فهرست مطالب

  • Volume:9 Issue:3, 2013
  • تاریخ انتشار: 1392/09/06
  • تعداد عناوین: 7
|
  • Y. Bayat*, M. Zarandi Pages 115-120
    The behavior of nanoscale energetic materials is quite different from micronsized energetic materials in many ways. Recently, some techniques such as sol-gel method, high speed air impaction and vacuum codeposition have been employed to obtain nanoscale energetic materials. However, only few attentions were paid to nanoscale energetic materials because of the fabrication difficulty. In this paper, the simple preparation of a nitramine 2,4,6,8,10,12 hexanitro 2,4,6,8,10,12 hexaazaiso wurtzitane (HNIW) with nanometer size by microemulsion method is presented. The microemulsion systems contained tween80, 2-propanol and n-butyl acetate as the oil phase. On the base of DLS measurement average particle size is 8 nm. The prepared nanoparticles are semispherical based on SEM picture.
    Keywords: Microemulsion, HNIW, Nanoparticle, Surfactant, Nonionic
  • M. Moradian, M. Moradian*, Z. Boroumand Pages 121-126
    Widespread arsenic contamination of mining wastewater of Zarshouran (West Azerbaijan province) has led to a massive epidemic of arsenic poisoning in the whole of surrounding areas. It is estimated that approximately all agriculture fields are being irrigated with the water that its arsenic concentrations elevated above the World Health Organization’s standard of 10 parts per billion. A novel advanced magnetic matter adsorbent using magnetite embedded within nanosized Fe3O4 was prepared and applied for separation of arsenic metal ion from aqueous solution. This adsorbent combines the advantages of magnetic nanoparticles with magnetic separability and high affinity toward arsenic metal ions, which provides distinctive merits including easy preparation, high adsorption capacity, and easy isolation from sample solutions by the application of an external magnetic field. The adsorption behaviors of arsenic from an aqueous medium, using iron magnetite nanoparticles were studied by using equilibrium batch and column flow techniques. The effects of pH, contents of loaded magnetic matter nanoparticles, ionic strength, adsorbent dose, contact time, and temperature on adsorption capacity of the magnetic beads were investigated. All the results suggested that the mentioned nanoparticles could be excellent adsorbents for As(II) and As(III) contaminated water treatment.
    Keywords: Advanced nano, magnetic matter, Adsorption, Arsenic removal, Magnetite nanoparticles, Zarshouran gold mine
  • N. Farhadian* Pages 127-138
    The aim of this study is investigating the transport mechanism of ibuprofen chiral isomers inside single wall carbon nano tube (SWCNT) using mathematical modeling. To achieve this goal, molecular dynamics simulation has been performed to evaluate the interactions of ibuprofen isomers with SWCNT in an aqueous solution. Results show that both chiral forms of ibuprofen molecules enter and remain inside SWCNT from their methyl side chains and their movement is not along the centerline of the tube. The distance of the closest atom of the drug molecule from SWCNT surface is around 2.26A˚. A tilted angle between ibuprofen molecule and internal surface of SWCNT is detected to be around 34◦. Moreover, these ibuprofen chiral forms interact to each other from their carboxylic side chain. This causes ibuprofen fluctuation inside SWCNT around the tube axis. Also, calculated results do not show any significant differences between selectivity of SWCNT toward R- and S- chiral forms of ibuprofen molecule. This confirms that both ibuprofen chiral forms have the same transport mechanism inside SWCNT.
    Keywords: Carbon nano tube, Molecular dynamics simulation, Chirality, Ibuprofen, Chiral forms
  • P. Boroojerdian* Pages 139-142
    Semiconductor nanoparticles exhibit size dependent properties due to quantum confinement effect that are not present in their bulk counterparts. In this work, extremely fine and pure SnO2 nanoparticles of ~1.1 nm size were synthesized by a solution process, in which amorphous precipitate of SnO2 was crystallized by microwave heating. The particles sizes varied from ~1.1 to ~2.7 nm. By XRD analysis, the particle size, crystal structure and purity of the samples were determined. The UV-Vis measurements of SnO2 nanoparticles, showed that, excitonic peaks existed at ~237, ~250 and ~279 nm corresponding to ~1.1, ~2 and ~2.7 nm clusters respectively. The STM analysis showed that the nanoparticles were spherical in shape, having narrow size distribution.
    Keywords: Tin Oxide, Nanoparticles, Microwave heating, Semiconductors, SnO2
  • R. Malekfar*, A. Cheraghi, G. Ahmadi, H. Nanakar, A. Mansori, A. Amerian Pages 145-150
    In this work the synthesization process of nanocrstallite Nd:KTP powders by modified Pechini method was studied. The results of XRD studies indicate that KTP nanocrystallites doped by Nd has orthorhombic phase. The structural and lattice modes of the synthesized nanocrystallite products were investigated by using Micro Raman back scattering and FT-IR transmission spectroscopies. SEM imaging technique was applied for the observation of grain sizes and the morphology of the nanoparticles. The Debye-Scherrer formula was used to confirm the grain sizes determined by the SEM slides. In overall conclusion, it can be claimed that XRD, SEM and back scattering Raman spectroscopy are suitable methods to study the quality and characterization of nanocrystallite materials such as KTP family nanocrystals.
    Keywords: Nd, KTP, Nanocrysallite, Pechini method, Raman scattering, XRD
  • R. Ahmadi*, A. Khodadadi Darban Pages 151-162
    In this paper, size distribution of nano-bubbles was measured by the reliable and fast method of laser diffraction technique. Nano-bubbles were produced using a nano-bubble generator designed and made based on hydrodynamic cavitation phenomenon in Venturi tubes. A Central Composite Design with Response Surface Methodology was used to conduct a five factor, five level factorial experimental design on the main process variables including frother concentration, solution temperature, pH, air flow rate and pressure drop in the cavitation tube nozzle. The statistical analysis used to develop a model for predicting the median size of nanobubbles (D50) showed that the frother concentration, solution temperature and air flow rate have the highest effect on the size of nanobubbles. Results demonstrated that with increasing the frother concentration and the air flow rate, the median nanobubble size (D50) decreased. The results also indicated that an addition of 20~ 40°C temperature, increased the median size of the nanobubbles formed in the solution. In the optimum condition, the frother concentration, solution temperature and air flow rate were found to be 69.5 mg/h-1, 20°C and 0.3 Lmin-1, respectively. In this study, the minimum median size of the nanobubbles produced in the laboratory and predicted by the prediction model was 130.75 and 129.83 nm,respectively, which showed that the model results properly fitted with experimental results.
    Keywords: Nanobubbles, Hydrodynamic cavitation, Laser diffraction technique, Response surface methodology
  • M. M. Zerafat, M. Shariaty-Niassar*, S. J. Hashemi, S. Sabbaghi, A. Ghaee Pages 163-172
    Nanofiltration-based separation processes have found diverse applications in industrial and environmental problems recently, due to several advantages such as lower energy requirement and elevated flux rates compared with their Reverse Osmosis (RO) counterparts. Several attempts have been made for modelling NF-based separation processes ranging from rigorous space-charge approaches to simpler Irreversible Thermodynamic (IT) models and yet none has satisfied the whole predictive expectations either as a result of unacceptable computational requirements or oversimplifying assumptions. Also, few attempts have been made for the modelling of NF behaviour in strong salt solutions. Thus, a new model incorporating the new phenomena to compensate for the shortcomings can help shed light to find new directions.This study is an effort for modelling the NF-based separation processes by using the Modified extended Nernst-Planck (MENP) equation for solute transport through membrane active layer and advectiondiffusion for concentration and velocity interactions due to feed cross-flow over the membrane surface.MENP takes into account the variations of activity coefficient and its influence on retention due to ionic strength variations. In the case of pure salt solutions (NaCl & Na2SO4), the effect of ionic strength and charge density on the rejection will be investigated. The results show that higher ionic strengths result in lower retentions and charge density has an extended effect in the modified model.
    Keywords: Nanofiltration, Extended Nernst, Planck, Convection, Diffusion