JOURNAL OF NANOSTRUCTURE IN CHEMISTRY
Year:2013 | Volume:3 | Issue:3|Papers Count:14

Curcuma longarhizome (turmeric), walnut, and henna are medicinal plants which are traditionally used for fiber colorations. In this study, the viscose rayon fabrics were dyed with different mordant at a variety of conditions. The dyed fabric and treated fabric with Ag nanoparticles were evaluated for antibacterial activity against pathogenic strain of Gramnegative (Escherichia coli) bacteria. Durability of antibacterial activity to laundering was also investigated. The results indicated that treated fabrics with these natural dyes had excellent antibacterial activity as well as Ag nanoparticles before and after wash.

A pencil graphite electrode (PGE) electrodeposited by nanostructure polypyrrole (PPy) conducting polymer film doped with 5-sulfosalicylic acid (SSA) as sensing material (PGE/PPy/SSA-Cu) was successfully developed for the detection of Cu (II) in aqueous solutions. For the preparation of the copper-sensing electrode, electrodeposition of a polypyrrole film was carried out using cyclic voltammetry in a solution containing 10.0 mM pyrrole and 5.0 mM 5-sulfosalicylic acid. The introduced electrode in the current paper can be fabricated simply and was found to possess high selectivity, showed wide working concentration range, fast response time (<20 s), long lifetime, and very good sensitivity to Cu (II) ion. The prepared electrode exhibited a linear Nernstian response within the copper ion concentration range of 1.0×10-5 to 1.0×10-1 M with a slope of 29.60±0.30 mV per decade over the pH range of 4.0 to 6.0. Under the optimized conditions, a detection limit of 5.42 mM was obtained. Applications of this electrode for determination of copper ion in real samples and as an indicator electrode for potentiometric titration of Cu2+ion using EDTA are reported.

It is shown that the oscillator strengths and dipole moments of the transitions for one-particle states of charge carriers that originated in semiconductor quantum dots take on large values, significantly exceeding the typical values of the corresponding values for semiconductor materials. In the framework of the dipole approach, it is shown that large values of the cross section of light in the studied quasi-zero-dimensional systems enable the use of such nanosystems as new strongly absorbing nanomaterials.

ZnS is one of the most important semiconducting materials, and this paper discusses the wet chemical synthesis of ZnS nanoparticles in cubic and hexagonal structures. The effect of polyvinyl alcohol concentration on the ZnS particle formation is studied, and ZnS nanocrystals smaller than the Bohr exciton radius have been prepared using the capping agent polyvinyl alcohol. ZnS nanocrystals of about 1.54 nm have been prepared, and their optical absorption shows interband transitions. It is found that the polyvinyl alcohol concentration has a tremendous effect on the particle growth, since particle sizes were varied with the concentration of polyvinyl alcohol. The important result is that the strain was seen negative due to the contraction of the particles. The important finding of this experiment is that the preparation of the hexagonal ZnS nanoparticles is possible at lower temperature when a particular concentration of trisodium citrate and polyvinyl alcohol is used simultaneously with the ZnS precursors.

Nanoparticles of carvedilol are prepared by ultrasonic method. Particle sizes and morphology of nanoparticles are dependent on the power of ultrasound irradiation and sonication time. Results show an increase in the particle size with increasing the power of ultrasound irradiation. The particle size increased with increasing sonication time. The produced carvedilol nanoparticles were characterized by X-ray diffraction, infrared spectroscopy, and scanning electron microscopy.

Research on photocatalytic degradation rate of azo dyes using TiO2/SrTiO3 nanocomposite in the photocatalysis process was the main goal of the present study. The TiO2/SrTiO3 nanocomposite was first synthesized under ultraviolet (UV) irradiation and sonication, and then, its photocatalytic activity has been examined under UV irradiation. The absorbance of samples was measured using a UV-vis spectrophotometer. The structure and morphology of the nanocomposite were investigated by scanning electron microscopy and the crystalline structure by X-ray diffraction spectroscopy. The results reveal that adding nano-SrTiO3 to nano-TiO2 showed the most promising photocatalytic activity toward dye degradation.

The present paper describes experimental and theoretical aspects of the effective thermal conductivity, electrical conductivity, and viscosity of nanofluids. The thermal conductivity, electrical conductivity, and viscosity of nanofluids increase with the nanoparticle volume fraction. The nanofluid was prepared by synthesizing Al2O3 and Ag nanoparticles using microwave-assisted chemical precipitation method and then dispersed in distilled water using a sonicator. Water nanofluid with nominal diameters of 20 and 40 nm at various volume concentrations (0.25% to 5%) at a temperature of 15oC was used for the investigation. The thermal conductivity, electrical conductivity, and viscosity of nanofluids were measured, and it was found that the viscosity and electrical conductivity increase is substantially higher than the increase in thermal conductivity. The pure base fluid thermal conductivity displayed a Newtonian behavior at 15oC; it transformed to a non-Newtonian fluid with the addition of a small amount of nanoparticles j>3%.

The thrust to develop eco-friendly procedures for the production of nanoparticles arises from the extremely recent nanotechnology research. Extracellular biosynthesis of gold nanoparticles was achieved by an easy biological procedure usingKlebsiella pneumoniae as the reducing agent. After exposing the gold ions to K. pneumoniae, rapid reduction of gold ions is observed foremost to the formation of gold nanoparticles in colloidal solution. UV-vis spectrum of the aqueous medium containing gold nanoparticles showed a peak around 560 nm. The crystalline nature of the particles was confirmed from an X-ray diffractometer. Transmission electron microscopy (TEM) micrograph analysis of the gold nanoparticles indicated that they were well dispersed and ranged in sizes 35 to 65 nm. The high crystalline in the FCC phase is evidenced by bright circular spots in a selected-area electron diffraction pattern and clear lattice fringes in the high-resolution TEM image. Fourier transform infrared spectroscopy revealed possible involvement of reductive groups on the surface of nanoparticles. The method exploits a cheap and easily available biomaterial not explored so far for the synthesis of metallic nanoparticles.

ZnO nanoparticles (NPs) were successfully fabricated by simple combustion process, in which Zn (CH3COO)2 precursors migrated with the aid of alcoholic fuel to the top of a burning lampwick and the chemical reactions occurred at the solvent-air interface of the ignited lampwick, yielding ZnO NPs. Ultraviolet-visible spectroscopic analysis and energy-dispersive spectroscopic elemental analysis revealed that the fabricated ZnO NPs are comprised mainly of Zn and O atoms. It was observed that most of the ZnO NPs exhibited an ellipsoidal shape having a particle size of 100 to 200 nm for short-length axes and 100 to 400 nm for long-length axes. To see the effectiveness of the fabricated ZnO NPs, it was employed as photocatalytic agent to degrade the organic dye, viz. Rhodamine B, and catalytic activities under both sunlight and UV light were analyzed and compared with respect to the commercially available ZnO (Fluka). The initial degradation rate in fabricated ZnO NPs was almost double than that of ZnO (Fluka). Furthermore, by exposing to sunlight for 1 h, the fabricated ZnO NPs degraded Rhodamine B dye more than 80%, whereas it was only approximately 35% for ZnO (Fluka). Photocatalytic activities might be attributed to porous structures with larger active surface area of the nanosized ZnO particles. With this advantage, 96% of organic contaminants were degraded by the fabricated ZnO NPs upon exposure to sunlight for 2 h.

The use of microorganisms in the synthesis of nanoparticles emerges as an eco-friendly and exciting approach. In the present investigation, we report the biosynthesis of silver nanoparticles employing the bacterium Salmonella typhirium. Silver nanoparticles were synthesized through the reduction of aqueous Ag+ ion using the growth culture supernatants in the bright conditions. The synthetic process was fast, and silver nanoparticles were formed within 4 min of silver ion coming in contact with the cell filtrate. An absorption peak at 427 nm in a Uv-vis spectrophotometer was detected indicating the presence of Ag nanoparticles. The morphology of nanoparticles was observed by transmission electron microscopy. The size of the nanoparticles was determined to be 87±30 nm, applying dynamic light scattering. Reduction degree of Ag+ was measured as 75% by atomic absorption spectrophotometry. The silver nanoparticles have been prepared from silver sulfate during this investigation for the first time.

The nanodiamonds (NDs) were produced on glass substrates by plasma-enhanced chemical vapor deposition (PECVD) method. Acetylene (C2H2) diluted in H2 were used as the reaction gasses as source of carbon and diluting gasses, respectively. The NDs have structures with high quality and density obtained by the selective Ni catalyst. The synthesized NDs have cubic structures with an average diameter of about 300 nm. This research focuses on the evolution of nickel catalyst under hydrogen/acetylene gasses at 320oC. The presence of the ND structure was confirmed by Raman spectroscopy, X-ray diffraction, and scanning electron microscopy analyses. It was found that the selective catalyst played an important role in producing ND structures by PECVD method on glass substrate in this research.

Nanocrystalline titania-based sulfonic acid (TiO2-Pr-SO3H) was used as an efficient and reusable catalyst for the synthesis of quinoxalines. The clean and mild acidity condition, quantitative yields of products, short reaction time, and low reaction temperature are attractive features of this method, making it suitable for heat- or acid-sensitive substrates, particularly in drug synthesis. In practice, this method affords an advantageous combination of satisfactory yields, easy product isolation, and purification.

Porous alumina template was prepared by constant voltage in three different electrolytes (0.45 M sulfuric acid, 0.3 M oxalic acid, and mixed solution of 0.45 M sulfuric and 0.3 M oxalic acids). In this paper, the effects of the electrolyte type on the morphology is studied, so the anodization is carried out in an oxalic acid, sulfuric acid, and a mixture of oxalic and sulfuric acids. The effect of these three different electrolytes was investigated by scanning electron microscopy. Results show that in sulfuric acid, the pore structure is smaller than the oxalic and a mixture of oxalic and sulfuric acid. Density of holes in sulfuric acid was higher than other electrolytes; however, arrangement of pores in oxalic acid was more regular than that of the others.

In this article, the effect of growth parameters on structural properties of TiO2 nanowires, synthesized by thermal evaporation process, have been studied. The nanostructures are characterized by scanning electron microscopy and X-ray spectroscopy. Our synthesized TiO2 nanowires were found, through X-ray diffraction measurements, to be crystalline rutile TiO2. We studied the effect of growth parameters such as the deposition temperature, the system pressure, and carrier gas flow on the growth and structure of our synthesized nanowires. It was found that their growth was governed by vapor–liquid–solid mechanism because of using Au catalyst. In this mechanism, the Ti layer deposited on the substrate diffused in to the solid Au catalyst; then, a liquid alloy of Au-Ti was formed to serve as preferred sites for the growth of TiO2 nanowires.