Background and Objective: Nano-sorbents are suitable for pollutants removing from aqueous environment. Therefore, the aim of this study was to compare magnetization of magnetic graphene oxide nano-composite by using co-precipitation and solvothermal methods. In addition More
Background and Objective: Nano-sorbents are suitable for pollutants removing from aqueous environment. Therefore, the aim of this study was to compare magnetization of magnetic graphene oxide nano-composite by using co-precipitation and solvothermal methods. In addition, the capability of nano-adsorbent was conducted in order to examine removal efficiency of Cd (II) from aqueous solution.
Method: Graphene oxide (GO) was synthesized by modified Hummers method and magnetized using co-precipitation and solvothermal procedures. The amine functionalization of as-prepared magnetic graphene oxide was performed by reflux method in the presence of ethylenediamine as functional group and cold synthesis method in the presence of dichloromethane as reaction solvent. The synthesized adsorbents were used for Cd (II) removal from aqueous solutions and the effects of pH, amount of adsorbent, contact time, initial concentration of Cd (II) ions and temperature were investigated.
Findings: According to FTIR, XRD and VSM analyses, the synthesized magnetic graphene oxide with co-precipitation showed higher magnetization values than that of from the solvothermal method. The adsorption results displayed that the synthesized adsorbent with solvothermal and reflux processes of amination has the highest adsorption capacity of 207 mg.g-1. But it is only 82 mg.g-1 with co-precipitation and cold amination process. Kinetic data showed better correlation with pseudo-second-order equation and the Freundlich model was found to fit for the isotherm data.
Discussion and Conclusion: The magnetization values of adsorbent in co-precipitation method was better while the adsorption capacity reduced. The loss of adsorption capacity was due to high loading of magnetic particles under surface of GO, which leads to block the carboxyl functional groups. This was also confirmed by elemental analysis. The amount of nitrogen was lower in co-precipitation process comparing to solvothermal method. In batch adsorption, the adsorption process was found to be endothermic and spontaneous in nature. The results suggest that the solvothermal and reflux procedures was more efficient in amine functionalization and adsorption process.
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In this paper, cobalt ferrite nanoparticles were synthesized using a co-precipitation method. The properties and characteristics of the cobalt ferrite nanoparticles were studied using XRD, VSM, and FESEM analyses. The FESEM images showed that the cobalt ferrite nanopart More
In this paper, cobalt ferrite nanoparticles were synthesized using a co-precipitation method. The properties and characteristics of the cobalt ferrite nanoparticles were studied using XRD, VSM, and FESEM analyses. The FESEM images showed that the cobalt ferrite nanoparticles had almost spherical morphology, and that the particle size distribution (determined with the help of Digimizer software) was in the range of 25–60 nm. Moreover, the average size of the nanoparticles was calculated to be in the range of 37-47 nm. The VSM results indicated superparamagnetic properties of the cobalt ferrite nanoparticles at room temperature. Besides, the saturation magnetization and coercivity were found to be 30 emu/g and 39 Oe, respectively. The specific loss power (SLP) was investigated by preparing ferrofluid concentrations of 3, 5, and 8 mg/ml under a magnetic field of 400 Oe and at a frequency of 400 kHz. In this case, the rate of the increase in temperature of the cobalt ferrite nanoparticles was measured in a certain period of time, and the related SLP was calculated. The results of the measurements showed that the highest rate of the heat generation occured at the concentration of 8 mg/ml, leading to an SLP value of 162 W/g.
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In this study, ZnWO4 nanoparticles were synthesized through co-precipitation method with sodium tungstate dehydrate (Na2WO4.2H2O) and zinc nitrate hexahydrate (Zn (NO3)2.6H2O) as starting materials. In order to optimize the conditions for obtaining smallest mean particl More
In this study, ZnWO4 nanoparticles were synthesized through co-precipitation method with sodium tungstate dehydrate (Na2WO4.2H2O) and zinc nitrate hexahydrate (Zn (NO3)2.6H2O) as starting materials. In order to optimize the conditions for obtaining smallest mean particle size, Central Composite Design (CCD) was used and three parameters of temperature, weight ratio of precursors, and pH value were studied in five levels. The obtained ZnWO4 nanoparticles were characterized by Field Emission Scanning Electron Microscopy (FE-SEM), powder x-ray diffraction (XRD), thermal gravimetric- differential scanning calorimetry (TG-DSC) and photoluminescence (PL). The results showed that optimal conditions for smallest mean nanoparticles with particle size of 37.3 6.9 nm were temperature =83 , weight ratio of precursor equal to 1.1, and pH=6. The resulting ZnWO4 nanoparticles were dry- pressed to green compact pellets with a diameter of 11mm and thickness of 1.5 nm at the compaction pressure of 500 MPa. The densification of nanoparticles compacts was carried out by a pressure less sintering at 950 for 2 hours in air atmosphere. Scintillation properties of pellets were determined by means of Gama-rays spectroscopy. The results showed that manufactured ZnWO4 pellets illustrated counting sensitivity to Cs137 and Am241 irradiation sources and couldn’t detect energy of Gama-rays emitted from this two source.
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Nano-crystalline Yttrium aluminum garnet (YAG, Y3Al5O12) were synthesized by normal co-precipitation method using yttria and aluminum nitrates as the starting materials and ammonium hydrogen carbonate (AHC, NH4HCO3) as precipitant. To investigate the effect of temperatu More
Nano-crystalline Yttrium aluminum garnet (YAG, Y3Al5O12) were synthesized by normal co-precipitation method using yttria and aluminum nitrates as the starting materials and ammonium hydrogen carbonate (AHC, NH4HCO3) as precipitant. To investigate the effect of temperature and holding time the resultant precursors were calcined at 900-1100 °C for 2 h also at 1100 °C for other durations (15, 30, 45 and 60 min). The evolution of phase composition and micro-structure of the as-synthesized YAG powders were characterized by different techniques such as X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, thermal analyses (TG/DTA), Specific surface area analyses (BET) and field emission electron microscopy (FESEM). The cubic YAG phase with an average grain size of 33 nm and specific surface area of 30 m2/g was completely formed at 1000 °C. In addition, pure YAG nano powders were obtained at 1100 °C in only 15 min calcination. Results showed that compared with increasing holding time, raising of temperature have more intense effect in increasing YAG crystal or particle size.
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A surfactant assisted Co-Precipitation method was employed for the synthesis of magnesium aluminate spinel with nanocrystalline size and high specific surface area. Calcination operations were performed in 800-1000° C for two hours. Different percentages of samarium More
A surfactant assisted Co-Precipitation method was employed for the synthesis of magnesium aluminate spinel with nanocrystalline size and high specific surface area. Calcination operations were performed in 800-1000° C for two hours. Different percentages of samarium were doped to magnesium aluminate spinel to examine the properties of magnesium aluminate spinel. The prepared samples were characterized by thermal gravimetric and differential thermal gravimetric analyses (TG/DTA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Transmission electron microscopy (TEM), and photoluminescence spectrum (PL). XRD results showed that nanocrystals of magnesium aluminate spinel were influenced by the type of surfactant in 800° C. The results of luminescence spectrum show that by increasing the amount of samarium after 0.15 of weight percentage, concentration suppression happens and reduces the intensity of luminescence properties.
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NO2 as a toxic gas in the environment and industry, is abundantly produced and needs to be detected. In this research, the measurement of NO2 gas using ZnMn2O4 nanoparticles made through a simple co-precipitation, process has been investigated. The structure and surface More
NO2 as a toxic gas in the environment and industry, is abundantly produced and needs to be detected. In this research, the measurement of NO2 gas using ZnMn2O4 nanoparticles made through a simple co-precipitation, process has been investigated. The structure and surface morphology of the prepared samples have been analyzed by X-ray diffraction and scanning electron microscopy, respectively. The X-ray diffraction spectrum shows that the structure of the sample is well formed without impurities. Electron microscope images show that the nanoparticles are formed as nanoplates with an average thickness of 30 nm. Gas sensing measurements were performed by exposing the sensor to %0.5 of NO2 gas at temperatures between 150 ℃ and 375 ℃. The measurements made in terms of temperature showed the maximum response at the temperature of 300 ℃, to %0.5 of NO2 gas. Also, the ZnMn2O4 sensor showed a repeatable and stable electrical signal. Therefore, ZnMn2O4 nanoparticles have a promising potential in the field of gas sensors.
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Ion distribution on the spinel structure of ferrite nanoparticles is one of the critical factors that
can affect magnetic properties. Therefore, if a method changes ion distribution, it can be used
for fabrication (synthesis) of nanoparticles with different magnetic p More
Ion distribution on the spinel structure of ferrite nanoparticles is one of the critical factors that
can affect magnetic properties. Therefore, if a method changes ion distribution, it can be used
for fabrication (synthesis) of nanoparticles with different magnetic properties that apply in the
diverse of technology field. In this work, the dependence of magnetic characteristics of the
cobalt-doped nickel ferrite nanoparticles on Polyvinyl alcohol (PVA) assisted co-precipitation
processes was studied. The structural and magnetic measurements were made employing XRD
and VSM. Nanoparticles with a cubic spinel structure and an average size of about 29 nm have
been synthesized, and their structure was confirmed using the XRD pattern and Sherrer’s
equation. According to the obtained hysteresis loops of the five sets of synthesized
nanoparticles, the coercive field and magnetization are different because of the interaction
between polymer and metal ions in the reaction medium that causes a kind of ion
immobilization and different ion distribution over the spinel structure. Such polymer-based
synthesis procedures can be used to fabricate of magnetic nanoparticles with tunable magnetic
properties.
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