نشریه شیمی کاربردی روز
پیاپی 60 (پاییز 1400)

Photocatalytic removal of bisphenol A, one of the most widely and emerging pollutants in the aquatic environment, was investigated by advanced oxidation process under natural sunlight. The removal process by a metal-organic framework, synthesized with phosphonic acid ligand, namely STA-12 (Fe) and hydrogen peroxide revealed excellent results. Therefore, the optimal conditions for the degradation of bisphenol A by the photo-Fenton mechanism were studied. The removal process follows the first-order kinetics with respect to the contaminant and a significant synergy was observed in the catalytic system of hydrogen peroxide/sunlight/STA-12 (Fe). The Optimal values for pH, irradiation time, catalyst amount and H2O2 dosage for oxidation of bisphenol A in 30 mg / l aqueous solution were determined to be 5, 90 minutes, 10 mg and 12 μl, respectively. Under these conditions, the best removal efficiency was 79.8%. Also, the mineralization value of organic pollutant was determined to equal 51% by measuring TOC. To determine the most important species that affected the photocatalytic reduction, trapping experiments were carried out, using various kinds of scavengers and the results showed that the hydroxyl radicals (•OH) are the main oxidizing agent in the photocatalytic system and superoxide radical and the holes in the photocatalyst surface are less involved in the process of contaminant degradation. Finally, a probable reaction mechanism has been investigated in detail. In addition, the catalyst has recyclability and stability in the photocatalytic reaction. This study is the first report for application of a phosphonate-based MOF for the removal of an emerging pollutant with a photo-Fenton mechanism and presents a new example of solar-driven advanced oxidation process for the treatment of aquatic sources and environmental protection.

Synthesis and study of the medicinal properties of new spiro compounds with various functional groups is of great interest to organic and pharmaceutical researchers because of their special structure and conformation. Multi-component reactions are one of the most popular methods for synthesis of these compounds. In this study, the three-component reaction between butyl amine, dimethyl acetylene carboxylate, and 1H-indene-1,2,3-trione in toluene reflux conditions, is described. The three rings heterocyclic Spiro furan was successfully synthesized and characterized by FTIR, 1H-NMR, 13C-NMR, and Mass spectrometry. Then during the cytotoxic studies, its anticancer properties were performed on the G-292 cancer cell lines via the MTT assay and the results were reasonable.

Carbon dioxide photocatalytic reduction is one of the promising methods used to produce a wide range of renewable hydrocarbon fuels using sunlight in the presence of photocatalysts. In this study, a series of nickel-doped titanium dioxide samples (0.5, 1, and 1.5 wt%) Were synthesized by Sol-gel method. After performing photocatalytic carbon dioxide recovery experiments and finding the optimum percentage of nickel, titanium dioxide sample with 1 wt% nickel (TNi1) showed the highest photocatalytic activity. Then, by impregnation method, 3% by weight of Cu (1, 2 and 3 wt%) was loaded onto the TNi1 structure. Finally, the sample loaded with 1 wt% copper on titanium dioxide doped with 1 wt% Ni (1Cu/TNi1) showed the highest photocatalytic activity and methane production was 12.6 μmol/gcat that was about 4 times higher than the amount of methane produced in the presence of pure TiO2. The synthesized nanophotocatalysts were characterized using X-ray diffraction (XRD) analysis, diffuse reflectance spectroscopy (DRS) analysis and photoluminescence (PL) analysis. Also, their specific surface area was measured by BET method and morphology of the particles was investigated by field emission scanning electron microscopy.

From the Passerini three-component reaction between cyclohexyl isocyanide, thiophene-2-carboxylic acid and aryl/alkyl aldehydes, some new compounds of 2-cyclohexylamino-2-oxo-1-arylethyl/alkyl thiophene-3-carboxylates have been synthesized in 30-45 min in yields in the range of 85% to 90%. Reactions were performed in water solvent and room temperature. The structure of the synthesized compounds was characterized using infrared (IR) and nuclear magnetic resonance (NMR). The use of water as a green solvent, the reaction without energy consumption and at room temperature, no use of catalyst, separation without the use of chromatographic techniques, and the high yields of the reaction are the significant advantages of this Passerini reaction. The antibacterial properties of the synthesized compounds were also tested. The results of experiments showed that these compounds exhibit good antibacterial properties.

The presence of sulfur-containing compounds in fossil fuels has been considered as major source of SOx. Oxidative desulfurization (ODS) is recognized as a promising process to remove sulfur compounds in fossil fuels. Furthermore, in recent years, polyoxometalates (POMs), renowned as green catalysts, have attracted worldwide attention for their high efficiency in ODS. In this research, activated carbon (AC) supported dawson type hetero-polyoxometalate composite has been synthesized and evaluated as a new catalyst in oxidative desulfurization of model fuel containing dibenzothiophene. The prepared Dawson/AC catalysts were analyzed using FTIR, XRD, SEM. In order to optimize the operating conditions of ODS using Dawson/AC as catalyst, three conditions such as temperature, catalyst dosage and oxidant dosage were studied. Under optimized conditions, sulfur removal up to 99.2% or even higher than that using Dawson/AC composite as catalyst in ODS can be achieved.

In this research, the electrochemical oxidation of 4-amino phenol (1) was studied by cyclic voltammetry and controlled potential coulometryin in the absence and presence of 2-mercaptobenzimidazole (3a), 2-mercapto-5-methyl benzimidazole (3b) and 2-mercapto-5-metoxy benzimidazole (3c) in aqueous/ethanol (70/30 v/v) mixture.The results revealed that p-quinone(2) derived from oxidation of 4-amino phenol (1) participate in Michaeladdition reactions with 3a-c via EC mechanism. To confirm the proposed mechanism, the electrochemical synthesis of 4-amino phenol (1) was performed in the presence of 2-mercapto benzimidazoles (3a-c), and the obtained products were identified by 1HNMR, FTIR and Mass spectroscopy. In this study, we synthesized a variety of products with good efficiency using controlled potential electrochemical oxidation at a surface of graphite electrode.

A simple and low-cost spectrophotometry method was proposed based on resonance Plasmon peak of silver nanoparticles for measurement of metanephrine(MN) drug. This method was based on reducing property of metanephrine and it was founded that this compound reduces silver ions in presence of polyvidone (PVP) as stabilizer compound. In this condition the formed silver nanoparticles show a localized surface plasmon resonance (LSPR) peak of about 423 nm. The resulted nano-particles were analyzed by transmission electron microscope (TEM) technique and nanoparticles size was estimated to be maximum of 200nm. Furthermore, realized that the absorption of solution depends on concentration of metanephrine and the maximum of absorption was found at 〖AgNO〗_3 concentration of 1.53 mM, NaOH concentration of 4.10 mM, 〖NH〗_3 concentration of 2.51 mM and 1.15 ml of PVP. Also, the proposed method showed a good linear relationship than MN concentration in the range of 2.5-20 µM and limit of detection was obtained as 0.6 µM for metanephrine. Finally, this method was used for measuring epinephrine in real samples and the acceptable results were obtained.

In this research work, the rGO/ZnFe2O4 photocatalyst was prepared by hydrothermal method and characterized and identified using X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), field emission scanning electron microscope (FE-SEM), Diffuse Reflectance Spectroscopy (DRS), vibrating-sample magnetometer (VSM), surface area analysis (BET) and Energy-dispersive X-ray spectroscopy (EDAX) techniques. The photocatalyst was used for the reduction of nitroaromatic compounds to their corresponding aromatic amines with hydrazine monohydrate. The catalyst showed the best activity in the reduction of 1,4-dinitrobenzen (%97 conversion in 40 min). The recyclability and reusability of the catalyst was evaluated for four times which showed no significant variation in the conversion of nitrobenzene photoreduction reaction.

In this study, two methods of soxhlet extraction and supercritical carbon dioxide extraction were used to extract the effective substances in bitter orange peel. In supercritical fluid extraction, the effect of operational parameters such as temperature, pressure, dynamic time and particle size at different levels on extraction efficiency was investigated. To investigate the more accurate effect of the parameters, the design of the experiment was carried out and the response method was used and a model was obtained for the percentage of extraction efficiency by changing the parameters. The extracted materials were compared with two methods. One of the most important extracted materials is ostol and limonene. The amount of ostol in oil extracted by supercritical carbon dioxide is significantly higher than soxhlet method. The best extraction conditions with supercritical carbon dioxide, dynamic time of 80 minutes, temperature of 35 °C, pressure of 157.26 bar and particle size of 0.4099 mm were obtained.

In this work electrochemical oxidation of some urazole derivatives (1–6) was studied both experimentally and theoretically. The results indicate that the urazoles are converted to oxidized forms (1ox-6ox) via two electron process. The produced species (1ox-6ox) are unstable and participate in hydrolysis reaction, and ring cleavage happens after electrochemical process. Depending on the substituent that is connected to the urazol ring, the rates of the hydrolysis are different. Because the charge of reaction site and bond order of C1-N1 bond are effective on the hydrolysis rate, using computational study, the effects of the both parameters on the hydrolysis rate were analyzed. It was found that various substituents by affecting on the both parameters change the hydrolysis rate. After drawing diagrams of charge of reaction site and bond order of C1-N1 bonds versus hydrolysis rate, it was shown that there are significant relationship between these parameters and hydrolysis rate. Finally these results were used to estimation of hydrolysis rate of some other urazoles (7-10) without conducting laboratory research.

2-Amino-4H-chromene compounds are belonged to an important heterocyclic groups that have extensive important in organic chemistry and medicine. The compounds have anti-cancer, anti-bacterial, anti-coagulation and anti-tumor properties and have applications to produce dye, make up and hygienic materials. Until know, several methods have been reported for the synthesis of the compounds. Most of them, suffers defects such as poisoning and volatile solvents, low yield, high length reaction time, and no reusability of used catalyst. In the present work, Sr2As2O7 pyrochlore material was used as a catalyst for the synthesis of 2-amino-4H-cromens derivatives using a three component one-pot synthesis method under microwave irradiation. The raw materials were aromatic aldehydes, malononitrile and beta-naphtol. Sr2As2O7 was synthesized by an ultrasonic assisted solvothermal method using H2O and C2H5OH solvents mixtures at the 1:1 volumetric ratio. The materials were characterized by PXRD, FESEM and FTIR techniques. Then, the catalytic performance of the synthesized nanomaterial was used for the synthesis of 2-amino-4H-chromene derivatives. To do the process, the reaction parameters such as reaction time, solvent type and catalyst amount were optimized and the reactions were performed under the conditions. It was found that the optimum conditions were 15 mg catalyst, H2O as solvent and 6-9 min reaction time.

In this study, a copper cobaltite nanostructure was prepared as a non-ferrous heterogeneous Fenton catalyst using a one-step solvothermal method. The prepared nanocatalyst was characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), infrared spectroscopy (FT-IR) and energy-dispersive X-ray spectroscopy (EDS). The prepared CuCo2O4 exhibited outstanding activity for the degradation of methylene blue (MB) in aqueous solutions under ultrasonic irradiations. The degradation efficiency of MB was only 27.4 % in the absence of catalyst, whereas it reached more than 95.0 % in the presence of the CuCo2O4 after 60 min of ultrasonic irradiation. The trapping experiments with two radical scavengers (tert-butanol and chloroform) showed that both hydroxyl and superoxide radicals are generated during the decomposition of H2O2 and played important roles in oxidation of MB. The prepared nanocatalyst demonstrated good catalytic stability over three successive runs, without any remarkable decrease in catalytic activity.