Journal of Applied Research in Chemistry
Year:2021 | Volume:15 | Issue:1|Papers Count:13

With the growth of the human population, the increasing activities of factories, and subsequently increasing the emission of environmental pollutants in the air, the rapid measurement of these pollutants in different environments is essential more than ever. Sensors based on metal-organic frameworks have surpassed other chemical sensors in terms of construction cost, simplicity of the method, short response time, and good reversibility, and have been able to obtain a special place in the detection of toxic and hazardous pollutants. These nanoporous compounds, which are formed by the connection of metal centers and organic ligands through coordination bonding, have gathered the attention of many researchers due to their high chemical and thermal stability. The utilization of different aspects of the new synthetic and structural of this systems has led to a diverse success in the field of chemical and physical properties, many of which are unprecedented. Metal-organic frameworks have shown promising horizon in sensing applications due to having unique properties such as large sizes of cavities, high surface area, selected adsorption of small molecules and optical responses in the presence of guest molecules. In this article, we investigated the principles of the design of organic metal-framework sensors and the sensing mechanisms of these compounds.

The amide bond constitutes the skeleton of biologically significant peptides and proteins. The amide group exists in many pharmaceutical compounds. Thus, the development of an efficient amidation method continues to be an essential scientific pursuit. In this research, a simple method was introduced for the direct and solvent-free formation of amides, and also for real-time product identification. At first, the ion mobility spectrum of perindopril erbumine salt was obtained, and the ionic species resulting from evaporation and ionization of this salt in corona discharge were identified. Subsequently, the formation of a product ion having heavier mass than protonated perindopril was demonstrated by applying thermal shock at 400 ° C to perindopril erbumine salt. The variation of the intensities of the peaks in the ion mobility spectra over the elapsed time, and also predicting the mass of the ionic species were examined to determine the nature of the newly formed product. Through the method described in this article the new product was identified to be an amide compound. The efficiency of the two-reference method for applying the mass-mobility correlation equation to predict the masses of ion species in the ion mobility spectrometry was demonstrated. The results of this study showed that applying thermal shock to perindopril erbumine in addition to degradation of the sample could cause to create new products through the formation of amide bond.

In the present research, CdO nanoparticles were synthesized using the chemical reduction method at six different temperatures. Due to have different calcination temperature, the nanoparticles were synthesized in different sizes. Structural and optical properties of nanoparticles were characterized using XRD and UV-Vis spectroscopy. Based on the results, the CdO nanoparticles have cubic structure with the particles size of 27 – 60 nanometer. To investigate the photocatalytic properties of CdO nanoparticles, dye degradation effect in the presence of CdO nanoparticles and UV beam was studied in a batch reactor as a function of time at three different pH values. Studies showed that the optical absorption was decreased as a function of time. The photocatalytic reaction revealed that the dye degradation in methylene blue was speeded up with increasing the pH value.

One of the most important processes in the petrochemical industry is FisherTropes synthesis. In this process, the synthesis gas, which mainly contains H2 and CO gases, is converted to a mixture of hydrocarbons. The Fischer-Tropsch process is a catalytic process that catalyst is an important and determining part of this process. Therefore, in this study, the cobalt-manganese-cerium tri-metal catalyst based on alumina (Al2O3) was prepared by the wet impregnation method. The optimal catalyst was identified using X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermal gravimetry analysis (TGA) techniques. Surface area of the catalyst was measured by BET method. The fabricated catalyst was used to perform the FisherTropes process in a laboratory fixed-bed microreactor and the effect of operating parameters such as temperature, pressure, and feed ratio on the selectivity and activity of the catalyst were investigated. According to the results, temperature of 300 ° C, pressure of 1 atm, and feed molar ratio of H2 / CO = 1. 1 were selected as the optimal operating conditions of the catalyst.

Nitrate ion in water causes human poisoning and is very dangerous. Photocatalytic removal of nitrate from water and conversion to nitrogen gas is of great importance. In this study, heterogeneous nanocomposite g-C3N4/kaolinite, due to its natural kaolin substrate has been considered to nitrate reduction in the presence of UV light. The results of nanocomposite photocatalyst analysis using FTIR, SEM, EDS, and XRD instruments have clearly shown that the surface of the kaolin is covered by graphitic carbon nitride. In this work, the nitrate aqueous solution containing nitrate ion (50 ppm) was subjected to a photocatalytic reaction. Nitrate removal results showed the highest rate of nitrate degradation in the first 60 minutes compared with graphitic carbon nitride and kaolin individually. With the removal efficiency of 93. 15% using the above method, the initial concentration of 50 ppm reaches 3. 5 ppm, nitrate ion, which is below the permissible level of nitrate according to the World Health Organization standard. Therefore, the use of nanocomposite is a convenient choice to remove nitrate from water due to the simplicity of the preparation and commercial access to the raw materials required for synthesis, as well as high efficiency and selectivity to N2 in nitrate degradation and non-contamination of effluent.

Insecticides can remain in the food products after using, and spread in the environment, surface soil and underground water. The existence of insecticides remainder in the food products is one of the most important concerns for consumers. They have undesirable effects to human health after a long time. In this research, simple and efficient ultrasound-assisted emulsification microextraction (USAEME) method was successfully developed based on applying low density organic solvents for the extraction and determination of fenitrothion insecticide in vegetable and water samples. Several factors influencing the extraction such as type and volume of extraction solvent, temperature, ionic strength, and centrifugation time were investigated and optimized. Under the optimum conditions, the calibration range was from 2. 0 to 100 µ g L-1 in water sample and from 0. 02 to 20 mg kg-1 in plant. The applicability of the proposed method was successfully evaluated by the extraction and determination of fenitrothion from some natural vegetable and water samples.

In this work, nickel and cobalt nanoparticles were synthesized with a green and one-pot method on graphene oxide substrate for reduction reaction of 4-nitrophenol, Heck and Sonogashira cross-coupling reactions. Several characterization techniques such as FTIR, FESEM, XRD, and VSM were employed to characterize the Co and Ni nanoparticle reduced graphene oxide composites which indicates that nickel and cobalt magnetic particles with a size of about 20-30 nanometers were uniformly anchored on graphene oxide nanosheets. In addition, results showed that incorporation of Co and Ni nanoparticles and GO produced much higher activity in cross-coupling and reduction reactions. The soft-ferromagnetic behavior of the RGO/CoxNi100-x nanocomposite demonstrated the easy separable from the reaction mixture and several times reusable without losing its catalytic activity, Hence, the RGO/CoxNi100-x composites can be a potential promising material to catalyze the cross-coupling reactions.

The main target of this investigation is to synthesize several non-metallic electrocatalysts with desirable performance and suitable price, for oxygen reduction reaction at cathode side. For this purpose, five electrocatalysts including graphene oxide (GO), nitrogen and sulfur doped graphene oxide (NS-RGO), copper metal organic framework (Cu-MOF), 6% GO-Cu-MOF, and 8% NS-RGO-Cu-MOF are synthesized by hydrothermal method. In continue, in order to investigate the structure, activity, performance of synthesized electro catalysts, physical and electrochemical tests are employed, and obtained results are compared to the commercial 20% Pt/C. According to the physical tests outcomes, the structure of the synthesized electrocatalysts is uniform, and the layering is correctly performed. Besides it was found that the size of electrocatalysts is about of nanometer. Based on the electrochemical tests, amongst the synthesized electrocatalysts, 8% NS-RGO-Cu-MOF has the best chemical activity. The onset potential of this catalyst is obtained by-0. 06 V vs Ag/AgCl. Also, the peak associated with oxygen reduction reaction is shown in-0. 08 V, which the current density in this voltage is-4. 8 mA/cm2. Besides, the number of transferred electrons (n) for 8% NS-RGO-Cu-MOF is computed to be 3. 53, which indicates the reaction occurrs near to the 4 electron pathway. The onset potential of 6% GO-Cu-MOF is gained by-0. 11 V vs Ag/AgCl.

This research introduces a simple, sensitive, and rapid ultraviolet-visible spectrophotometry method for determination of ultra-trace amount of Ranitidine (RAN) in several sample such as drinking water, tablet, serum (blood), and human urine using gold nanoparticles (AuNPs). The surface plasmon resonance (SPR) property of AuNPs and the interaction between RAN and AuNPs is the base of this method. The addition of RAN into AuNPs led to the aggregation of AuNPs. Transmission electron microscopy (TEM) proved aggregation of AuNPs in the presence of RAN. Also, the size of the nanoparticles distribution was evaluated by dynamic light scattering (DLS). The parameters that affect the absorbance such as pH, type and volume of buffer, AuNPs concentration, interaction time, ionic strength, and interfering ions were investigated and optimized. Linear range was obtained 25-300 μ gL-1 in the optimum conditions. Also, the correlation coefficient (R2=0. 9955) and the limit of detection (LOD), and limit of quantification (LOQ) were equal to 1. 45 μ gL-1, and 1. 63 μ gL-1, respectively. In addition, the effect of interfering species was investigated. Eventually, the results showed that the proposed method had a high potential for rapid, sensitive, and accurate determination of RAN.

In the present study, electromagnetic wave absorber nanocomposite foams based on Ethylene-propylene-diene-monomer (EPDM) and multi-walled carbon nanotubes (MWCNT) were fabricated using a chemical blowing agent and compression molding. Foam nanocomposites showed lower electrical percolation threshold and higher electromagnetic wave absorption compared to their solid counterparts. Above the percolation threshold, the foam nanocomposites show a shielding effectiveness of 28-45 dB in the X-band frequency range (8. 2-12. 4 GHz). It was shown that the dominant shielding mechanism is absorption for the prepared foams. Also, the electromagnetic shielding effectiveness of the foam was insignificantly affected under repeated bending. Our results indicate the high potential of cross-linked EPDM/MWCNT foams as a lightweight electromagnetic wave absorber with high flexibility and deformability.

In this study, the extraction of cobalt (II) ions from the chloride solution by using Cyanex301 as an extractant and two extraction methods such as solvent extraction and supported liquid membrane were investigated. The effect of different parameters such as pH of feed solution, concentration of Cyanex301 extractant, and stripping acid concentration were studied to determine the optimum conditions. For the liquid membrane process, the aqueous feed pH of 7. 5 and 1 mol/l of Cyanex301 in the membrane phase were the best conditions for extraction, whereas the best extraction efficiency by using the solvent extraction method was achieved with 0. 1 mol/L of Cyanex301 concentration. The extraction efficiency equal to 99. 11% was achieved within 15 min by solvent extraction technique, while the maximum extraction of Cobalt equal to 44. 76% was achieved within 180 min by means of liquid membrane. The result showed that the extraction of Cobalt by using the supported liquid membrane were not improved in comparison with using conventional solvent extraction method.

In the present study, magnetic ion-imprinted polymer (MIIP) synthesized by Pickering emulsion polymerization has been introduced as a selective adsorbent for ultrasonic-assisted solid phase extraction and preconcentration of Nickel (II). At the first step 2-acetyl benzofuran thiosemicarbazone as a chelating agent and core-shell hydrophobic magnetic nanoparticles (Fe3O4@OA) were synthesized. The polymerization process was carried out in the presence of stoichiometric ratio of ligandnickel ion, methacrylic acid, 2, 2′ azobisisobutyronitrile, chitosan nanoparticles and coreshell hydrophobic magnetic nanoparticles as the template, functional monomer, radical initiator, stabilizer agent, and water/oil emulsion magnetic carrier, respectively. The synthesized ligand and polymer were also characterized by FTIR analysis, Optical microscopy, SEM, EDX, vibrating sample magnetometer, XRD, Nitrogen adsorption– desorption isotherms, and the static water contact angles. The stoichiometric ratio of ligand to metal ion was investigated by the mole ratio method. The optimum conditions of the experiment was obtained by the multivariable design of experiments (BoxBehnken design) as 46 min for ultrasonic time, 7. 87 for pH and 78. 85 mg for adsorbent dosage. The selectivity, reusability, equilibrium, kinetic, and thermodynamic studies were also investigated in this research. Isotherm data of MIIPs well fitted the Langmuir model which indicated heterogeneous adsorption for Ni (II). Dynamic linear range, detection limit, and relative standard deviation (RSD) of the proposed method were reported as 0. 001 – 70 mg/l, 0. 004 and 3. 21%, respectively by atomic absorption technique. Trace determination of Ni (II) in some fish samples such as salmon, Tuna, Tilapia, butter fish was successfully carried out by the proposed method.

Using magnetic and recyclable catalysts to promote selective C– C bond formation could help in the design of safer and ‘ ‘ greener’ ’ chemical manufacturing process. This work describes the preparation of magneto Ni(II) complex (Fe3O4@PCAPic/NiII) as a novel semi-heterogeneous system and the evaluation of their potential catalytic activity towards the Henry (nitroaldol) reaction between nitroethane and a variety of aldehydes in aqueous medium. The morphology and structural feature of the catalyst were characterized using different microscopic and spectroscopic techniques such as FT-IR, UV-Vis, TGA, SEM, TEM, ICP, XRD, XPS, and VSM. The Fe3O4@PCA-Pic/NiII represented perfect catalytic efficiency and good diastereoselectivity for the nitroaldol reaction. Other notable advantages of this work include high stability and reusability of the catalyst, green reaction conditions, ease of separation of products, and cost-effectiveness. Also, this catalyst can be recycled by applying an external magnetic field and reused up to ten runs without significant loss of activity.