Journal of Applied Research in Chemistry
Year:2019 | Volume:12 | Issue:4 |Papers Count:15

Today, regarding to the air pollution caused by the smoke of cars and factories, measurements should be taken to detect and monitor the release of these contaminating compounds. Use of semiconductor metal oxide sensors is one of the methods for detecting of these compounds. These metal oxide gas sensors have many advantages, such as low cost and easy production, for detecting gases in domestic, commercial, and industrial applications. However, the performance of these sensors depends on a variety of factors, including the nature of the structure, morphology, doped additives, their structures, and so on. The most important of these sensors is tin dioxide. Therefore, in this review, the effects of various additives, including metal, metal oxide, and carbon, are investigated on the sensing properties of tin dioxide. The results revealed that these additives affect morphology, sensitivity, selectivity, response speed, and response temperature.

Feasibility of extraction of silver from tailing dam of Ahangaran mine was investigated by various leaching reagents including sulfuric acid, nitric acid, hydrochloric acid and sodium cyanide. The influence of mineral acids concentration indicats that the maximum silver recovery is obtained with 6 M hydrochloric acid, 4 M sulphuric acid and 5 M nitric acid and at leaching time of 80 min. The further increase in sulfuric and hydrochloric acid concentrations had no considerable effect on the increment of silver recovery. The role of H2O2 as oxidant agent was also evaluated on silver recovery. The results demonstrated that the most silver recoveries by sulphuric acid obtained at 2 M H2O2, and thereafter recovery reduced with increasing the H2O2 concentration. In addition, statistical design of experiments was used to evaluate the influential factors in the silver recovery using sodium cyanide. The findings indicated that among main factors, solid percentage and among interactions, interactive effect of solid percentage and pH had the most influence on silver extraction rate. The maximum silver recovery (58. 16 %) using sodium cyanide was achieved under following conditions: the pH ~11, solid percentage of 20, particles size of 75 μ m (200 mesh), 0. 1185 g/t NaCN, and leaching time of 4 h.

Ionic liquids are remarkable chemical compounds, which find biological applications in addition to solvent role in many areas of modern science. Herein, we describe a simple and effective method to synthesize two kinds of novel chiral ionic liquids based on pyridinium named 1-(4-((1-Carboxyethyl)carbamoyl)benzyl) pyridinium Chloride [CECBPy]Cl and 1-(4-(((1-Carboxyethyl)carbamothioyl)carbamoyl) benzyl) pyridinium chloride [CECTCBPy]Cl in two steps from alanine and their optical rotation properties have been measured by polarimeter instrument. These new ionic liquids were characterized by using IR, 1HNMR, 13CNMR, and MS spectroscopy. Evaluation of the antibacterial effects of synthetic compounds were carried out by determination of minimum inhibitory concentration )MIC) using broth micro-dilution method. Antioxidant activity of samples was measured with 2, 2-diphenyl-1-picrylhydrazyl radical scavenging activity. The results showed 1-(4-(((1-Carboxyethyl)carbamothioyl) carbamoyl) benzyl) pyridinium chloride [CECTCBPy]Cl has the best antioxidant effect.

Bentonite is a clay which has high surface area and makes it a good option for the placement of metal oxide nanoparticles, such as zinc oxide, thereby forming a nanocomposite. In the recent years, various applications of this kind of nanocomposites have been investigated by researchers in water and wastewater treatment. Accordingly, in this research, the bentonite was powdered by ball mills and then, ZnO/Bentonite nanocomposite was prepared by ultrasound irradiation and gel degradation method with starch. The nanocomposite was identified by XRD, FTIR, SEM and EDX techniques, and the efficiency of the sample was studied for removing of nitrate ions from water. The results showed that environmental factors such as pH, contact time, adsorbent amount, and nitrate concentration were effective in removal percentage. Optimal removing percentage of the nitrate solution with 30 mg/l was achieved by 0. 6 g of nanocomposite which could remove 70% of the nitrate from solution.

In this work, the effects of the nano-aluminum additive and mixing process on the thermal behavior of Al/CuO systems were verified by thermal analysis and field emission scanning electron microscope (FE-SEM) methods. The DSC analysis results showed that there was no exothermic reaction for μ m-Al/nm-CuO thermite mixture. However, the ignition of [μ m-Al95%+nm-Al5%]/nm-CuO, [μ m-Al80%+nm-Al20%]/nm-CuO, [μ m-Al50%+nm-Al50%]/nm-CuO and nm-Al/nm-CuO took place at 600. 9, 604. 0, 605. 5 and 608. 4° C, respectively. Analysis of thermal behavior of these mixtures showed that the insensitivity and energy of the thermites increased with increasing quantity of nm-Al in [μ m-Al+nm-Al]/nm-CuO formulation. Moreover, ultrasonic mixing decreased ignition temperature and increased heat of reaction of these ternary mixtures. This improvement in thermal properties was related to break up the agglomerates and better mixing quality by ultrasonic waves. In the next step, the reaction kinetics of physically mixed and ultrasonicated nm-Al/nm-CuO were investigated. The results revealed that sonicated nm-Al/nm-CuO thermite had lower activation energies than physically-mixed nm-Al/nm-CuO mixture. In addition, the ignition of ultrasonicated and physically-mixed nm-Al/nm-CuO mixtures occurred in one and two main steps, respectively.

The present work is including synthesis and characterization of conductivity of a super-absorbent conductive hydrogelnanocomposte and its controlled drug release. For this purpose, superabsorbent conductive hydrogel by Guar gum was synthesized based on grafting copolymerization of acrylic acid monomer and proximity of some carbon nanotubes; in addition, polymerization reaction was done in aqueous phase (distilled water) and in the presence of ammonium persulfate as initiator and Methylene bisacrylamide as cross-linked. The results were assessed by FT-IR, cyclic Voltammetry and Scanning Electron microscope. However, the effect of carbonnanotube’ s amount on nanocomposite was characterized by increasing this amount, the gel content, equilibrium swelling in distilled water, pH sensitivity, and conductivity increases. In the second stage, cisplatin drug was loaded in hydrogelnao composite and the percentage of drug release in phosphate buffer solution (PBS) was measured by appropriate electrical stimulation. The results show that the synthesized hydrogel is reasonable option for controlled drug release.

In this research for the first time, an adsorbent based on molecularly imprinted polymers (MIPs) for selective extraction of Naringenin using methacrylic acid (functional polymer), trimethylolpropane trimethacrylate (cross linker), azobisisobutyronitrile (initiator) via precipitation polymerization technique in a ratio (1: 4: 20) were synthesized. After template removal, nanoporous imprinted polymeric lattice was prepared which is able to extract Naringenin as a bioactive compound from the mixtures containing this component. Non-imprinted polymers (NIPs) with the same materials (instead of the template molecule) were synthesized to compare the efficiency of the MIPs. Selectivity of the MIPs for Naringenin has been evaluated. Quercetin as a similar molecule of the template was selected which the binding capacity for Naringenin and Quercetin were 284 mg. g-1 and 70 mg. g-1, respectively. Imaging scanning electron microscope (SEM) was used for morphological studies on the synthesized polymer particles and brannaueremmet-teller (BET) analysis method was applied to measure the porosity, specific surface area and poor diameters of the polymer.

Light olefins (ethylene, propylene, and butylene) can be produced from methanol through non-oil route. In this study, HZSM-5 catalyst was synthesized by hydrothermal method and characterized using X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), N2 adsorption-desorption (BET), Fourier transform infrared spectroscopy (FT-IR), and NH3 temperature programmed desorption (NH3-TPD) analysis. The catalysis included microsphere morphology which led to mesoporous structure formation and acceleration of diffusion. Based on characterization, the catalysis represented high crystallinity, high surface area and appropriate acidity properties. The results showed that the catalysis provided high methanol conversion (99. 5%), selectivity of light olefins (82%), and long-term catalytic lifetime (72h). In order to increase the production yield, suitable reaction groups and kinetics in consistent with the catalysis performance was determined and methanol to olefin (MTO) process was simulated. The simulation results showed well agreement with the experimental data. Optimization of kinetic and operational parameters of MTO resulted in high methanol conversion and light olefins selectivity as 100 % and 94. 1 %, respectively. The catalysis performance in the MTO process under the optimized operational conditions was confirmed the simulation results which indicated practicality of applied simulation and optimization.

In this study, a new sorbent based on dimethylglyoxim/sodium dodecyl sulfate-immobilized on TEOS-coated magnetic nanoparticles (Fe3O4@SiO2@SDS/DMG) was prepared as a simple, inexpensive, and fast method for pre-concentration and determination of trace amounts of palladium. In the proposed approach, the analytes retained on the sorbent are effectively eluted with thiourea– HCl solution and the absorbance of analyte was determined by flame atomic absorption spectrometry. The effects of different parameters on extraction efficiency such as effect of pH, extraction time, type and amount of eluent, and amount of absorbent phase were investigated and optimized by batch procedures. Under the optimum experimental conditions, the preconcentration factor, detection limit, linear range, and relative standard deviation (RSD) of palladium (II) ions were 250, 0. 49 μ gl-1, 125-3750μ gl-1, and 2. 26 % (for 125μ gl-1, n=6), respectively. Finally, the method was successfully applied to the evaluation of Pd2+ in different environmental water samples.

Here we report the synthesis of a novel covalently immobilized calix[4]arne derivative as a chiral stationary phase (CSP) for HPLC. In the structure of CSP, the upper rim of calix[4] arne is substituted with two L-alanine units and the lower rim of calix[4]arene is linked to the silica gel by thiol-ene click chemistry. Elemental analysis of the CSP showed 120 μ mol of chiral selector bonded per gram of silica gel. 1-Hexene was used for end-capping of unreacted mercapto groups on silica gel. The CSP is chemically bonded to the silica and can be used in the normal-phase mode, reversed-phase mode, and with halogenated solvents mobile phases, if desired. The chromatographic performance of the CSP was evaluated with enantioseparation of the 3, 5-dinitrobenzoyl (DNB) derivatives of some amino acids.

In this research, magnetite NPs via sol/gel method was coated with ZnO and TiO2. Phases, microstructures, and magnetic properties of binary and ternary core/shell nanoparticles were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrational magnetometer (VSM). Photocatalytic activities in methylene blue degradation under sunlight irradiation for 120 min were recorded using UV/Vis spectrophotometer, changes were studied using the photoluminescence spectrum (PL), and the specific surface areas were obtained by the nitrogen adsorption/desorption apparatus (BET). The results showed that 10 mg/ml core/ shell nanoparticles during 120 min under sunlight radiation could degrade >90% of methylene blue molecules. However, the increase in the number of shells causes the change in the type of semiconductors from direct to indirect; following that heterogeneous interface reduces the photocatalytic efficiency.

Due to the importance of the amount of hydrazine in water samples from the environmental point of view as well as frequent usage of this matter, the concentrations of this substance were to be measured in different samples. In this study, a new and simple electrode was fabricated for measuring hydrazine. The electrode was a carbon paste electrode modified by strontium ferrite nanoparticles. The electrode showed good sensitivity and selectivity for the electroanalysis of hydrazine due to the presence of nanoparticles. Voltammetric and chronoamperometric techniques proposed a good catalytic oxidation of hydrazine at the electrode surface. The hydrazine sensor was showed two linear calibration range which covers 0. 5 to 20 micromolar and 20 to 600 micromolar. The selectivity of the electrode for measuring the hydrazine was good. Also the repeatability, reproducibility, and lifetime of the electrodes were acceptable. Determination of hydrazine in aqueous samples such as tap water and well water were performed. The obtained recovery percentages showed that the ability of the electrode in determination of real samples is reliable.

In this research, with a new strategy and convenient conditions, a novel bridgeless calix dimer was synthesised. Quinone-Hydroquinone calix[4]arene (4) was synthesised from calixquinone derivative in the presence of copper (II) acetate and 1, 4-diaminobutane. The obtained dimer structure was characterised by various spectroscopic methods such as 1H-NMR, 13C-NMR, and IR spectroscopies. Since the macrocyclic molecules and in particular, calix[4]arene macrocycle derivatives, have wide usage as suitable receptors for recognising natural molecules. So, the synthesized compound was used. Also, the sole role of dopamine in central nervous and cardiovascular systems made it to be chosen as a guest molecule. The formation complex constant between Quinone-Hydroquinone calix[4]arene (4) as host and dopamine (guest) was calculated by fluorescence spectroscopy. The results indicated that the synthesized dimer (4) had not only a good ability to be the selective recognition of dopamine but also an appropriate repeatability.

In this study, a suitable method for the preparation of Rosiglitazone on laboratory scale using 4-bromo benzaldehyde, 4, 2-thiazolidinedione and 2-chloropyridine, as the starting materials, is presented. In the key step of this four-step process, palladium complexes have been used which significantly increase the reaction efficiency and overall yield compared to previous methods. In the first step, by the reaction of 2-chloropyridine with N-methyl ethanolamine the intermediate compound 2-(methyl (pyridine-2-yl)amino) ethane-1-ol is obtained which is converted to 4-(2-(methyl(pyridine-2-yl)amino)ethoxyl)benzaldehyde in the presence of palladium acetate and 4-bromo benzaldehyde. Finally, the desired product is obtained by condensation reaction of this intermediate with 2, 4-thiazoldinedione followed by reduction.

Organophosphorus compounds enter the environment naturally or after human use as pesticides or chemical fertilizers, and ultimately enter the food chain of organisms. Due to their undesirable effects, it is absolutely necessary to detect these toxins at very low concentrations before they enter the life cycle. Biosensors are suitable tools for detecting these toxins. In this study, a mono-enzyme biosensor based on inhibiting the cholineoxidase enzyme with its immobilization on a modified electrode with carboxylate carbon nanotubes was fabricated and in the presence of 1mM enzyme substrate (choline chloride), the minimum detection limit for diazinon was obtained (0. 56 μ M) and two linear ranges (1. 5-2. 4 μ M and 5. 5-17. 5 μ M) was observed. The detection of low concentrations of diazinon by this biosensor and high performance liquid chromatography (HPLC) were compared. The result of the biosensor had 3. 5% error relative to HPLC.