Phase Transformation of Al2O3-SiO2-ZrO2 Composite Membranes

2010 ◽  
Vol 177 ◽  
pp. 329-333 ◽  
Author(s):  
Qian Ping Wang ◽  
Xiu Shu Tian ◽  
Shu Xian Liu ◽  
Wei Hua Wu ◽  
Zhuan Hong Huang ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Composite Membrane ◽  
Average Pore Size ◽  
Sol Gel ◽  
Composite Membranes ◽  
Optical Microscope ◽  
Phase Transformation Temperature ◽  
Low Carbon ◽  
Average Pore ◽  
Amorphous Sio2

Membrane separation process, which greatly meets the demand of reducing the environmental pollution in the modern industry, has become one of the most important strategies in the durative low carbon economy development.. This paper has studied the transformation structure mechanism of of Al2O3-SiO2-ZrO2 composite membrane produced by the sol-gel method on a porous α-Al2O3 support and the effects of SiO2 and ZrO2 in γ-Al2O3 membrane. Porous Al2O3-SiO2-ZrO2 composite membrane of the average pore size 2~4µm was obtained first time through controlling various factors, The structure crystal type and surface state are characterized by means of optical microscope, XRD, SEM, and IR. The results show that the membrane calcined at 1000°C obtain a composition of γ-Al2O3, t-ZrO2 and amorphous SiO2. The phase transformation has not appeared when heated at 1200°C. As the thermostability of the modified membrane being improved, the phase transformation temperature in the sintering process could be delayed. Therefore, the membranes properties are greatly improved.

scholarly journals Performance of Composite Membrane for Palm Oil Wastewater Treatment

2019 ◽  
Vol 23 (2) ◽  
Author(s):  
E. Yuliwati ◽  
H. Porawati ◽  
Elfidiah Elfidiah ◽  
A. Melani
Keyword(s):  
Pore Size ◽  
Surface Properties ◽  
Composite Membrane ◽  
Palm Oil ◽  
Average Pore Size ◽  
Membrane Surface ◽  
Composite Membranes ◽  
Separation Performance ◽  
Average Pore ◽  
Oil Wastewater

Polyvinylidene fluoride (PVDF) composite membranes were prepared via phase inversion method by dispersing titanium dioxide (TiO2) in the dope solution. It is aimed to study the effects of TiO2 on the membrane surface properties and thus its separation performance. The PVDF membranes modified by various TiO2 contents were characterized with respect to cross-sectional structure, average pore size, effective porosity, hydrophilicity, permeability and rejection. Maximum values of membrane hydrophilicity, membrane porosity and average pore size were achieved upon addition of 1.95% TiO2. It is found that changes in the membrane surface properties are closely corresponded with the membrane fouling. The maximum flux and rejection of organic pollutants from palm oil wastewater were recorded at 82.5 L/m2 h and 98.8 %, respectively using PVDF composite membrane incorporated with 1.95% TiO2.

Preparation and Characterization of Al2O3/TiO2/PVDF Polymer Composites Ultrafiltration Membrane

2012 ◽  
Vol 253-255 ◽  
pp. 865-870
Author(s):  
Sun Hong ◽  
Song Hua ◽  
Lu Yan
Keyword(s):  
Pore Size ◽  
Size Distribution ◽  
Composite Membrane ◽  
Polyvinylidene Fluoride ◽  
Retention Rate ◽  
Average Pore Size ◽  
Waste Water Treatment ◽  
Composite Membranes ◽  
Average Pore ◽  
Nanometer Particles

The polymer polyvinylidene fluoride (PVDF) membranes were modified by blending with nanometer particles to improve its hydrophilic property and anti-fouling performances in the process of waste water treatment. The organic macromolecule composite ultrafiltration (UF) membranes modified by the inorganic nanometer TiO2 and Al2O3 were prepared by a phase inversion process. The composite membranes performances, such as water flux, mechanical strength, water contact angle, retention rate, pores size and pores size distribution, were compared to those of organic membranes. The surface and sectional structures of membranes were observed by scanning electron microscope (SEM). The experimental results show that the composite membrane water fluxes increases 79.5% than that of organic membrane with 3% nanometer particles addition and the proportion of TiO2 and Al2O3 is 1:1. The composite membrane average pore size is larger than that of organic membrane and the pore size distribution is more uniform. The composite UF membrane has not only maintained PVDF membrane’s favorable performances but also improved its permeation performance, intensity, hydrophilic and anti-fouling performances.

Silica Sol-Gel Supported Nickel Nano-Catalyst for Hydrogen Production Using Microreactors

2005 ◽  
Vol 885 ◽  
Author(s):  
Krithi Shetty ◽  
Shihuai Zhao ◽  
Wei Cao ◽  
Naidu V. Seetala ◽  
Debasish Kuila
Keyword(s):  
Steam Reforming ◽  
Average Pore Size ◽  
Sol Gel ◽  
Supported Catalyst ◽  
Silica Sol ◽  
Average Pore ◽  
Steam Reforming Of Methanol ◽  
Nano Catalyst ◽  
Before And After ◽  
Reforming Reactions

ABSTRACTThe goal of this research is to investigate the activities of a non-noble nano-catalyst (Ni/SiO2) using Si-microreactors for steam reforming of methanol to produce hydrogen for fuel cells. The supported catalyst was synthesized by sol-gel method using Ni (II) salts and Si(C2H5O)4 as starting materials. EDX results indicate that the actual loading of Ni (5-6%) is lower than the intended loading of 12 %. The specific surface area of the silica sol-gel encapsulated Ni nano-catalyst is 452 m2/g with an average pore size of ∼ 3 nm. Steam reforming reactions have been carried out in a microreactor with 50 µm channels in the temperature range of 180-240 °C and atmospheric pressure. Results show 53% conversion of methanol with a selectivity of 74 % to hydrogen at 5 l/min and 200 °C. The magnetic properties of the catalysts were performed using a Vibrating Sample Magnetometer (VSM) to study the activity of the catalysts before and after the steam reforming reactions. The VSM results indicate much higher activity in the microreactor compared to macro-reactor and Ni forms non-ferromagnetic species faster in the microreactor.

Sol-Gel Derived Silica Layers for Low-k Dielectrics Applications

2000 ◽  
Vol 612 ◽  
Author(s):  
Sylvie Acosta ◽  
André Ayral ◽  
Christian Guizard ◽  
Charles Lecornec ◽  
Gérard Passemard ◽  
...  
Keyword(s):  
Average Pore Size ◽  
Sol Gel ◽  
Porous Silica ◽  
Thin Layers ◽  
Gaseous Ammonia ◽  
Potential Candidate ◽  
Average Pore ◽  
Synthesis Strategy ◽  
Silica Layers ◽  
Highly Porous

AbstractPorous silica exhibits attractive dielectric properties, which make it a potential candidate for use as insulator into interconnect structures. A new way of preparation of highly porous silica layers by the sol-gel route was investigated and is presented. The synthesis strategy was based on the use of common and low toxicity reagents and on the development of a simple process without gaseous ammonia post-treatment or supercritical drying step. Defect free layers were deposited by spin coating on 200 mm silicon wafers and characterized. Thin layers with a total porosity larger than 70% and an average pore size of 5 nm were produced. The dielectric constant measured under nitrogen flow on these highly porous layers is equal to ∼ 2.5, which can be compared to the value calculated from the measured porosity, ∼ 1.9. This difference is explained by the presence of water adsorbed on the hydrophilic surface of the unmodified silica.

Synthesis, characterization, and photocatalytic activity of silver and zinc co-doped TiO2 nanoparticle for photodegradation of methyl orange dye in aqueous solution

2019 ◽  
Vol 97 (9) ◽  
pp. 642-650 ◽  
Author(s):  
Gabriel O. Oladipo ◽  
Akinola K. Akinlabi ◽  
Samson O. Alayande ◽  
Titus A.M. Msagati ◽  
Hlengilizwe H. Nyoni ◽  
...  
Keyword(s):  
Methyl Orange ◽  
Pore Size ◽  
Average Pore Size ◽  
Sol Gel ◽  
Average Crystallite Size ◽  
Rutile Phase ◽  
Absorption Bands ◽  
Average Pore ◽  
Methyl Orange Dye ◽  
Co Doped

In this study, TiO2 nanocrystals, 1 mol% Ag-doped TiO2, and 1 mol% Ag and 0.6 mol% Zn co-doped TiO2 powders were synthesized by the sol–gel route. Their photocatalytic activities on methyl orange dye under visible irradiation were investigated. The powders were characterized by X-ray diffraction (XRD), UV–visible spectroscopy (UV–vis), Brunauer–Emmett–Teller (BET), and Fourier transform infrared spectroscopy (FTIR). The XRD results revealed the presence of a rutile phase with an average crystallite size of 9 and 11 nm. The UV–vis spectra showed a red-shift towards a longer wavelength with the corresponding decrease in band gap from 2.9 to 2.5 eV. The BET surface areas of the nanoparticles ranged from 4.7 to 11.8 m2 g−1 with an average pore size between 18.9 and 56.6 nm. The Ag-doped TiO2 has the largest surface area of 11.8 m2 g−1, whereas the Ag–Zn co-doped TiO2 was found to have the highest pore size and volume. The absorption bands at 750–500 cm−1 were attributed to the –O–Ti–O– bond in the TiO2 lattice. The photocatalytic efficiency was highest at an optimum pH of 4.1 for Ag–Zn co-doped TiO2. The results confirmed that Ag-doped and Ag–Zn co-doped TiO2 were more effective than pure TiO2. The kinetic data were fitted into a pseudo first-order equation using a Langmuir–Hinshelwood kinetic model.

scholarly journals Fabrication and Characterization of Strontium-Substituted Hydroxyapatite-CaO-CaCO3 Nanofibers with a Mesoporous Structure as Drug Delivery Carriers

Pharmaceutics ◽  
2018 ◽  
Vol 10 (4) ◽  
pp. 179 ◽  
Author(s):  
Shiao-Wen Tsai ◽  
Wen-Xin Yu ◽  
Pai-An Hwang ◽  
Sheng-Siang Huang ◽  
Hsiu-Mei Lin ◽  
...  
Keyword(s):  
Drug Carrier ◽  
Drug Loading ◽  
Average Pore Size ◽  
Sol Gel ◽  
Mesoporous Structure ◽  
Drug Carriers ◽  
Burst Release ◽  
Doping Amount ◽  
Sem Images ◽  
Average Pore

Hydroxyapatite (HAp) is the main inorganic component and an essential part of hard bone and teeth. Due to its excellent biocompatibility, bioactivity, and osteoconductivity, synthetic HAp has been widely used as a bone substitute, cell carrier, and therapeutic gene or drug carrier. Recently, numerous studies have demonstrated that strontium-substituted hydroxyapatite (SrHAp) not only enhances osteogenesis but also inhibits adipogenesis in mesenchymal stem cells. Mesoporous SrHAp has been successfully synthesized via a traditional template-based process and has been found to possess better drug loading and release efficiencies than SrHAp. In this study, strontium-substituted hydroxyapatite-CaO-CaCO3 nanofibers with a mesoporous structure (mSrHANFs) were fabricated using a sol–gel method followed by electrospinning. X-ray diffraction analysis revealed that the contents of CaO and CaCO3 in the mSrHANFs decreased as the doping amount of Sr increased. Scanning electron microscopy (SEM) images showed that the average diameter of the mSrHANFs was approximately 200~300 nm. The N2 adsorption–desorption isotherms demonstrated that the mSrHANFs possessed a mesoporous structure and that the average pore size was approximately 20~25 nm. Moreover, the mSrHANFs had excellent drug- loading efficiency and could retard the burst release of tetracycline (TC) to maintain antibacterial activity for over 3 weeks. Hence, mSrHANFs have the potential to be used as drug carriers in bone tissue engineering.

Porous TiO2-Al2O3 Photocatalyst: The Effects of Calcination Time

2012 ◽  
Vol 496 ◽  
pp. 165-168 ◽  
Author(s):  
Wen Jie Zhang ◽  
Hong Liang Xin
Keyword(s):  
Composite Materials ◽  
Average Pore Size ◽  
Sol Gel ◽  
Specific Area ◽  
Maximum Activity ◽  
Calcination Time ◽  
Average Pore ◽  
Porous Tio2 ◽  
Al2o3 Composite ◽  
Ft Ir

Porous TiO2-Al2O3 composite materials were prepared through sol-gel method after calcination at 500 oC for different time. FT-IR spectra of porous TiO2-Al2O3 composite materials revealed that the samples are composed of Al2O3 and TiO2. The sample calcinated for 2.5 h had the maximum specific area of 128.9 m2•g-1. High pore volume and average pore size were possessed by the samples calcinated for 1 h and 3 h. While being calcinated at 500 oC, photocatalytic activities of the materials increased at first and then dropped down with the increasing calcination time. The sample calcinated for 3 h showed the maximum activity of 35%.

Preparation and Structural Analysis of Magnesium Oxide Aerogels

MRS Advances ◽  
2017 ◽  
Vol 2 (57) ◽  
pp. 3505-3510
Author(s):  
Jiankai Zhang ◽  
Xiaohong Chen ◽  
Ran Liu ◽  
Huaihe Song ◽  
Zhihong Li
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Magnesium Oxide ◽  
Specific Surface Area ◽  
Average Pore Size ◽  
Sol Gel ◽  
Average Pore ◽  
X Ray ◽  
Water As Solvent ◽  
Saxs Analysis

ABSTRACTMagnesium oxide aerogels were made by sol-gel process using magnesium methoxide as precursor, methanol and deionized water as solvent with ethanol supercritical fluid drying. The influences of the different factors on the gel time and the specific surface area of magnesium oxide aerogels were studied, and the structure and morphology were characterized by Scanning Electron Microscopy (SEM), Transmission Electron Microscope (TEM) and X-ray diffraction (XRD), and the Small Angle X-ray Scatter (SAXS) was utilized to determine the fractural structure of the magnesium oxide aerogels. The results show that MgO aerogels belong to the typical mesoporous materials with rich network and highly developed pore structure, and the specific surface area is 904.9 m2/g, the apparent density is 0.055 g/cm3, the average pore size is 19.6 nm. The results of SAXS analysis show that the fractal dimension of the MgO aerogels is 2.32 in high q area which proves the existence of rough surface and pore fractal structure.

scholarly journals Gadolinium-Mesoporous Silica as a Potential Magnetic Resonance Imaging Contrast Agents

2018 ◽  
Vol 34 (5) ◽  
pp. 2603-2607
Author(s):  
Diana Rakhmawaty Eddy ◽  
Anni Anggraeni ◽  
Retna Putri Fauzia ◽  
Iman Rahayu ◽  
Abdul Mutalib ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Mesoporous Silica ◽  
Contrast Agents ◽  
Biomedical Application ◽  
Average Pore Size ◽  
Sol Gel ◽  
Mri Contrast Agents ◽  
Resonance Imaging ◽  
Average Pore

Gadolinium-mesoporous silica (Gd-MS) has been used widely as an alternative for synthesizing gadolinium-based Magnetic Resonance Imaging (MRI) contrast agents. In this study, Gd-MS was prepared by using the sol-gel method. Transmission Electron Microscopy (TEM) results gave an average pore size value of 38.184 nm, while the surface value of gadolinium mesoporous silica which is high at 580,666 nm. We describe the synthesis, characterization, and stability test of a novel type of magnetic nanoparticles based on Gd-Si oxide. The particles are nanosized and can enter cell easily. This is a completely novel biomedical application of mesoporous silica materials.

A Modified Chemical Route for Synthesis of Zirconia Thin Films Having Tunable Porosity

2008 ◽  
Vol 1074 ◽  
Author(s):  
Manish Kumar ◽  
G. B. Reddy
Keyword(s):  
Thin Films ◽  
Average Pore Size ◽  
Sol Gel ◽  
Dip Coating ◽  
Porous Films ◽  
Average Pore ◽  
Chemical Route ◽  
Porous Microstructure ◽  
Chemical Synthesis Route ◽  
Deposited Films

ABSTRACTA new chemical synthesis route is reported for deposition of zirconia thin films having adjustable porosity with average pore size in nanometer range. Deposition method is simply a sol-gel dip coating in which HCl is used as catalyst. TEM and FTIR studies of deposited films show porous microstructure, which depends critically on ageing of sol used. The shift in binding energy of Zr 3d5/2 (at 182.4 eV) attributes the formation of zirconia. Optical results show high transmittance (> 80%) in VIS-NIR region and effective refractive indices values (neff) tend to decrease for films prepared with higher aged sol. Porosity enhancement from 15-52% is observed by neff comparing with refractive index of non porous films (nz).

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