Field on the Forced Convection Heat Transfer of Fe2O3 / Water Nanofluid in the Developing Thermal Region (original) (raw)
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2013
At the present work, the effect of synthesis temperature and atmosphere on the magnetic and color properties of the magnetite (Fe 3 O 4) magnetic nanparticles was studied and magnetic and colorimetric properties of them were correlated. The precipitation occurred by pH adjustment of ferrous/ferric mixed salt-solution with ammonium hydroxide addition. The synthesis was performed in the temperature range of 25°C to 80°C in ambient and nitrogen protected atmospheres. The magnetite nanoparticles were characterized by vibrating sample magnetometer (VSM) analysis. Crystallite size was calculated via reclaimed Sherrer , s formula. The magnetic properties revealed that temperature variations shows appreciable effect on magnetic properties when the synthesis is performedin ambient atmosphere but is not effective when it is performed in inert atmosphere. The colorimetric parameters were calculated in two color spaces CIEL * a * b * and CIEL * C * h°. The results showed that the color of nanopigments tend to red shade when synthesis was performed in ambient atmosphere and to black shade when synthesis was done in nitrogen atmosphere. J. Color Sci. Tech. 6(2013), 347-353© Institute for Color Science and Technology.
خواص حرارتی، نفوذپذیری نسبت به بخار آب و مورفولوژی بیونانوکامپوزیتهای پلیلاکتیکاسید (PLA)
2014
The present study developed an improved nanocomposite based on polylactic acid (PLA) biopolymer. The structural properties of PLA nanocomposites of clay and cellulose nanoparticles were evaluated for level and water vapor permeability (WVP) using thermal and casting methods. Thermal tests (DSC) showed that pure PLA had a glass transition point (T g) of 53.83, a melting point (T m) of 153.95°C and crystallization (x%) of 41.36%. With the incorporation of clay nanoparticles, T g and x% increased, while T m showed no significant change. The micro-crystal cellulose (MCC) nanoparticles were not compatible with the polymer matrix, so there was no effect on the thermal properties. WVP results showed that pure PLA had high permeability; the addition of clay nanoparticles strongly decreased WVP. The sample with 7% clay had a permeability of 0.92×10-11 g/m.S.Pa. WVP of the film increased significantly as a result of the hydrophilic nature of the MCC. The SEM images of the samples confirmed the results.
Ni(II) Removal from Aqueous Solutions using Nanostructured Sorbent MCM-41 Modified by Zncl 2
2015
In this study, MCM-41 was prepared via hydrothermal method in presence of ethanol as a cosolvent and co-surfactant in alkaline media. Inorganic sorbent ZnCl 2-MCM-41 was synthesized via covalent grafting method by dispersion of samples into pure toluene for solid state interaction between silanol groups of MCM-41 surface and ZnCl 2 particles. Samples were characterized by nitrogen adsorption analysis, XRD, BET surface area, and FTIR spectrometry. MCM-41 BET surface area measured was 1099 m 2 /g, which was later reduced to 602 m 2 /g after incorporation of ZnCl 2 particles onto MCM-41 surface. Effect of different experimental conditions such as solution temperature, pH, contact time, and initial concentration of Ni (II) ions were investigated on the amount of nickel adsorption. For experimental data, the Langmuir isotherm showed a better fit than Freundlich isotherm, which indicates that nickel adsorption onto inorganic sorbent was homogeneous and monolayer. At optimum conditions, maximum adsorption capacity of Ni (II) by sorbent obtained was 303 mg/g according to Langmuir isotherm. Pseudo-second order model predicted kinetic of nickel adsorption onto synthesized sorbent better than other models. Free energy was 9.8 kJ/mol determined by Dubinin-Radushkevich model, which confirms chemical nature of nickel adsorption onto synthesized sorbent.
Journal of Economic Geology, 2017
Introduction The Qahr-abad fluorite deposit is located in the area of 36°10′ 3′′ N and 46°34′ 21′′E within the Sanandaj-Sirjan district east of the Kurdistan province , Iran and it is located ~57 km southeast of the city of Saqqez (Kholghi Khasraghi, 1999). This deposit is developed as scatter lenses, veins, and veinlets (stockwork structure) within carbonate rocks of Elika formation and controlled by the regional NW–SE trending Zagross thrust nappe system. Fault trends in this area are perpendicular to fault trends in the Zagros zone. The fault dips are nearly vertical and mineralization has occurred in the brecciation fault zone (Talaii, 2010). The rough geological instruction of the deposit has indicated that it is similar to worldwide Epithermal deposits. The mineralization occurs as replacement (type I)/ open-space (type II) vein fillings and bodies within Mesozoic lime stones (mostly Upper Triassic and Lower Jurassic members of the Elika Formation), where they crop out to form...
Journal of Color Science and Technology, 2015
In this research, C-TiO 2 @Fe 3 O 4 magnetic nanocomposite was prepared via a sol-gel method and the removal of Direct Blue 71 pollution in precence of visible light has been investigated. In this nanocomposite core is magnetic nanoparticles of magnetite and shell is the carbon-doped TiO 2. The surface morphology, structure, and crystalline phase of the nanocomposites were characterized using XRD, SEM and HRTEM techniques. Studies showed that the Fe 3 O 4 core has inverse cubic spinel structure and in shell C-TiO 2 , Titanium dioxide has the anatase structure. Photocatalytic activity studies showed that as-prepared nanocomposites had high photodegradating behavior (95%) to Direct Blue 71 compared to the pure TiO 2 nanoparticles. The effect of process parameters such as, catalyst loading, and initial concentration of Direct Blue 71 on the extent of degradation was investigated. The photocatalytic activity remained 85% after three reusing.
DOAJ (DOAJ: Directory of Open Access Journals), 2014
Introduction:Cadmium is a heavy metal with high toxicity and is best known as a carcinogen element. For protecting human health and environment it is necessary to remove excess Cadmium from industrial wastewater before discharging it to surface and ground water. In this study the efficiency of Zinc Oxides Nanoparticles in Cadmium removal from aqueous solution was evaluated. Methods: This is a laboratory experimental study. Adsorption tests were performed in a batch reactor in a laboratory scale using zinc oxide nanoparticles and the effect of initial cadmium concentrations, adsorbent dose, pH, and contact time on the removal efficiency was studied. Theresidual cadmium concentration in the solutionwas determined using flame atomic absorption spectroscopy Varian AA20 made in Australia. Finally for designing graphs, we used Excel software. Results:The results indicated that the adsorption process is affected by different parameters such as initial pollutant concentrations, adsorbent dose, pH, and contact time and Cadmiumremoval efficiency increases with increasing adsorbent dose and reaction time and decreases with increasing initial concentration of Cadmium. Therefore, it is observed that by raising the initial Cadmium concentration, the adsorption rate increases. The maximum efficiency of adsorptionin pH=7amounted to 89.6%. Conclusion:It is concluded that Zinc Oxide nanoparticles have proper efficiency in removal of Cadmium from aqueous solutions and can be used in the treatment of wastewater that contains ion Cadmium.However, its efficiency is deeply dependent on ion strength and the interaction of other metals in wastewater.
Journal of Advanced Materials In Engineering, 2015
Ni-SiC composite coatings are successfully employed as a protective coating in the inner walls of engine cylinders. In this study, Ni-SiC, Ni-SiC-MoS 2 and Ni-SiC-Gr composite coatings were prepared from a sulfamate bath. Both mechanical and ultrasonic stirring were used simultaneously during the process. Taking into account the working temperature of engine cylinders, the wear behavior of coatings was evaluated at 25 to 300 ºC and the high temperature tribological properties of the coatings were investigated. Based on the results obtained from the wear tests, all three coatings showed almost good friction coefficient values at 25 and 100 ºC, which were close to each other. By increasing the temperature to 200-300 °C, the friction coefficient and weight loss values strongly increased. However, addition of solid lubricants caused the values to decrease. The Ni-SiC-Gr coating at all temperatures showed a good and stable behavior.
2016
Introduction: Azo groups of dyes used widely for coloring yarn. Methylene blue is one of this group's dyes therefore with benzene rings in its structure caused the toxicity and its persistence in the environment. So that the its deficiency of proper treatment can cause the irreparable damage to the environment. One of the ways to removal these dyes from natural sources are absorbed by the absorbent. So the aim of this study is Kinetic and isotherm study of methylene blue adsorption by powdered pumice from the aquatic environment. Methods: Adsorption process was investigated in vitro at neutral pH, a constant concentration of dye and adsorbent dosage. The residual concentration of the dye solution through adsorption was measured at a wavelength nm 665 by using a spectrophotometer (Cary 50 manufacturers of Perkin Elmer). In order to understand how to adsorption, obtained data were fitted with Langmuir, Freundlich, Temkin, Harikens-jura and Dubinin-Radushkevich isotherms and Pseudo-first-order, Pesedo-second-order, Intraparticle diffusion and Elovich Kinetics. Results: Results showed that in the between of five isotherm models, the adsorption process is most obeyed of Harikens-jura isotherm (R 2 =0.9914). Also the adsorption process has appropriate obeyed of both Langmuir and Freundlich isotherms (R 2 =0.9633 and R 2 =0.9365) and it is means that the adsorption process occurs in a mono-layer and multi-layer. The low of mean free energy (E= 0.323 KJ/mol) in Dubinin-Radushkevich showed that the physical absorption process is dominant adsorption. Also adsorption process is obeyed of pseudo-second-order model. Conclusion: According to the results, can say Methylene blue adsorption multi-layer is most occurs than mono-layer and the pumice is the effectiveness adsorbent for removal methylene blue dye (RL=0.2).