INTERNATIONAL JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY (IJNN)
Year:2017 | Volume:13 | Issue:2|Papers Count:10

In this study, the change of porosity and roughness of carbon nanostructures, including fullerenes, carbon nanotubes and graphene was investigated according to oxidation process. The effect of oxidation was more sensible on smoother surface of nanostructures. Oxidation increases surface roughness of graphene up to 5.2% and porosity up to 35.2%. While, roughness of hummers graphene is 13.1% higher than pure graphene. According to AFM results, oxidation can increase porosity and roughness of the surface. The amount of this increase is clearly a function of surface smoothness and multi-dimensional geometry of nanostructure. The functionalization processes have a positive effect on reducing the clustering phenomenon of nanoparticles and reduction of nanostructure particle size in their clusters that causes increases in surface porosity and roughness. So, functionalization processes can strongly change morphology of the nanoparticles in terms of structure, surface properties and geometry and according to these changes, nanostructures shows different behaviors.

In this study, cadmium sulfide nanoparticles (CdS NPs) were prepared, characterized and used as a new adsorbent for simultaneous removal of Pb (II) and Cu (II) ions from aqueous solutions. Using a batch adsorption method, the effects of solution pH, contact time, adsorbent dose, and temperature were studied and optimized. Removal efficiencies, higher than 98% were obtained for both the metal ions at the optimum conditions. The adsorption process was rapid, as equilibrium was achieved within 15 min. The kinetic and isotherm experiment data could be well described with the pseudo-second order kinetic model and the Freundlich isotherm model. The maximum adsorption capacities for Pb (II) and Cu (II) ions were 200 mg/g and 166.7 mg/g, respectively. The thermodynamics of adsorption process such as changes in standard free energy, enthalpy and entropy were also discussed. This study revealed that CdS NPs are effective adsorbent for rapid removal of Pb (II) and Cu (II) ions from aqueous solutions.

In this paper, a kind of core-shell magnetic mesoporous microspheres of Fe3O4@SiO2@meso-SiO2 with high surface area was prepared, where magnetic Fe3O4 nanospheres were used as the inner core, tetraethyl orthosilicate (TEOS) as silica source, and cetyltrimethylamonium bromide (CTAB) as pore forming agent. Methanol-enhanced supercritical CO2 extraction has been attempted on structurally order mesoporous shell to remove the cationic template of CTAB and the effects of operating conditions i.e. pressure and temperature on the extraction efficiency were investigated. The influence of the methanol-enhanced supercritical CO2 on the structural properties of magnetic mesoporous silica nanocomposites was examined in detail by means of FE-SEM, FTIR, XRD, N2 adsorption/desorption and VSM. The obtained results reflected that the methanol-enhanced supercritical CO2 extraction had well preserved the structural stability of Fe3O4@SiO2@meso-SiO2 with high surface area ca. 569 m2/g. The strong magnetization value (60 emu/ g) of the core-shell particles suggests their suitability for magnetic separation in a short time.

In this study the adsorption of selenium molecule (Se2) on the outer surface of zigzag (5, 0), (8, 0) and (10, 0) carbon nanotubes has been investigated. We examined number adsorbed orientations as well as different adsorption sites on nanotubes. The adsorption energies, equilibrium distances, energy differences between the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) and interaction angles between nanotubes and selenium molecule have been studied in details. The results showed that the best angle of the selenium molecule with the nanotubes is zero degree. Selenium adsorption on the external surface of zigzag nanotubes increased their electrical conductivity. It is found that an increase in nanotubes diameter leads to an increase in their stability. The adsorption energy values of selenium molecule on the surface of zigzag (5, 0) and (8, 0) nanotubes was low and negative; therefore this was a physical adsorption and exothermic. Independent to the orientation, the adsorption process of Se2 on (10, 0) nanotube showed chemisorption with large charge transfer from nanotube to adsorbed molecule.

In this study, a method for extraction and preconcentration of trace amounts of organophosphorus pesticides (OPPs) in environmental water using magnetic solid phase extraction (magnetic-SPE) followed by high performance liquid chromatography (HPLC) with UV detection was developed. The magnetic carbon nanotube adsorbents (Fe3O4/CNT) were synthesized by grafting carbon nanotubes to magnetic Fe3O4 particles by a facile hydrothermal method. The synthesized Fe3O4/CNT nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and vibrating sample magnetometer (VSM). These nanoparticles were used for extraction and preconcentration of OPPs (fenitrothion, profonofus, and ethion) in environmental water samples at low concentration. The influence of four variables including adsorption time, weight of sorbent, salt addition, and pH in the extraction process were predicted and optimized by Response Surface Method (RSM). Under optimized conditions, it showed good linearity between 0.5-10, 0.5-10, 0.5-30 ng ml-1 with determination coefficients (R2) of 0.993, .0995, and 0.994 for extraction of ethion, profonofus, and fenitrothion, respectively. Limit of detection (LOD) for extraction of ethion, profonofus, and fenitrothion were also evaluated under optimized conditions as 0.124, 0.097, and 0.108, respectively. The analysis also showed good reproducibility with the RSD values 4.4, 2.7, and 4.5 at the 10 ng ml-1 level (n=5) for ethion, profonofus, and fenitrothion, respectively.

In the present work Mn3O4 nanoparticles (NPs) with spinel structure were synthesized successfully via combustion route with MnIII (acac)3 as precursor in two different temperatures. The morphology of the synthesized Mn3O4 were investigated by field emission scanning electron microscope (FESEM) and structural analysis was studied by powder X-ray diffraction (PXRD) technique that it indicated that the Mn3O4 nanoparticles with space group of l41/amd Structural analysis was performed by fullprof program employing profile matching with constant scale factors. The lattice parameters for both samples were found a=b=5.7621 Å and c=9.4696 Å, a=b=g=90o. In addition, the size of the Mn3O4 nanoparticles obtained from the Transmission Electron Microscopy (TEM) that the average is 20 nm. Magnetic property of synthesized Mn3O4 was done by Vibration Sampling Magnetometer (VSM) that confirm the paramagnetic behavior. The optical properties of the obtained materials were investigated by Furrier-Transform Infrared spectroscopy (FTIR) and Ultraviolet-Visible spectrum (UV-Vis). The thermal stability was determined by Thermo Gravimetric Analysis (TGA).

Cadmium chalcogenides with appropriate band gap energy have been attracting a great deal of attention because of their potential applications in optoelectronic devices. In this work CdS thin films were deposited on p-type silicon substrates by sol - gel spin coating method at different substrate temperatures. The CdS deposited wafers were characterized by X ray diffraction method (XRD), Scanning Electron Microscopy (SEM), Photoluminescence spectroscopy (PL), Raman spectroscopy and Fourier Transform Infra - Red spectroscopy (FTIR). XRD analysis showed that the films have crystallites with classical hexagonal structure along (0 0 2) plane. The grain size was found to be in the range of 111.79 nm to 167.66 nm varying with the annealing temperature. The SEM micrograph of annealed CdS thin film showed uniform granular structures with very well defined grain boundaries all over the surface. The Raman spectra of the CdS films presented a well-resolved line at 300 cm-1 (1LO) and at 611 cm-1 (2LO). PL spectrum showed a broad peak centered around 2.19 eV (508.5 nm) which can be attributed to the defect/trap related transitions. FTIR analysis showed absorption bands corresponding to Cd and S. The electrical property revealed that the resistivity decreases when the samples were annealed.

Magnetic nanoparticles are of great interest for researchers from a wide range of disciplines, including nano-magnetic fluids, nanocatalysis, biomedical applications, magnetic resonance imaging, and specifically environmental remediation. Nanomaterial like Iron Oxide (Fe3O4) is one of the most promising candidates to remove heavy metals and dyestuffs from the industrial effluent. Among these, Fe3O4 is the extensively used smart material with magnetic properties that having high surface area. High surface to volume ratio provides more surfaces for chemical reaction for the surface adsorption. Fe3O4 nanoparticles have been synthesized using a sonochemical method using ultra frequency in aqueous solution under optimized conditions. The as-synthesized nanoparticle was analyzed using different characterization tools. The Transmission Electron microscope (TEM) images revealed 10-12 nm spherical shape nanoparticles; the crystalline structure was confirmed by X-Ray Diffraction (XRD). The functional groups were identified by Fourier Transform-Infra Red Spectroscopy (FT-IR), revealed the bending and stretching vibrations associated with Iron Oxide (Fe-O) nanoparticles. In the present study, for the efficient adsorption of dyestuff effluents, the samples collected were subjected to adsorption and decolorization at definite time intervals with Fe3O4 nanoparticles. The amount of Iron oxide was kept constant for the reaction and the concentrated dyestuff effluents were diluted ten times and observe the absorption in UV -Vis Spectroscopy. It was found that the spherical shaped Fe3O4 proved to be the potential material for the adsorption of dyestuff effluents. The result concluded that the effective adsorption and decolorization of contaminants is observed in the maximum time period of 30 minutes with the minimum amount of Fe3O4.

Drilling fluids are an essential component of the rotary drilling process used to drill for oil and gas on land and offshore environments. The injection of this nano particle into drilling fluid increases the viscosity levels fluids. In these experiments, the rheological properties of the fluid including apparent viscosity (AV), plastic viscosity (PV), yielding point (YP), mud cake thickness and fluid loss (FL) were studied before and after the addition of the nanoclay with different concentrations. In this study, nano particles of clay were used in order to enhance the rheological properties of drilling fluids. The results showed nanoclay controls the fluid loss and is resistant to high temperatures and also fluid loss. We also found that nanoparticles varying in concentration (0.1 to 1 Wt %) and also size 1, 50 and 500 nm are shown to be effective at improving fluid rheology.

The interaction of Fe2O3, Fe3O4 and SiO2 nanoparticles with proteinase K activity was investigated using UV-vis spectroscopy. Proteinase K EC (3.4.21.14) is a member of serine protease family, which is produced from fungus Tritirachum album Limber. The effects of nanoparticles on proteinase K activity were studies at 40oC in pH 7.0 using sodium phosphate as buffer. It was found that in the presence of nano-Fe2O3 and nano-Fe3O4, Vmax was decreased but Km was constant. This results indicated that nano-Fe2O3 and nano-Fe3O4 acted as noncompetitive inhibitors. In the presence of nano-SiO2 the amount of Km increased but Vmax decreased, that showed nano-SiO2 acted as a mixed inhibitor. The dissociation constant (Ki) value for binding nano-Fe2O3, nano-Fe3O4 to proteinase K was equal to 11mM and 8.5mM respectively that indicated the binding of nano-Fe3O4 to the enzyme was stronger than nano-Fe2O3. The KI and Ki value for nano-SiO2 was 22.5mM and 8mM respectively.