Sharif Digital Repository

Complexes of Ni II-(N,N′-bis(2-hydroxy, 3-methoxy benzaldehyde)-1,2-propandiimine) can be electro-polymerized onto GC electrode in an alkaline solution to give an electro-active film strongly adhered on the electrode surface. In alkaline solution, this poly-(Ni II{sal-1,2-pn(3-OMe) 2})/GC film shows the typical voltammetric response of a surface-immobilized redox couple, as can be anticipated for the Ni 2+/Ni 3+ transitions into the film. In addition, the film exhibits a potent and persistent electro-catalytic activity towards the oxidation of 1- and 2-propanol. In CV studies, in the presence of these alcohols, poly-(Ni II{sal-1,2-pn(3-OMe) 2})/GC electrode shows a new oxidation peak for the... 

Purpose. Variable-Temperature Kinetics has been used to obtain the rate constants of the reaction at various temperatures during one kinetic run. Methods. Pseudo-first-order rate constants for the transesterification of procaine with aliphatic alcohols ethanol, n-propanol and tert-butanol were obtained by the fluorescence spectroscopy using the variable-temperature kinetics (VTK) method. Results. The activation parameters of the reactions were calculated (24-28 kcal.mol-1). The half-life of the procaine decreases in the ethanol solution compared with the other alcoholic solutions in the presence of sodium ethoxide. Conclusions. The investigation time of the reactions is reduced to one-tenth... 

Electro-oxidation of alcohols (methanol, ethanol, 1-propanol and 2-propanol) on nickel dispersed into a thick layer of poly-o-aminophenol on graphite electrode (GE/POAP-SDS/Ni) was investigated. Ni-doping into the polymeric film was achieved chemically followed by enrichment of Ni(III) through cycling the potential. The electro-oxidation of alcohols on GE/POAP-SDS/Ni were found to be dominated by direct electro-oxidation with some contribution from Ni(II)/Ni(III) couple. Rate constants for the electro-oxidation of methanol, ethanol, 1-propanol and 2-propanol as derived by chronoamperometry were 1.65 × 105, 1.31 × 105, 2.53 × 104 and 1.40 × 104 cm3 mol-1 s-1, respectively. Impedance... 

Nickel modified graphite electrodes (G/Ni) prepared by galvanostatic deposition were examined for their redox process and electrocatalytic activities towards the oxidation of methanol, ethanol, 1-propanol and 2-propanol in alkaline solutions. The methods of cyclic voltammetry (CV), chronoamperometry (CA) and impedance spectroscopy (EIS) were employed. In CV studies, the electrochemical response, peak current varied in the order of MeOH > EtOH > 1-PrOH > 2-PrOH. Under the CA regime, a higher catalytic rate constant obtained for methanol oxidation was in agreement with CV measurements. Lower charge transfer resistance was obtained for low carbon alcohols oxidation and significantly higher... 

Charge-transfer (CT) complexes formed from the reactions of 4-nitropyrocatechol (4-nCat) as an electron acceptor with four amino alcohols: 2-aminoethanol, 1-amino-2-propanol, 4-aminobutanol and N-(2-hydroxyethyl)-1,3-diaminopropane (NHEDAP) as electron donors, have been studied spectrophotometrically in H2O and H2O/EtOH at 20, 25, 30, 35 and 40 °C. The calculated values of the oscillator strength and transition moment confirm the formation of CT-complexes. The thermodynamic and spectroscopic parameters were also evaluated for the formation of CT-complexes. The equilibrium constants ranged from 9.00 to 2.20 l mol-1 (M-1). These interactions are exothermic and have relatively large standard... 

Absorption of carbon dioxide (CO2) in aqueous solutions can be improved by the addition of other compounds. However, this requires a large amount of equilibrium data for solubility estimation in a wide ranges of temperature, pressure and concentration. In this paper, a model based on an artificial neural network (ANN) was proposed and developed with mixtures containing monoethanolamine (MEA), diethanolamine (DEA), methyldiethanolamine (MDEA), 2-amino-2-methyl-1-propanol (AMP), methanol, triethanolamine (TEA), piperazine (PZ), diisopropanolamine (DIPA) and tetramethylensulfone (TMS) to predict solubility of CO2 in mixed aqueous solution (especially in binary and ternary mixtures) over wide... 

Rate constants, k A, for the aromatic nucleophilic substitution reaction of 2-chloro-3,5-dinitropyridine with aniline were determined in different compositions of 2-propanol mixed with hexane, benzene, and 2-methylpropan-2-ol and 1-ethyl-3-methylimidazolium ethylsulfate ([Emim][EtSO4]) with dimethyl sulfoxide at 25 C. The obtained rate constants of the reaction in pure solvents are in the following order: 2-methylpropan-2-ol > dimethyl sulfoxide > 2-propanol > hexane > benzene > [Emim][EtSO4]. Molecularmicroscopic solvent parameters corresponding to the selected binary mixtures were utilized to study the kinetics of a nucleophilic substitution reaction in order to investigate and compare the... 

The microscopic features of binary solvent systems formed by molecular solvents (methanol, ethanol, 2-methylpropan-2-ol, water, pyridine, acetonitrile, 1-propanol, 2-propanol, dimethylformamide) and the ionic liquid ([bmim]BF 4) as cosolvent were used to select mixed solvents with particular characteristics. Molecular-microscopic solvent parameters corresponding to these binary mixtures were utilised to study the kinetics of the nucleophilic substitution reaction between 2-chloro-3,5-dinitropyridine and aniline to investigate and compare the effects of the solvents on a model chemical reaction. For these mixtures, the solvation behaviour is dominated by both the dipolarity/ polarisability... 

The alcoholic suspensions of titania nano-particles were prepared using the methanol, ethanol, isopropanol and butanol as the solvents as well as triethanolamine (TEA) as an dispersant. The colloidal stability of suspensions, both in the absence as well as presence of TEA, was studied by measuring the zeta potential, sedimentation, pH and electrical conductivity of suspensions, dispersant adsorption and particles size distribution. Results showed that in the absence of TEA, the stability of the suspensions increases with the molecular size of alcohol (from methanol to butanol), while the zeta potential decreases. It was also observed that with the addition of TEA up to the optimum dosage (4... 

In this article an attempt was made to fabricate defect-free asymmetric polysulfone (PSf) membranes for the separation of oxygen and nitrogen. The approach is based on the enhanced delayed demixing by blending surface modifying macromolecules (SMMs) in the casting solution and by immersing the cast film in isopropanol for a certain period before it is immersed in water. Different SMMs, including hydrophobic and charged SMMs, were synthesized, characterized, and blended to the host PSf. It was found that the charged SMM could indeed contribute to the removal of defective pores from the skin layer and enhancement of oxygen/nitrogen selectivity. The experimental results were further interpreted... 

Introduction - Recently, there have been growing attention on the modification and optimisation of new extraction and quantification methods, caused by the lack of environmentally friendly methodologies for the extraction of phytochemicals from complex matrices. In the case of pharmaceutical compounds, not only the extraction procedure but also the analysis method should be efficient, precise, fast and easy.Objectives - The essential pharmaceutical characteristics and trace concentration of withanolides led us to modify and optimise the previously reported extraction and quantification procedure for withaferin A (WA) as a candidate for withanolides.Matrial and methods - The WA from the... 

Two types of nanosized photocatalyst, TiO 2 P-25 and ap/Ag/AgBr/TiO 2, were used for decolorization of Acid Blue 92 (AB92) in dark, visible light (V-L), and UV media. Under UV and V-L, the effect of three possible photodegradation processes of AB92 including photocatalytic degradation, self-photosensitization, and direct photolysis were studied. Results showed that in UV/photocatalysts, photocatalytic degradation is the major process for photodecolorization. However, in the presence of TiO 2, self-photosensitization has the major role under V-L. Because of the presence of AgBr as photoactive center in ap/Ag/AgBr/TiO 2, the main process is the photocatalytic degradation in V-L. By using... 

As noteworthy properties of amine aqueous solutions, the densities and viscosities of aqueous N-Methyldiethanolamine (MDEA) solutions and mixtures of MDEA with 2-Amino-2-methyl-1-propanol (AMP), Diisopropanolamine (DIPA), Monoethanolamine (MEA), and Diethanolamine (DEA) were estimated under CO2 gas loading using Adaptive Neuro-Fuzzy Inference System (ANFIS), Multi-Layer Perceptron Artificial Neural Network (MLPANN), Support Vector Machine (SVM), and Least Square Support Vector Machine (LSSVM). The density and viscosity were estimated as a function of temperature, CO2 loading, pressure, and molecular weight of mixtures. In this regard, the actual data points were collected from the... 

Integrally skinned asymmetric membranes for the separation of O 2 and N 2 were fabricated by the phase inversion technique from polysulfone, polyetherimide, and polyimide. Two types of surface modifying macromolecules (SMMs) including hydrophilic SMM (LSMM) and charged SMM (cSMM) were synthesized and blended with the casting solution to modify the membrane surface. The cast film was then immersed in the first coagulant alcohol (methanol, ethanol, or isopropanol) for a predetermined period, before being immersed in the second coagulant (water). The SMMs used in these experiments were laboratory synthesized by the two-step process of polyurethane prepolymer synthesis and end capping, before... 

A series of g-C3N4-SnO2/TiO2 nanotubes/Ti plates were fabricated via simple dipping of TiO2 nanotubes/Ti in a solution containing SnCl2 and g-C3N4 nanosheets and finally annealing of the plates. Synthesized plates were characterized by various techniques. The SEM analysis revealed that the g-C3N4-SnO2 nanosheets with high physical stability have been successfully deposited onto the surface of TiO2 nanotubes/Ti plate. Photocatalytic activity was investigated using two probe chemical reactions: oxidative decomposition of acetic acid and oxidation of 2-propanol under irradiation. Antibacterial activities for Escherichia coli (E. coli) bacteria were also investigated in dark and under UV/Vis...