Stability of Aqueous Suspensions of High Surface area Zirconia Powders in the Presence of Polyacrylic Acid Polyelectrolyte

1992 ◽  
Vol 271 ◽  
Author(s):  
Michel M. R. Boutz ◽  
R. J. M. Olde Scholtenhuis ◽  
A. J. A. Winnubst ◽  
A. A. J. Burggraaf
Keyword(s):  
Surface Area ◽  
Polyacrylic Acid ◽  
Ph Value ◽  
High Surface ◽  
High Surface Area ◽  
Tetragonal Zirconia ◽  
Aqueous Suspensions ◽  
Optimum Ph ◽  
The Stability ◽  
Zirconia Powders

ABSTRACTIn this paper results of efforts to prepare stable aqueous suspensions of high surface area (> 100 m2 /gr) yttria stabilized tetragonal zirconia powders are presented using a low molecular weight ammonium polyacrylic acid deflocculant. Zetapotentials, viscosities, agglomerate sizes and sedimentation volumes have been measured to find the optimum pH and deflocculant concentration. It has been found that the optimum pH-value coincides with the pH at which the polyacrylic acid is fully dissociated. Using deflocculant concentrations below the optimum value leads to a highly unstable system, while concentrations above the optimum value influence the stability in a much weaker way.

Adsorption and Decoloration of Nitroso Dye Based on Eggshell Membrane

2011 ◽  
Vol 183-185 ◽  
pp. 963-966
Author(s):  
Ning Liu ◽  
Tao Liu
Keyword(s):  
Ph Value ◽  
High Surface ◽  
High Surface Area ◽  
Freundlich Isotherm ◽  
Eggshell Membrane ◽  
Eosin B ◽  
Optimum Ph ◽  
Egg Shell Membrane ◽  
Natural Biomaterial ◽  
Egg Shell

Eggshell membrane is a natural biomaterial with macropores lattice and high surface area. The bio-sorption and decolorization of organic dye eosin B was investigated based on eggshell membrane. The effect of adsorption time, pH value and temperature of eggshell membrane on the decolorization of eosin B was studied. Time for adsorption to reach equilibrium is 100 min. Optimum pH value is 2.0 for the adsorption. And the amount of dye removed by egg shell membrane was increasing as temperature ascending. At room temperature and optimum conditions, 95% of eosin B could be removed and maximum adsorption of 40.9 mg/g had been achieved. The adsorption behavior of eggshell membrane towards eosin B fit well with Freundlich isotherm.

Nitrogen and Water Sorption Properties of Ethyl-Substituted Silica Aerogels and Xerogels

1994 ◽  
Vol 371 ◽  
Author(s):  
Chunling Liu ◽  
Sridhar Komarneni
Keyword(s):  
Pore Structure ◽  
Surface Area ◽  
Water Sorption ◽  
Ph Value ◽  
High Surface ◽  
High Surface Area ◽  
Silica Aerogels ◽  
Modified Silica ◽  
Surface Areas ◽  
Water Sorption Properties

AbstractHigh surface area ethyltrimethoxysilane (ETMS) modified silica aerogels and xerogels were synthesized by cohydrolyzing the mixtures of ETMS and tetramethylorthosilicate (TMOS). The effects of ETMS content, pH value and solvent addition were investigated. The surface area, pore structure and hydrophobicity were studied using nitrogen and water sorption measurements. By ETMS modification of TMOS gels, high surface area, density and hydrophobicity were achieved. The 25 mole% ETMS-75 mole% TMOS was found to be the best composition for both aerogel and xerogel, which are hydrophobic and have surface areas of 1221 and 832 m2/g, respectively.

One-Step Hydrothermal Synthesis of MoS2 Nano-Flowers with High Surface Area and Crystalline

2012 ◽  
Vol 531-532 ◽  
pp. 508-511 ◽  
Author(s):  
Yan Juan Li ◽  
Nan Li ◽  
Xiao Yan ◽  
Yue Chi ◽  
Qing Yuan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Hydrothermal Synthesis ◽  
Surface Area ◽  
Ph Value ◽  
High Surface ◽  
High Surface Area ◽  
Ammonium Molybdate ◽  
Molar Ratio ◽  
Sulfur Source ◽  
One Step

One-step and controlled pH hydrothermal synthesis of transition metal disulfide using double molybdenum sources to synthesize MoS2 nano-flowers at low temperature was first reported. Anhydrous molybdenum pentachloride (MoCl5) and four sulfur ammonium molybdate ((NH4) 6Mo7O24•4H2O) were the molybdenum source and CS (NH2) 2 was the sulfur source. Through hydrothermal method, MoS2 was obtained at 180 °C. The pH value of system was controlled by adjusting the molar ratio of MoCl5 and (NH4) 6Mo7O24•4H2O. The products were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), surface area (BET) and transmission electron microscopy (TEM). The results show that the products were hexagonal MoS2 with a high crystalline and flower-like structure consisted of small particles. The thickness of petals is a few to tens of nanometers. By changing the molar ratio of molybdenum sources, the resultant phase from the mixed phase transited to the pure phase and the purity of synthetic MoS2 crystal increaseed.

scholarly journals Catalysis of Methanol-Air Mixture Using Platinum Nanoparticles for Microscale Combustion

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
James R. Applegate ◽  
Howard Pearlman ◽  
Smitesh D. Bakrania
Keyword(s):  
Surface Area ◽  
Platinum Nanoparticles ◽  
Flow Reactor ◽  
Catalyst Activity ◽  
High Surface ◽  
High Surface Area ◽  
Catalyst Loading ◽  
Bulk Temperature ◽  
Flow Parameters ◽  
The Stability

High surface area, active catalysts containing dispersed catalytic platinum nanoparticles (dp∼11.6 nm) on a cordierite substrate were fabricated and characterized using TEM, XRD, and SEM. The catalyst activity was evaluated for methanol oxidation. Experimental results were obtained in a miniature-scale continuous flow reactor. Subsequent studies on the effect of catalyst loading and reactor flow parameters are reported. Repeat tests were performed to assess the stability of the catalyst and the extent of deactivation, if any, that occurred due to restructuring and sintering of the particles. SEM characterization studies performed on the postreaction catalysts following repeat tests at reasonably high operating temperatures (∼500°C corresponding to ∼0.3Tmfor bulk platinum) showed evidence of sintering, yet the associated loss of surface area had minimal effect on the overall catalyst activity, as determined from bulk temperature measurements. The potential application of this work for improving catalytic devices including microscale reactors is also briefly discussed.

Preparation of high surface area CaCO3 for SO2 removal by absorption of CO2 in aqueous suspensions of Ca(OH)2

2010 ◽  
Vol 202 (1-3) ◽  
pp. 101-110 ◽  
Author(s):  
Jung-Hsin Yang ◽  
Shin-Min Shih ◽  
Chi-Ing Wu ◽  
Clifford Yi-Der Tai
Keyword(s):  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
So2 Removal ◽  
Aqueous Suspensions

scholarly journals Nanostructured TiO2 Doped with Nb as a Novel Support for PEMFC

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Edgar Valenzuela ◽  
Victor Ramos-Sanchez ◽  
Alejandro Adolfo Lambert Arista ◽  
Oumarou Savadogo
Keyword(s):  
Surface Area ◽  
High Surface ◽  
Electronic Conductivity ◽  
Catalyst Support ◽  
High Surface Area ◽  
Particle Dispersion ◽  
Metallic Oxide ◽  
Oxide Support ◽  
The Stability

Nowadays, one of the major issues of the PEMFC concerns the durability. Historically, carbon has been used as a catalyst support in PEMFC; nevertheless, under the environmental conditions of the cell, the carbon is oxidized, leaving the catalyst unsupported. In order to increase the stability and durability of the catalyst in the PEMFC, a novel nanostructured metallic oxide support is proposed. In this work, TiO2 was doped with Nb to obtain a material that combines chemical stability, high surface area, and an adequate electronic conductivity in order to be a successful catalyst support candidate for long-term PEMFC applications. The TiO2-Nb nanostructured catalyst support was physically and electrochemically characterized. According to the results, the TiO2-Nb offers high surface area and good particle dispersion; also, the electrochemical activity and stability of the support were evaluated under high potential conditions, where the TiO2-Nb proved to be much more stable than carbon.

scholarly journals Thermal degradation of defective high-surface-area UiO-66 in different gaseous environments

RSC Advances ◽  
2021 ◽  
Vol 11 (61) ◽  
pp. 38849-38855
Author(s):  
Muhammad Athar ◽  
Przemyslaw Rzepka ◽  
Debora Thoeny ◽  
Marco Ranocchiari ◽  
Jeroen Anton van Bokhoven
Keyword(s):  
Thermal Degradation ◽  
Surface Area ◽  
Decomposition Product ◽  
High Surface ◽  
High Surface Area ◽  
Tetragonal Zirconia ◽  
Heating Up

The crystallinity of the framework of UiO-66 with defects is lost upon heating at 250 °C, whereas the decomposition starts at ∼450 °C depending on the conditions. Tetragonal zirconia forms as a dominant decomposition product on heating up to 600 °C.

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