Iranian Journal of Chemistry and Chemical Engineering
Volume:33 Issue: 1, Jan-Feb 2014

Tetrahydrobenzo[b]pyran derivatives 1 were utilized for the synthesis of several new pyrano[2,3-d]pyrimidine derivatives 2. Compound 2 was obtained in the presence of Ac2O/H2SO4 (as a catalyst) and was confirmed by spectroscopic data such as IR, 1H NMR and 13C NMR. Ab initio calculation was carried out to study geometric optimization, thermodynamic parameters, aromaticity and dynamic process of conformational analysis for compound 2.

In this study, pyrite was produced by hydrothermal precipitation from the reaction between FeSO4 and Na2S2O3 at high pressure and high temperature in a stirred reactor. The solid product was purified by means of solvent extraction to remove sulfur. Powder was characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and thermal analyses. Results indicated that pyrite was produced as nanostructure with high purity.

A facile and simple method was proposed to control the size and shape of the MgO nano structures with high surface area in the presence of efficient and cheap templates like PEG 200, PEG 600, PEG 4000 and sorbitol at low temperature within a little time. Nano rods and Nanoparticles have been achieved by applying these templates and altering other growth parameters. The products were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Thermo Gravimetric Analysis (TGA). The surface area of the samples was characterized by BET method. The effect of the growth parameters such as template, pH, Mg2+/template, molar ratio and temperature on the growth and morphology of MgO nano structures have been investigated in details. By tuning these parameters MgO nano rods and nano particles can be formed.

An efficient method for purification of Yard-Glass Shaped Boron Nitride NanoTubes (YG-BNNTs) fabricated via a Chemical Vapour Reaction (CVR) route has been developed. Impurities including carbon, Boron Nitride (BN), and Fe species in the pristine YG-BNNT sample are removed by a combined physical and chemical procedure which involves ultrasonication, high temperature oxidation, hot-water washing and acid washing. The samples at different stages of the purification process are monitored using X-Ray powder Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS) and Transmission Electron Microscopy (TEM). The results reveal that the carbon and BN impurities could be easily eliminated. However, the catalyst nanoparticles (Fe3C) encaged in the tubes prove to be effectively shielded from oxidation and acid corrosion. Although the content of catalyst nanoparticles could be satisfactorily reduced to about 1.0 wt% by prolonged ultrasonication and acid washing, a small number of such magnetic nanoparticles are still left in the final purified YG-BNNTs. The YG-BNNTs exhibit a typical ferromagnetic behavioureven after a longtime oxidizing and acid washing treatment, indicating that they could be potentially used for harsh-environment magnetic devices.

Polysulfide resins,with trade name of G4 and G112, with short and long chain lengths respectively, were used as reactive modifiers to toughen epoxy resin. The effects of molecular weights of G4 and G112 on impact resistance, dielectric constant, thermal conductivity as well as decomposition heat and adhesion properties of toughened epoxy were investigated. The impact strength and the dielectric constant of epoxy resin were enhanced by increasing of polysulfide so that the effect of the G112 is higher than the G4. For the same weight percent of G4 and G112, the G112 modified epoxy resin has lower Cure enthalpy than the G4 modified epoxy resin. Addition of modifier with long chain up to 10 weight percent was also leaded to higher bond strength with aluminum sheets. also, It is observed that the thermal conductivity of epoxy decreasing with incresing modifier chain length.

Unmodified zeolites show little affinity for anions due to the fact that their surfaces are negatively charged. However modification of zeolites with amines turns their negative surface charge to positive and creating higher adsorption capacity for anions. In this study, polyaniline-clinoptilolite composite was prepared by polymerization of anilinium on the surface of zeolite. The composite was characterized by elemental analysis and X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM) and Fourier Transform InfraRed (FT-IR) techniques. The adsorption capacity of the composite for removal of CrO42- from aqueous solutions was studied under different experimental conditions including initial concentration, pH, temperature, and contact time. The maximum adsorption capacity of this adsorbent was higher than the values reported for similar adsorbents. The adsorption process was kinetically fast and the equilibration was attained after 30 minutes. The Langmuir and Freundlich isotherm models were applied to describe the equilibrium adsorption and the Freundlich model agreed well with the experimental data.

The removal of xylenol orange from aqueous solution onto the coal ash was investigated at room temperature. The results show that the adsorption capacity ofxylenol orange increased as the adsorption time increased and then equilibrium established after 30 min adsorption time. The results obtained revealed that the coal ash removed about 80 % of xylenol orange from the aqueous solution within 40 min. The effect of pH also studied, which showed that the adsorption of xylenol orange on the coal ash decreased as pH increased. The equilibrium adsorption isotherm data was fitted in Langmuir and Freundlich model equation and was found that the data followed both Langmuir and Freundlich isotherm models. Furthermore, we used a statistical measure (rank equation) in order to measure the strength of the relationship between the adsorption of xylenol orange onto coal ash and different adsorption time, and adsorption of different concentration of dye at equilibrium time.

Dispersive Liquid-Liquid MicroExtraction technique based on Solidification of a Floating Organic drop (DLLME-SFO) combined with flame atomic absorption spectrometry was developed for determination of thallium in water sample. An appropriate mixture of acetone and 1-undecanol was rapidly injected into an aqueous sample containing TlCl4- which forms an ion pair with brilliant green reagent and as a result a cloudy mixture was formed. After centrifugation, the test tube was cooled for 5 min and the solidified 1-undecanol drop formed on the top of the solution was transferred into a suitable vial and it was dissolved in 300µL of acetone and finally introduced into the flame atomic absorption spectrometer. Several factors affecting the extraction process, such as the volume of the extractant and disperser solvents, centrifugation time, concentration of brilliant green, concentration of HCl, ionic strength, volume of diluting solvent and interferences were studied. Under the optimum operating conditions, the calibration graph was linear in the range of 240-6000ng/mL with a limit of detection of 90 ng/mL and preconcentration factor was 17. The Relative Standard Deviation (RSD) for five replicate measurements of thallium was 3.6%. The accuracy of the method was assessed using a certified reference material (unalloyed zinc) and spiked tap water. The results demonstrated high accuracy, recovery and applicability of the presented method.

Isotactic poly (1-butene), ipbu-1, was synthesized by using a metallocene catalyst. The thermodynamic phase behavior of polymer–organic solvents systems is very important in every polymer application. In this paper, the solid–liquid equilibrium of ipbu-1 with different organic solvents (1-heptyne, cyclo octane) was studied by a mathematical model. By considering the experiments temperature-mole fraction results, phase diagram of the polymer solvent systems could be constructed. The temperature and activity coefficient based on mole fraction phase diagrams were predicted by using Pareto genetic design of GMDH-type neural network. The results were very encouraging and congruent with the experimental data.

To perform any economic management of a petroleum reservoir in real time, a predictable and/or updateable model of reservoir along with uncertainty estimation ability is required. One relatively recent method is a sequential Monte Carlo implementation of the Kalman filter: the Ensemble Kalman Filter (EnKF). The EnKF not only estimate uncertain parameters but also provide a recursive estimate of system states such as pressures and saturations. Due to high computational cost, however, the EnKF is limited to small size ensemble set in practice. On the other hand small ensemble size yield spurious correlation within covariance of state. A remediation to this problem is to employ covariance localization to remove long range spurious correlations. In this study, five distance base localization functions have been implemented and analysis on two different cases to obtain a better history matching with EnKF. The results indicate that quartic correlation function produce better results than others especially to the popular fifth-order correlation function meanwhile maintain more total variance at the end of the assimilation.

Formation of asphaltene deposition during oil production, processing and synthesis is known as a fundamental problem of petroleum reservoir worldwide. Asphaltene is a petroleum fraction that can lead to increasing the operating costs in these industries. Variations in operational pressure, temperature and fluid composition are generally the significant cause of asphaltene precipitation. In this study, a regular solution model with liquid-liquid equilibrium criteria between asphaltene-rich phase and solvent-rich phase (maltene phase) is presented in order to calculate asphaltene precipitation. As a result, to achieve this objective, the Flory-Huggins (F-H) theory is applied and the definition of the interaction parameter in the traditional form of F-H model is modified. In this work, an empirical correlation is adapted using regular solution theory to predict the solubility parameters and eventually the DE (Differential Evolution) optimization strategy is applied to calculate optimum values of the justifiable parameters in the model. The results of the developed model are finally compared with the existing asphaltene precipitation data in various solvent ratios from the literature and it is shown that they are in acceptable agreement with the experimental data. Hence, the proposed model is capable of good prediction of asphaltene precipitation in a widespread range of the solvent ratios.