Scientia Iranica
Volume:22 Issue: 3, 2015

A novel micro/nano-porous superabsorbent hydrogel was synthesized via graft copolymerization of acrylamide (AAm) onto salep (a polysaccharide mixture) and gelatin (a protein) hybrid backbone, after hydrolysis of this system. The Taguchi method was applied for the experiments and standard 18 orthogonal arrays (OA) with seven factors and three levels for each factor proposed trial conditions. Considering the results of 18 trials according to analysis of variance (ANOVA), optimum conditions were suggested. In addition, swelling kinetics, swelling in various organic solvents, the absorbency under load (AUL) and On-Off switching behavior were investigated. Also, the hydrogel formation was confirmed by Fourier transform infrared spectroscopy (FTIR). Surface morphology of the synthesized hydrogels was assessed by scanning electron microscope (SEM) and showed micro/nano-porous structure. Also, the surface area and total pore volume of the optimized hydrogel were measured by Brunauer-Emmett-Teller (BET) technique.

To obtain a rapid, efficient and green synthesis of fulleropyrazoline derivatives, ultrasonic irradiation has been applied to the reaction mixtures containing substituted phenylhydrazones, C60 and PhI(OAc)2. This procedure allowed us to achieve products at room temperature in a good yield and short time without any side product. This convenient procedure will provide a further increase of the diversity within the fullerene derivatives.

Fe2+supported on hydroxyapatite- core-shell magnetic γ-Fe2O3 nanoparticles (γ-Fe2O3@HAp-Fe2+ NPs) is reported as a novel, efficient, reusable and heterogeneous catalyst. In this protocol, we used this catalyst for the synthesis of 4-dihydropyrimidin-2(1H)-ones/thiones in good to high yields by the reaction of aromatic aldehyde, β-dicarbonyl and urea/thiourea under solvent free condition.The catalyst can be readily isolated by using an external magnet and no obvious loss of activity was observed when the catalyst was reused in seven consecutive runs. The mean size and the surface morphology of the nanoparticles were characterized by TEM, SEM, VSM, XRD and FTIR techniques.

A facile and environmentally benign procedure for the synthesis of pyranopyrazoles and biscoumarin derivatives، using non-toxic and magnetically separable catalyst in water as green solvent، is reported.

1-Butyl-3-methyl imidazolium phosphotungstate was used successfully as a mild catalyst in the synthesis of 14-ethyl and various 14-aryl-14H-dibenzo [a,j]xanthenes derivatives via condensation reaction of acetaldehyde and different aromatic aldehydes with 2–naphtol. This study represents a simple, efficient, and easily recoverable catalyst in the synthesis of biologically active molecules. The project included the search for the optimum composition of the hybrid catalyst and the study of reusability of prepared catalyst.

The load-carrying capacity and wear properties of selected triaryl substituted imidazoles were evaluated using a four-ball test machine. These derivatives show better antiwear performance in comparison to paran oil alone, which is con rmed by an Atomic Force Microscope. Thus, these substituted imidazole derivatives can be used asan antiwear agent for steel balls. Triarylimidazoles were synthesized by a one pot three component reaction assisted by recyclable and novel 1-ethyl-3-methylbenzimidazolium iodide [Embim]+I􀀀 in ecofriendly aqueous condition. This inexpensive, easily synthesized catalyst eciently catalyzes the condensation of 1,2-diketones, aromatic aldehyde and ammonium acetate. Besides the recycling of the catalyst, the short reaction time, excellent product yield and use of water display both economic and environmental advantages.

An efficient method for the stereoselective synthesis of (Z)-1-bromo-1-alkenes through debrominative decarboxylation of anti-2,3-dibromoalkanoic acids using KF/Al2O3 is described. KF/Al2O3 showed to be an effective base in this reaction leading to a relatively high selectivity and good to excellent yield of the (Z)-1-bromo-1-alkenes

A series of tetrahydrotetrazolo[1,5-a]quinazoline derivatives were prepared by the three-component condensation reaction of 5-aminotetrazole (5-AT), benzaldehydes, and dimedone in the presence of p-toluenesulfonic acid (p-TSA) as a solid acid catalyst under solvent-free conditions. This protocol provides a simple one-step procedure with the advantages of easy work-up, mild reaction conditions and environmentally benign.

Aconvenient one-pot multi-component reaction of aromatic aldehydes, 1,3-dicarbonyl compounds, amine and nitromethane in the presence of 10 mol % ZnO nanoparticles for the synthesis of highly substituted pyrroles is described. The products were obtained in moderate to good yields via one-pot tandem reaction. This method offers several advantages such as good yields, simple procedure, non hazardous reaction condition and starting from easily accessible substrates.

In fractured reservoirswith relativelylow matrix permeability, i.e. small matrix block size with respect to capillary threshold height, diffusionbecomes an important recovery mechanism. In this work, we have attemptedto model the mass transfer between matrix and fracture by considering afractured porous media as a single matrix block with an adjacent fracture.An appropriate model should be applicable in the case of the matrix being saturated with both saturated and undersaturated oils. The proposed model presents such versatility.The model is a modification for the formulation ofJamili et al.(SPE132622)which suffered from several drawbacks such as use of classical Fick''s law, use of Hua and Whitson (SPE21893)to calculate diffusion mass transfer coefficients between fracture and matrix and use of Darcy''s law to model convection mass transfer between fracture and matrix. In this work we surveyed these drawbacks and amended them. Subsequently, the improved model has been validated through a gas injection experiment. Following model validation, the effects of matrix permeability, initial gas saturation and injection rate on the recovery rate are investigated. The numerical analysis showed that the effect of gas injection rate on the recovery rate is considerable.

One of the most important issues in controller design and analysis of a nonlinear system is the degree of nonlinearity in the system. Helbig et al. proposed a method in which the system along with a linear reference model (which is the sum of a couple of rst order transfer functions) are stimulated with a set of input patterns. The outputs of these systems are then compared and the nonlinearity measure of the system is obtained as normalized di erence between the outputs of these two systems. In this paper, the linear reference model is replaced with two simpler linear models. The proposed method has been used for the assessment of the nonlinearity measure of various nonlinear systems that are used as standard benchmarks by the nonlinear process control research community. The results show that, despite the use of this simpler model with less parameters the calculated nonlinearity measure is almost similar to the one obtained by Helbig''s method. Furthermore, the nonlinearity measure obtained by the proposed method can be calculated very much faster.

A mathematical model for the impregnation step in the preparation of supported catalysts was developed. The kinetic parameters required for model solution were obtained by considering reversible competitive adsorption of ions on the same surface sites. The effect of pH of impregnation solution and impregnation time, as two critical operating parameters, was investigated and their influence on radial distribution was evaluated. The model was applied to Pt-Sn/Al2O3 catalyst in the presence of HCl. The experimental data required for model solution were obtained from impregnation tests performed in a tubular fixed-bed reactor with external circulation for impregnation solution; similar to configurations used in industrial cases. Kinetic parameter values obtained in the present modeling were compared with those reported in literature for similar cases. The order of magnitude for the present results is in acceptable range. As the distribution of active metal in supported catalyst plays an important role in its performance, this model is an invaluable tool by which such distributions can be predicted.

Phenolic compounds are important environmental pollutants that removing and separating them from the water and industrial wastewater, especially in the oil industry, are essential before entering the environment. At present research, the efficiency of the adsorbent silica aerogel for removing 4-Chlorophenol(4-CP) and 4-Bromophenol(4-BP) as phenolic compounds from aqueous solution was studied. Then, the effects of various factors such as contact time, pH and initial concentration were analyzed. It was observed that the amount of adsorption increases at low pH and this amount increases by incrementing the concentration of the emissions. Additionally, increasing the amount of adsorbent causes a decrease in halophenols. Results show that 4-BP much better than 4-CP adsorbed onto silica aerogel. Langmuir and Freundlich adsorption isotherms have been applied to model the equilibrium adsorption data. The study on the adsorption isotherms of these contaminants show that adsorption of these emissions follows the Freundlich isotherm. In addition, adsorption kinetics using pseudo-first-order equation, pseudo-second order, elovich and intra-particle diffusion model were analyzed. The results showed that the uptake of these compounds follows the intra-particle diffusion model and pseudo-second order equation