Influence of Gel Aging Time on the Properties of Various Silica Aerogels Synthesized from Water Glass

2016 ◽  
Vol 866 ◽  
pp. 176-180 ◽  
Author(s):  
Sevil Yücel ◽  
Burcu Karakuzu ◽  
Pınar Terzioğlu ◽  
Tülay Merve Temel
Keyword(s):  
Aging Time ◽  
Water Glass ◽  
Silica Aerogels ◽  
Bet Surface Area ◽  
Porous Network ◽  
Surface Areas ◽  
Calcium Magnesium ◽  
Desorption Isotherms ◽  
Microscopy Techniques ◽  
Adsorption Desorption

In the present paper, water glass was used to synthesize silica aerogels and calcium magnesium silica aerogels. The present research was aimed to investigate the effect of gel aging time (1 and 24 hours) on the physical and surface properties of aerogels. Brunauer-Emmett-Teller, Barrett-Joyner-Halenda, Fourier Transform Infrared spectroscopy and scanning electron microscopy techniques were used to characterize aerogels. Successful formation of nanopores (2.8-4.4 nm) was approved by N2 adsorption/desorption isotherms. The aerogels contained porous network structure with different surface areas (388.9-729.9 m2 g-1). Aging for longer times led to an ability to decrease the density of the aerogels. The bulk density was higher in silica aerogels than in calcium magnesium silica aerogels. The well-tailored network matrix with high BET surface area (729.9 m2 g-1) and low density (0.116 g cm-3) was achieved via 24 hours gel aging of calcium magnesium silica aerogel.

Variation in Pore Structure Characteristics with Composition in the High Volatile Bituminous Coal of Binchang Area

2014 ◽  
Vol 962-965 ◽  
pp. 890-898
Author(s):  
Jin Ping Li ◽  
Da Zhen Tang ◽  
Ting Xu Yu ◽  
Gang Sun
Keyword(s):  
Low Temperature ◽  
Pore Structure ◽  
Parallel Plate ◽  
Bituminous Coal ◽  
Nitrogen Adsorption ◽  
Bet Surface Area ◽  
Test Results ◽  
Structure Characteristics ◽  
Desorption Isotherms ◽  
Adsorption Desorption

Pore structure characteristics and the effect of lithotype and maceral on pore for three types of high-volatile bituminous coals from Binchang area were investigated by combined low-temperature nitrogen adsorption/desorption, nuclear magnetic resonance (NMR), scanning electron microscope (SEM) and maceral analysis. The low temperature N2 adsorption/desorption test results show that: micropores are more abundant than transitional pores with high BET surface area; two types of pore structures can be identified by adsorption/desorption isotherms; Pore morphology is mainly represented by well-connected, ink-bottled, cylindrical and parallel plate pores. NMR T2 distributions at full saturated condition are apparent or less obvious trimodal and three types of T2 distributions are identified; Seepage pores are better developed when compared with the middle-high rank coal. Further research found that the three coal lithotypes are featured by remarkably different pore structure characteristics and maceral contents of coal are linearly correlated to some of pore structure parameters.

TiO2-BASED COMPOSITE FILMS FOR THE PHOTODEGRADATION OF OXYTETRACYCLINE

2015 ◽  
Vol 22 (02) ◽  
pp. 1550024 ◽  
Author(s):  
HUI LI ◽  
LING-XIAO GUAN ◽  
JI-JUN FENG ◽  
FANG LI ◽  
MING-MING YAO
Keyword(s):  
Visible Light ◽  
Surface Area ◽  
Composite Films ◽  
Bet Surface Area ◽  
Pl Spectra ◽  
Desorption Isotherms ◽  
Safety Of Drinking Water ◽  
Adsorption Desorption ◽  
Co Doped ◽  
Scanning Electron

The spread of the antibiotic oxytetracycline (OTC) has been thought as a threat to the safety of drinking water. In this paper, the photocatalytic activity of the nanocrystalline Fe/Ca co-doped TiO 2- SiO 2 composite film for the degradation of OTC was studied. The films were characterized by field emission scanning electron microscopy (FE-SEM) equipped with energy-dispersive spectroscopy (EDS), N 2 adsorption/desorption isotherms, photoluminescence (PL) spectra, and UV-Vis diffraction reflectance absorption spectra (DRS). The FE-SEM results indicated that the Fe/Ca co-doped TiO 2- SiO 2 film was composed of smaller nanoparticles compared to pure TiO 2 or TiO 2- SiO 2 film. The BET surface area results showed that the specific surface area of the pure TiO 2, TiO 2- SiO 2 and Ca 2+/ Fe 3+ co-doped TiO 2- SiO 2 is 118.3 m2g-1, 294.3 m2g-1 and 393.7 m2g-1, respectively. The DRS and PL spectra revealed that the Fe/Ca co-doped TiO 2- SiO 2 film had strong visible light adsorption and diminished electrons/holes recombination. Experimental results showed that the Fe / Ca co-doped TiO 2- SiO 2 film is effective in the degradation of OTC under both UV and visible light irradiation.

Mineralogical and physico-chemical properties of Heu-type zeolitic rocks SE of Ankara, central Turkey

Clay Minerals ◽  
2017 ◽  
Vol 52 (2) ◽  
pp. 191-202 ◽  
Author(s):  
Muazzez Çelik Karakaya ◽  
Necati Karakaya ◽  
Fuat Yavuz
Keyword(s):  
Chemical Properties ◽  
Bet Surface Area ◽  
Type I ◽  
Type Ii ◽  
Intermediate Type ◽  
Type Iii ◽  
Physico Chemical ◽  
Desorption Isotherms ◽  
Central Turkey ◽  
Adsorption Desorption

AbstractThis study focused on the mineralogical and physico-chemical properties of heulandite/clinoptilolite (Heu/Cpt)-rich zeolitic tuffs SE of Ankara (Turkey) and evaluated their potential for use as adsorbents. The main Heu/Cpt minerals correspond to the intermediate type and the Cpt-type of the heulandite series. Minor chabazite, erionite and rarely analcime and accessory feldspars, mica, smectite, and quartz were also detected. Three types of Heu were recognized according to their thermal behaviour. Cpt (type-III Heu) was thermally stable at 600°C, whereas type-I Heu collapsed and type-II Heu partially collapsed. The Si/Al ratios of the Hul/Cpt ranged from 3.54 to 5.03, the Γ parameter (Γ = Ca/Al + 0.115*Al) varied between 0.78 and 1.85 and Al + Fe3+varied between 6.27 and 8.00. The Na, K and Ca contents of Heu/Cpt varied widely and the Heu had an intermediate composition between types II and III. The Mg + Ca content is greater than the Na + K content in Heu-type II and smaller in Heu-type III zeolites. The BET surface area and the pore-size of the samples varied between 10.15 and 194.27 m2/g, and between 1.41 and 12.42 nm, respectively. The N2adsorption and desorption isotherms were comparable, but the adsorption/desorption capacity is greater in type III than in type II Heu zeolites. The cation exchange capacities of the Heu/Cpt-rich samples ranged from 185 to 280 meq/100 g.

Effects of High Temperature on the Microstructure of Cement Mortar

2014 ◽  
Vol 556-562 ◽  
pp. 969-972 ◽  
Author(s):  
Son Tung Pham ◽  
William Prince
Keyword(s):  
High Temperature ◽  
Elevated Temperature ◽  
Calcium Silicate Hydrate ◽  
Cement Mortar ◽  
Nitrogen Adsorption ◽  
Size Distributions ◽  
Surface Areas ◽  
Specific Surface Areas ◽  
Desorption Isotherms ◽  
Adsorption Desorption

The objective of this study was to examine microstructural changes of cement mortar due to elevated temperature from 105 to 500°C. Changes at the meso and microscopic levels were followed by nitrogen adsorption desorption isotherms, from which the pores size distributions and specific surface areas were determined. The results show a decrease in volume of micropores and an increase in volume of mesopores which reflect clearly the shrinkage and structural transformation of the calcium silicate hydrate due to high temperature.

Preparation of Silver Metallic Sponge from Macroporous Carbon Template

2006 ◽  
Vol 510-511 ◽  
pp. 770-773
Author(s):  
Jia Yan ◽  
An Jie Wang ◽  
Dong Pyo Kim
Keyword(s):  
Heat Dissipation ◽  
Reduction Reaction ◽  
Bet Surface Area ◽  
Borohydride Reduction ◽  
N2 Adsorption ◽  
Carbon Template ◽  
Desorption Isotherms ◽  
Porous Silver ◽  
Adsorption Desorption ◽  
Macroporous Carbon

Silver-containing porous frameworks have been extensively used in catalysis, electrochemistry, for heat dissipation and biofiltration. In this study, porous silver sponge was prepared by using a sacrificial macroporous carbon template. Aqueous AgNO3 was infiltrated into the carbon template and reduced to Ag by borohydride reduction reaction, followed by burning of the sacrificial template in air at 500~650°C. The products were characterized by SEM, XRD, and N2 adsorption-desorption isotherms. The Ag sponge exhibited a BET surface area of 12 m2/g.

scholarly journals Template-Based Synthesis of Nanoporous Hydroxyapatite

ISRN Ceramics ◽  
2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
E. Salimi ◽  
J. Javadpour ◽  
M. Anbia
Keyword(s):  
Pore Structure ◽  
Nonionic Surfactant ◽  
Surface Area ◽  
Cetyltrimethylammonium Bromide ◽  
Surfactant Concentration ◽  
Nonionic Surfactants ◽  
Bone Substitutes ◽  
Surface Areas ◽  
Desorption Isotherms ◽  
Adsorption Desorption

Hydroxyapatite (HAp) particles, a potential starting material for bone substitutes, with nanopores were synthesized in the presence of cetyltrimethylammonium bromide (CTAB) and P123 as cationic and nonionic surfactants as the structuring units. Effect of nonionic surfactant concentration on surface areas is also investigated. Based on N2 adsorption-desorption isotherms investigation, surface area increased up to 50 m2/g by using P123 and 147 m2/g by using CTAB as porosity agent. Pore structure remained even after the removal of surfactant and calcinations at 400°C.

scholarly journals Lignin Based Activated Carbon Using H3PO4 Activation

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2829
Author(s):  
Zhongzhi Yang ◽  
Roland Gleisner ◽  
Doreen H. Mann ◽  
Junming Xu ◽  
Jianchun Jiang ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Surface Area ◽  
Low Cost ◽  
High Surface ◽  
High Surface Area ◽  
Dye Adsorption ◽  
Nitrogen Adsorption ◽  
Bet Surface Area ◽  
Surface Areas ◽  
Adsorption Desorption

Activated carbon (AC) with a very high surface area of over 2000 m2/g was produced from low sulfur acid hydrotropic lignin (AHL) from poplar wood using H3PO4 at a moderate temperature of 450 °C (AHL-AC6). ACs with similar surface areas were also obtained under the same activation condition from commercial hardwood alkali lignin and lignosulfonate. Initial evaluation of AC performance was carried out using nitrogen adsorption-desorption and dye adsorption. AHL-AC6 exhibited the best specific surface area and dye adsorption performance. Furthermore, the adsorption results of congo red (CR) and methylene blue (MB) showed AHL-AC6 had greater adsorption capacity than those reported in literature. The dye adsorption data fit to the Langmuir model well. The fitting parameter suggests the adsorption is nearly strong and near irreversible, especially for MB. The present study for the first time provided a procedure for producing AC from lignin with Brunauer–Emmett–Teller (BET) surface area >2000 m2/g using low cost and low environmental impact H3PO4 at moderate temperatures.

A facile method to fabricate monolithic alumina–silica aerogels with high surface areas and good mechanical properties

2020 ◽  
Vol 40 (6) ◽  
pp. 2480-2488 ◽  
Author(s):  
Fei Peng ◽  
Yonggang Jiang ◽  
Junzong Feng ◽  
Liangjun Li ◽  
Huafei Cai ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Surface ◽  
Silica Aerogels ◽  
Surface Areas ◽  
Monolithic Alumina

scholarly journals Synthesis and Characterization of Nanoporous Monetite Which Can Be Applicable for Drug Carrier

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Esmael Salimi ◽  
Jafar Javadpour
Keyword(s):  
Surface Area ◽  
Cetyltrimethylammonium Bromide ◽  
Drug Carrier ◽  
Synthesis And Characterization ◽  
X Ray ◽  
Plate Shape ◽  
Desorption Isotherms ◽  
Adsorption Desorption

Wormhole-like mesostructured monetite was successfully synthesized using cetyltrimethylammonium bromide (C19H42BrN, CTAB), as a porosity agent. X-ray techniques and FTIR reveal that the crystalline grains consist of highly crystalline pure monetite phase. Monetite rods with diameter around 20–40 nm and length in the range of 50–200 nm were confirmed by FESEM and TEM. Based on N2adsorption-desorption isotherms investigation, surface area increased up to 31.5 m2/g due to the removal of surfactant after calcinations at 400°C. The results indicate that CTAB can not only affect monetite crystallization but also change particles morphology from plate shape to rod-like.

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