Effect of Carbon Pre-Treatment on Pd Dispersion in Synthesis of Pd/C Catalyst

2014 ◽  
Vol 804 ◽  
pp. 149-152 ◽  
Author(s):  
Ji Sun Kim ◽  
Jae Ho Baek ◽  
Myung Hwan Kim ◽  
Seong Soo Hong ◽  
Man Sig Lee
Keyword(s):  
Surface Area ◽  
Nitrogen Adsorption ◽  
Area Ratio ◽  
High Dispersion ◽  
Co Chemisorption ◽  
Pd Dispersion ◽  
Before And After ◽  
Pre Treatment ◽  
Treated Carbon ◽  
Adsorption Desorption

In this study, we confirmed effect of carbon pre-treatment on Pd dispersion in synthesis of Pd/C catalyst. Physical characteristics on the surface of before and after pre-treated carbon were analyzed by nitrogen adsorption-desorption analysis. The dispersion and size of Pd particles were analyzed by XRD, FE-TEM and CO-chemisorption. After pre-treatment, surface area of carbon were decreased. And mesopore area ratio were increased with decreasing micropore area ratio. In the case of pre-treated carbon, we confirmed high dispersion of Pd particles.

Texture Evaluation of Sol-Gel Derived Mesoporous Bioactive Glass

2013 ◽  
Vol 284-287 ◽  
pp. 230-234
Author(s):  
Yu Jen Chou ◽  
Chi Jen Shih ◽  
Shao Ju Shih
Keyword(s):  
Surface Area ◽  
Calcination Temperature ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Nitrogen Adsorption ◽  
Bioactive Glasses ◽  
Transmission Electron ◽  
Sol Gel Process ◽  
Adsorption Desorption

Recent years mesoporous bioactive glasses (MBGs) have become important biomaterials because of their high surface area and the superior bioactivity. Various studies have reported that when MBGs implanted in a human body, hydroxyl apatite layers, constituting the main inorganic components of human bones, will form on the MBG surfaces to increase the bioactivity. Therefore, MBGs have been widely applied in the fields of tissue regeneration and drug delivery. The sol-gel process has replaced the conventional glasses process for MBG synthesis because of the advantages of low contamination, chemical flexibility and lower calcination temperature. In the sol-gel process, several types of surfactants were mixed with MBG precursor solutions to generate micelle structures. Afterwards, these micelles decompose to form porous structures after calcination. Although calcination is significant for contamination, crystalline and surface area in MBG, to the best of the authors’ knowledge, only few systematic studies related to calcination were reported. This study correlated the calcination parameters and the microstructure of MBGs. Microstructure evaluation was characterized by transmission electron microscopy and nitrogen adsorption/desorption. The experimental results show that the surface area and the pore size of MBGs decreased with the increasing of the calcination temperature, and decreased dramatically at 800°C due to the formation of crystalline phases.

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.

scholarly journals ADSORPTION PROPERTIES OF TITANIA-SILICA MEMBRANES OBTAINED ON CERAMIC SUBSTRАTE

2018 ◽  
Vol 54 (3) ◽  
pp. 274-280
Author(s):  
T. F. Kouznetsova ◽  
A. I. Ivanets ◽  
J. D. Sauka
Keyword(s):  
Surface Area ◽  
Quartz Substrate ◽  
Cetylpyridinium Chloride ◽  
Nitrogen Adsorption ◽  
Mesoporous Structure ◽  
Adsorption Properties ◽  
Molar Ratio ◽  
Silica Membranes ◽  
Metal Silicate ◽  
Adsorption Desorption

Titania-silica membranes on a porous quartz substrate are prepared by its direct contact with metal silicate sol at various Ti/Si ratios in the conditions of coagel sedimentation and presence of cetylpyridinium chloride. The study of textural and adsorption properties of membranes is conducted by low-temperature nitrogen adsorption-desorption, including methods of t-plots and DFT theory. It was shown that obtained membranes have mesoporous structure with the specific surface area and pore hydraulic diameter varied in intervals of 64–217 m2 /g and 4–11 nm, respectively. Developed values of surface area remain up to molar ratio of Ti/Si = 50/50.

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 Physicochemical Study of 3,4-Dichlorophenoxyacetic Acid Intercalated into Hydrotalcite-Like Compound by Ion Exchanged Method

2016 ◽  
Vol 846 ◽  
pp. 440-447
Author(s):  
Sheikh Ahmad Izaddin Sheikh Mohd Ghazali ◽  
Siti Halimah Sarijo ◽  
Mohd Zobir Hussein
Keyword(s):  
Surface Area ◽  
Anion Exchange ◽  
Layered Double Hydroxide ◽  
Nitrogen Adsorption ◽  
Basal Spacing ◽  
Dichlorophenoxyacetic Acid ◽  
Exchange Method ◽  
Type Iv ◽  
Double Hydroxide ◽  
Adsorption Desorption

The intercalation of herbicide, 3,4-dicholorophenoxyacetic acid (3,4D), into zinc-aluminium-layered double hydroxide (LDH) for the formation of a new nanocomposite ZADX, was accomplished via anion exchange method. Due to the intercalation of 3,4D with LDH interlayer domain, basal spacing expanded from 8.9Å in the ZAL to 17.7-19.0 Å in the ZADX. The percentage loading of 3,4D in the ZADX is 51.4 % (w/w). The FTIR spectra of the nanocomposite shows resemblance peaks of the 3,4D and Zn-Al-layered double hydroxide indicating the inclusion of 3,4D into the layered double hydroxide. Surface area of the resulting nanocomposite increased from 1.3 to 7.14 m2g-1 with the nitrogen adsorption-desorption of type IV.

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.

Height-independent topographic parameters of worn surfaces

2011 ◽  
Vol 2 (1) ◽  
pp. 35-40
Author(s):  
I. Barányi ◽  
Á. Czifra ◽  
Gabor Kalácska
Keyword(s):  
Fractal Dimension ◽  
Surface Area ◽  
Friction And Wear ◽  
Area Ratio ◽  
Mean Square ◽  
Surface Area Ratio ◽  
Surface Microtopography ◽  
Steel Material ◽  
Before And After ◽  
Topographic Parameters

Surface microtopography plays a dual role in the course of friction and wear processes. It affectsthe contact and temperature conditions, and it undergoes significant changes in accordance with the wearmechanism. Fractal dimension (Df), root mean square gradient (Sdq), surface area ratio (Sdr) and surfacekurtosis (Sku) parameters of microtopographies provides opportunities for understanding more deeply thewear processes independently from the amplitude of the roughness. Wear experiments and surfaceroughness measurements before and after wear were performed. Investigations extended to wear in thecourse of the non-lubricated ferrodo-steel material pairs, and lubricated camshaft-bushing pairs.

A Facile Template Approach for Preparing Microstructures of Bimodal Crystalline Mesoporous Titania Powders

2012 ◽  
Vol 616-618 ◽  
pp. 1797-1800
Author(s):  
Yu Mei Gong ◽  
Qing Liang ◽  
Jing Chuan Song ◽  
Ling Ming Xia
Keyword(s):  
Electron Microscope ◽  
Surface Area ◽  
Nitrogen Adsorption ◽  
Mesoporous Titania ◽  
Mass Ratio ◽  
X Ray Diffraction ◽  
Average Pore ◽  
X Ray ◽  
Transmission Electron ◽  
Adsorption Desorption

This paper presents the preparation of bimodal crystalline macro-/mesoporous titania powders by using a pluronic polymer (EO20PO70EO20, P123) as a template through a hydrothermal treatment. The as-prepared powders were characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption, scanning electron microscope (SEM) and transmission electron microscope (TEM). The results reveal that the amount of P123 has a significant effect on the surface area of the mesoporous titania. When the mass ratio of P123:TBOT is 1:14, the crystalline macro-/mesoporous titania has the largest surface area (120.96 m2/g), the average pore diameter of this sample reaches a minimum of 6.67 nm.

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.

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