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Scientia Iranica - Volume:24 Issue: 6, Nove-Dec 2017

Scientia Iranica
Volume:24 Issue: 6, Nove-Dec 2017

  • Transactions on Chemistry and Chemical Engineering (C)
  • تاریخ انتشار: 1396/10/10
  • تعداد عناوین: 10
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  • M. Masteri-Farahani *, M. Modarres Pages 2993-3001
    A heterogeneous catalyst for the epoxidation of olefins was prepared by encapsulating Keggin-type phosphotungstic acid (H3PW12O40) into the mesopores of SBA-16. After the encapsulation, the pore entrance size of SBA-16 was reduced through a silylation method to encompass the catalyst in the mesopores and allow the easy diffusion of the reactants and products during the catalytic process. The prepared catalyst was characterized by FT-IR and inductively coupled plasma-optical emission (ICP-OES) spectroscopies, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The analysis results revealed that the mesoporous nature of SBA-16 has been conserved after encapsulation of the catalyst and followed silylation step. The catalytic activity of the prepared material was assessed in the epoxidation of olefins with H2O2. The heterogeneous catalyst was recovered and reused up to five cycles without considerable decrease in activity
    Keywords: mesoporous SBA-16, heteropoly acid, Keggin, immobilization, Epoxidation
  • Raghavendra Mahadevaiah, Haraluru Shankaraiah Lalithamba *, Sharath Shekarappa, Rajanaika Hanumanaika Pages 3002-3013
    Green synthesis of nano MgO particles and their application for the formylation of isocyanates of N-Fmoc/Cbz/Boc protected amino acids were reported. Nano magnesium oxide catalysed reaction of isocyanate with 96% formic acid has been established to obtain formamides. For this, the carboxyl group of protected amino acids were activated via mixed anhydride method and treated with NaN3. The formed azides were converted into its isocyanates through Curtius rearrangement and treated with HCOOH and catalytic amount of nano MgO. The advantages of this method were remarkably simple and economically low cost nano metal oxide under milder reaction conditions. Most importantly, MgO can be easily separated and other basic impurities were removed through a simple work-up. This protocol showed high efficiency in catalysing this transformation in a greener fashion. The molecular docking study of the synthesized compounds was performed against the macromolecules sortase-A and glucosamine 6-phosphate synthase to understand the binding interactions. The results of in vitro antibacterial activities of the synthesized compounds were supported by docking analysis.
    Keywords: Formamides, Nano MgO, Curtius rearrangement, Molecular docking, Antibacterial activity
  • Bi Bi Fatemeh Mirjalili *, Marzieh Dehghani Tafti Pages 3014-3021
    Nano-kaoline/BF3/Fe3O4 as an eco-friendly nanocatalyst was used for quinoxaline preparation via condensation of 1,2-phenylene diamines and 1,2-diketones. This simple protocol proceeds under grinding condition and has many advantages such as easy workup and high product yields.
    Keywords: 1, 2-Phenylene diamine, Benzil, Kaoline, Magnetic catalyst, Nano-kaoline-BF3- Fe3O4
  • Bagher Eftekhari-Sis *, Masoumeh Sarvari Karajabad, Shiva Haqverdi Pages 3022-3031
    2-[(2-Pyridylmethyl)amino]acetic acid (PMAA) functionalized Fe3O4 superparamagnetic nanorods efficiently catalyzed three-component reaction of malononitrile, aromatic aldehydes and phenolic or enolic components, such as α-naphthol, β-naphthol, dimedone or kojic acid, to synthesize a variety of chromene or pyran derivatives in good to high yields. PMAA functionalized Fe3O4 magnetic nanorods were prepared via simple coprecipitation from an aqueous solution of Fe2 and Fe3 ions using NH4OH in the presence of glycine, followed by subjecting with 2-pyridine carbaldehyde and then NaBH4-mediated reduction of in-situ generated imine. Obtained nanorods were characterized by FT-IR, XRD, TGA, SEM, EDX, TEM, BET and VSM analysis.
    Keywords: Fe3O4, Magnetic nanorods, Three-component reactions, Chromene, Pyran
  • Maedeh Arvani, Hamide Mohammad Aliha, Abbas Ali Khodadadi, Yadollah Mortazavi * Pages 3033-3040
    SnO2 was ultrasonically deposited-precipitated in the presence of different amounts of graphene oxide (GO) prepared by the modified Hummers’ method. The resulting nanocomposites were used as the sensing material for detection of 1000 ppm CO and VOCs including ethanol, acetone and toluene and CH4 in a temperature range of 150-300°C. The nanocomposites were characterized by Raman spectroscopy, XRD, BET surface area measurement, FT-IR and SEM methods. It seems that SnO2 layers were deposited on the GO surface and incorporated into the matrix. This results in 47% increase in the nanocomposite BET surface area. Addition of 0.1 wt% GO to SnO2 increases the response to CO by about 6 times, at 300°C. As an optimum amount of 0.05 wt% GO is included in the SnO2, up to 2 fold enhancement in response to ethanol and toluene is observed. At 250oC, the highest response to ethanol is obtained, which is 120, 114, 1400 and 15 times larger than the responses to CO, toluene, methane and acetone, respectively, making the sensors quite selective to ethanol. Furthermore, this sensor exhibited good response in the low concentration of ethanol.
    Keywords: Gas sensor, graphene oxide, Breathalyzer, Ethanol, SnO2
  • Mohammad Malakootian, Hossein Jafari Mansoorian *, Mostafa Alizadeh, Abdolvahab Baghbanian Pages 3041-3052
    This study was performed to measure the potential utilization of agro-waste to generate nanoparticles and evaluate the capability of it’s as a low cost adsorbent for removal of phenol. Adsorption studies for phenol removal by using Aloe vera and Mesquite leaves nanoparticles carried out under various experimental conditions including pH, nano-bioadsorbent dosage, phenol concentration, contact time, temperature and ionic strength in a batch reactor. The adsorption kinetics by pseudo-first order and pseudo-second order models and isotherm technique by Freundlich and Langmuir isotherms models were applied. The results showed that the rate of phenol adsorption increases in both nano-bioadsorbents with an increase of pH up to 7, adsorbent dosage up to 0.08 gL-1, phenol initial concentration up to 32 mgL-1, contact time up to 60 min and raising in temperature. The adsorption data followed the Freundlich isotherm model. The kinetic studies indicated that the adsorption of phenol with nano-bioadsorbents was best described by the pseudo second order kinetics. We found that the nanoparticles prepared from Aloe vera and Mesquite leaves had a high capability in adsorption of phenol, beside the point that they could be accessed at a low cost. These agro-wastes can be used to remove phenol from aqueous environments.
    Keywords: Agricultural solid waste, Aloe vera, Mesquite, Nanoparticle, Phenol Removal, Adsorption Isotherms, Adsorption Kinetics
  • Hamid Didari, Mahdi Salami Hosseini *, Reza Yegani Pages 3053-3063
    In the present study, attempts are made to study the behavior of a viscoelastic fluid in hollow fiber membrane production process. For this purpose, the fluid is considered to obey the Giesekus’ model and flow is taken as steady, two-dimensional and isothermal flow. The flow field is obtained using DEVSS/SUPG scheme combined with a free surface tracking method. The obtained results are compared to the case of Newtonian fluid. It is shown that the extrudate swell is 20% more in the case of viscoelastic fluid. Moreover, the elastic behavior of the viscoelastic fluid significantly affects the velocity field in the extrudate outside the die. It causes the fluid flow to become reversed in the middle part of the extrudate as the direct result of the stress relaxation process, whereas such a behavior is not seen for Newtonian fluid. Also, the first normal stress difference (FNSD) distribution in the extrudate is obtained and its variation is discussed. Furthermore, the effect of operational parameters including die back pressure and take-up velocity are investigated. Finally, the predicted extrudate swell for various operation conditions is compared to experimental results showing a good agreement between experimental and simulated data.
    Keywords: extrudate swell, finite element method, Gieseku's model, hollow fiber membrane, viscoelastic fluid
  • Amir Vahid *, Mohammad Qandalee, Sahar Baniyaghoob Pages 3064-3073
    H2S is a major toxic compound that could be found in air, water, Fossil fuels and causes some worse effects such as acidic rain and corrosion. In the present work SBA-3 (Santa BarbarA University no. 3) with three different weight percent’s of ZnO, i.e. 5%, 10% and 15% was synthesized via an in situ approach. All synthesized samples were characterized using atomic absorption spectrometry, X-ray diffraction (XRD), nitrogen adsorption and transmission electron microscopy (TEM). The obtained results from XRD and nitrogen adsorption confirmed that all the samples almost retained their ordered structure after incorporation of ZnO nanoparticles within the mesopores of SBA-3. TEM images show that ZnO nanoparticles arranged along the direction of mesopores of SBA-3. Then, adsorption of H2S from a model gas was investigated. A three factor Box–Behnken design with five center points and one response was performed for the evaluation of effect of three process parameters, i.e. ZnO wt%, space velocity and temperature on the adsorption of H2S and a quadratic model (r2 : 0.9185) was developed to navigate the design space. Temperature had the largest and space velocity had the lowest effect on the breakthrough of H2S. The optimum breakthrough time (tbp) was 588 min.
    Keywords: air pollution, H2S, Mesoporous materials, Removal, Zinc oxide
  • Meral Coban, Seda Hazer, Ayse Aytac * Pages 3074-3080
    The objective of this study is an investigation of the effects of carbonic agent and nanoclay loading level on the properties of the added flame retardant and plasticized polylactic acid (PLA) composites. Pentaerythritol (PER) was used as a carbonic agent in the composites. The flammability behaviour of these composites was investigated with the increasing nanoclay loading level. Flame retardant properties of plasticized PLA composites which are consisting of PER and nanoclay as a synergistic agent were evaluated. While the nanoclay loading levels were changed between 1-5 wt% of these samples, PER loading levels were fixed at 2 wt%. Besides, effects of increased PER loading level were also investigated with 3 wt% clay loading. Samples were produced by using extrusion and injection molding techniques. The morphological, thermal and mechanical properties were studied. The flammability was evaluated by using limiting oxygen index (LOI) and vertical burning test (UL-94). The results showed increased PER level didn’t significantly change LOI values of the PLA based nanocomposites. In addition, the highest LOI value was observed as 32 for 1 wt% nanoclay including sample. While adding PER to the PLA/PEG/TPP increased the elongation at break value, adding of the nanoclay decreased this value for nanocomposites.
    Keywords: poly(lactic acid), flame retardant, triphenyl phosphate (TPP)
  • Handan Uysal, Si, Di, Ka GenC, Arif Ayar * Pages 3081-3086
    Artificial azo dyes are widely used as coloring agents for foodstuffs, drugs and cosmetics. In this study, the toxic effect of four different synthetic food dyes (Ponceau 4R, Sunset Yellow, Amaranth, Tartrazine) on 72±4h larvae of Oregon (R) wild type of Drosophila melanogaster were investigated. In addition, depending on chronic feeding, the life span of the flies determined. For this purpose, six different concentrations of the food dyes (5, 10, 15, 20, 25 and 30 mg mL-1) were selected by preliminary studies to determine the LD100 values.The effects of the food dyes on longevity were studied separately in female and male populations. It was determined that the maximum mean life span of the female and male D. melanogaster populations decreased with increasing concentrations of food dyes. Based on the results obtained from the larval mortality and life span experiments, the order of toxicity for food dyes was Tartrazine>Amaranth> Sunset Yellow ≥ Ponceau 4R.
    Keywords: Drosophila melanogaster, Food Azo dyes, Longevity, Larval mortality, Toxic effects