Journal of Applied Research in Chemistry
Year:2017 | Volume:11 | Issue:3 |Papers Count:11

Nanocrystalline powder (Cu0.2ZnNi3.27O5.29) was prepared by co-precipitation method.The electrochemical activity of nanoparticles (Cu0.2ZnNi3.27O5.29) alone in comparison with the combination of carbon nanotubes and palladium nanoparticles for methanol electrochemical oxidation were investigated. The effects of some factors, such as scan rate, methanol, and electrolyte concentration were studied. According to the results, the current density and charge amount of the electrochemical oxidation of methanol on glassy carbon electrode modified by Cu0.2ZnNi3.27O5.29 and carbon nanotubes and palladium nanoparticles have better efficiency. The CV curves on the GC/Pd- Cu0.2ZnNi3.27O5.29-CNT electrode in 0.96 M methanol and 1M NaOH at various sweeping rate in the range of 25-300 mVs-1 were recorded. The linear relationship between the square root of the scan rate and peak current density estimates the control of the methanol oxidation via the mass transport of the methanol.

One of the best methods for extracting cerium from Ferrosilicon Magnesium (FeSiMg) is using organic solvents. In this study, a simple, fast and sensitive spectrophotometric method for the determination of trace amounts of cerium in Ferro Silicon Magnesium was studied. Accordingly, some organic solvents have investigated and chloroform reagent was chosen as the superior solvent for cerium extraction in Ferrosilicon Magnesium and maximum extraction of 95.5% was achieved. The effect of extraction parameters, such as volume of solvent, contact time of aqueous/organic phases, and pH were studied. The high yield obtained under optimized conditions of 11 mL of chloroform reagent, contact time of 3 min, and pH of 10.7. Results of the batch process were compared with the results of certified reference materials by using Inductively Coupled Plasma and X-Ray Fluorescence methods and low differences were revealed. So the proposed technique was applied with high accuracy and precision for determination of cerium.

In this study, the thermal decomposition of ammonium perchlorate (AP) with the coating of nano-manganese oxalate (MnC2O4•2H2O) gel has been investigated. The Coating of nano-manganese oxalate has characterized by X-ray diffraction (XRD). The image of the sample obtained by scanning electron microscope (SEM) has indicated a uniform coating of MnC2O4•2H2O on the ammonium perchlorate particles. At the beginning, non-agglomerated nano-manganese oxide has been prepared from nano-manganese oxalate during the thermal decomposition of ammonium perchlorate (AP) and then has been considered as a nano-metal oxide catalyst on the thermal decomposition of ammonium perchlorate using differential scanning calorimetry (DSG) and thermal gravimetric analysis (TG). The results have shown that the decomposition temperature of ammonium perchlorate in the presence of nano-manganese oxide has reduced from 417 to 311oC through the mechanism of electron transfer. In addition, the result of TG analysis is used to evaluate the theoretical kinetic parameters (Eaa and logAa) by Flynn–Wall–O method.

In this research, three natural extracts of pomegranate, red tea, and green tea were used in dye- sensitized solar cell (DSSC). The characteristics of DSSCs made of three natural dyes were investigated by photovoltaic measurements and electrochemical impedance spectroscopy technique. A solar cell fabricated of the ruthenium dye (N719), as a standard dye, was used for comparison. The DSSCs were assembled using two glass plates (anode and cathode) coated with transparent conducting oxide. The anode thin film was prepared on the conductive glass plate using titanium dioxide (TiO2) nanoparticles by doctor blade method. The cathode electrode was coated by a catalyst Pt. Comparing these dyes with 29 natural dyes investigated by other researchers revealed that the red tea extract can be used as a reasonable dye in solar cells. The red tea cell showed a fill factor of 0.42 and an efficiency of 1.02%.

Graphene nanosheets were deposited and reduced on a glassy carbon electrode from a colloidal graphene oxide solution using cyclic voltammetry. Chemical reduction and immersion for reducing and depositing of graphene was also investigated to compare with the electrochemical method. Cobalt nanoparticles were also synthesized via an electrochemical approach. The resulting electrodes were characterized with scanning electron microscopy and cyclic voltammetric response of the graphene-Co NPs composite electrodes in the phosphate solutions were compared in this study and it was made clear that the composite electrodes fabricated with the electrochemical methods gave better response and signal towards the phosphate ion. Based on the resulted data, it leads to conclusion that the cathodic reduction method is the preferred one to fabricate graphene-based composite electrodes, in comparison with the chemical reduction/immersion method. Findings from the current study can be applied in future for designing and fabricating electrochemical sensors based on graphene and nanometal particles as sensing agents.

Quadrupolar parameters of nuclei can be used as a tool to understand the electronic structure of the compounds. Sodium alanate (NaAlH4) is a potential hydrogen storage material due to its outstanding hydrogen capacity; however, its high thermodynamic stability is unfavorable for dehydrogenation processes. Carbon nanostructures as catalyst can reversibly store hydrogen. Understanding the bonding nature of Al and H is essential for improving its dehydrogenation performance. In this work, the charge density distribution of NaAlH4 was studied in the presence of some carbon nanostructures. For this purpose, using calculated NQCCs of hydrogen atoms, the electronic structure of pure NaAlH4 with NaAlH4 in the presence of some carbon nanostructures were compared. The results show that fullerene–NaAlH4 composite demonstrates better catalytic properties with very small 2H-NQCC. Therefore, hydrogens in the mentioned composite have weaker bond with Al. In other words, easier condition for dehydrogenation in fullerene–NaAlH4 is expected. The electric field gradient (EFG) at the site of quadrupolar nuclei was calculated to obtain NQCC parameters using Gaussian 03 at HF/6-31G* level of theory.

The chemistry of heterocycles is one of the broadest branches of organic chemistry. Heterocycles represent a broad spectrum of organic compounds and classifications. They are indispensable structural motifs not only because of their biological relevance but also given their diverse applications. Especially in medicinal chemistry and chemical biology, heterocycles are used extensively as valuable synthetic organic building blocks. Among the various classes of heterocycles, imidazoles, thiazoles, chromens, 3, 4-dihydropyrimidin-2(1H)-ones/thiones, and 1, 4-dihydropyridine are very important organic compounds that have been extensively used in diverse fields. These organic heterocycles have exchangeable hydrogens, which are important in identifying their structure. In this study, we have examined exchangeable hydrogens in some heterocyclic aromatic including tri-substituted imidazoles, 2-aminothiazoles, chromens, and Biginelli and Hantzch heterocycles using Proton Nuclear Magnetic Resonance (1H-NMR) spectroscopy which will help in identifying the precise structures.

In this research, with the aim of improving mechanical properties of polystyrene (PS), montmorillonite (MMT) nanosheets were selected as reinforcing agent. PS-MMT nanocomposite was prepared by dispersing MMT nanosheets in a PS solution. Taguchi experimental design method was used to determine the optimal conditions for preparation of nano composite. The effects of five factors including MMT percentage, type of solvent, type of polystyrene, film drying temperature, and stirring time were investigated in different levels. Optimal conditions were determined by using of the signal/noise (S/N) method. It was distinguished that the highest and lowest effects belong to polystyrene type and solvent type, respectively. In S/N method, all factors are significant in the confidence level of 95%. Scanning electron microscopy (SEM) coupled with an energy dispersive X-ray system (EDX) was used to characterize the composition and structure of nanocomposite film prepared in optimal condition.

In this research, PSA process was studied to purify hydrogen from methane using activated carbon as adsorbent. This process is extensively used for purification of hydrogen in the hydrogen production units. The purge-to-feed (P/F) ratio and adsorption time were considered as variables. Moreover, the PSA process was modeled by considering all the important parameters such as hydrogen purity percent, recovery, and productivity. The central composite design (CCD) was used for experimental design, modeling, and optimization of the process. With this method, a model was applied for each parameter regardless of complex and time-consuming equations which generally were employed in the literature. The statistical analysis reveals that for each response, a distinct second order polynomial equation with F-value more than 300, p-value less than 0.0001, and R-squared more than 0.993 is able to predict the response. Furthermore, the predicted value from models had no significant difference with experimental values. Based on established models, as the purge-to-feed (P/F) ratio increased, the hydrogen purity increased, while the recovery and productivity decreased. The recovery and productivity first increased and then decreased as adsorption time increased. As adsorption time increases, purity has approximately constant value up to 10 min and then declines that can be attributed to less amount of available fresh adsorbent at a higher adsorption time. Moreover, with respect to models, the parameters were maximized.

In this work, fatty acid content of soybean, canola, and sunflower oils in Golestan zone were determined using gas chromatography (GC). Epoxidation of these oils were performed using hydrogen peroxide in a molar ratio of 1.7 :1 of (H2O2:C=C), 7, and 10 hours and three different temperatures of 25, 50, and 75 degrees Celsius and atmospheric pressure along with stirring. Epoxidation efficiency of oils was investigated by determination of epoxide number via titration method and FTIR spectroscopy. The results show that unsaturated amount, time, and temperature were effective parameters in the epoxidation of vegetable oils. Sunflower and canola oils have the highest and the lowest unsaturation amounts, respectively; therefore, formed the highest and lowest of epoxidation respectively. Giving more time to epoxidation results in raising of the reaction efficiency. Temperature was also a very important parameter in epoxidation of vegetable oils. So that higher or lower temperature than 50oC causes the reduction of epoxidation efficiency. Finally, the maximum values of obtained epoxy for sunflower, soybean, and canola oils in 10 hours at 50oC were obtained 6.25 %, 6.11%, and 4.53%, respectively.