نشریه شیمی کاربردی روز
پیاپی 63 (تابستان 1401)

In this paper, the immobilization of lipase from Candida rugosa on hydrophilic Na-montmorillonite (MT) and hydrophobic modified montmorillonite (MTS) is investigated. Hydrophobic MTS was prepared by changing the nature of hydrophilic MT with cetrimonium bromide surfactant. The enzymatic activity of lipase immobilized on Na-montmorillonite (LMT) and lipase immobilized on modified montmorillonite (LMTS) was investigated in the production of biodiesel from waste cooking oil. The support modification and enzyme immobilization were evaluated by BET, XRD, and SEM techniques. The effects of temperature, time, water content, and the molar ratio of methanol to oil on biodiesel yield were also investigated. The results showed that the activity of LMTS was much better than LMT. Under optimal conditions, the biodiesel yield produced by LMTS was about 86.4%. LMTS showed good storage stability, and after 30 days of storage at 4 ℃, the biodiesel yield was about 64.2%, while the biodiesel yield of free lipase (FL) was about 57.1%. In addition, LMTS had good reusability compared to LMT, and the biodiesel yield after 10 cycles was about 51.6%.

The adsorption of carbon dioxide molecules on four H-saturated porous graphene sheets with different pore sizes and a poreless graphene sheet was investigated and compared with the adsorption of nitrogen molecules on them. Reactive molecular dynamics was used in this study, which took into account the possibility of chemical bond formation and dissociation as well as the effects of polarity. This research demonstrates that all porous graphene sheets and non-cavity graphene sheets absorb carbon dioxide molecules more than nitrogen molecules and can be used to separate these two gases. However, the size and shape of the cavities have no significant impact on gas molecule adsorption on these plates.

In the present paper, the Formose reaction to produce polyols in methanol solvent in the presence of an aerosil (fumed silica) catalyst is first investigated. The mechanism of Formose reaction is actually the same aldol condensation that occurs in an alkaline media and is accelerated by the presence of a heterogeneous catalyst. The products observed in the reaction medium are ethylene glycol and glyceraldehyde. Finally, the selectivity of the synthesis of these products was compared and evaluated with the two corresponding products synthesized through the Formose reaction in aqueous solvent. The present study shows that in the presence of fumed silica catalyst in aqueous solvent, the production of ethylene glycol decreases with increasing pH from 7.6 to 9.3, while the conversion of ethylene glycol to glyceraldehyde increases. As a result, the amount of ethylene glycol in the reaction mixture decreases at alkaline pHs compared to neutral pHs; in contrast, the selectivity of the reaction to the production of glyceraldehyde increases. Changing the solvent from water to methanol also reduces production efficiency. Therefore, it indicates the low selectivity of the methanolic medium compared to the aqueous medium to produce two products, 1,2-ethanediol and 2,3-dihydroxypropanal.

The current research aims to synthesize carbon quantum dots-chitosan nanocomposites (CQDs-CS) and investigate the effects of its adding on the various properties of cotton fabric like color fastness, color features and antimicrobial activity. To achieve this goal, initially carbon quantum dots-chitosan nanocomposites (CQDs-CS) were synthesized in different weight percentages, and then examined and characterized through a variety of spectrometry methods including FTIR, HR-TEM, Photoluminescence, UV-visible and FESEM. Next, chemical treatment of the cotton fabric by CQDs-CS was studied via FESEM spectrometry, color fastness analysis, colorimetric parameters, and Mueller-Hinton broth antibacterial testing. Findings evinced that chemical treatment of cotton fabric by CQDs-CS nanocomposites led to a minor improvement of light fastness, washing fastness and some colorimetric data. Moreover, the synthesized nanocomposites caused the both gram positive (Staphylococcus aureus) and gram negative (Escherichia coli) bacteria present in the cotton fabric to be significantly eliminated.

In the current study, Ti/nanoZnO electrode was prepared by the electrophoretic deposition (EPD) method. The crystal structure, morphology, elemental analysis, and electrochemical properties of the prepared electrode were studied through X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) with an X-ray spectrometer attached, cyclic voltammetry (CV), linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), chrono-amperometry (CA), and chrono-potentiometry (CP). Obtained results showed that the prepared Ti/nanoZnO electrode possessed a uniform coating with more porous morphology, reduced charge transfer resistance, and improved electrochemical stability. Electrocatalytic performance was evaluated by studying the electrochemical removal of Reactive orange 7 (RO7) dye as a target pollutant on the Ti/nanoZnO electrode. Independent operating parameters namely pH, current density, electrolyte concentration, and reaction time were selected to model and optimize the removal process by central composite design (CCD). The color removal efficiency of 20.73% was obtained for RO7 after 60 min under optimum conditions. Eventually, from the findings of this study, it can be concluded that modifying the titanium (Ti) substrate using ZnO nanoparticles could significantly improve the electrochemical properties of the bare Ti electrode.

In this study, a new modeling method using QSAR model and artificial neural network is used to predict the aggregation number of some anionic surfactants in aqueous solution at 25 °C. The micelle aggregation number was determined using electrical conductivity measurements and the Evans method for anionic surfactants in aqueous solutions. However, the obtained results based on conductibvity strategy were not in good agreement with those of fluorescence method. Since the fluorescence method is a more accurate method for calculating the aggregation number of micelles, the results of the fluorescence method have been used in this study. In order to correlate the molecular structure of these surfactants with their aggregation number, a quantitative structure-property relationship (QSPR) study was performed. An artificial neural network (ANN) model was developed to predict the aggregation number of anionic surfactants by using four out of more than 3200 molecular descriptors, calculated by Dragon software, as input variables. The importance of selected descriptors were computed based on ANN method and listed as follows in descending order: nC> X5V> MWC05> MWC04. The complete set of 24 anionic surfactants was randomly divided into a training set of 16, a test set of 4, and a validation set of 4 compounds. Also, multiple linear regression (MLR) analysis was utilized to build a linear model by using the same descriptors. Correlation coefficient (R2) and root mean square error (RMSE) of the ANN and MLR models (for the whole data set) were 0.94, 4.99 and 0.82, 8.38, respectively. The higher R2 of the ANN method showed that the relationship between the descriptors and the aggregation number of the compounds is nonlinear.

One of the most challenges in the textile dyeing industry is produced toxic and contaminated effluents, which must remove these toxic compounds from wastewaters before discharging them into the sewerage. One of the best methods for removing these toxic maters is to use oxidant material such as ozone. Recently, electrochemical ozone generation has been considered a simple, inexpensive and effective process. In this research the removal of C. I acid red 361 with azo structure as a widely used in the carpet industry, remove it from effluent less attention, were removed by an electrochemical method with titanium modified with tin oxide doped with antimony, Nickel and carbon nanotubes. The surface of the titanium electrode was coated with a mixture of salts (tin, antimony and nickel) and carbon nanotubes by spin-coating and pyrolysis method. The cyclic voltammetry technique was used to compare the anodic current and the initiation potential of water splitting on the bare and modified electrodes. The UV-Vis technique was used to confirm ozone production on bare and modified electrodes. Removal of C. I acid red 361 from dye solution was performed with the modified electrode at a constant current density of 20 mA cm-2 at different times. Parameters such as initial dye concentration, contact time, pH and dye degradation kinetics were investigated. The results showed that the removal of C. I acid red 361 from the solution increased with increasing contact time with ozone so that during 30 minutes electrolysis of dye degradation was performed with an initial concentration of 100 ppm with 99% efficiency.

In this study, at first, 2-amino-1,4-dihydropyrimidine was synthesized by the reaction of guanidine hydrochloride, 4-methybenzaldehyde and ethyl benzoylacetate in the presence of sodium hydrogencarbonate as catalyst. Also, Fe3O4 nanoparticles were synthesized and functionalized via sequential reactions with chloropropyl(trimethoxy)silane and 2-aminopyridine. The resulting nanoparticles were used as environmentally benign magnetic nano-catalyst for the synthesis of some novel ethyl 2-amino-4-aryl-8-(4-methylphenyl)-3-cyano-6-phenyl-8,4-dihydro-1H-pyrimido[1,2-a]pyrimidine-7-carboxylate derivatives via a one-pot reaction of 2-amino-1,4-dihydropyrimidine, an aromatic aldehyde, and malononitrile. All the reaction steps are performed under ultrasound irradiation. Simple operation, high reaction yields, reusability of the catalyst for several times, short reaction times and easy separation of catalyst are the key advantages of using this catalyst.

Polyaniline (PANI) is an inherently conducting polymer (ICP) which has different applications in sensors, batteries, separation membranes and corrosion protective of metals. Synthesis of polyaniline with optimum properties and its remarkable conductivity has been studied. In this study, polyacid-doped PANI has been synthesized by chemical polymerization in the presence of modified acidic copolymer as template in different weight ratios. This template was prepared with modification of copolymer (Glycidylmethacrylate -Maleic anhydride) by using sulfanilic acid which is water soluble polyacid and containing sulfonic groups. Desired polymers have been characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) images, X-ray diffraction (XRD) and Thermogravimetric analysis (TGA). XRD patterns of PANI and modified PANI showed that the modified PANI has been formed in nanoscale crystallite sizes. Measuring the conductivity by using four point probe technique indicated that conductivity is increased in polyacid-doped PANI. Finally TGA data showed the thermal stability of HCl-doped polyaniline was more than polyacid-doped PANI.

Co-immobilization of several enzymes on the same matrix might enhance the efficiency of bioremediation of water resources. In pursuit of this objective, laccase and tyrosinase are especially important due to their reliance on molecular oxygen during the oxidation of various compounds. Accordingly, in this research, the substrate spectra of a laccase (obtained from Neurospora crassa) and a tyrosinase (obtained from Agaricus bisporus) were studied through analysis of their reactions with different diazo derivatives of phenol, catechol, guaiacol, and aniline, which were made from an identical molecular structure. The results were explained in view of the influential parameters on the substrate selectivity of each enzyme. The outcome of this research indicates that co-immobilization of laccase with a tyrosinase possibly expands the spectrum of the target pollutants, however, it does not guarantee the efficacy of the system against aniline derivatives.

In this research, the flowering branches of shami Lavandula angustifolia plant, from the mountains of Ilam province and the flowering branches of Larestani Lavandula angustifolia plant from Bushehr province were collected, dried and ground in the shade. Their methanolic and aqueous-methanolic extractive were extracted by maceration, soxhlet and ultrasonic methods and some important compounds were identified by the GC-MS method. Due to the large variety of extractives from Lavandula angustifolia extract, column chromatography, plate chromatography, thin layer chromatography and crystallization were used to separate the important combination of gallic acid from methanolic extract. The compound was finally purified as a white powder and identified by spectroscopic methods, and a high-performance liquid chromatography (HPLC) device was used to determine the percentage of Gallic acid. The silver nanoparticles were then prepared by green method from Lavandula angustifolia extract and examined in silver nitrate solution using UV-vis spectroscopy in the wavelength range of 200 to 800 nm. Also, Field Emission Scanning Electron Microscope (FE-SEM) for particle morphology, XRD for the particle scattering pattern and with FT-IR device, the functional groups responsible for reducing and stabilizing silver nanoparticles were evaluated.

In this study, a paraphenylene diamine-organic polymer adsorbent was synthesized for removal of the cationic and anionic organic pollutants. Adsorbent was characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (FE-SEM), energy diffraction X-ray spectroscopy (EDX-mapping) and BET analysis. Methylene blue and methyl orange were selected as cationic and anionic organic pollutant model. Then the effect of factors such as pH, initial concentration, amount of adsorbent, temperature, contact time and presence of electrolyte on the adsorption efficiency was investigated. The optimum conditions for removal of methylene blue were 0.01 g of adsorbent, pH 7, temperature 25 ° C and contact time of 5 min. For removal of methyl orange the optimum conditions were 0.01 g of adsorbent, pH 4, temperature 25 ° C and contact time of 5 min. According to the obtained data, Freundlich isotherm was consistent with both methylene blue and methylene orange adsorption data. The maximum experimental adsorption capacity was 48.1 mg.g-1 for methylene blue and 38.6 mg.g-1 for methyl orange, respectively. Also, the adsorption data for both dyes were consistent with the second-order kinetic model. Simultaneous removal of two dyes using adsorbent with removal efficiency of more than 99% was successful. The adsorbent was successfully applied for removal of the selected dyes from real industrial wastewaters.

Due to the progress of science and technology in health and medicine, selenium is mentioned as an excellent antioxidant in preventing the growth of cancers cell and even helping the process of cell growth. In most countries, plant foods are the main source of selenium. Among these plant sources, a kind of green-blue algae from the species of cyanobacteria should be mentioned, which is introduced as Spirulina algae. In addition to providing the body with the selenium it needs, spirulina is an excellent source of essential proteins, minerals, vitamins and amino acids. However, the amount of selenium required by the body and the fact that its excessive increase causes toxicity doubles the need to pay attention to its accurate quantitative measurement. These measurements are usually performed with costly and long-term methods such as ICP-AES. Therefore, in this study, the suitable specific ligand (Diaminotoluene) for selenium was used with low cost and high availability, using simple, low cost and fast technique as UV-spectrophotometric method.The results of the analytical method validation indicated that this ligand has high productivity and also this method should be quite suitable for replacement with high cost methods such as ICP-AES. In addition, this method used can provide all the parameters required to analytical method validation.