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Particle Science and Technology - Volume:2 Issue: 1, Winter 2016

Journal of Particle Science and Technology
Volume:2 Issue: 1, Winter 2016

  • تاریخ انتشار: 1395/11/28
  • تعداد عناوین: 6
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  • Yasser Vasseghian, Mojtaba Ahmadi, Mohammad Joshaghani Pages 1-13
    This study investigates removing ash and pyrite sulphur from bitumen by column flotation process. Central composite design (CCD) of response surface methodology (RSM) was applied for modeling and optimization of the percentage of ash and pyrite sulphur removal from bitumen. The effects of five parameters namely the amounts of collector and frother agents, particle size, wash water rate and feed rate on percentage of ash and pyrite sulphur removal from bitumen were investigated. The used bitumen sample has 26.4% ash and sulphur content of 9.6% (6.81% in the pyrite sulphur form). All the tests were carried out under aeration rate of 4L/min and pulp containing 5% of solid using pine oil and kerosene as frother and collector agents, respectively. The coefficient of determination, R2, showed that the RSM model can specify the variations with the accuracy of 0.971 and 0.975 for ash and pyrite sulphur removal from bitumen, respectively, thus ensuring a satisfactory adjustment of the model with the experimental data. The RSM was used to optimize the process conditions, which showed that initial amount of collector of 2.00kg/tbitumen, amount of frother of 0.2ppm, particle size of 101.29mesh, wash water rate of 0.5L/min and feed rate 1.26L/min were the best conditions. Under the optimized conditions, the maximum percentage of ash and pyrite sulphur removal from bitumen was 88.74% and 90.89%, respectively.
    Keywords: Ash removal, Pyrite sulphur removal, Bitumen, Column Flotation process, Response surface methodology
  • Nader Rostamizadeh, Mirabdullah Seyedsadjadi, S. A. Sadjadi Pages 15-22
    This paper investigates hollow and porous alumina nanospheres that were previously synthesized to be used for the dehydration of methanol to dimethyl ether (DME). As hollow nanostructures possess characteristics such as low density and high surface to volume ratio, their catalytic activity between hollow and porous structure is compared. For this purpose, three most important parameters (acidity, temperature and weight hourly space velocity (WHSV)) affecting the performance of these catalysts were investigated. The catalysts were characterized by scanning electron microscopy (SEM), BET, X-ray diffraction (XRD), and the temperature programmed desorption of ammonia (NH3-TPD) techniques. Results show that the optimum operating condition for hollow alumina nanosphere can be achieved at temperature of 275 ºC and WHSV of 20 h-1 compared with operating condition for porous alumina at temperature of 325 ºC and WHSV of 20 h-1.
    Keywords: methanol, dehydration, dimethyl ether, hollow, alumina nanospheres
  • Oner Yusuf Toraman Pages 23-29
    This study investigates the influence of some chemical additives such as methanol, ethanol, sodium oleat, chloroform and sodium hexametaphosphate (SHMP) on the dry fine grinding of calcite (X50= 33 µm) using a stirred media mill. The experiments were carried out by a batch operation, and the change in colour properties (Ry, whiteness and yellowness) of calcite powder. The results showed that the chemical additives promote the fine grinding of calcite obtained with ethanol and methanol at a range of 0.5%. Ry and whiteness values of the ground calcite products very slightly increased from 94.10 and 87.04 to 94.76 and 87.75 respectively with grinding aid (ethanol) increased from 0% to 1%. Ry value was affected slightly adversely with sodium oleat, chloroform and SHMP indicating that the quality of colour of calcite deteriorates. It was also found that ΔRy increases with increasing amount of grinding aids from 0% to 0.5% for methanol and ethanol, indicating that the quality of colour of calcite heals.
    Keywords: Stirred media mill, fine grinding, calcite, grinding aid, colour properties
  • Arash Amani, Ali Reza Solaimany Nazar, Hasan Sabzyan, Gholamhassan Azimi Pages 31-39
    The effects of water/oil volume ratio, type and concentration of demulsifier, water salinity and mixing speed on the average water droplets size in water-oil emulsion are evaluated at different times through NMR measurements.The type and concentration of demulsifier have the greatest effects on the average droplet size with 38% and 31.5%, respectively. The water/oil volume ratio, water salinity and mixing speed are significant factors with 13.1%, 7.5% and 5.71%, respectively. The commercial demulsifier Break 6754 has the greater influenceon the average droplet size compared to the acrylic acid. The water droplets size increases upon increasing the concentration of demulsifier, the water volume ratio and the salinity of water and decreases upon increasing the mixing speed.
    Keywords: NMR measurement, water, oil emulsion, droplet size, demulsifier
  • Leila Khoshrooyan, Ali Eliassi, Maryam Ranjbar Pages 41-47
    The effect of catalyst particle size on dehydration of methanol to dimethyl ether is investigated using fixed bed and micro-channel reactors at different temperatures and weight hourly space velocities. The experiments were carried out at 290 and 320oC. The space velocities were changed from 10 up to 90h-1 and from 1.22 to 3.65h-1 for fixed bed and micro-channel reactors, respectively. Considering the catalyst particle size effect on dehydration reaction, the particle size was changed from 0.063 to 1mm. Commercial gamma alumina was used as catalyst in all the experiments. The fabricated micro-channel reactor had 40 channels with 1mm diameter and 6 cm length. The channels were sub-coated with alumina and finally were coated with gamma alumina as dehydration catalyst. The results showed that methanol conversions were increased by increasing the temperature and decreasing the particle size of the catalyst. Furthermore, methanol conversion in micro-channel reactor was less than for fixed bed reactor under the similar WHSVs, due to the special geometrical shape of the micro-channels.
    Keywords: Methanol Dehydration, Fixed Bed Reactor, Micro-Channel Reactor, Catalyst Particle Size, DME
  • Maryam Omidvar, Esmaeil Koohestanian, Omid Ramezani Azghandi Pages 49-54
    The research investigates synthesized Nano-structured PbO2 using ball milling. The structure and morphology of the samples were determined in the process of milling by means of XRD and SEM. The size of particles was estimated through DLS analysis. The TEM image of the synthesized powder verifies the achievement of Nano dimensions. Design and analyses of the results using Taguchi methodology reveal that the size of synthesized Nano-structured PbO2 decreases as ball to powder ratio (BPR) increases while the average size of the particles increases as mechanical milling speed increases from 200 to 250 rpm. Considering the results of TEM, the size of the synthesized Nano-structured PbO2 by means of mechanical milling was estimated to be 50 Nanometers. In addition, the even distribution and spherical morphology of the synthesized powder by this method is crystal clear in SEM images. Additionally, the result of the statistical analysis of particle size based on the effective parameters by means of Minitab software showed that BPR parameter had the greatest impact on the size of particles; BPR increase improved the objective parameter as compared with other parameters under study. According to the results obtained by Minitab software and considering the little influence of time on particle size decrease and in order to minimize the costs of synthesis, it is suggested the synthesis process be done in two hours and the BPR parameters be increased so as to decrease the size of particles.
    Keywords: Synthesis, Mechanical milling, PbO2, Nano, structure, Design of experiment