Li ◽  
Guozheng Zhang ◽  
Zihao Wang ◽  
Xue-Zhi Song ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Structure ◽  
Surface Area ◽  
Specific Surface Area ◽  
Photoelectron Spectroscopy ◽  
Gas Sensing ◽  
Nitrogen Adsorption ◽  
X Ray ◽  
Adsorption Desorption ◽  
Sensing Performance

In this work, we present a strategy to improve the gas-sensing performance of NiFe2O4 via a controllable annealing Ni/Fe precursor to fluffy NiFe2O4 nanosheet flowers. X-ray diffraction (XRD), a scanning electron microscope (SEM), nitrogen adsorption–desorption measurements and X-ray photoelectron spectroscopy (XPS) were used to characterize the crystal structure, morphology, specific surface area and surface structure. The gas-sensing performance was tested and the results demonstrate that the response was strongly influenced by the specific surface area and surface structure. The resultant NiFe2O4 nanosheet flowers with a heating rate of 8 °C min−1, which have a fluffier morphology and more oxygen vacancies in the surface, exhibited enhanced response and shortened response time toward ethanol. The easy approach facilitates the mass production of gas sensors based on bimetallic ferrites with high sensing performance via controlling the morphology and surface structure.

Influence of Synthesis Condition on N2 Adsorption Characteristics of Anatase TiO2 Particles Prepared in an Aqueous Solution

2008 ◽  
Vol 388 ◽  
pp. 103-106
Author(s):  
Yoshitake Masuda ◽  
Kazumi Kato
Keyword(s):  
Aqueous Solution ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Anatase Tio2 ◽  
N2 Adsorption ◽  
Tio2 Particles ◽  
Bet Specific Surface Area ◽  
Desorption Isotherms ◽  
Adsorption Desorption

TiO2 was crystallized to form particles in aqueous solutions containing ammonium hexafluorotitanate and boric acid. XRD diffraction patterns indicated they were in a single phase of anatase TiO2. TiO2 particles prepared at 90 °C exhibited N2 adsorption-desorption isotherms of type IV. BET specific surface area of the particles was estimated to 13 m2/g. On the other hand, TiO2 particles prepared at 50 °C exhibited N2 adsorption-desorption isotherms of type I. BET specific surface area of the particles was estimated to 168 m2/g. Crystal growth of TiO2 was strongly affected by synthesis temperature. Nano-sized pores or surface structure of TiO2 particles prepared at 50 °C would increase N2 adsorption volume to realize high BET specific surface area. Additionally, aqueous solution process described here had an advantage that TiO2 crystallized at ambient temperature. Anatase TiO2 was prepared without annealing at high temperature which caused aggregation of particles and disappearance of surface nanostructures. The particles with large surface area can be thus utilized for catalyst, cosmetic, photocatalyst, dye-sensitized solar cell or sensors.

Micropore formation in heated synthetic Al-goethites from a ferrous system

Clay Minerals ◽  
1996 ◽  
Vol 31 (1) ◽  
pp. 75-79 ◽  
Author(s):  
H. D. Ruan ◽  
R. J. Gilkes
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Nitrogen Adsorption ◽  
Micropore Volume ◽  
Al Substitution ◽  
Pore Area ◽  
Aluminium Substitution ◽  
Moderate Effect ◽  
Desorption Isotherms

AbstractNitrogen adsorption and desorption isotherms were obtained for microcrystalline, platy crystals of synthetic Al-substituted goethites synthesized from the ferrous system and heated to 260°C. Specific surface area, cumulative pore area and frequency of mesopore wall-separations of 2–15 nm in size increased as Al substitution increased. Nanometre-size micropores developed at heating temperatures between 200 and 240°C and decreased during the growth of hematite crystals between 240 and 260°C. Aluminium substitution had little effect on micropore development and a moderate effect on mesopore development. The increases in micropore volume and specific surface area due to heating are much smaller than is reported in the literature for large, lath-like crystals of goethite that develop abundant slit-shaped micropores.

Modifying the Silver–Titania Nanocomposites with Carbonaceous Materials to Remove the Pollutants from Domestic Waste Water

2021 ◽  
Vol 21 (4) ◽  
pp. 2278-2291
Author(s):  
Anca Peter ◽  
Leonard Mihaly Cozmuta ◽  
Camelia Nicula ◽  
Anca Mihaly Cozmuta ◽  
Catalina Mihaela Talasman ◽  
...  
Keyword(s):  
Waste Water ◽  
Photocatalytic Activity ◽  
Salicylic Acid ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Domestic Wastewater ◽  
Nitrogen Adsorption ◽  
Domestic Waste ◽  
Adsorption Desorption

The aim of this study was to prepare and characterize nanostructured composites based of TiO2, carbonaceus materials (GN or GO) and Ag and the test their capacity to remove the pollutants from domestic wastewater. The composites were characterized by IR and UV-Vis spectroscopy, X-ray diffraction, electron microscopy and nitrogen adsorption–desorption measurements. The photocatalytic activity was measured from the experiment of salicylic acid (SA) degradation. The capacity to remove the pollutants from domestic wastewater was performed by considering the absorbance of residual solution at 200 nm. The non-calcined composites have high specific surface area (˜300 m2/g), but nitrogen adsorption–desorption isotherms showed a porous structure with closed pores. The porosity of the thermal treated composites is about 10 times less, but the pores are open. The salicylic acid was 94% degraded over all composites, showing their efficient photoactivity. A percent of 70% of pollutants were removed over the calcined composites with GN and ˜67% on those with GO. It was no statistically significant difference between the photocatalytical efficiency of GN- and GO-based composites. Even if the calcined composites have the specific surface area about 10 times lower, their lower gap energy, higher degree of crystallinity and photocatalytic activity make them efficient candidates for removal of pollutants from domestic waste water. The photodegradation mechanism occurred mostly by π–π interactions between GN/GO and pollutant molecules.

Graphene Oxide-Supported Two-Dimensional Microporous Polystyrene

2013 ◽  
Vol 1549 ◽  
pp. 25-29 ◽  
Author(s):  
Yi Ouyang ◽  
Dingcai Wu ◽  
Ruowen Fu
Keyword(s):  
Graphene Oxide ◽  
Energy Storage ◽  
Carbon Tetrachloride ◽  
Specific Surface ◽  
Atom Transfer Radical Polymerization ◽  
Surface Area ◽  
Nitrogen Adsorption ◽  
Two Dimensional ◽  
Desorption Energy ◽  
Adsorption Desorption

ABSTRACTIn this paper, a microporous-containing graphene oxide/polystyrene (M-GO/PS) was designed and prepared by surface-initiated atom transfer radical polymerization (SI-ATRP) of PS from GO surface and then crossrlinking by carbon tetrachloride. The structures of the molecular brush of PS and the related crosslinking M-GO/PS were determined by FTIR, TG, SEM and nitrogen adsorption-desorption analysis. The experimental results showed that PS molecular brush were successfully grown on to the surface of GO. After crosslinking, the PS component was crosslinked into many round nanoparticles with a diameter of 20-30 nm, and therefore the specific surface area of GO/PS obviously increased. This kind of porous M-GO/PS composite was promising for the application in adsorption-desorption energy storage areas.

scholarly journals TEXTURAL AND MORPHOLOGICAL CHARACTERIZATION OF COPPER(II)-EXCHANGED ROMANIAN CALCIUM BENTONITE

2017 ◽  
Vol 20 (3) ◽  
Author(s):  
ANA-MARIA GEORGESCU ◽  
GHEORGHE BRABIE ◽  
ILEANA DENISA NISTOR ◽  
CLAUDE PENOT ◽  
FRANÇOISE NARDOU
Keyword(s):  
Ion Exchange ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Nitrogen Adsorption ◽  
Desorption Isotherm ◽  
Scanning Electron Micrographs ◽  
Adsorption Desorption ◽  
Calcium Bentonite ◽  
Scanning Electron

<p>Romanian calcium bentonite was modified by copper(II) ion-exchange, by varying the copper precursors (chloride, sulphate) and synthesis parameters (pH, temperature, time). The quantification of the Cu(II) ions was carried out by atomic absorption spectrophotometer. The modified bentonites were characterized by textural analysis (specific surface area by the Brunauer-Emmett-Teller method (BET) and by nitrogen adsorption/desorption isotherm), structural composition (X-ray diffraction (XRD)) and morphological analysis (scanning electron microscopy (SEM)). Analysis of the nitrogen adsorption/desorption isotherm shows that ion exchanged bentonites, not only contain mesopores, but micropores in larger quantities too. The values of the specific surface area increased by about 20 m<sup>2</sup>/g compared with raw bentonite, but the interlamellar distance values do not vary substantially. Scanning electron micrographs were acquired to demonstrate changes in the texture of the clay before and after ion exchange.</p>

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