scholarly journals The Structure and Properties of Sepiolite with Partial Lattice Ions Substituted by Aluminum Ions

2021 ◽  
Vol 9 ◽  
Author(s):  
Huiwen Chen ◽  
Junming Geng ◽  
Zepeng Zhang ◽  
Rui Jiang ◽  
Jingya Zhai ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Bonding Strength ◽  
Surface Acidity ◽  
Functional Materials ◽  
Structure And Properties ◽  
Obvious Change ◽  
Aluminum Ions ◽  
Weather Resistance

Sepiolite was modified with Al3+ via hydrothermal reaction. The substitution amount of Al3+ for Mg2+ and Si4+ located at sepiolite lattice and the influence of substitution amount on the structure, specific surface area, and surface acidity of Al-modified sepiolite were investigated. On this basis, indigo–sepiolite composite pigments were prepared by Al-modified sepiolite and indigo via grinding method to evaluate the influence of Al-modified sepiolite on the structure, bonding strength, and weather resistance of composite pigment. The crystal structure of Al-modified sepiolite had no obvious change after modification. Al3+ mainly substituted Mg2+ located at the octahedron of the sepiolite lattice, and the substitution amount was positively related to the dosage of Al3+. The specific surface area of Al-modified sepiolite decreased and the distribution of channel size became wider after Al modification. In addition, the absolute value of zeta potential decreased as well as the solid acid sites increased with the increase of Al substitution in Al-modified sepiolite. For indigo–sepiolite composite pigments, the structure of Al-modified sepiolite had no obvious change as well. The adsorption amount of indigo in composite pigment after treating by DMSO and Al content as well as weak acid amount in Al-modified sepiolite presented linear correlation, indicating that Al modification could enhance the bonding strength between indigo and Al-modified sepiolite by increasing the amount of coordinated water with Al. For indigo, Al-modified sepiolite could brighten the color and reduce the weather resistance of the prepared composite pigment. The results of this study provide a new idea and basis for regulating the structure and properties of clay and for studying the preparation of composite pigment and clay functional materials.

scholarly journals Design and Photocatalytic Activity of Mesoporous TiO2/ZrO2 Thin Films

2005 ◽  
Vol 23 (6) ◽  
pp. 497-508 ◽  
Author(s):  
Yu. Gnatyuk ◽  
N. Smirnova ◽  
A. Eremenko ◽  
V. Ilyin
Keyword(s):  
Thin Films ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Surface Acidity ◽  
Sol Gel ◽  
Pluronic P123 ◽  
Vis Spectroscopy ◽  
Gel Technique ◽  
Doped Titania

Optically transparent, crack-free mesoporous titania and zirconia-doped titania thin films were fabricated by the sol—gel technique using the non-ionic amphiphilic triblock copolymer Pluronic P123 as the template. The structure and optical properties of these films were characterized using TEM, low-angle XRD, DTA/TG measurements, UV—vis spectroscopy and hexane adsorption investigations. It was found that addition of ZrO2 into the TiO2 matrix retarded sintering of the films, thereby increasing the specific surface area after treatment up to 500°C. The catalytic activity of the mesoporous TiO2 and TiO2/(5–30%) ZrO2 films in ethanol photo-oxidation increased with increasing specific surface area and surface acidity of the samples.

Effect of Sintering Temperature on the Structure and Properties of Attapulgite-Based Nanofibrous Membranes

2017 ◽  
Vol 898 ◽  
pp. 1929-1934
Author(s):  
Ye Kai Zhu ◽  
Da Jun Chen
Keyword(s):  
Specific Surface ◽  
Pore Size ◽  
Surface Area ◽  
Specific Surface Area ◽  
Sintering Temperature ◽  
Average Pore Size ◽  
Pure Water ◽  
Water Fluxes ◽  
Structure And Properties ◽  
Nanofibrous Membranes

Attapulgite (AT)-based nanofibrous membranes (NFMs) were fabricated via a facile papermaking procedure, and the AT-based NFMs were sintered at three different temperatures (240 °C, 400 °C, and 600 °C). The effect of sintering temperature on the structure and properties, such as specific surface area, pore size distribution, porosity, mechanical property, pure water fluxes of AT-based NFMs, were investigated. The results showed that average pore size, total pore volume, and porosity of AT-based NFMs increased with increasing of the sintering temperature, while specific surface area and flexural strength of AT-based NFMs decreased. The optimal sintering temperature for AT-based NFMs was 400 °C. In addition, it was also found that the swelling degree of AT-based NFMs in aqueous solutions was suppressed and the pure water fluxes of AT-based NFMs were improved by sintering process.

scholarly journals Physicochemical and Biological Characterization of Ti6Al4V Particles Obtained by Implantoplasty: An In Vitro Study. Part I

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6507
Author(s):  
Jorge Toledano-Serrabona ◽  
Francisco Javier Gil ◽  
Octavi Camps-Font ◽  
Eduard Valmaseda-Castellón ◽  
Cosme Gay-Escoda ◽  
...  
Keyword(s):  
Cell Viability ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
In Vitro Study ◽  
Vitro Study ◽  
Equivalent Diameter ◽  
Metal Debris ◽  
Aluminum Ions

Implantoplasty is a mechanical decontamination technique that consists of polishing the supra-osseous component of the dental implant with peri-implantitis. This technique releases metal particles in the form of metal swarf and dust into the peri-implant environment. In the present in vitro study, the following physicochemical characterization tests were carried out: specific surface area, granulometry, contact angle, crystalline structure, morphology, and ion release. Besides, cytotoxicity was in turn evaluated by determining the fibroblastic and osteoblastic cell viability. As a result, the metal debris obtained by implantoplasty presented an equivalent diameter value of 159 µm (range 6–1850 µm) and a specific surface area of 0.3 m2/g on average. The particle had a plate-like shape of different sizes. The release of vanadium ions in Hank’s solution at 37 °C showed no signs of stabilization and was greater than that of titanium and aluminum ions, which means that the alloy suffers from a degradation. The particles exhibited cytotoxic effects upon human osteoblastic and fibroblastic cells in the whole extract. In conclusion, metal debris released by implantoplasty showed different sizes, surface structures and shapes. Vanadium ion levels were higher than that those of the other metal ions, and cell viability assays showed that these particles produce a significant loss of cytocompatibility on osteoblasts and fibroblasts, which means that the main cells of the peri-implant tissues might be injured.

scholarly journals W-Sn Mixed Oxides and ZnO to Detect NOx and Ozone in Atmosphere

Proceedings ◽  
2018 ◽  
Vol 2 (13) ◽  
pp. 836
Author(s):  
Ambra Fioravanti ◽  
Sara Morandi ◽  
Alessia Amodio ◽  
Mauro Mazzocchi ◽  
Michele Sacerdoti ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Mixed Oxides ◽  
Gas Sensing ◽  
Molar Fraction ◽  
Functional Materials ◽  
X Ray Diffraction ◽  
X Ray

Thick films of zinc oxide (ZnO) in form of nanospheres or hexagonal prisms and of tungsten-tin (W-Sn) mixed oxides at nominal Sn molar fraction (0.1, 0.3 and 0.5) were prepared. The functional materials were synthesized and characterized by SEM and TEM, X-ray diffraction, specific surface area measurements, UV-Vis-NIR and IR spectroscopies. The gas sensing measurements highlighted that ZnO is more performant in form of nanoprisms, while W-Sn sensors offer a better response towards NOx and ozone with respect to pure WO3.

scholarly journals Mesostructuring layered materials: self-supported mesoporous layered double hydroxide nanotubes

Nanoscale ◽  
2021 ◽  
Author(s):  
Alysson Ferreira Morais ◽  
Dimy Nanclares ◽  
Ivan Guide Nunes da Silva ◽  
Alfredo Duarte ◽  
Fernando Assis Garcia ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Layered Double Hydroxide ◽  
Specific Surface Area ◽  
Functional Materials ◽  
Layered Materials ◽  
High Specific Surface Area ◽  
Hierarchical Porosity ◽  
Soft Templating ◽  
Double Hydroxide

Synthesis of layered materials exhibiting hierarchical porosity remains challenging, but nevertheless worthwhile because it turns such solids into functional materials with high specific surface area. Using a soft-templating strategy in...

scholarly journals EFFECT OF PHYSICOCHEMICAL PROPERTIES OF d-METAL OXIDES ON SUNFLOWER OIL TRANSESTERIFICATION

2021 ◽  
pp. 113-120
Author(s):  
Yurii Melnyk ◽  
Stepan Melnyk ◽  
Halyna Mahorivska ◽  
Viktor Reutskyy
Keyword(s):  
Specific Surface ◽  
Metal Oxides ◽  
Surface Area ◽  
Specific Surface Area ◽  
Sunflower Oil ◽  
Aqueous Suspension ◽  
Surface Acidity ◽  
Weak Acid ◽  
Transesterification Reaction ◽  
Acidity And Basicity

The physicochemical indicators of d-metal oxides (NiO, CuO, MnO, FeO, PbO, ZnO) which are heterogeneous catalysts for the transesterification process of sunflower oil triglycerides by ethanol and butan-1-ol have been determined. The available specific surface area, surface acidity and basicity, as well as the hydrogen potential change of the catalyst suspension in water were determined for the oxides. The available specific surface area of the oxides was determined by titration of their aqueous suspension with a solution of methylene blue with a predetermined concentration. The surface acidity and basicity of the catalysts were determined by back titration of samples treated with an aqueous solution of ammonia and acetic acid, respectively. It was found that all investigated d-metal oxides have a low specific surface area. The value of specific surface area is in the range of 0.6-1.5 m2/g. The surface acidity and basicity of the catalysts is 0.13-0.27 mmol/g and 0.019-0.066 mmol/g, respectively. It is shown that the change in the aqueous suspension hydrogen potential of the investigated catalysts relative to the distilled water pH is maximum for NiO and ZnO and it is 0.6-0.65, while for CuO this change is the smallest and it is only 0.3. The character of the pH change curves and the pH values of the oxides suspension in equilibrium condition indicate the presence of weak acid sites in the studied catalysts. The indicated catalysts characteristics are compared with the results obtained in the transesterification process of sunflower oil triglycerides by ethanol and butan-1-ol. It was found that there is a correlation between the surface acidity of catalyst and the reaction initial rate of triglycerides transesterification by ethanol and butan-1-ol. At the same time, such a correlation is absent for the surface basicity of the catalysts. This is consistent with the data on the catalysis of the triglyceride transesterification reaction only by strong major active sites. It is concluded that the transesterification reaction of sunflower oil triglycerides by ethanol and butan-1-ol occurs predominantly on the weak acid centers of the d-metal oxides.

Methanol to C2 and C4 fuels over (Nb/Al)-pillared clay catalysts

RSC Advances ◽  
2016 ◽  
Vol 6 (33) ◽  
pp. 27915-27921 ◽  
Author(s):  
F. C. F. Marcos ◽  
A. F. Lucrédio ◽  
J. M. Assaf ◽  
E. M. Assaf
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Low Cost ◽  
Surface Acidity ◽  
Pillared Clay ◽  
Catalytic Reactions ◽  
Large Specific Surface Area ◽  
Clay Catalysts

Pillared interlayer clay (PILC) is a low cost material, which is characterized by a large specific surface area, high pore volume and surface acidity that make it effective in catalytic reactions.

Stability constants for silicate adsorbed to ferrihydrite

Clay Minerals ◽  
1994 ◽  
Vol 29 (3) ◽  
pp. 341-350 ◽  
Author(s):  
H. C. B. Hansen ◽  
T. P. Wetche ◽  
K. Raulund-Rasmussen ◽  
O. K. Borggaard
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Equilibrium Constants ◽  
Surface Acidity ◽  
Surface Characteristics ◽  
Complexation Constant ◽  
Diffusion Controlled ◽  
Surface Equilibrium ◽  
Optimization Routine

AbstractIntrinsic surface acidity constants (Kalintr, Ka2intr) and surface complexation constant for adsorption of orthosilicate onto synthetic ferrihydrite (Ksi for the complex ≡FeOSi(OH)3) have been determined from acid/base titrations in 0.001-0.1 M NaClO4 electrolytes and silicate adsorption experiments in 0.01 M NaNOi electrolyte (pH 3-6). The surface equilibrium constants were calculated according to the two-layer model by Dzombak ' Morel (1990). Near equilibrium between protons/hydroxyls in solution and the ferrihydrite surface was obtained within minutes while equilibration with silicate required days-weeks, both reactions probably being diffusion controlled. Applying the values for specific surface area and site densities for ferrihydrite used by Dzombak ' Morel (1990) (600 m2 g–1, 3.4 μmole m–2) the constants pKalintr = 6.93 ± 0.12, pKa2intr = 8.72 ± 0.17 and log Ksi = 3.62 were calculated by using the FITEQL optimization routine. Use of the specific surface area actually measured (269 m2 g-1) gave a poorer fit of the experimental data. Due to the slow adsorption of silicate and hence long shaking times, changes in the surface characteristics of the ferrihydrite seem to take place, probably a decrease in the concentration of surface sites. Adsorption isotherms calculated using the derived equilibrium constants showed that approximately twice the amount of silicate was adsorbed at pH 5 compared with pH 3.Infrared spectroscopy of silica adsorbed to ferrihydrite showed Si-O stretching absorption maxima in the range 940-960 cm-1. The shift of the absorption maximum to higher wavenumbers with increasing amount of silicate adsorbed is probably due to an increase in the frequency of Si-O-Si bonds between orthosilicate adsorbed at adjacent sites. Small amounts of goethite were identified in the adsorption products.

Capillary Absorption of Liquid by Powder Compact and its Application on Preparation of Repeatable Cement Compacts

2010 ◽  
Vol 163-167 ◽  
pp. 2916-2919
Author(s):  
Ye Qing Shen ◽  
Min Deng
Keyword(s):  
Absorption Coefficient ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Powder Compact ◽  
Capillary Absorption ◽  
Structure And Properties ◽  
Cavity Size ◽  
Orthogonal Experiments ◽  
Deviation Degree

Preparation of repeatable cement compacts may contribute to quantitively research of processing, structure and properties of cement materials. Capillary absorption of liquid by powder compact was briefly reviewed. Deviation degree of absorption coefficient (Dac) was designed for evaluation on repeatable preparation of cement compacts. Dry cement was compacted in special moulds. A group of orthogonal experiments were designed to investigate repeatable preparation of the compacts. Results show the most important factor influencing on repeatable preparation is the cavity size of mould. The influence of force and specific surface area of cement is generally below 1.41%. According to optimum scheme for preparation, Dac is 0.00%. Repeatable preparation of cement compacts may provide a new method for quantitatively research of cement materials.

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