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 Adsorptive removal of azithromycin from aqueous solutions using raw and saponin-modified nano diatomite

2019 ◽  
Vol 80 (5) ◽  
pp. 939-949
Author(s):  
Siavash Davoodi ◽  
Behnaz Dahrazma ◽  
Nasser Goudarzi ◽  
Hajar Ghasemian Gorji
Keyword(s):  
Aqueous Solutions ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Low Cost ◽  
Maximum Adsorption Capacity ◽  
X Ray ◽  
Low Concentrations ◽  
Intra Particle Diffusion ◽  
High Concentrations

Abstract This study aims to investigate the performance and mechanism of raw (R-ND) and saponin-modified nano diatomite (M-ND) in the removal of azithromycin from aqueous solutions. Adsorbent characterization was performed using X-ray fluorescence, Brunauer–Emmett–Teller (BET), scanning electron spectroscopy, dynamic light scattering and energy-dispersive X-ray analyses. It was shown that the specific surface area of R-ND was 119.5 m2/g, 14-fold higher than that for raw diatomite, and for M-ND it was 90.1 m2/g. Various adsorption conditions, i.e. adsorbent dosage, pH, initial concentration and contact time were investigated. According to the results, despite reducing the specific surface area by 25%, modification of nano diatomite by saponin markedly enhanced its performance in the removal of azithromycin. The maximum adsorption capacity of R-ND and M-ND in the removal of azithromycin was 68 and 91.7 mg/g, respectively. Fourier transform infrared spectroscopy results revealed that azithromycin was adsorbed by O-H groups on the diatomite surface. Weber–Morris intra-particle diffusion (IPD) model suggested that while IPD is not the rate-controlling step in high concentrations of azithromycin, it is the only step that controls the rate of adsorption in low concentrations. In comparison to R-ND, M-ND showed a higher efficiency in the removal of azithromycin and, therefore, it can be used as a promising low-cost adsorbent to remove azithromycin from aqueous solutions.

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.

scholarly journals The Role of the Aluminum Source on the Physicochemical Properties of γ-AlOOH Nanoparticles

2020 ◽  
Vol 39 (1) ◽  
pp. 89
Author(s):  
Rafael Romero Toledo ◽  
Luis M. Anaya Esparza ◽  
J. Merced Martínez Rosales
Keyword(s):  
Electron Microscopy ◽  
Physicochemical Properties ◽  
Surface Area ◽  
Low Cost ◽  
Nitrogen Adsorption ◽  
Bet Surface Area ◽  
Precipitation Method ◽  
X Ray ◽  
Aluminum Salts ◽  
Adsorption Desorption

The effect on the physicochemical properties of aluminum salts on the synthesis of γ-AlOOH nanostructures has been investigated in detail using a hydrolysis-precipitation method. X-ray fluorescence (XRF), Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM), were used to characterize the synthesized samples. The specific surface area, pore size distribution and pore diameter of the different γ-AlOOH structures were discussed by the N2 adsorption-desorption analysis. According to the results of the nanostructure, characterization revealed that for synthesized γ-AlOOH nanostructures from AlCl3 and Al(NO3)3, obvious XRD peaks corresponding to the bayerite phase are found indicating an impure γ-AlOOH phase. Furthermore, the nitrogen adsorption-desorption analysis indicated that the obtained γ-AlOOH nanoparticles from Al2(SO4)3 of technical grade (95.0 % of purity) and low cost, possess a high BET surface area of approximately 350 m2/g, compared to the obtained nanostructures from aluminum sources reactive grade, which was attributed to the presence of Mg (0.9 wt.%) in its nanostructure.

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.

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>

Preparation and Characterization of Monolithic Al2O3 Aerogels

2016 ◽  
Vol 852 ◽  
pp. 591-595
Author(s):  
Heng Chen ◽  
Xue Ye Sui ◽  
Chang Ling Zhou ◽  
Chong Hai Wang ◽  
Fu Tian Liu
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Sol Gel ◽  
Nitrogen Adsorption ◽  
Supercritical Drying ◽  
Aluminium Chloride ◽  
Porous Network ◽  
Drying Technology ◽  
Adsorption Desorption

Al2O3 aerogels were obtained through sol-gel process and ethanol supercritical drying technology using anhydrous aluminium chloride (AlCl3) and propylene oxide as precursor and gelation initiator respectively. Monolithic Al2O3 aerogels with porous and large specific surface area were achieved in our studies. Morphology and properties of Al2O3 aerogels were investigated by techniques of X-ray diffraction, Nitrogen adsorption/desorption analysis, Scanning electron microscopy, and Fourier transform infrared spectroscope. The results showed that the Al2O3 aerogels possessed a porous network microstructure made up of needles or rod-shaped particles and a specific surface area of 398 m2/g at 600°C. It was transformed to θ-Al2O3 after calcined at 1200°C.

scholarly journals Nanometer Pore Structure Characterization of Taiyuan Formation Shale in the Lin-Xing Area Based on Nitrogen Adsorption Experiments

Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 298
Author(s):  
Chenlong Ding ◽  
Jinxian He ◽  
Hongchen Wu ◽  
Xiaoli Zhang
Keyword(s):  
Specific Surface ◽  
Pore Structure ◽  
Surface Area ◽  
Specific Surface Area ◽  
Shale Gas ◽  
Pore Volume ◽  
Ordos Basin ◽  
Total Pore Volume ◽  
Nitrogen Adsorption ◽  
Taiyuan Formation

Ordos Basin is an important continental shale gas exploration site in China. The micropore structure of the shale reservoir is of great importance for shale gas evaluation. The Taiyuan Formation of the lower Permian is the main exploration interval for this area. To examine the nanometer pore structures in the Taiyuan Formation shale reservoirs in the Lin-Xing area, Northern Shaanxi, the microscopic pore structure characteristics were analyzed via nitrogen adsorption experiments. The pore structure parameters, such as specific surface area, pore volume, and aperture distribution, of shale were calculated; the significance of the pore structure for shale gas storage was analyzed; and the main controlling factors of pore development were assessed. The results indicated the surface area and hole volume of the shale sample to be 0.141–2.188 m2/g and 0.001398–0.008718 cm3/g, respectively. According to the IUPAC (International Union of Pure and Applied Chemistry) classification, mesopores and macropores were dominant in the pore structure, with the presence of a certain number of micropores. The adsorption curves were similar to the standard IV (a)-type isotherm line, and the hysteresis loop type was mainly similar to H3 and H4 types, indicating that most pores are dominated by open type pores, such as parallel plate-shaped pores and wedge-shaped slit pores. The micropores and mesopores provide the vast majority of the specific surface area, functioning as the main area for the adsorption of gas in the shale. The mesopores and macropores provide the vast majority of the pore volume, functioning as the main storage areas for the gas in the shale. Total organic carbon had no notable linear correlation with the total pore volume and the specific surface area. Vitrinite reflectance (Ro) had no notable correlation with the specific surface area, but did have a low “U” curve correlation with the total pore volume. There was no relationship between the quartz content and specific surface area and total pore volume. In addition, there was no notable correlation between the clay mineral content and total specific surface area and total pore volume.

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