Iranian Journal of Chemistry and Chemical Engineering
Volume:31 Issue: 1, Jan-Feb 2012

1-Butyl-3-methylimidazolium bromide ([bmim]Br) as an ionic liquid promoted selectively oxidation of aliphatic and aromatic sulfides to the corresponding sulfoxides and the oxidative coupling of thiols to disulfides by NaBrO3 in excellent yields under neutral conditions.

Cr(III), Co(II), Ni(II), Cu(II) and Zn(II) salts of 2-(4-nitrophenylaminocarbonyl)benzoic acid were characterized by physical, analytical and spectroscopic studies and checked for their in-vitro antimicrobial activity against three bacterial strains, Mycobacterium smegmatis (Gram +ve), Escherichia coli (Gram -ve), Pseudomonas aeuroginosa (Gram -ve) and three fungal strains, Nigrospora oryzae, Aspergillus niger and Candida albicans. The antimicrobial activities of the metal complexes were found to be greater than those of 2-(4-nitrophenylaminocarbonyl)benzoic acid alone.

A new fibrous adsorbent was prepared by grafting Acrylic Acid /Acryl Amide (AA/AAm) co-monomers onto Poly(Ethylene Terephtalat) (PET) fibers. The resulting sorbent has been characterized by Fourier Transform InfraRed spectroscopy (FT-IR), Thermo Gravimetric Analysis (TGA), Scanning Electron Microscopy (SEM) and elemental analysis and studied for the preconcentration and determination of trace Pb+2 ion from water sample. The effects of reaction conditions such as monomer mixture ratio, grafting yield, polymerization. The time and temperature on grafting were investigated. Batch adsorption method was used for the pre concentration studies. Recovery of Pb+2 was 100.2% at optimum conditions. The adsorption capacity of the adsorbent was found 44.1mg/gforPb+2.

Tungsten trioxide nanoparticles with two different sizes (average particle sizes about 50 and 80 nm) were prepared by the spray pyrolysis method. Photo degradation of Congo Red (azo dye) showed that photo catalytic property of the as-prepared WO3 nanoparticles with average size about 80 nm is higher than the sample with average size about 50 nm. Photo degradation of Rhodamine B (cationic triarylmethane dye) showed that photo catalytic property of the as-prepared WO3 nanoparticles with average size about 50 nm is higher than the sample with average size about 80 nm. The samples were characterized with X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), EDX analysis and UV-visible spectrum. Different interactions between dyes and the photo catalyst surface, probably causes the inverse behavior of WO3 nanoparticles with two different sizes in Congo Red and Rhodamine B photo degradation reactions.

Tungsten trioxide nanoparticles with monoclinic structure and average particle size about 80 nm were prepared by the spray pyrolysis method. WO3 nanorods with hexagonal structure and average dimension about 15 × 100 nm were synthesized in gram quantities by modified hydrothermal method at lower temperature and shorter reaction time in comparison to the previous research. Photo degradation of Congo Red showed that the as-prepared WO3 nanoparticles is more effective than nanorod structure. WO3 nanorods actually had no effect in Congo Red photo degradation. Therefore in this reaction, spherical morphology is superior to column morphology. The samples were characterized with X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), EDX analysis, UV-visible spectrum and Transmission Electron Microscopy (TEM).

The improvement of the physical properties of Indium Tin Oxide (ITO) layers is quite advantageous in photovoltaic applications. In this study the ITO film is deposited by RF sputtering onto p-type crystalline silicon (c-Si) with (100) orientation, multicrystalline silicon (mc-Si), and glass substrates coated with ZnO and annealed in vacuum furnace at 400°C. Electrical, optical, structural and morphological properties of the ITO films were analyzed by four point probe, UV/VIS/IR spectrophotometer, X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM). The quality of films deposited on buffer layer is found to be superior to those grown directly on a substrate. The structural, optical and electrical studies reveal that ZnO buffer layers improve the crystalline quality, optical and electrical properties of ITO thin films.

We utilize isotherm models in contributing to scholarly knowledge in simple terms, to measure the forces or energy defining certain adsorption phenomenon. Gas Chromatography coupled with Mass Spectrophotometer detector (GCMS) was utilized to measure equilibrium phase atrazine after adsorption onto Shea nut Shells (SS) acid derived activated carbon. Data were fitted into the D-R and Temkin isotherm relationships for energy data estimation of Sorption energy value (BD), mean free energy (ED) and heat of sorption (B). They were estimated as 0.7600mol2KJ-2, 0.8111 kjmol-1 and 0.790Jmol-1 respectively. The parameter predicting the type of adsorption was evaluated BD, B < 20kJ/mol and ED<8 which is an indication that physisorption (Non specific adsorption) dominates chemisorption and ion exchange. The D-R model with a higher correlation coefficient values, R2 = 0.979 proves a better choice in explaining sorption energies. Generally, shea nut shells can be used as alternative precursors for activated carbon production via the two steps and acid treatment method.

Thermodynamic restrictions and simultaneous effects of operational conditions on the homogeneous rhodium-catalyzed carbonylation of methanol are studied in this line of research. It is shown that the general NRTL-Virial model can be appropriated to study thermodynamics of the carbonylation. It is obtained that the reaction is kinetically and thermodynamically reasonable at temperatures above 420K and below 520K, respectively. Moreover, at carbon monoxide partial pressures above 10 bar, the reaction rate is independent of the partial pressure. These results are in full accord with those reported in the literature. In addition, PCO > 2 bar is necessary for initializing the reaction. The parameters involved in the rate expression, equilibrium constants, CO solubility, and rate constant, are determined. The equilibrium constants are calculated with B3LYP/SDD ab initio method, and the value of Henry’s coefficient for CO (HCO) is determined as a function of temperature and methyl acetate conversion. The results predicted by this function agree well with those proposed by the general NRTL-Virial model with the errors below 11%. The Variation of CO solubility with acetic acid and methyl acetate concentrations is in good agreement with that obtained by others. It is found that the determined parameters give satisfactory predictions in modeling and simulation of the reaction.

Thin layer drying of Russian olive (Elaeagnusan gastifolial L.) fruit using a hot air dryer in order to calculate effective moisture diffusivity, activation energy and energy consumption has been evaluated in this article. The selected variables included three levels of air velocity of 0.5, 1 and 1.5 m/s and three air temperature levels of 50, 60 and 70°C. Increased air temperature increased effective moisture diffusivity but increase in air temperature had an inverse effect. Effective moisture diffusivity (Deff) calculated for russian olive fruit in different temperatures and air velocities ranged between 5.56×10-11 to 3.18×10-10 (m2/s). The resulting values for activation energy had a minimum of 48.18 kJ/mol for 1.5 m/s air velocity up to a maximum of 63.83 kJ/mol for 0.5 m/s air velocity. The values for total and energy consumption in thin layer drying russian olive ranged between 16.34-75.04 (kW.h).

The purpose of the present paper is to develop light beam method to measurement of interfacial area in a rectangular gas-liquid bubble column. Total interfacial area can be determined in bubble column filled by transparent liquid by light transmission method. According to pervious researches, the fraction of parallel light is function of interfacial area and optical path length that these two parameters imply Transmission Number or NT. The drop diameters were measured in the range of 2.2 to 5 mm, and in this range, the specific area is found to depend only upon the light transmission. Three different systems with various liquid phases have been used in this work. It had been proved that light transmission method for dilute suspension or stationary gas phase has a good consequence. In this work, good agreement between actual and calculated interfacial area proves that light transmission method would be able to determine interfacial area in multiple scattering, and it is possible to use earlier mathematic model to measure interfacial area in multiple scattering in gas-liquid bubble columns.

Asphaltene instability is one of the major problems in gas injection projects throughout the world. Numerous models have been developed to predict asphaltene precipitation; The scaling equation is an attractive tool because of its simplicity and not involving complex properties of asphaltene. In this work, a new scaling model is presented to account for asphaltene precipitation due to gas injection at reservoir conditions. Extensive published data from literature have been used in model preparation. To check predictive capability of the equation, miscible gas injection experiments are conducted for a southwest Iranian oil reservoir. Experimental results show that methane injection has significant effect on asphaltene precipitation and direct effect of temperature is less severe than other parameters. In addition to the accuracy and simplicity, the proposed equation provides universal parameters which make this approach novel for evaluation of future gas injection projects when simple PVT data are available.

This study examines the effects of change in the concentrations of monovalent and divalent ions in the polymer-contained surfactant solution on the macroscopic behavior of viscous-modified surfactant waterflooding in heavy oil reservoirs. Salts that are used in this set of floods were sodium chloride, magnesium chloride, and calcium chloride. The results indicate that four different ranges of salinity (in terms of CaCl2 concentration) exist. Each of these ranges renders a unique behavior regarding the ultimate oil recovery trends. There exists a range of salinity in which the ultimate oil recovery does not change with the salinity increase. The second salinity range is beyond the salt tolerance (i.e., first salinity range) of the polymer-contained surfactant solution, which results in a decrease in the ultimate oil recovery. In the third range of salinity, ultimate oil recovery is enhanced due to the plugging of high-permeable pores. In the fourth salinity range, precipitation increases as the salinity increases and more pore throats (even some pores with intermediate permeability) are plugged and, thus, the ultimate oil recovery decreases.

For technical and economic success of miscible gas injection projects, an accurate laboratory measurement of Minimum Miscibility Pressure (MMP) at reservoir conditions is essential. On the other hand, compositional reservoir simulator is a useful tool in gas injection studies and prediction of MMP. The main goal of this paper is to describe a procedure to generate a three phase sequential type of compositional reservoir simulator. The solution method is completely addressed. A compositional thermodynamic program for equilibrium calculation, and pseudo-component determination was developed. Another purpose of this study is to prepare an experimental setup for investigating the effect of CO2 concentration in injecting gas on oil recovery and MMP. Some displacement tests using slim tube apparatus were performed and recoveries and MMPs were measured. Finally, experimental results were compared with the model predictions. A good agreement was achieved between the experimental data and model predictions.

Production of several yeast products occur in presence of mixtures of monosaccharides. To study effect of xylose and glucose mixtures with system aeration and nitrogen source as the other two operative variables on xylitol production by Pichia guilliermondii, the present work was defined. Artificial Neural Network (ANN) strategy was used to mathematically show interplay between these three controllable factors and the xylitol productivity response. In the first stage, model fitting was performed using Response Surface Methodology (RSM) and the appropriate fraction of this design then was applied for the ANN training step (Levenberg Marquardt ‘LM’ algorithm). The best ANN model configuration with the three test input variables composed of six neurons in the hidden layer and tangent sigmoid (TANSIG) and linear transfer function (PURELIN) were used as the activation functions for the data processing from inputs to the hidden layer and from the constructed neurons to the output nodes. The network performance was evaluated by Mean Squared Error (MSE) and the regression coefficient of determination (R2). These values respectively, for the RSM model fitting were 2.327× 10-4 and 0.9817, and for the ANN training data were 2.29 × 10-8 and 0.9999. While MSE and R2 values for the other two steps of ANN were 4.56 × 10-3 and 0.9741 (validating step) and1.52× 10-3 and 0.9325 (testing step), respectively. Positive synergism of ANN with RSM was confirmed.