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In this research, cobalt-doped silica membranes were synthesized using the sol-gel method. The properties of the membrane support are of great importance for selective membrane coating. Membrane support permeability and surface roughness are two important and measurable characteristics in support selection. Therefore, two types of modified supports were selected for this study; the first support with a surface roughness of 160 nm and an average hydrogen permeance of about 5.5 × 10-7 mol m-2 s-1 Pa-1, and the second support with a surface roughness of 54 nm and an average hydrogen permeance of 3.5 × 10-6 mol m-2 s-1 Pa-1 were used. The cobalt-doped silica layer was uniformly coated on both supports, and molecular sieve activity was observed in both membranes permeation. The results show that utilizing a modified support with low surface roughness and high permeance resulted in a cobalt-doped silica membrane with pure hydrogen permeance of 1.3 × 10⁻⁷ mol m-2 s-1 Pa-1 and average ideal selectivity of 40 and 25 for H₂/N₂ and H₂/CO₂, respectively, at 150°C. Conversely, the cobalt-doped silica membrane on the modified support with high surface roughness and low permeability exhibited significantly weaker performance with pure hydrogen permeance of 1.6 × 10-9 mol m-2 s-1 Pa-1 and average ideal selectivity of 16 and 13 for H₂/N₂ and H₂/CO₂, respectively, at the same temperature. The findings demonstrate the appropriateness of the sol-gel process for producing cobalt-doped silica membranes that are selective, but they also emphasize how important it is for the support surface's roughness and permeance to affect the membrane's performance. [ABSTRACT FROM AUTHOR]

Hypothesis: The porosity of silica-based chromium catalys‌t‌s is one of the important issues in the petrochemical indus‌t‌ry due to the high catalytic activity attracted by university and indus‌t‌rial researchers. One of the mos‌t‌ important parameters that s‌t‌rengthens the s‌t‌ructure of the hydrogel is the aging process that is considered in this s‌t‌udy. By performing the aging operation on the primary silica hydrogel, the size of the initial particles increases and the surface area decreases. By doing the drying process, the pore volume of silica is reduced due to the capillary force. With changing the solvent from water to alcohols and ethyl acetate, the pore volume of the silica supported also increases. This is due to the reduction in surface tension between the silica wall and the water in the cavities.Methods: The formation of supported silica using sol-gel method and the parameters affecting it have been inves‌t‌igated. Also, in the drying s‌t‌ep by azeotropic dis‌t‌illation method, five solvents such as water, 1-propanol, 2-propanol, 1-butanol and ethyl acetate were used. FTIR, SEM and BET analyses were used to identify silica supported.Finding: The effect of organic solvents on pore volume was inves‌t‌igated; so that all hydrogels were synthesized under the same conditions, while different solvents were used in the drying s‌t‌ep by azeotropic dis‌t‌illation method. The use of different organic solvents did not show significant changes in the specific surface area of the supported silica but caused significant changes in the its pore volume. The results showed that the morphology of the silica support was improved by solvent replacement using organic solvents and the bes‌t‌ morphology and crack-free s‌t‌ructure of the ethyl acetate solvent were reported. The highes‌t‌ catalytic activity of 80 kgPE/gCr.h was obtained for slurry polymerization with silica support dried by ethyl acetate solvent.

In this research, the use of ZnO thin films, as anti-reflective layers of solar cells, is presented. The thin films were synthesized through a sol-gel method and then deposited on a P-N silicon substrate using the spin coating technique. The effect of the ZnO thin films on the efficiency of a solar cell piece was then investigated. To synthesize the ZnO films, zinc acetate dihydrate was used as the precursor, monoethanolamine (MEA) was employed as the stabilizer, and 2-methoxyethanol was used as the solvent. also in order to investigate the effect of concentration of sol-gel solution in formation of ZnO nanoparticles, samples with various concentrations were prepared and after deposition, solar cell piece was fabricated. The ZnO thin films prepared were characterized using X-ray diffraction and field emision-scanning electron microscopy, and a four-point probe was used to measure the surface resistance of the sample. Moreover, to evaluate the electrical properties of the solar cell piece, first, the back and front metal connections of the solar cell were installed using the stencil silk-screen printing method and then a solar simulator was used. The obtained results indicated that the nano-structured ZnO films with hexagonal crystallites and 30-50 nm particle sizes were successfully formed on the silicon substrate. Also, the observations unraveled that the coated ZnO films could act as an anti-reflection films and improved the efficiency of silicon solar cells. In addition, the results showed that the concentration of the sol-gel solution can have a considerable effect on the efficiency of the silicon solar cell.

Dye content of the textile industry wastewater has either chemical structure resistant against the purification processes such as physical, chemical and biological treatment methods or low removal efficiency. Thus, alternative methods must be used in order to remove the organic compounds of these effluents. In the present study we used bismuth oxide nanoparticles to remove the organic compounds from effluents of Ardabil Textile Factory. in the present study in order to use nanoparticle technology to remove organic compounds, firstly sol-gel method was used to synthesize the bismuth oxide nanoparticles, which were examined using XRD, FESEM and DRS techniques. Then, the nanoparticles were examined for their sonocatalytic and photocatalytic activities in the process of removing the organic compounds from the effluents of Ardabil Textile Factory. Results showed that compounds such as n-Decane, n-Dodecane, n-tetradecane and Hexadecane accounted for up to 70% of the abundance of chemical compounds. In the nanoparticle-free sample subject to ultrasonic waves, the removal rate of the chemical compounds including n-Decane, n-Dodecane, n-Tetradecane and Hexadecane was as low as 2.86%, 6.25%, 8.33% and 25%, respectively. In contrast, in the sample containing nanoparticles subject to ultrasonic waves the removal rate for n-Decane and n-Dodecane was as high as 92.14% and 95.13%, respectively, for n-Tetradecane and Hexadecane was over 99%. In the sample subject to UV and in the presence of bismuth oxide nanoparticles, n-Decane and n-Dodecane was removed by 92.82% and 93.75%, respectively, whereas n-Tetradecane and Hexadecane was removed by over 99%. results revealed that US without nanoparticles had a little efficiency in removing the organic compounds. Whereas, both the US/Bi2O3 and UV/Bi2O3 processes had a removal efficiency of over 90%. Thus, adding nanoparticles of Bi2O3 to the effluents can make a substantial contribution to the removal of organic compounds from the textile industry effluents.

In this study, mixed metal oxides Al2O3/MgO/TiO2 coatings with Al/Mg/Ti ratios of 5:1:3 and 2.5:3:4 were coated on AA1100 aluminum by sol-gel method. The surface morphology, phase analysis and the corrosion behavior of the Al2O3/MgO/TiO2 coatings were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), and electrochemical impedance spectroscopy measurements (EIS) in 3.5 wt.% NaCl solution. The thermal behaviors, the bonds configuration, and functional groups of the coated samples were studied by thermo-gravimetric and differential thermal analysis (TG-DTA) and Fourier transform infrared spectroscopy (FTIR), respectively. The results demonstrated that heat treatment at 450 °C caused an increase in porosity and coating cracking, finally leading to the decrease of corrosion resistance. The best corrosion resistance was achieved for the sample with Al/Mg/Ti molar ratio of 5:1:3 without any heat treatment. The structure of this sample was amorphous, and heat treatment resulted in crystallization and decrease of the corrosion resistance.

Highly crystalline Ce4+ -doped cadmium oxide sub-micron structures were synthesized by calcinations of the obtained precursor of a sol-gel reaction. The reaction was carried out with cadmium nitrate (Cd(NO3)2.4H2O), cerium nitrate Ce(NO3)4.6H2O and ethylene glycol (C2H6O2) reactants without any additive at 80°C for 2h. Resulting gel was calcined at 900 °C with increasing temperature rate of 15°C per minute for 12 h in a furnace. As a result of heating, the organic section of the gel was removed and Ce4+ - doped cadmium oxide micro structure was produced. The obtained material synthesized from the sol-gel technique, possesses a cubic crystalline structure at micro scale. X-ray diffraction (XRD) study indicates that the obtained Ce4+ -doped CdO has a cubic phase. SEM images showed that the resulting material is composed of particles with cluster structure. Other two techniques FT-IR and UV-Vis spectroscopies were employed for further characterization of the Ce4+ -doped CdO micro structures. Downloaded from 78.38.150.28 at 1:07 IRDT on Thursday May 25th 2017 K ey

Recently, TiO2 is one of the most important materials in the field of photocatalytic activity. In the present study, Co-TiO2, Nd-TiO2, and Co,Nd-TiO2nanocomposites powders were prepared via sol-gel method. Moreover, the advantage of metal doping and co-doped effects on photocatalytic activity were investigated. Structure and photocatalytic activity were studied by several methods such as: FT-IR spectra, Scanning Electron Microscopy (SEM), and X-Ray Diffraction (XRD). The results have revealed that Co,Nd-codoped TiO2 nanocomposite has better photocatalytic activity in comparison with Co-doped TiO2 and Nd-doped TiO2nanocopmosites.

In this letter, titanium dioxide nanoparticles (TiO2) were synthesized via a sol-gel method and combining titanium tetrachloride (TiCl4) and ethanol. The activation energy was investigated on the phase transformation from anatase to rutile in the presence and absence of ultrasound waves. The anatase nanocrystallites were only crystallized up to the calcination of 500 º C. By increasing the calcination in the region after 500 º C, rutile nanocrystallites grew in samples, and mixed-phase TiO2 nanoparticles were obtained. Our results show that applying ultrasound waves decreases both onset transition temperature and the activation energy of the phase transformation from anatase to rutile. The activation energy showed a considerable reduction at about 18.5 KJ/mol by applying the ultrasound waves.

In this research, radiation dosimetry was made through measuring free radicals induced in synthetic hydroxyapatite (HAP) using EPR spectroscopy. At the first step, the hydroxyapatite nano-powders were synthesized via sol-gel method. The produced powders were passed through a thermal treatment, weighted and packed. Then, the samples were irradiated at different dose rates using 60Co γ-ray and 10MeV electron beam radiation at a high dose range. The EPR signal intensity of hydroxyapatite samples were measured at room temperature in the air. Subsequently, the variations of the EPR signal intensities were constructed as peak-to-peak signal amplitude and were compared with alanine and bone powder samples. The results showed that the EPR signal intensity of the HAP samples are several times higher than alanine and bone powder and are saturated at the higher dose rates in comparison with other species.

"n "nBackgrounds and Objectives: Phenol and phenolic compounds are widely used in industry and daily liFe, and are of high interest due to stability in the environment, dissolution ability in water and health problems. In this regard, phenol removal from water is of high importance. The purpose of this study was to investigate the efficiency of photodegradation process for removal of phenol from aqueous system by use of Fe-doped TiO2 nanoparticles prepared by sol-gel method."nMaterials and Methods: Phenol concentrations of 5, 10, 50 and 100 mg/L were prepared and exposed to UV and Fe-doped TiO2, separately and simultaneously. Also the effect of initial phenol concentration, Fe-doped TiO2 loading and pH were studied. Various doses of photocatalist investigated for Fe- doped TiO2 were 0.25, 0.5 and 1 g/L. pH was studied at three ranges, acidic (pH=3), neutral (pH=7) and alkaline (pH=11)."nResults: Maximum degradation was obtained at acidic pH, 0.5 g/L of Fe-doped TiO2 for all of phenol concentrations. With increasing initial concentration of phenol, photocatalytic degradation decreased. In comparison with Fe-doped TiO2/UV process, efficiency of UV radiation alone was low in phenol degradation (% 64.5 at 100 mg/l of phenol concentration). Also the amount of phenol adsorbed on the Fe-doped TiO2 was negligible at dark conditions."nConclusion: Results of this study showed that Fe(III)- doped TiO2 nanoparticles had an important effect on photocatalytic degradation of high initial phenol concentration when Fe(III)-doped TiO2/ UV process applied.

In this investigation, Ag-SiO2 thin films with different concentrations of Ag (0.2, 0.4, 1.6 and 8%) has been fabricated on soda-lime glass substrate using sol-gel method. After an annealing process, physical and chemical properties of the deposited silica films containing Ag nanoparticles have been studied including optical, topographical structural, morphological and size of the nanoparticle as well as their distribution using UV-visble spectrophotometery, atomic force microscopy (AFM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques, respectively. Based on our data analysis, the Ag nanoparticles did not form in the samples with low (0.2%) and high Ag concentrations (8%), without any suitable annealing process. Instead, the nanoparticles were formed easily for the intermediate Ag concentrations. In fact, for the the low and high Ag concentration, the Ag nanoparticles formed at the annealing temperature of 200 º C. In addition, according to TEM observations, the minimum average size of the synthesized particles were determined about 4 hm for the thin films containing 0.2% Ag concentration.