Iranian Journal of Chemistry and Chemical Engineering
Volume:29 Issue: 2, Mar-Apr 2010

Sulfonic acid functionalized SBA-15 (SBA-Pr-SO3H) as a new nanoporous acid catalyst was used in the one-pot synthesis of polyhydroquinolines derivatives via the Hantzsch four component condensation reaction of aldehydes,  - ketoesters, dimedone and ammonium acetate under solvent free conditions with short reaction time in excellent yields. SBA-Pr-SO3H was proved to be an efficient heterogeneous nanoporous solid acid catalyst (pore size 6 nm), which could be easily handled and removed from the reaction mixture by simple filtration, and also recovered and reused without loss of reactivity.

Two N4-type Schiff base ligands named N,N'-bis(2-pyridylmethylidene)-1,2-diiminoethane (L1) and N,N'-bis(2-pyridylmethylidene)-1,3-diiminopropane (L2) have been synthesized by the reaction of pyridine-2-carbaldehyde with ethylenediamine and propylenediamine, respectively. The binding abilities of L1 and L2 in dichloromethane towards Cu2+, Cd2+, Co2+, Ni2+, Zn2+ and Pb2+ ions were evaluated by performing competitive extraction experiments on the mixtures containing theses ions from aqueous picrate and nitrate media as a function of the aqueous phase pH. The results show a pronounced selectivity of the ligands towards copper and cadmium ions among the tested metal ions. It is shown that the copper/cadmium selectivity of the ligands is profoundly influenced by the nature of anions accompanying the extracted complexes. In fact, the ligands are more efficient complexing agent for cadmium ions in the presence of nitrate and acetate anions, whereas this selectivity changes towards copper ions in the presence of picrate, perchlorate and thiocyanat ions.

The distribution of gallium() and indium () between hydrochloric or sulphuric acid solution with sec-nonylphenoxy acetic acid(CA-100) in kerosene has been investigated under various conditions. CA-100 is a new organocarboxylic extractant, which has been shown to be efficient for gallium() and indium() whereas germanium(), which was not extracted. The extraction system is studied as a function of initial pH, equilibration time, CA-100 concentration and aqueous ionic media(Cl- and SO42-). Extraction mechanism is discussed on the basis of slope-analysis method, constant molecular series method and saturation capacity method. It was found that sec-nonylphenoxy acetic acid was extracted into the organic phase by formation of the MA3HA species from chloride media and in the form of MA3 from sulphate media.(M=Ga and In) The equilibrium equations are proposed on the basis of the results that obtained.

Various concentrations of copper are embedded into silica matrix to xerogel form using copper source - Cu(NO3)2∙3H2O. The xerogel samples are prepared by hydrolysis and condensation of tetraethyl orthosilicate (TEOS) by the sol-gel method and with determination of new molar ratio of components H2O/TEOS to be 6.2. In this investigation, the necessary amount of trihydrated copper nitrate is added to the solution in such a manner that the concentration of the copper oxide in final solution reach to 1, 2 and 5 wt% (samples A, B and C respectively). After ambient drying, the gel samples are heated from 60 to 1000˚C at a slow heating rate (50°C/h). The absorption and transmittance spectrum of various concentrations of copper are studied by Uv-vis spectrophotometer. Thermal treatment effects are characterized by FTIR, TGA, TEM, SEM, XRD, BET and TPR methods at different temperatures.

Mesoporous TiO2 has been prepared using a nonionic block copolymer (Pluronic P-123) as structure-directing agent with sol-gel method. Characterization of the product was carried out by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetry-differential scanning calorimetry (TG-DSC), Nitrogen sorption isotherms, and UV-vis absorption spectroscopy. These analyses showed that under controlled synthesis conditions, a wormlike mesostructured TiO2 with high surface area (110 m2g-1) and appropriated band gap (~3 eV) is obtained. Moreover, the pore walls of the nanostructured TiO2 solid are formed by incipient crystallites of anatase, which is a significant achievement regarding its possible photocatalytic applications. The activity of the prepared photocatalyst was evaluated by degradation of Congo Red azo dye. It has excellent photocatalytic efficiencies and more than 76% dye was decolorized in 90 minute.

The use of colored semiconductor oxide like copper (II) oxide and nickel (II) oxide for photocatalytic bleaching of rose bengal was investigated in detail. In order to harness the solar energy, the effective wavelength of the photocatalyst is to be expanded into the visible region and that increases the rate of photocatalytic bleaching of the dye. Progress of the reaction was observed spectrophotometrically. The comparative studies of photocatalytic activity of copper (II) oxide (CuO) and nickel (II) oxide (NiO) was made using photocatalytic bleaching of rose bengal as modal system. The effect of various parameters like concentration of dye, pH, amount of semiconductor, light intensity etc. on the rate of photocatalytic bleaching of the dye was also observed. On the basis of rate of the reaction (rate constant) the order of photocatalytic activities of the semiconductor oxides was found to be CuO > NiO. A tentative mechanism for the photocatalytic bleaching of rose bengal has also been proposed.

Salicylic acid-Formaldehyde-m-Cresol (SFM) terpolymer had been synthesized in DMF media by conventional method. The resulting resin had been characterized by FTIR spectra, elemental and thermogravimetric analyses. The morphology of SFM resin had been studied by SEM and Optical photograph. Various parameters like rate of equilibration, effect of pH on ion exchange capacity and effect of concentration on ion exchange capacity had been studied. The maximum sorption capacities at 0.05M concentration for Ni(II) and Cu(II) were 0.7905 (pH-6.0) and 0.6315 (pH-5.5) mmol/g of dry resin respectively. The distribution coefficient (Kd) for five metal ions [Ni(II), Cu(II), Zn(II), Cd(II) and Pb(II)] were determined in various concentration of tartaric acid electrolyte at different pH. The quantitative separations of heavy metal ions and transition metal ions from their admixtures [Cu(II)- Pb(II), Pb(II)- Zn(II), Ni(II)- Cd(II)] had been performed by using distribution coefficient (Kd).

Adsorption and desorption behavior of Gd(III) ion on macroporous weak acid resin(MWAR) had been investigated. The influence of operational conditions such as contact time, initial concentration of Gd(III) ion, initial pH of solution and temperature on the adsorption of Gd(III) ion had been examined. Experimental data were exploited for kinetic and thermodynamic evaluations related to the adsorption processes. Adsorption isotherms were attempted to be obtained the model parameters at different temperature and to be fitted better to Langmuir model than to Freundlich model within the studied concentration range. The maximum adsorption capacity of Gd(III) ion on MWAR was 384 mg/g at 298 K, calculated from Langmuir model. The apparent activation energy was Ea = 18.0 kJ/mol and adsorption rate constant was k298 = 1.22×10-5 s-1,respectively. Thermodynamic parameters such as changes in the enthalpy (ΔH), entropy (ΔS) and Gibb’s free energy (ΔG) indicated that Gd(III) ion adsorption by MWAR was an endothermic and spontaneous process in nature, and more favorable adsorption was obversed when the ambient temperature was high Gd(III) can be eluted with the composition of 0.5mol/L HCl and 0.5 mol/L NaCl solution.

In this study for the first time a new description of compressibility factor is renderedbased on the virial expansion. The compressibility factor as a function of M-factor is qualitatively and quantitatively expressed. At first, we present how may the third, fourth and higher order virial coefficients be logically ignored in order to simplify the virial equation. The results show, when the compressibility factor is presented as a function of M-factor instead of pressure, an improved regression operation on experimental data is possible. Moreover, the results show the compressibility factor will not depend on kind of substance, if it is considered as a function of M-factor. Also we found that the compressibility factor can easily be estimated by a second order polynomial in respect to M-factor or in more mature form at most by a third order polynomial.The simplifying effects of M-factor to present the compressibility factor of some binary mixtures are investigated. It was found that the classical mixing rules can never be applied for predicting the compressibility factor under special conditions. Also we affirm the distinct characteristics of M-factor compared to its composer parameters, qualitatively. A quantitative study on M-factor properties, which supplies a prolegomena to a new comprehensive equation of state, was accomplished as well. We find the favorable EOS is a multi-domain function estimating experimental data with high accuracy.

This paper reports a CFD modeling study on the possibility of using high temperatureand low oxygen content exhaust gases as oxidant for combustion in an industrial furnace by a written computer program. Under these conditions, the predicted results for the flow and heat transfer properties are compared with those under the several cases of conventional and highly preheated and diluted air combustion (HPDAC) conditions. Although the calculation procedure is a two dimensional one with the vorticity and stream function as the main hydrodynamic variables; its results can yet be also valid for the three dimensional case. Because of the weakness of the standard or other traditional k-ε models in predicting the spreading rate of axisymmetric jets, and also for the sake of economy and lack of boundary conditions, here the turbulent transport properties are obtained from an algebraic formula. An infinitely single-step chemical reaction (physically controlled) and a model known as “four flux” are considered as combustion and radiation models, respectively. The qualitative and quantitative verification of high temperature and low oxygen content air/exhaust gases combustions and conventional (low and high air temperature) combustions results have been checked and compared, respectively, with those reported in the literature. Finally, in this investigation three modified concepts and new formulas have been proposed and used to define the gas temperature uniformity, the chemical flame size and the maximum flame temperature as the HPDAC’S main unique features achievement criteria.

In the computational fluid dynamics (CFD) modeling of gas-solids two phase flow,the effect of boundary conditions play an important role in predicting the hydrodynamiccharacteristics of fluidized beds. In this work, the hydrodynamics of conical fluidized bed containing dried TiO2 nano-agglomerates were studied both experimentally and computatioally. The pressure drop was obtained by pressure measurements and mean solid velocity in the different axial and radial positions and their experimental values were measured by a parallel 3-fiber optical probe. The Eulerian-Eulerian multiphase model and granular kinetic theory with using Gidaspow (1994) drag function were applied in simulations. The effect of three different types of boundary conditions (BC) including no-slip/friction, free-slip/no-friction and high-slip/small-friction which were developed by Schaeffer (1987) and Johnson and Jackson (1987) were investigated. The results ofthe model were compared with the experimental data. The numerical simulation using free-slip/no-frictionBC agreed reasonably well with the experimental pressure drop measurements. The pressure drops predicted by the simulations were in agreement with the experimental data at superficial gas velocities higher than the minimum fluidization velocity, Umf. The results for simulated mean axial solid velocity showed that the free-slip/no-friction BC was in better agreement with the experimental data compared with other boundary conditions.

A numerical and experimental investigation of flow and heat transfer in a gas- liquid Thermosyphon Heat Exchanger "THE" with built in heat pipes and aluminum plate fins for moderate Reynolds numbers has been carried out. It's module is composed of 6 rows and 15 columns copper pipes with aluminum plate fins with dimensions of 130cm height, 47cm width and 20cm depth. The tubes have been filled with water with filling ratios of 30%, 50% and 70%. The density and thickness of fins are 300 fin/m and 0.4mm, respectively. The configuration of tubes is in-line with 30mm pitch. This paper presents the distribution of temperature and thermal performance of "THE" by using CFD modeling. A good comparison of the present CFD modeling results for the modeling thermosyphon heat exchanger with experimental results of hydrodynamic and thermal behavior is achieved.

Asphaltene precipitation and deposition is a serious problem in many Iranian fields. The deposited asphaltene results in partial or total blockage of the wellbore and wellstring reducing or completely seizing oil production. This paper studies the asphaltene problem and mitigation methods in wellstring systematically. It presents new approach based on the combination of thermodynamic modeling of asphaltene precipitation with hydrodynamic well modeling. The developed model is capable to determine the asphaltene precipitation and deposition interval through the wellstring. Therefore, it could study the effect of hydrodynamic parameters such as wellhead pressure, well flow-rate and tubing size on the mitigation of asphaltene deposition. The conventional way to treat asphaltene deposition was through remediation which attacks the problem after it occurs. This model is capable to determine the severity of asphaltene deposition even before start of production. The model was applied to simulate the asphaltene precipitation in one of the south Iranian oil fields (Kupal) and important guidelines have been studied to mitigate the risks associated with asphaltene deposition. The results of modeling show that change in hydrodynamic condition could reduce and mitigate asphaltene deposition damage. But in some cases it would not be possible to prevent asphaltene precipitation completely. Therefore, the approach for flow assurance in those cases would be to change the well completion and inject asphaltene inhibitor, in order to prevent deposition of asphaltene flocculates.

In petroleum production, Produced Water Re-Injection (PWRI) has earned much interest among disposal methods of the produced water. However, presence of the contaminants in the produced waters usually results in formation damage in well bores and their surrounding fracture systems. In the present study, modeling of external cake formation on a fracture in unsteady-state conditions is discussed. The existing force vectors of different nature are analyzed in detail at first, as the second step force and fluid mass balances specific to the case are derived. Finally, by solving the formulated governing equations, cake thickness, permeate velocity and cross flow velocity profiles in unsteady-state conditions are obtained.

A bacterial culture was isolated from oil-contaminated soil based on its ability to metabolize the quinoline as the sole source of nitrogen. In this research Bacillus licheniformis strain was identified based on the result of 16S rRNA analysis. Optimized conditions were obtained with full factorial experimental design method using design expert software at temperature: 32oC, agitation speed: 200rpm, quinoline concentration: 400 ppm.The efficiency of Bacillus licheniformis for biodegradation of quinoline at the optimum conditions was determined to be 35%. Two-phase cultivation media were used with 5, 10, 15 and 20% heavy crude oil concentration in aqueous media. Resting cells of Bacillus licheniformis was shown to be capable of removing about 25% of total nitrogen in 5% heavy crude oil. GC analysis showed a decreasing trend in the activity of this strain against crude oil concentration

Microbial cells have been successfully used as biosorbents to remove heavy metals from wastewater. In some cases, dead cells appear to offer more advantages than living cells in the removal and recovery of heavy metal ions from industrial wastewater. Maintaining higher biosorption capability and understanding the biosorption properties of dead cells are the keys to heavy metal removal and recovery from wastewater using dead cells as biosorbents. The present experiment showed that the dead Pseudomonas putida 5-x cells killed by dilute HCl had a higher Ni2+ biosorption capacity due to the retention of a complete cell structure during the acid treatment process. The biosorption process of the dead cells was faster than that of the living cells. Metabolic-independent physical adsorption played a major role in the Ni2+ sorption by the dead cells. The pH obviously affected the biosorption capacity of the dead cells, because of the variation of the hydrogen ion concentration and cell surface property, as well as occurrence of micro-precipitation along with the change of solution pH. Considering both biosorption capacity and desorption efficiency, pH 6.5-7.0 is a suitable condition for Ni2+ biosorption by dead P. putida 5-x cells killed with dilute HCl.