Ceramic membranes are considered as alternatives for their polymeric counterparts due to high mechanical strength and thermal resistance; thus long lifetime. Usually, asymmetric ceramic membranes are synthesized including several layers with different pore size distributions with the top-layer playing the main separation role. Titania has several properties such as photocatalytic activity and chemical stability making it sutitable as an option for the top-layer. This study is devoted to the preparation and characterization of a ceramic membrane, dip-coating of mesoporous interlayers and preparation of a microporous anatase top-layer via sol–gel technique. Moreover, the performance of the membrane modified by nano-copperis investigated for salt rejection enhancement. Membranes were characterized by FE-SEM and X-ray diffraction. The sol particle size was determined using DLS. Cross-flow filtration setup was used for membrane permeability and salt retention experiments. Membrane top-layer showed crystal structures including rutile and anatase phases. By increasing salt concentration, chloride rejection is decreased and retention is increased by increasing the pressure. In case of modified membranes using nano-copper, higher retentions are observed, with 35% rejection for NaCl and 73% for Na2SO4. پرونده مقاله

Nowadays chemical and electrostatic demulsification techniques are typically used to separate water-in-crude-oil emulsions. The need to improve demulsification techniques has led to the use of various additives among which nanoparticles have emerged as a novel alternative. Most of the exploited crude oils exist in an emulsion state, where may cause serious problems during processing. Chemical demulsifiers, bottle tests, and electrostatic desalters are commonly used to separate water from crude oil emulsions but there are some issues involved with these methods. Therefore, using new technologies like nanotechnology can help improve the desalting process. First, Fe3O4 and Fe3O4-chitosan nanocomposite were synthesized via the co-precipitation method. Fe3O4-chitosan nanoparticles were characterized by X-ray diffraction and Fourier transform infrared spectroscopy. The results showed that ultrafine Fe3O4 nanoparticles were prepared and coated by chitosan. In this study, Fe3O4 and Fe3O4-chitosan nanocomposite were utilized to improve emulsion destabilization. The effect of different parameters on the separation performance was studied and the best conditions were determined. The results showed that the application of certain nanostructures in crude oil emulsions improves the performance of demulsification up to 86% and decreases the amount of demulsifier consumption in the desalting process. پرونده مقاله

Y-type zeolite can be considered among the most applied zeolites at industrial scale especially for catalytic transformations among various zeolites. Various synthesis techniques are employed to produce zeolite Y among which hydrothermal technique is considered as the most prevalent. In this study, synthesis of Y-type nano-zeolite was investigated through template-free hydrothermal technique. At various temperatures and aging times, zeolite Y was synthesized in the 10-30 nm size range with a first stage temperature of 25 °C and 87 °C as the second stage temperature. The as-synthesized zeolite was characterized using X-ray diffraction (XRD), Fourier-Transform Infrared (FTIR) spectroscopy, Field-Emission scanning electron microscopy (FE-SEM), Nitrogen adsorption–desorption, Transmission electron microscopy (TEM), and NH3-TPD and utilized as the nano-catalyst in methanol to dimethyl ether (DME) conversion process. Based on the results, at 400 °C, 53.7 % conversion to DME was obtained with 100% purity using hydrogen form of zeolite Y (H-Y) nano-catalyst. Natural zeolite is also considered as a proper additive to economize the product. پرونده مقاله

The potential of nanofluids for the improvement of heat transfer coefficient in various heat exchangeequipment has been considered and studied as a major application during recent decades. In this research,heat transfer coefficient of ZnO, TiO2 and ZnO/TiO2 nanofluids in a shell and tube heat exchanger has beenstudied experimentally. ZnO nanoparticle was synthesized through precipitation technique. Sol-gel andmechanical techniques were employed to synthesize the ZnO/TiO2 nano-composite. Particle size analysis(PSA), XRD, FTIR and FE-SEM techniques were used to characterize ZnO/TiO2 nano-composite. Based onthe results, the nanofluid heat transfer coefficient was enhanced by increasing the nanofluid concentrationand temperature. The heat transfer coefficient of TiO2 was higher than that of ZnO nanofluid and the heattransfer coefficients of nano-composites were higher than that of ZnO and TiO2 nanofluids and the basefluid. Also, the heat transfer coefficient and the overall heat transfer coefficient were increased 3.79 to9.09 times and 4.27 to 9.14, respectively by increasing the nano-composite content. پرونده مقاله

Ceramic membranes are considered as alternatives for their polymeric counterparts due to highmechanical strength and thermal resistance; thus long lifetime. Usually, asymmetric ceramicmembranes are synthesized including several layers with different pore size distributionswith the top-layer playing the main separation role. Titania has several properties such asphotocatalytic activity and chemical stability making it sutitable as an option for the top-layer.This study is devoted to the preparation and characterization of a ceramic membrane, dipcoatingof mesoporous interlayers and preparation of a microporous anatase top-layer viasol-gel technique. Moreover, the performance of the membrane modified by nano-copperisinvestigated for salt rejection enhancement. Membranes were characterized by FE-SEM andX-ray diffraction. The sol particle size was determined using DLS. Cross-flow filtration setupwas used for membrane permeability and salt retention experiments. Membrane top-layershowed crystal structures including rutile and anatase phases. By increasing salt concentration,chloride rejection is decreased and retention is increased by increasing the pressure. In case ofmodified membranes using nano-copper, higher retentions are observed, with 35% rejectionfor NaCl and 73% for Na2SO4. پرونده مقاله