جستجوی مقالات مرتبط با کلیدواژه "zeolite y" در نشریات گروه "شیمی"

This research study utilized the synthesis method of the Cr-V@MOF5 catalyst to integrate findings from multiple prior studies. The oxidative dehydrogenation method was chosen due to its exothermic nature and lack of thermodynamic constraints on catalytic conversion, which are advantages over catalytic dehydrogenation without oxidation and thermal breakdown. In this research at Islamic Azad University in Omidiyeh, the catalytic bases of zeolite and metal-organic framework (MOF) were used. The synthesized catalysts were modified by some improvers, and each improver was assessed to find out which one is suitable for this oxidative dehydrogenation process. The goal was to reach the optimal point of propane-to-propylene conversion using statistical analysis. Design Expert software was utilized to ascertain the difference between the laboratory data and the optimized objective function. Subsequently, a comparison was made regarding the quantity of propylene produced in the presence of two distinct catalysts. The results revealed that the presented synthesis method is not repeatable. Also, the results showed that since the organometallic framework catalyst had a larger surface area compared with the ZSM-48 zeolite, it had a better catalytic performance than the zeolite catalyst. The functional comparison of zeolites and organometallic frameworks in terms of structure and the results of propylene production resulting from the performance of these two catalysts is also among the achievements of the project.

In this study, nanoscale zero-valent iron supported onto Zeolite Clinoptilolite (NZVI/Zeolite) was synthesized from a facile method as an adsorbent for removing Cu (II) from aqueous solutions. Field Emission Scanning Electron Micrographs (FESEM) showed no aggregation, and dot mapping revealed the uniform dispersion of iron onto the surface of the zeolite. The surface area of synthesized NZVI/Zeolite was obtained at about 132.14 m2/g by BET analysis. Also, the isotherm adsorption of Cu (II) onto NZVI/Zeolite was best fitted with the Temkin isotherm (R2=0.894) and maximum adsorption capacity (qm) of Cu (II) onto NZVI/Zeolite was 61.72 mg/g. The maximum removal of Cu (II) by NZVI/Zeolite was about 99.98% at pH=8, the dosage of adsorbent = 0.1 mg/L, Cu (II) concentration = 60 mg/L, and time = 30 min. The reusability of nanocomposite after five consecutive cycles showed 12.72% reduction in the removal of Cu (II). These results suggest that NZVI/Zeolite has excellent potential for the removal of Cu (II) from aqueous solutions.

Carbon monoxide is one of the main air pollutants, mainly produced from the incomplete combus tion of fossil fuels. This s tudy aims to oxidize carbon monoxide by copper oxide nanoparticles immobilized on zeolite13X subs trate. The present inves tigation was conducted to determine the effect of carbon monoxide concentration parameters (in the range of 200-1400 ppm) and reaction temperature (in the range of 100-500 °C) on the efficiency of carbon monoxide conversion by CuO/Zeolite 13X nanocatalys t. The design of the experiment and the determination of the number of experiments were analyzed using the central composite design method, and the s tatis tical tes t of analysis of variance was done using the response surface method. Also, the s tructural and morphological characteris tics of the nanocatalys t were inves tigated using BET, BJH, FE-SEM, EDX, and XRF tes ts. The results show that CuO/Zeolite 13X nanocatalys t efficiently oxidizes carbon monoxide. The highes t conversion efficiency of 82.6% was obtained at a temperature of 400 °C and a carbon monoxide concentration of 500 ppm as the optimal conditions. According to the EDX tes t results, copper oxide nanoparticles with a weight percentage of 5.9% were loaded on the Zeolite 13X subs trate. Design Expert11 software reduced the cubic model with an R2 coefficient of 0.98.

The Zeolitic adsorbent is successfully synthesized by natural Iranian kaolin to the separation of hydrogen sulfide from a gas mixture. In this work, zeolite 13X from modified natural Iranian kaolin at 65 °C for 72 h at various concentrations of caustic soda solution was synthesized using a metakaolinization process at 900 °C for 2h. By Taguchi’s experimental design, the best duration and temperature of crystallization were 72 h and 65 °C. Prepared zeolite 13X was characterized using X-Ray Diffraction (XRD), Fourier Transforms InfraRed (FT-IR) spectroscopy, Scanning Electron Microscopy (SEM), and N2 adsorption-desorption methods. In addition, the adsorption capacity of zeolite 13X for 310 ppm of hydrogen sulfide mixed with hydrocarbon gas-like butane was investigated using a volumetric method by two different detectors and different temperatures. After the adsorption process, the amount of H2S in output gas was about 108 ppm and this confirms approximately more than 65% adsorption at 25 bar and 298K. The results are is in good agreement with experimental results.

Zeolite A was synthesized via a two-step hydrothermal transformation of kaolin. The kaolin was first transformed to meta kaolin by calcination at 600OC, then treated with 3M NaOH solution (1:5 ration) in a stainless-steel autoclave with a teflon liner. The mixture was heated to 121°C for 2h to insert the sodium ions into the metakaolin structure. The treated kaolin clay was washed three times with deionized water to remove the excess unreacted NaOH, filtered and dried in an oven at 100°C overnight. Different analytical techniques were used to characterize the synthesized  Zeolite A and the individual zeolie/metal oxide nanocomposites including X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive x-ray (EDX), X-ray fluorescence (XRF), Furrier transform infrared (FTIR), and Brunnuer Emmett teller (BET) analysis. FTIR confirmed the presence of Si-O, Si-Al, Al-O, and metal oxygen bonds. SEM/EDX revealed a cubic morphology with some bigger particles that are mono dispersed and partially spherical, along with different compositions of the elements present. XRD showed a face-centered cubic (FCC) structure with 25.73 nm lattice, while XRF confirmed the presence of SiO2, Al2O3 as well as with different major and trace metal oxides. The BET analysis showed 3.9457 and 4.3044 (m2/g), 0.6032 and 0.5598 (cm3/g), 603.087 and 617.503(Ǻ) for both the kaolin clay and the synthesized zeolite A, respectively. The results of this synthesis route demonstrate that Zeolite A was successfully synthesized.

In this study, a new Zeolite Al/Na (ZAN) was synthesized and characterized and then a new modified Carbon Paste Electrode with ZAN was made to determine Acetaminophen. Electrochemical studies using Linear Sweep Voltammetry and differential pulse voltammetry were used to determine electrochemical  Acetaminophen . In the presence of Acetaminophen , modified electrode with ZAN shows a specific anodic peak at ~ 0.59 volts which is the result of using electrocatalytic oxidation of  Acetaminophen . The determination limit of this method to measure  Acetaminophen was 5.8 µM, the relative standard deviation for 7 repeated measurements was 1.1 % and linear range of the calibration to measure  Acetaminophen was 10 up to 115 µM . for the characterization of ZAN nanostructures we used SEM (Scanning Electron Microscopy), DLS (Dynamic Light Scattering) and FT-IR (Fourier-Transform Infrared spectroscopy).

Uranium is one of the most threatening elements due to its radioactivity and high toxicity. In the course of the nuclear fuel cycle, significant amounts of uranium are released into the environment. Biosorption technology offers the advantages of low operating costs and high efficiency in metal removal from aqueous solutions. In this work, the sorptions of uranyl ions from aqueous solutions by Saccharomyces Cerevisiae (SC) on zeolite clinoptilolite were investigated. First, a characterization of the natural zeolite was performed by classical chemical analysis and, then the influence of solution pH, temperature, contact time and, initial concentration on the sorption of uranyl was investigated. The concentration range of uranyl in the solution was between 0.02 and 1 mmol L-1, which was determined by the inductively coupled plasma optical emission spectrometry method (ICP-OES). Further results showed that metal binding occurred extracellularly at the cell wall surface and the rate of sorption of uranyl ions by free yeast cells was rapid from SC. Also, comparison of the results from BET for the primary and modified biomass shows an increase in the surface area of the modified biomass as a result of adsorption on clinoptilolite zeolite. The equilibrium adsorption ratio and distribution of uranium hydrolysis products for all samples was calculated and showed that the points corresponding to initial concentrations of less than 0.1 mmol L-1 have higher and narrower absorption fractions. Moreover, the adsorption rate decreases at concentrations higher than 0.2 mmol L-1 compared to low concentrations.

In recent years, intensive attempts have been made to remove toxic heavy metals and radionuclides from wastewater. Uranium is one of the most threatening elements due to its radioactivity and high toxicity. Significant amounts of uranium are released into the environment throughout the nuclear fuel cycle. Biosorption technology offers the advantages of low operating costs and high efficiency for metal removal from aqueous solutions. In this work, the sorption of uranyl ions from aqueous solutions by Saccharomyces Cerevisiae (SC) as free cells and in an immobilized form on Zeolite Clinoptilolite was investigated. First, a characterization of the natural zeolite was carried out by classical chemical analysis, XRD, FTIR, and TG/DTG, and then the influence of solution pH, temperature, contact time, and initial concentration on uranyl sorption was investigated. The concentration range of uranyl in the solution was between 0.02 and 1 mmol L-1, which was determined by the ICP-OES method. In addition, the immobilization of 17.1 × 108 cells ml-1 number of yeast cells on clinoptilolite was optimized and observed using an SEM. More results demonstrated that metal binding was carried out extracellularly at the cell wall surface and the rate of uranyl ion uptake by free yeast cells of SC is rapid. The equilibrium adsorption ratio for all samples was calculated and showed that the points corresponding to initial concentrations lower than about 0.1 mmol L-1 have a higher and closer absorption fraction. Moreover, at concentrations higher than 0.2 mmol L-1, the adsorption rate decreases compared to low concentrations.

In the present study, the Ag NPs/Zeolite 13X nanocomposite as an effective catalyst was prepared through reduction of Ag+ ions using Tragopogon graminifolius extract as the reducing and stabilizing agent and Ag NPs immobilization on Zeolite 13X surface in the absence of any stabilizer or surfactant. Several techniques such as FT-IR spectroscopy, UV-Vis spectroscopy, X-ray Diffraction (XRD), Scanning Electron Microscopy (FE-SEM), Energy Dispersive X-ray Spectroscopy (EDS) and Transmission Electron Microscopy (TEM) were used to characterize Zeolite 13X, Ag NPs, and Ag NPs/ Zeolite 13X. Moreover, the catalytic activity of the Ag NPs/Zeolite 13X nanocomposite was investigated in the reduction of 4-nitrophenol (4-NP) and chromium (VI) at room temperature. On the basis of results, Ag NPs/Zeolite 13X nanocomposite was found to be high catalytic activity according to the experimental results in this study. In addition, Ag NPs/Zeolite 13X nanocomposite can be recovered and reused several times in the reduction of 4-NP and chromium (VI) with no significant loss of catalytic activity.

The Cu(II) complex of 2,6-pyridine dicarboxylic acid (PydcH2, dipiconilic acid) was successfully prepared and readily trapped in the nanocavity of zeolite-X (NaX) through a flexible synthetic method. The characterization of nanocomposite ([Cu(pydcH2)(pydc)]-NaX) was performed by FT-IR, XRD, BET isotherm, SEM, TEM, and elemental analysis, that approved the encapsulating of coordination compound in the channels of NaX, with no change in the zeolite structure and morphology. The catalytic activity of the prepared material was also studied in respect of the oxidation of aniline with hydrogen peroxide as an oxidizing agent. The experiments were performed to optimize aniline oxidation under different extents of catalyst, temperature, and time. Optimized reaction conditions of this catalyst exhibited moderate activity (~92%) of aniline oxidation. This catalyst was stable in the oxidation of aniline as recovered and reused for an additional three runs. The outcomes reflected that the catalyst was reusable with no considerable loss in the catalytic activity.

In this research, zeolite Na-Y was synthesized from Kaolin without an organic template under the non-hydrothermal condition to adsorb sulfur compound. Model fuel desulfurization was optimized by employing the Box-Behnken experimental design with 2 center points, the three parameters, and one response value. The objective was to find how sorption capacity is related to alkali fusion temperature, crystallization time, and aging time. Optimal DBT adsorbent was synthesized at 550 °C, minimum crystallization time, and maximum aging time. The zeolite samples were characterized by FT-IR and XRD. The crystallinity of the samples was lower than the crystallinity of commercial zeolite Y. During zeolite preparation, there was a competition between zeolite Na-Y, Na-P, Na-X and Na-A. The equilibrium results were well fitted by the Langmuir and Freundlich isotherms for the best adsorbent. The largest DBT adsorption capacity, 32.67 mg DBT/g, was calculated for the optimal adsorbent. Pseudo-first order and pseudo-second-order models were evaluated to understand the kinetics of the adsorption process. The reduction of DBT obeyed the second-order model of kinetic. Ni-Y and La-Y zeolites were prepared by the liquid-phase ion-exchange method. The maximum DBT adsorption capacity has been observed for Ni–Y (∼72.25 mg DBT/g) and La–Y (∼66.59 mg DBT/g).

In this paper, we have reported removal of Bisphenol A (BPA) by Hydroxyapatite/NaP zeolite (HAp: Zeolite ) nanocomposite which synthesized in previous our work and characterized by using different methods such as X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscope, Energy Dispersive X-ray analysis, surface area, and thermogravimetric analysis. To investigate the purification performance for removal BPA batch experiments were used. The results showed that the removal capacity could reach an equilibrium value of 11.125 mg/g in the initial BPA concentration of 50 mg/L. Some parameters such as initial concentration, pH, contact time, adsorbent dosage, and the temperature were studied that result shows this nanocomposite have high capacity for adsorption of BPA. The kinetic study presented that it agreed well with the pseudo-second-order model (R2= 0.994). Furthermore, thermodynamics studies were carried out, and result showed an exothermic condition for adsorption process. An artificial neural networks (ANNs) model was developed to predict the performance removal process based on experimental information which shows an association between the predicted results of the designed ANN model and experimental data. Results showed that the neural network model predicted values are found in close agreement with the batch experiment result with a correlation coefficient (R2) about 0.99051 and mean squared error 0.005938.

A streamlined and efficient method for the synthesis of 2-amino-4H-chromenes is achieved by one-pot three-component reaction of aldehydes, 2-naphthol and malononitrile in the presence of ZnO nanoparticles loaded on zeolite-Y (ZnO@zeolite-Y) as a highly active catalyst under solvent-free conditions. ZnO@zeolite-Y has been successfully prepared via hydrothermal technique and its structure was confirmed using nanoscale-like identification techniques included FT-IR, XRD, FE-SEM, EDX analyses and BET surface area measurements. The higher environmental compatibility and sustainability factors such as reusability of the catalyst as an important principle in green chemistry, use of solvent-less technique as a green synthetic approach and easy isolation of the product along with good yields, make the present protocol a true green process for the synthesis of chromenes compared to conventional methods.

The aim of the present study was to determine the cefixime (CFX) through highly sensitive and simple electrocatalytic method. The electrocatalytic oxidation of CFX was performed on the surface of the modified carbon paste electrode (MCPE) with synthesized nano-sized ZSM-5 zeolite using the cyclic chronoamperometry and voltammetry methods. Also this work probed the application of the nano-zeolite in electrode structure and prepare zeolite MCPE. Due to the porous structure of the zeolite framework, the nickel (Ni) (II) ions were embedded into the zeolite framework through the immersing MCPE with synthesized zeolite in a 1.0 M Ni chloride solution. An excellent redox activity was practically seen for the Ni2+/ Ni3+ couple on the MCPE surface in alkaline solution. The Ni ions were acted as a mediator for the oxidation of CFX and catalyzed the electron transfer in this process. The CFX molecules were successfully oxidized on the surface of proposed electrode. The chronoamperometric method was used and catalytic reaction rate constant (K) was 3.5 ×106 cm3/s-1/mol-1 for the CFX oxidation. This electrocatalytic oxidation had a good linear response in the CFX concentration range of 25×10-6– 25×10−5 M with a regression correlation coefficient of 0.993, and the detection limit (3δ) of the method was 26×10-7 M. The diffusion coefficient of CFX molecules (D=6.47×10-5 cm2/s-1) was calculated based on the chronoamperometry studies.

In this research, Ni(8%)/TiO2/Zeolite NaX nanophotocatalyst was synthesized andevaluated as a desulfurizer catalyst from hydrophane 10 base oil. Various tests,including X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Analysis (EDXA), Transmission Electron Microscopy (TEM), AtomicForce Microscopy (AFM), and BET/BJH were used to evaluate the photocatalystsynthesis process. Initially, using Design of Experiment (DOE) technique, optimuminfluential parameters were predicted, and 2D plus 3D diagrams were plotted.Then, 50 ml of oil containing 3782 ppm total sulfur, 0.6 g catalyst, 0.8 g adsorbent,and 3 h contact time were able to remove 20% of sulfur when exposed to thevisible light. Sulfur was measured at all steps using inductively coupled plasma(ICP) technique. The final results suggested that the nanophotocatalytic processis a feasible way when compared to difficult and complicated steps with harderconditions.

A computational study of the electronic structure and stability of complexes formed between Zeolite Y and boric acid was carried out at the HF and B3LYP levels using 6-31G* basis set. Five structures located as local minimum in PES of complex (structures d, e, f, g, and h). The most stable structure is formed due to hydrogen bonding between two hydroxyl of boric acid and both oxygen of AlO2 in Zeolite (structure e).