فصلنامه نانو مواد
پیاپی 19 (پاییز 1393)

In this article, ZnO nanorods were synthesized after the optimization of pH, temperature and time of reflax as well as calcination parameters via coprecipitation method. The average diameter size of synthesized nanorods is 90 nm and its structure is wurtzite hexagonal. In order to utilize of visible light in photocatalysis reactions efficiently, for the first time, the synthesized ZnO was sensitized with porphyrin compound which are reactive agent in visible light. The obtained photocatalysts were characterized through FT-IR, DRS, XRD and SEM analyses. To investigate the photocatalytic activity of synthesized photocatalysts, the photo degradation of dye pollutant such as methylene blue and methyl orange was carried out. The results showed that photocatalyst synthesized with porphyrin can degrade 89% of MB in the 240 min under visible light illumination. Therefore, porphyrin compounds are high effective agents in the activation of ZnO in the visible light.

Alumina/aluminum titanate composites with 2, 10 and 20 wt.% Al2TiO5 were prepared using reaction sintering of alumina and titania. Nano and micro sized TiO2 powders were used to composites fabrication. X-ray diffraction analysis results revealed the perfect reaction of nano and micro TiO2 with alumina at 1500 ºC cause to formation of Al2TiO5 as secondary phase. The alumina relative density increased from about 94% for monolithic alumina to about 97% at presence of TiO2 additions for all composites series. The density increment curve of the composites at the presence of nano TiO2 addition was above the micro-sized addition. The density of composite contain 20 wt.% Al2TiO5 the density increased from 97% at presence of micro-sized TiO2 to 98% for nano type. Also the strengths values of the nanocomposites series were higher than the micro composites. Specially, for the composites contains 10 wt.% aluminum titanate the bending strength for nano and microcomposites were 292 and 269 MPa respectively.

In this research, the synthesis of TiO2 nanostructures was done by sol-gel method. Also, the effect of various parameters of this method on the manner of synthesis of this compound was studied. The phase study and powder morphology, was evaluated by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. According to patterns of X-ray diffraction of the produced samples in 400 and 500 °C, all of them have a pure rutile phase. Also, in this survey, effect of nanoparticles of TiO2 on equilibrium absorption diagram, oxygen and water vapor permittivity, was studied on the starch films. This survey aimed at studying the effect of TiO2 nanoparticles on the oxygen and water vapor permittivity on starch films. In this survey, production of the starch films with TiO2 nanoparticles in concentrations of 0, 1, 3 and 5 was observed. FTIR diagrams showed that the interactions done were completely physical and no chemical reaction occured. Generally, according to the surveys conducted, edible films containing nano TiO2 can be used as active packaging in the food industry.

One of the common methods of synthesis of nanoparticles is precipitation from the liquid phase. This method is highly regarded due to better size and morphology control of nanoparticles. In this research, potassium chloride nanoparticles were produced by induced crystallization in presence of polyvinyl pyrrolidone (PVP). Induction time of nanoparticles formation was measured for nucleation mechanism determination and calculation of the effective parameters. The results show that primary nucleation takes place with and without the presence of PVP and an increase in concentration of PVP causes an increase in interfacial tension of nanoparticles.

In this study, first polyacrylonitrile composite nanofiber layers containing differentpercentages of multi-wall carbon nanotubes and zinc oxide nanoparticles were fabricated by electrospinning. Surface morphology of nanofibers was studied by scanning electron microscopy (SEM). Then, ultraviolet radiation transmission through the samples was measured by UV/Vis/NIR spectrophotometer. Results show that by increasing concentration of MWNTs and ZnO in thenanofibers, the percentage of ultraviolet radiation transmission through thesampledecreases strongly. Protection against ultraviolet radiation of PAN/MWNTs composite nanofibers is more than PAN/ZnO composite nanofibers.

In this research, γ-Al2O3 nanoparticles were synthesized by sol-gel method. The morphology and structure of the synthesized samples were studied and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT IR) techniques. Using XRD, the average particle size is estimated to be 29 nm. The decontamination reactions of mustard and nerve agents, simulant of 2-chloroethyl ethyl sulfide (2-CEES) and dimethyl methyl phosphonate (DMMP) have been investigated via γ-Al2O3 nanoparticles catalyst at ambient temperature. The GC analysis results illustrated that 100% of 2-chloroethyl ethyl sulfide was decontaminated by catalyst at hexane solvent after 10 h. The degradation products of this reaction including ethyl vinyl sulfide (EVS) and hydroxyl ethyl ethyl sulfide (HEES) were identified via using GC-MS analysis. Also, the 31PNMR analysis emphasized that 97% of dimethyl methyl phosphonateby this catalyst was decontaminated under similar conditions.

PVA/TiO2 nanocomposite thin films were prepared at different TiO2 nanoparticles ratio 20, 30, 40 and 50) employing electro spinning method. Morphology and structure of nanocomposites were characterized by X-ray diffraction and scanning electron microscopy (SEM). The results indicated the anatase structure of TiO2 nanoparticles in the PVA matrix and proved that nanoparticles were successfully coated by polyvinyl alcohol molecules. Also, optical properties of samples were characterized by diffuse reflectance spectroscopy (DRS). The film prepared at extreme ratio of TiO2 (50:50) was found to be suitable for application in solar cell as a window layer due to the crystalline phase, favorable band gap (3.31 eV) and higher optical transmittance.

In this research nickel oxide nanostructures were synthesized by thermal decomposition. Theresults show the great effect of different conditions of gel preparation, such as concentration, temperature and time of calcination on the characteristics of the synthesized powder. Phase investigation, morphology and structure of nickel oxide powder obtained were evaluated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR), respectively. The results of infrared spectroscopy and X-ray diffraction analysis confirms the formation of nickel oxide nanostructures by two deposited agents the oxalic acid and potassium carbonate. The formation of single-phase nickel oxide nanostructures with the lowest average grain size in terms of using potassium carbonate was obtained 55 nm with spherical morphology. Temperature results in the formation of nickel oxide, potassium carbonate is less than the oxalic acid. According to the results, the temperature of nickel oxideformation in the case of using potassium carbonate was less than using oxalic acid. Also, SEM results indicated proper dispersion, uniformity and less agglomeration of nickel oxide powder was synthesized using oxalic acid.