Scientia Iranica
Volume:21 Issue: 6, 2014

A green and simple procedure for the thiocyanation of aromatic and heteroaromaric compounds in the presence of a catalytic amount of phthalic acid in water/ethanol is described. The reactions proceed at high yields, short reaction times and mild conditions.

A simple and selective method for the determination of cadmium ions in environmental samples by ICP-AES after solid-phase extraction was developed. The method is based on the sorption of Cd2+ ions on alumina modi ed by 1-((5-nitrofuran- 2-yl)) thiosemicarbazide (NFMTC) at pH of 6. The metal. .........

Sulfamic acids are very important compounds with a little consideration in the literature that have wide range of applications in our life. Various N-alkyl and N-cycloalkyl sulfamic acids selected and their acidity was calculated in gas and aqueous media. pkavalues obtained with the use of two thermodynamic cycles that differ in the reference molecule which were used with them. Obtained pka values show strong acidity for sulfamic acids. We used density functional theory for all calculations.

The acidity and stability constants of M (MNPPAP)[1] M: Cu2+, Cu (Bpy[2])2+, or Cu(Phen[3])2+ complexes, were determined by potentiometric pH titration. It is shown that the stability of the binary Cu (MNPPAP) complex is determined by the basicity of the carboxylate group on one side and amine group on the other side. It is demonstrated that the equilibrium, Cu(Har[4])2+ + Cu(MNPPAP) Cu(Har)(MNPPAP) + Cu2+, is displacement due to the well known experience that mixed ligand complexes formed by a divalent 3d ion, a heteroaromatic N base and an O donor ligand possess increased stability. The other part of this displacement, which amount on average to no increased stability of the mixed ligand Cu (Bpy)(MNPPAP) and Cu(Phen)(MNPPAP) complexes. The stability constants were determined by potentiometric pH titration in aqueous solution. The order of the stability constants was reported. A comparative investigation between ternary complexes of MNPPAP, Trp[5] and Gly[6] is made. The comparison of stability constants of these ternary complexes show that Cu (Har) (MNPPAP) and Cu (Har) (Gly) exist in open form but Cu (Har)(Trp) is found near 100% in closed form. The differences between the above mentioned stability constants based on stacked form of Cu (Har) (Trp). The last provides for increased stability compared with Cu (Har)(MNPPAP).

The batch-adsorption experiments are carried out for anionic dye(methyl orange) using uncalcined mesoporous materials, calcined mesoporous materials and modified mesoporous materials by impregnation method using polyelectrolyte (PDDA, poly (diallydimethylammonium chloride)) as a modification agent. The resulting samples were characterized by XRD, FT-IR and nitrogen adsorption–desorption analysis. The results indicate that uncalcined MCM-48 silica mesoporous molecular sieves (noted as MCM-48) can be used as the effective adsorbent for the removal of methyl orange (MO) from aqueous system. The effect of various factors such as chemical modification, contact time, initial concentration, adsorbent dose, agitation speed, and solution pH and reaction temperature has been studied. The experimental data obtained with MCM-48 fits best to the Langmuir isotherm model and exhibits a maximum adsorption capacity (qmax) of 769.23 mg g−1; and follows the second-order equation.

In this work, efficient synthesis of 9-aryl-1,8-dioxo-octahydroxanthene derivatives from 1,3-cyclohexanediones and arylaldehydes in the presence of catalytic amount of melamine trisulfonic acid (MSTA) is described. The reaction is studied under thermal (solvent-free/80 °C),microwave (solvent-free/180 W/90 °C) and ultrasound (solvent/34-37 kHz/350 W/60 °C) conditions.

New indolenines I(1-18) were prepared by Fischer indole synthetic reaction of hydrazines derivatives H(1-6) with isoproylmethylketone K1, 2-methylcyclohexanone K2 and diisopropyl ketone K3 in presence of citric acid as a new catalyst at reflux condition in high yield.

The present study deals with the removal of Novacron Black dye with peanutpeels biomass, a low cost agricultural waste. The batch mode experiments were performed to compare the biosorption potential of selected biosorbent in its native, glutaraldehydetreated and immobilized form. Experiments were conducted as a function of pH, biosorbent dose, contact time, initial dye concentration and temperature. Glutaraldehyde-treated biomass exhibited better biosorption capacity as compared to the native and immobilized peanut peels. Maximum biosorption capacity (37.1 mg/g) of Novacron Black dye by peanut peels was observed at pH 2 using 0.05 g biosorbent. Equilibrium data were analyzed by Langmuir, Freundlich and Temkin isotherm models. Langmuir isotherm model tted very well to the equilibrium data. The kinetic data was modeled using pseudo- rst-order, pseudo-second-order and intra-particle di usion models. Negative values of
G depicted the spontaneous nature of biosorption process. Column studies were performed to optimize the bed height, flow rate and initial dye concentration. The results revealed that the best biosorption was achieved at greater bed heights, lower flow rates and higher initial dye concentrations. Bohrat-Adams model tted very well to the column data of Novacron Black dye biosorption onto peanut peels biomass.

A convenient and mild methodology is described for the preparation of 3,4-dihydropyrimidin-2(1H)-ones in the presence of sodium alginate as the biopolymer catalyst. The sodium alginate was found as a novel, very mild, recyclable, efficient, eco-friendly and very noteworthy biopolymer catalyst.

An efficient and environmentally friendly method for the synthesis of 2-amino-chromen-5(6H)-onesas important pharmaceutical compounds has been developed using [N,N''-bis(benzoylacetone)-1,2-ethylenediimine]Mn(III) chloride (2.5 mol%) as a heterogeneous and inorganic catalyst. A mixture of an appropriate aldehyde, malononitrile and dimedone in the presence of a catalytic amount of Mn(III) complex resulted in excellent yields (95-100%) of the corresponding products at ambient temperature. This new methodology is of interest due to use of water as a green solvent, its short reaction time, high yields and no further purification.

A new local composition model, Segmental-Wilson Non-Random Factor (S-Wilson-NRF), based on volume fraction is developed. The new activity coefficient model consists of combinatorial and residual terms that the combinatorial Flory-Huggins equation and the S-Wilson-NRF function are used for the entropy and enthalpy terms, respectively. This model for non-polymeric systems reduces to Nonelectrolyte-Wilson-NRF model. The present model with two dependent adjustable energy parameters is applied to correlation of the activity of solvent for 24 binary polymer systems at various number-average molar masses of polymer and temperatures. Moreover, the results of the present model are compared with the other local composition models such as Nonrandom Two-Liquid (NRTL), NRTL-Nonrandom Factor (NRTL-NRF) models and the Flory-Hugginsmodel. Finally, the new model is applied for correlation of the excess molar enthalpy of the binary polymer solutions at the different conditions. As a conclusion, the results of the new model are in good agreement with the experiment.

This work reports on the synthesis, characterization and application of organometallic complexes as Fuel Borne Catalysts (FBC). Cerium 2-ethylhexanoate, iron 2- ethylhexanoate and copper 2-ethylhexanoate were used as FBCs. Due to their hydrophobic character, these complexes can be easily solubilized in diesel fuel and converted to metal oxides particles, which eciently catalyze the oxidation of diesel soot, also known as Particulate Matter (PM). An experimental setup (pre-mixed pre-vaporized ame) was designed and constructed to study the e ects of a fuel borne catalyst on the oxidation properties of particulate matter. To better understand the role of metal complexes on soot oxidation, the kinetics of oxidation of metal-containing soot particles was measured. To do this, particulate matter was generated by spraying the catalyst containing the solution and diesel fuel into a mixing chamber. Di erent concentrations of Fe, Ce and Cu complexes were added to the fuel. The oxidation temperature was reduced by 116C for the case of 50 ppm Fe, a very important factor in the regeneration of diesel particulate lters. However, an unexpected increase in activation energies was seen. This happens when the process becomes less endergonic with the addition of di erent sources of FBC. It was also observed that the presence of an iron complex in fuel signi cantly decreased CO emission during soot oxidation.

In particulate systems, formation and fragmentation of agglomerates/aggregates are the major phenomena in the case of dynamic processing of suspensions. In the present work, the dispersion of the agglomerates was studied in shear flow fields (SFF) and elongational flow fields (EFF) using population balance Method. Since there is no direct data on EFF, predicted data obtained through Discrete Element Method was used to obtain a proper break-up kernel for EFF. So, a power-law break-up kernel was proposed for EFF and an exponential one was considered for SFF. It was shown that increasing the intensity of deformation rate in both flow fields, sped upthe break-up process and the mean aggregates/agglomerates sizes shift toward the finer flocs. This effect was more pronounced for SFF showing more sensitivity to the deformation rate. It was concluded that because of the ability of EFF in agglomerate break-up, it would break the agglomerates even in lower deformation rate. Since agglomerate could rotate in SFF, the final agglomerate size would show more dependency on the deformation rate. Results depicted that EFF leads to broader agglomerate size distribution in comparison with SFF. The final fragment size showed more dependency to the agglomerates structure in SFF compared to EFF.

CO2 sequestration is a pretty new eld with little relevant published data considering the relative permeability of CO2-brine systems at in-situ conditions. Precise determinations of relative permeability data in gas injection experiments are difficult and expensive; also, several factors a ect the accuracy. In this paper, to predict CO2- brine relative permeability curves, a Shan-Chen type multi-component multiphase lattice Boltzmann model for two-phase flow for a 2D porous medium was developed. Fully periodic and ull-way«bounce back boundary conditions were applied to the model to get in nite domain of fluid with non-slip solid nodes. Incorporation of an external body force was performed by the Guo scheme. The influences of pore structure and capillary number on relative permeability curves were studied in order to establish realistic conditions for investigation of CO2-brine relative permeabilities. The corrected relative permeability curves for pore structure and capillary number were tangibly in agreement with experimental data.