International Journal Of Bio-Inorganic Hybrid Nanomaterials
Volume:2 Issue: 1, Spring 2013

In this work, we investigated synthesis, magnetic properties of silica coated metal ferrite,(CoFe2O4)/SiO2 and Manganese doped cobalt ferrite nanoparticles (MnxCo1-xFe2O4 withx= 0.02, 0.04 and 0.06)/SiO2 for possible biomedical application. All the ferrites nanoparticles were prepared by co-precipitation method using FeCl3.6H2O, CoCl2.6H2O and MnCl2.2H2O as precursors, and were silica coated by Stober process in directly ethanol. The composition, phase structure and morphology of the prepared core-shell cobalt ferrites nanostructures were characterized by powder X-ray diffraction (XRD), Fourier Transform Infra-red spectra (FT-IR), Field Emission Scanning Electron Microscopy and energy dispersive X-ray analysis (FESEM-EDAX). The results revealed that all the samples maintain ferrite spinel structure. While, the cell parameters decrease monotonously by increase of Mn content indicating that the Mn ions are substituted into the lattice of CoFe2O4. The magnetic properties of the prepared samples were investigated at room temperature using Vibrating Sample Magnetometer (VSM). The results revealed strongly dependence of room temperature magnetic properties on (1) doping content, x; (2) particles size and ions distributions.

In this work, ZnCaO2 (zinc oxide-calcium oxide) nanocomposite were synthesized at different temperatures (500-700°C) by sol-gel method based on polymeric network of polyvinyl alcohol (PVA). The synthesized samples were characterized by SEM/EDAX, FT-IR and XRD techniques. It was found that synthesized nanocomposites have 1.62, 2.05 and 13.91%wt of CaO, respectively. The obtained results show that each particle of nanocomposite has been made of a CaO core which is completely covered by ZnO layers. The smaller average diameter of synthesized nanoparticles (at 600°C) calculated by XRD technique found to be 33 nm for prepared ZnCaO2 nanocomposite. This compound has been used as adsorbing removal for agricultural pesticide. The 2-chloroethyl ethyl sulfide (2-CEES) and dimethyl methyl phosphonate (DMMP) are for the class of compounds containing phosphonate esters and sulfurous with the highly toxic that used such as pesticides, respectively. The adsorption/destruction reactions of 2-CEES and DMMP have been investigated by using ZnCaO2 nanocomposite. Reactions were monitored byGC-FID (gas chromatography) and FT-IR techniques and the reaction products were characterized by GC-MS. The results of GC analysis for the weight ratio of 1:40 (2-CEES/DMMP: ZnCaO2 nanocomposite) at room temperature showed that 2-CEES molecule is destructed about perfectly in the n-pentane solvent by nanocomposite after 12 hours and it changed to less toxic chemical hydrolysis and elimination products and identified via GC-MS (gas chromatographymass spectrometry) instrument, were hydroxyl ethyl ethyl sulfide (HEES) and ethyl vinyl sulfide (EVS), respectively. On the other hand, the 31PNMR analysis emphasized that 100% of DMMP molecule after 14 hours in the n-pentane solvent was adsorbed.

ZnO and ZnO: Mn nanocrystals were synthesized via reverse micelle method. The structural properties of nanocrystals were investigated by XRD. The XRD results indicated that the synthesized nanocrystals had a pure wurtzite (hexagonal phase) structure. Resistive gas sensors were fabricated by providing ohmic contacts on the tablet obtained from compressed nanocrystals powder and the installation of a custom made micro heater beneath the substrate. Sensitivity (S= Ra/Rg) of ZnO and ZnO: Mn nanocrystals were investigated as a function of temperature and concentration of ethanol and gasoline vapor. The obtained data indicated that optimum working temperatures of the ZnO and ZnO: Mn nanocrystals sensors are about 360°C and 347°C for ethanol vapor and about 287°C and 335°C for gasoline vapor. Based on gas sensing results, although Mn impurity reduces the Sensitivity but the sensor got saturated at much higher gas concentration.

Effect of nanosilver (NS) on the heat-transferring rate to the core section of mediumdensity fiberboard (MDF) mat was studied here. A 400 ppm aqueous nanosilver suspension was used at three consumption levels of 100, 150, and 200 mL/kg, based on the weight of dry wood fibers; the results were then compared with the control MDF panels. The size range of nanosilver was 30-80 nm. Results showed that the uniform and even dispersion of nanoparticles throughout the MDFmatrix significantly contributed to the faster transfer of heat to the core section. As to the loss of mat water content after the first 3-4 minutes under the hot press, the core temperature slightly decreased in the control panels. However, heat transferring prope rty of nanosilver contributed to keeping the core temperature rather constant in the nanosilver-150 and 200 treatments. The surface layers of the mat rapidly absorbed the heat, resulting in the depolymerization of part of the resin. It can therefore be concluded that the optimum nano suspension content should not necessarily be the highest one.

In this work, we report synthesis of superparamagnetic iron oxide nanoparticles at roomtemperature using microemulsion template phase consisting of cyclohexane, water, cetyltrimethylammonium bromide CTAB as cationic surfactant and butanol as a cosurfactant. Silica surface modification of the as prepared nanoparticles was performed by adding tetraethoxysilane TEOS to alkaline medium. The structure, morphology, and magnetic properties of the products were characterized by X-ray powder diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and vibrating sample magnetometer (VSM) at room temperature. The results revealed formation of iron oxide nanoparticles, with an average size of 8.8-12 nm, a superparamagnetism behavior with fast response to applied magnetic fields and Zero remanence and coercivity.

The comparison of growth processes and fluorescent properties of CdZnTe semiconductor quantum dots that are synthesized in different concentrations of Zn2+ in water are discussed in this paper. The samples are characterized through absorbtion (UV) and photoluminescence spectra (PL). The results show that when the reaction time is prolonged, the absorption peak and fluorescent emission peak present obvious red shifts and the diameters of the Quantum dots continuously increase. Under the best reaction conditions, the highest quantum yield can be attained by using thioglycollic acid (TGA) as modifier when the reaction time is 300 min.

A simple, highly sensitive, accurate and selective method for determination of trace amounts of Co(II) in water samples is presented. Isocyanate treated graphite oxides (iGOs) solid phase extraction adsorbent was synthesized by covalently isocyanate onto the surfaces of graphite oxides. The stability of a chemically (iGOs) especially in concentrated hydrochloric acid which was then used as a recycling and pre concentration reagent for further uses of (iGOs). The method is based on (iGOs) of Co(II) on surfactant coated C18, modified with a isocyanate treated graphite oxides (iGOs). The retained ions were then eluted with 4 mL of 4 M nitric acid and determined by flame atomic absorption spectrometry (FAAS) at 283.3 nm for Co. The influence of flow rates of sample and eluent solutions, pH, breakthrough volume, effect of foreign ions on chelation and recovery were investigated. 1.5 g of surfactant coated C18 adsorbs 40 mgof the iGOs which in turn can retain 15.2±0.8 mg of ions. The limit of detection (3σ) for Co(II) was found to be 3.20 ng L-1. The enrichment factor for both ions is 100. The mentioned method was successfully applied on determination of Cobalt in different water samples. The ions were also speciated by means of three columns system.

Chemical Vapor Deposition (CVD) is one of the most important methods for producing Carbon Nanotubes (CNTs). In this research, a numerical model, based on finite volume method, is investigated. The applied method solves the conservation of mass, momentum, energy and species transport equations with aid of ideal gas law. Using this model, the growth rate and thickness uniformity of produced CNTs, in a horizontal CVD reactor, at atmospheric pressure, are calculated. The furnace temperature and inlet hydrocarbon concentration variations are studied as the effective parameters on CNT growth rate and thickness uniformity. It is indicated that by increasing the furnace temperature, the CNT growth rate increases, while the thickness uniformity shows decreasing. The results show that the growth rate of produced CNTs could be improved by increasing the inlet hydrocarbon concentration, but the latter causes more non uniformity on the CNTs height.