JOURNAL OF APPLIED CHEMISTRY
Year:2019 | Volume:14 | Issue:50|Papers Count:25

One of the problems of اydrogen production by the electrochemical method is forming and remaining of hydrogen bubbles on the surface of the electrode, which leads to considerable reduction in efficiency of hydrogen generation. The aim of this study is to investigate the effect of surface active agents on the quick departure of hydrogen bubbles and efficiency increase in electrochemical production of hydrogen in the electrolyte solution of the electrolysis cell. In this work, the common Platinum electrode used as a cathode electrode; and three surface active materials, anionic (sodium dodecylbenzene sulfonate; SDBS), cationic (Cetyltrimethyl Ammonium Bromide; CTAB), and neutral (TritonX-100), are employed in order to investigate the effect of surface active agents. The efficiency of these surface active agents on hydrogen production is investigated by voltammetric methods with regard to current density, initial potential, flow stability, and charge transfer resistance. The results indicate that electrochemical generation of hydrogen in 0. 5 M sulfuric acid containing 0. 5 mM of active surface material (SDS) is the most efficient one at room temperature.

In this study, the removal of sunset yellow dye from aqueous solutions using orange peel powder (OPP) as an agricultural waste and modified by co-precipitating it with Fe3O4 magnetic nanoparticles (MNP-OPP) as adsorbents by a batch system was investigated. The effects of some important physical and chemical parameters such as the initial dye concentration, sorbent dosage, exposure time, temperature and pH, on the sorption of selected dye by introduced adsorbents were investigated. Optimum conditions for the removal of dye were determined. Among the different parameters investigated, it was found that the pH of the solution has the most pronounced effect on the sorption capacity of OPP and MNP-OPP. The experimental data were analyzed using Langmuir, Freundlich, Temkin and Dubinin-Radushkevich (D-R) isotherm models. The results indicate that the Freundlich and the Langmuir models provide the best correlation for SY-OPP and SY-MNP-OPP systems, respectively. The results indicated that orange peel modified with Fe3O4 nanoparticles is suitable as adsorbent material for adsorption of sunset yellow dye from aqueous solution.

The present work investigates synthesis and characterization of two organoplatinum(II) complexes comprising various isocyanide ligands with general formula of [PtR'2(CNR)2] (R' = p-tolyl, R = 2-chloro-6-methylphenyl (1) and 2-naphtyl (2)). The resulting complexes were characterized by multinuclear (1H, 13C, 195Pt) NMR spectroscopy by assistance of two dimensional (HH COSY and HSQC) NMR technique. Besides, HH-NOESY (Nuclear Overhauser Effect Spectroscopy) technique was employed to provide more accurate 1HNMR assignments. In order to have a better structural vision for the complexes, the structures were optimized by DFT (Density Functional Theory) method in CH2Cl2 solution. The molecular docking studies were performed for complexes 1 and 2 while it revealed the specific binding site, binding mode and the best orientation of the complexes to DNA.

In this research work, magnetite nanoparticles were prepared, functionalized with molybdenum(VI) salophen complex and characterized using physico-chemical technique. The prepared nanocatalyst was tested for catalytic oxidation of sulfides. The catalytic reaction optimized by changing of solvent, temperature of reaction, time of reaction, [oxidant]/[sulfides] ratio and amount of catalyst. Phenyl methyl sulfide, diphenyl sulfide, dimethyl sulfide, dipropyl sulfide, dibutyl sulfide, Benzyl phenyl sulfide, bis(4-hydroxyphenyl) sulfide, diallyl sulfide and benzothiophene. We obtained the best results in solvent-free condition. The amount of catalyst was optimized by 35% aqueous H2O2 as environmental friendly oxidant. The nanocatalyst is so effective for selective oxidation of thioanisole, dimethyl sulfide, with a >99% conversion, and excellent turnover frequency (131000 h-1<) in shortest time (5 min). The catalyst was easily separated from reaction mixture by using an external magnetic field and reused for several time without significant decreasing in activity.

In this research, flame retardant polymer-nanocomposites with polyester fibers and inorganic nano materials were prepared to investigate the reduction of flammability. Nano calcium tetraborate (CaB4O7) and Nano barium tetraborate (BaB4O7) were synthesized by precipitation method onto polyester fibers to achieve flame retardant fiber nanocomposite. The prepared fiber nanocomposites were characterized by several techniques such as x-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), fourier transform infrared spectroscopy (FT-IR), vertical flammability test, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The CaB4O7 and BaB4O7 with less than 100 nm in size, was found to be well-dispersed throughout the matrix without the formation of large aggregates which is showed efficient flame-retardancy properties. The optimum values for donation of flame-retardancy were obtained 8. 02 and 9. 5% for calcium tetra borate and barium tetra borate, respectively. TGA/DTG and DSC analysis of pure, treated fibers was accomplished and their thermograms were compared and commented. The results show that the fl ame retardancy mechanism of obtained flame retardant coated fiber is a condensed-phase phenomenon due to the formation of a protective char layer that acts as a mass transport barrier and a thermal insulator.

In order to investigate the effect of pectin and dextran polymers on the adsorptive capacity of TiO2/bentonite nanosorbents, two nanocomposites of TiO2/pectin/bentonite and TiO2/dextran/bentonite were made by sol-gel method. Their investigation by FT-IR spectroscopy confirms the expected microstructure, and XRD results confirm the formation of anatase titania crystalline phase and also crystalline structure of bentonite. FESEM images showed the formation of TiO2 nanoparticles. These two nanocomposites were used for removing copper (II) ion from water and the effective factors on removal were investigated that maximum removal for both nanocomposites is in pH=7, adsorption dosage of 0. 04g and temperature of 25° C, but contact times for two composites of TiO2/pectin/bentonite and TiO2/dextran/bentonite were equal to 20 and 30 minutes and adsorptive capacity for them were 40. 16 and 22. 12 mg Cu2+ per gram of adsorbent, respectively. Investigating the effect of interference ions had no considerable influence on removal efficiency. The results show that adsorption of Cu2+ by TiO2/pectin/bentonite and TiO2/dextran/bentonite nanocomposites follows Langmuir and Freundlich isotherms.

A novel and efficient method has been developed for preparation of benzoxazole, benzimidazole and benzthioazole via one-pot condensation of N, N'-disubstituted thioamides with 2-aminophenol, 2-aminothiophenol, and 1, 2-diaminobenzene using N, N'-dibromo phenytoin as a mild oxidant. Hence, thioamides were reacted with 2-aminophenol, 2-aminothiophenol, and 1, 2-diaminobenzene respectively in the presence of N, N'-dibromo phenytoin in DMF to produce benzoxazole, benzimidazole and benzthioazole derivatives in moderate to good yields. Possibility of synthesis of three different heterocycles which have important industrial, agricultural, and biological applications, is one of the advantages of the presented method. Performing the reaction under very mild temperature and in short time is still another merit of the current method.

By using the experimental density data, some volumetric properties including excess molar volume, partial molar volume, partial molar volume in infinite dilution for ternary system 1, 3 dichloro 2-propanol+ 1-Hexanol + dimethyl malonate and their corresponding binary solutions at temperatures 293. 15-313. 15 K have been evaluated. Redlich-Kister equation has been applied to fitting the excess molar volumes data and then by applying derived parameters, partial molar volumes are appraised. Nagata-Tamura equation, Cibulka and Sing equation are applied to excess molar volumes of ternary system. Results showed that all values of excess molar volumes for binary and ternary considered systems were positive. Based on the results of measurements, different possible interactions which are present are discussed.

In the present research, doped nano-sized copper(I) oxide (Cu2O) on melamine– formaldehyde resin as a heterogeneous and efficient nano-catalyst has been employed for green and mild synthesis of 3, 5-disubstituted isoxazoles under ultrasonic irradiation. In this approach, 1, 3-dipolar cycloaddition reaction of structurally diverse alkynes and nitrile oxides (in situ generated from imidoyl chlorides) in the presence of this heterogeneous nano-catalyst under ultrasonic irradiation in water as a green solvent affords 3, 5-disubstituted isoxazole derivatives in good to excellent yields. The use of green solvent, mild reaction conditions, short reaction time, recoverability and reusability of catalyst, and simple purification process are important advantages of the present method.

An analytical approach for the determination of trace amounts of Co(II) and Ni(II) has been proposed using a home-made tablet-based dispersive liquid-liquid microextraction method performed in a narrow-bore tube followed by flame atomic absorption spectrometry. In this method, a mixture of tartaric acid, sodium bicarbonate, and NaCl are used to make the disperser tablet. Then µ L-level of an extraction solvent is added on the tablet, and it is released into a narrow-bore tube containing sample solution and a complexing agent. An acid-base reaction between tartaric acid and sodium bicarbonate is immediately occurred, and the produced CO2 leads to dispersion of the extraction solvent as tiny droplets into the solution and subsequent extraction of the analytes. The proposed method made possible the determination of Co(II) and Ni(II) in the ranges of 0. 1-15. 0 and 0. 3-18. 0 µ g L-1, respectively. Repeatability of the proposed method, expressed as relative standard deviation, was obtained 3. 6% and 2. 8% (n=6, C=1 µ g L-1) for Co(II) and Ni(II), respectively. Relative recoveries (89-97%, obtained at two fortification levels) confirmed the usefulness of the method for analysis of the analytes in the environmental water samples. The method was shown to be fast, reliable, and environmentally friendly with low organic solvent consumption.

In this work, Kanemite was prepared from rice husk ash and used as a heterogeneous base catalyst for production of biodiesel from sunflower oil. The catalyst was characterized by PXRD, FESEM and FT-IR. The transesterification conditions, such as the catalyst dosage, molar ratio of methanol to oil, reaction temperature and reaction time were investigated and optimized. The results revealed that by a catalyst loading of 5 wt. %, methanol to oil ratio of 24: 1, reaction temperature of 65 ° C and reaction time of 4h, conversion of biodiesel reached 97. 2%. Moreover, the catalyst could be reused up to five cycles under the optimum reaction conditions without significant loss of product yield.

In this research, to obtain the clean fuel, a new organic-inorganic hybride nanocomposite, (TBA)4PW11Fe@PVA, was successfully synthesized by sol-gel method and used as a catalyst for oxidative desulfurization (ODS) of gasoline. This nanocatalyst has been prepared by reaction of (TBA)4PW11Fe and PVA. The incorporation of the materials was confirmed by FT-IR, UV-vis, XRD and SEM characterization methods. The catalytic activity of the catalyst was tested on oxidative desulfurization of gasoline by using CH3COOH/H2O2 as oxidant. Besides, the results were compared with the oxidation process of prepared model fuel under the same conditions. The results show that the synthesized catalyst has a very effective ability to remove sulfur compounds from gasoline with high yield. The percentage of removal of sulfur compounds for dibenzothiophene (DBT), benzothiophene (BT), thiophene (Th) and gasoline was 97, 97, 96 and 96%, respectively. The synthesized heterogeneous nanocatalyst could be separated and recycled successfully after five times. The advantages of this method are non-toxicity, mild reaction and environment friendly.

A molybdenum(VI) Schiff base complex as an efficient and highly heterogeneous catalyst was developed by immobilization of a molybdenum complex on the surface of modified Fe3O4 magnetite nanoparticles. The obtained nanoparticles were employed as catalysts for the selective oxidation of sulfides to corresponding sulfoxides using urea hydrogen peroxide as the oxidant. Furthermore, the obtained catalysts showed not only high catalytic activity in oxidation reactions but also high degree of chemical stability in various organic solvents. This nanocatalyst can be easily recovered from the reaction system by using an external magnet and reused several times with high yields. The complete characterization of catalysts was carried out by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM) and FT-IR techniques.

Al(III), Cu(II) and Fe(II) ions have important role in human health, environment, agriculture and industry. The aim of this work is sensing and simultaneous determination of of these ions in aqueous solution. It was distinguished that Eriochrome cyanine R (ECR) can form coloured complexes by all of these ions. PLS regression method was applied to overcome the overlapping of peak spectrum in UV-Vis region. In optimization operation, wavelength range of 450-650 nm, pH = 6, time reaction=30 min and ligand concentration = 150(mg/L) were selected for subsequent single ion calibration and multicomponent analysis. Dynamic range for Al(III), Cu(II) and Fe(II) ions are 0. 06-0. 60 and 1. 0-3. 0 and 0. 20 – 1. 0( mg/L) in multicomponent regression analysis respectively. Optimum factor number for determination of these ions was found 4, 6, 8 and R2 (pred) was 0. 76, 0. 93 and 0. 73 respectively. For evaluation of PLS model, 21 synthetic solution was made from Al(III), Cu(II) and Fe(II) ions and tested by proposed model. It was proved that method was very appropriate for precision and accurate analysis of these ions simultaneously

The corrosion accompanied with hydrogen gas evolution process is the main obstacle preventing the widespread use of aluminum in the industry. The use of corrosion inhibitors is one of the most effective measures for protecting metal surface against corrosion in acidic environments. In this research, the inhibition effect of carboxymethyl cellulose (CMC) on the corrosion of aluminum in 2 M H2SO4 solution has been investigated by open circuit potential (OCP), potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and energy dispersive analysis of X-ray (EDAX) techniques. The results of the experiments show that CMC inhibits aluminum corrosion in 2 M H2SO4 solution, and the inhibition efficiency enhances with increasing concentration of CMC. The polarisation curves indicated that the CMC protection mechanism is a mixed type inhibitor in sulphuric acid solution. Also the inhibition category under this condition belongs to geometric blocking metal surface. In addition, the analysis on the morphology and composition of the aluminum surface suggests that CMC molecules through their polar functional groups physically absorb on the aluminum surface and form a protective and stable layer on the aluminum surface and prevent its corrosion.

The nanoparticles of NiO supported on mesoporous MCM-41 were synthesized and were well characterized with X-ray diffraction (XRD) and transmission electron microscopy (TEM). In this research catalytic activities of the supported NiO nanoparticles for cyclohexene oxidation to 2-cyclohexene-1-ol, cyclohexenone and cyclohexene oxide with tert-butylhydroperoxide (TBHP) and hydrogen peroxide (H2O2) as the oxidant, in the presence of solvent were studied. For the n%NiO/MCM-41 nanocomposites (n = 5, 10 and 15% NiO), a dimethylformamide: dichloromethane (3: 7) solvent mixture was applied. To achieve higher conversion of cyclohexene and better selectivity toward main products, factors such as oxidant type, solvent and the loading amount of nickel oxide were studied, and optimized conditions were investigated. tert-Butylhydroperoxide was specified to be better oxidant than hydrogen peroxide as higher activity of catalyst were observed when TBHP was used. Among used nanocomposites, 10%NiO/MCM-41 exhibit the highest activity in this oxidation reaction. With mesoporous MCM-41 supported 10% NiO and under these reaction conditions, the conversion percent of cyclohexene is 82. 9% with 67. 5% selectivity of cyclohexenone.

In this study, Polyethersulfon/Diatomaceous composite membranes were prepared by Phase Inversion method with different percent of diatomaceous particles as additive. The physical and chemical characterization of membrane, morphology and water contact angle were investigated by FT-IR, TGA, SEM and CA techniques. The effect of diatomaceous particles on water flux and Bovine Serum Albumin percentage removal were discussed. Difference in the pore structure and finger like cross section morphology with the presence of diatomaceous particles were observed in PES membranes. The results showed membrane performances such as hydrophilicity and water flux were enhanced by adding diatomaceous particles and modified membranes showed better antifouling properties.

Synthesis, Characterization and Crystal Structure Determination of a New Complex Containing Ni(II) and Au(III) with 2, 3, 5, 6-tetrakis(2-pyridyl)pyrazine (tppz) Ligand Robabeh Alizadeh1*, Sedighe Kargolpar1, Vahid Amani2, Hamid Reza Khavasi3 1School of Chemistry-Damghan University-Damghan Iran. 2Department of Chemistry, Farhangian University, Tehran, Iran 3Faculty of Chemistry-Shahid Beheshti University-Tehran – Iran New complex [Ni(tppz)2][AuCl4]2n (1) was synthesized from the reaction of HAuCl4. 3H2O) in acetonitrile) and Ni(II) chloride (in DMF) with 2, 3, 5, 6-tetrakis(2-pyridyl)pyrazine (tppz) (in DMF) and characterized by elemental analysis, UV-Vis, IR and NMR spectral methods. Furthermore, the crystal structure of Complex 1 was determined by single crystal X-ray diffraction. According to crystal structure analysis the complex was crystallized in space group Pcnb of the orthorhombic system and unit cell dimensions are a = 9. 7926(6) Å , b = 18. 071(1) Å , c = 29. 249(2) Å , α = β = γ = 90 º . Complex 1 contains cationic and anionic parts. The coordination number of Ni and Au atoms in cationic and anionic parts are six and four, respectively. The Ni and Au atoms have distorted octahedral and tetrahedral geometry, respectively. The crystal structure of 1 was stabilized by C-H… Cl and C-H… N hydrogen bonding and C-H… π and Au-Cl… π interactions.

In this study, layer-by-layer deposition method by sodium alginate polymer and carbon nanoparticles were used for modification of glassy carbon electrode surface. The modified electrode surface was studied by using scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The SEM images has been utilized to estimate the size of carbon nanoparticles on electrode surface which is approximately 47-57 nm. Gallic acid and ascorbic acid the antioxidant compounds naturally present in foods were determined with modified glassy carbon electrode using differential pulse voltammetry technique. The effect of. scan rate and pH parameters were optimized. In optimal conditions, using differential pulse voltammetry, the linear range for the concentration of gallic acid and ascorbic acid are 0. 1-100. 0 and 1. 0-1000. 0 µ M and the limit of detection equal to 0. 057 and 0. 368 µ M is estimated respectively. Finally, Gallic acid was determined in some herbs such as marjoram, thyme and mallow.

In this study, due to the importance of dipeptide compounds in diagnosis of disease or as drug compounds, new dipeptide compounds were synthesized using pyrimidine derivatives of thymine and uracil. The reaction of Methyl 2-(5-methyl-2, 4-dioxo-4, 3-dihydropyrimidine-1 (2 H)-yl) acetate and methyl 2-2, 4-dioxo-4, 3-dihydropyrimidine-1 (2H)-Il) acetate with diamine derivatives lead to the production of dipeptide derivatives in good yield. Then, using the computational design of the drug by the molecular docking method, the inhibitory effect of synthetic compounds on the LasR regulatory protein of Pseudomonas aeruginosa quorum sensing system, which plays an important role in regulating the expression of pathogenic genes in bacteria, were investigated. The results of the study showed that synthetic compounds have a significant inhibitory effect on the LasR protein.

In this research, two new zinc (II) coordination networks containing 1, 4-terphthalic acid (H2BCD) or 2-amino-terphthalic acid (NH2-H2BDC) linkers and a long pillar ligand 1, 4-bis[(pyridine-4-yl)methylene]benzene-1, 4-diamine (4-bpmb) have been successfully prepared and characterized. The compounds were prepared by the reaction of zinc(II) acetate or nitrate salts, H2BCD or NH2-H2BDC dicarboxylate ligands and pyridyl-based 4-bpmb ligand under solvothermal condition at 120° C for 48 hours in DMF solvent. The compounds were also prepared by ultrasonic irradiation and mechanochemical (solvent free) methods in short reaction times and high yields. The compounds show reversible iodine sorption/release behavior in solution. In addition, conversion of the zinc-organic architectures into ZnO nano-particles has also been investigated.

The cellulose-triazole-TiO2 bionanocomposite synthesized via click reaction and utilized as a nanobioadsorbent for removal of Hg+2 ions from aqueous solution by batch technique. The adsorption parameters such as pH, contact time, adsorbent dosage, temperature, initial metal ions concentration and the regenerability of Cell. Com were investigated. The optimized adsorption conditions were found to be at pH 7, contact time 45 min, adsorbent weight 0. 01 g and initial metal ion concentration of 20 ppm at 25 º C. The Langmuir, Freundlich and Temkin isotherm models were evaluated using adsorption experimental data. The high absorption capacity obtained from the Langmuir equation (Hg+2 = 133. 3 mg g-1) is related to the synergistic effect of TiO2, triazole ring and cellulose moieties in the structure of Cell. Com. Among the pseudo-first order, pseudo-second order and intraparticle diffusion kinetic models, the experimental data was best fitted with the pseudo-second order model. Thermodynamic parameters indicated a spontaneous and endothermic adsorption process. The Cell. Com adsorption behavior represents that a monolayer chemical adsorption is the rate-determining step. The adsorption-desorption process for Cell. Com was performed in HCl solution at least 3 cycles without significant loss of the adsorption capability.

In this study, a green and efficient method for the synthesis of biologically-active bis(indolyl)methane compounds (BIMs) has been described through the condensation of indole with different carbonyl compounds in the presence of SO3H-functionalized mesoporous silica materials (MCM-41-SO3H) catalyst under ball milling. Synthesis of BIMs is proceed very well in the presence of nano-ordered MCM-41-SO3H under solvent-free conditions using ball-milling technique at room temperature. The MCM-41-SO3H can be used at least four consecutive times under optimized conditions with a slight decrease in its catalytic activity. High to quantitative yields of the desired products, low loading of the catalyst, short reaction times at ambient temperature, reusability of the catalysts, and avoiding the use of toxic solvents are significant advantages of this green protocol.

In this paper, the rice husk has been used as an abundant and low cost precursor to prepare activated carbon with high surface area for removal of alizarin yellow from water. To prepare activated carbon chemical activation with phosphoric acid has been used. Microwave heating source was used to reduce the treatment time and energy consumption of carbon active preparation. The obtained activated carbon was characterized by SEM, XRD, FT-IR techniques. The influences of adsorbent dosage and temperature on alizarin yellow adsorption were studied. The obtained activated carbons showed a good adsorption capacity for removal of Alizarin yellow from water. Adsorption of alizarin yellow onto the prepared activated carbons was studied by thermodynamics, equilibrium and kinetics point of views. Pseudo first order, pseudo second order, Elovich, Bangham, Langmuir and fractal-like Langmuir models were used to analysis the experimental kinetics data. The equilibrium data were analyzed using Langmuir, Freundlich, Redlich-Peterson, Sips and Temkin models. The best results to fit equilibrium and kinetic experimental data was obtained with Sips isotherm and fractal-like Langmuir model, respectively. The thermodynamic properties of adsorption were determined by thermodynamics study.