فهرست مطالب

  • Volume:3 Issue: 6, 2020
  • تاریخ انتشار: 1399/07/09
  • تعداد عناوین: 9
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  • Mohtaram Janighorban, Nahid Rasouli *, Nasrin Sohrabi, Mehrorang Ghaedi Pages 701-721
    In this work, a novel chemically adsorbent based on Zn2Al-layered double hydroxide (LDH) that modified by indigo carmine (IC) (Zn2Al-LDH/IC) was synthesized. The chemical composition and morphology of the synthesized Zn2Al-LDH/IC were investigated using the X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), field emission scanning electron microscopy (FE-SEM), and energy-dispersive X-ray spectroscopy analysis. Response surface methodology (RSM) using the central composite design (CCD) is applied to optimize the adsorption process parameters for Cd(II) removal from the aqueous solution using a novel chemically modified nano Zn2Al-layered double hydroxide (Zn2Al-LDH/IC). The combined effect of adsorption parameters such as contact time, initial Cd(II) concentration, adsorbent amount and initial pH of solution were studied. The results obtained by ANOVA analysis displayed the relative significance of the process parameters in the adsorption process. The optimum conditions to remove Cd(II) from aqueous solution were at the initial Cd(II) concentration of 52 mg/L-1, pH 4.13, the adsorbent dose 0.06 g, temperature of 36.5 °C and contact time 36 min. In optimum conditions, high adsorption efficiency and maximum adsorption capacity were 47.3% and 6.11 mg/g, respectively.  Adsorption of Cd(II) by nano Zn2Al-LDH/IC could be well examined with Langmuir and Freundlich isotherms and the pseudo second-order kinetic model was fitted to the adsorption kinetic data. Furthermore, the thermodynamic data exhibited that the adsorption process of Cd(II) by nano Zn2Al-LDH/IC was spontaneously and exothermic.
    Keywords: Nano Layered double hydroxide, optimization, Central Composite Design (CCD), Response surface methodology (RSM)
  • Anil Kumar Bahe, Ratnesh Das *, Gowhar Ahmad Naikoo, Pankaj Kosti, Sushil Kashaw Pages 722-729
    In the present study, we successfully synthesized a series of indoles with a variety of aromatic aldehydes via one-pot route. The excellent results of the bis(indoly) methane (BIM) derivatives was obtained at the presence of 5.0 mol% p -toluene sulfonic acid in acetonitrile at room temperature using conventional process. All the as-synthesized compounds were bioactive. The synthesized BIM derivatives were evaluated for the antibacterial activity (in vitro) against the Staphylococcus aureus, and the results were compared with the standard Kanamycin. The results confirmed that, majority of the as-synthesized compounds revealed splendid antibacterial activity.
    Keywords: Antibacterial Activity, Bis(indolyl) methane derivatives, Catalyst, Kanamycin, Staphylococcus aureus (MTCC1144)
  • Olaniyi Kamil Yusuff *, Abdulrafiu Tunde Raji, Modinah Adenike Oladayo Abdul Raheem, David Boluwaji Ojo Pages 730-739
    The molecular dynamics (MD) simulation of two structures of human insulin hexamers (Zn-hexamer and Znfree-hexamer) in explicit solvent was performed and the role of the Zn2+ ions in the hexamer’s cavity as it may affect the propensities of the dissociation of insulin hexamer into dimers and monomers investigated. The starting structure of the Zn-hexamer contains two cavity water molecules and two Zn2+ ions in addition to the amino acids residues of the insulin hexamer while the starting structure Znfree-hexamer is made up of only the amino acids residues of the insulin hexamer. The MD simulation was performed for 1 µs under the isothermal-isobaric conditions (NPT) conditions using the GROMACS software, amber ff99-SB force field, TIP 3P water model with periodic boundary conditions imposed on x-, y- and z- directions. Structural analyses of the two experimental structures were carried out and root mean square deviations (RMSD) and root mean square fluctuations (RMSF) computed from the referenced initial structures. The average RMSD value of the backbone atoms for the Zn-hexamer is 0.293 nm and Znfree-hexamer is 0.785 nm. The structural analysis revealed that, there were dimer’s dissociation and pronounced fluctuations of the amino acids residues in the Znfree-hexamer compared to the Zn-hexamer during the MD simulation. This is evident in the higher inter-dimer distances of the six glutamate-13(β) residues in the Znfree-hexamer which confirmed the influence of the removal of the Zn2+ ions and cavity water molecules on dissociation of the insulin hexamer.
    Keywords: insulin, Zn-hexamer, Znfree-hexamer, Explicit solvent, Cavity water
  • MohammadReza Jalali Sarvestani *, Zohreh Doroudi Pages 740-749

    In this research study, the detection and removal of nalidixic acid by boron nitride nanocluster (B12N12) were investigated using the DFT, infra-red (IR), natural bond orbital (NBO) and frontier molecular orbital (FMO) computations. The calculated negative values of adsorption energy, Gibbs free energy changes, and great amounts of thermodynamic equilibrium constants demonstrated nalidixic acid adsorption on the surface of B12N12 was spontaneous, irreversible and experimentally feasible. The values of adsorption enthalpy changes and specific heat capacity (CV) revealed that, the interaction of the adsorbate and adsorbent was exothermic and B12N12 was an ideal nanostructure for the construction of new thermal sensors for detection of nalidixic acid. The influence of temperature on the thermodynamic parameters was also investigated and the results demonstrated that, the adsorption process was more favorable at room temperature. The NBO results indicated in all of the studied configurations covalent bonds were formed between nalidixic acid and B12N12 and their interaction was chemisorption. The density of states (DOS) spectrums showed that, the bandgap of boron nitride nanocage after the adsorption of nalidixic acid decreased from 14.864 (eV) to 7.314 (eV), indicating that the electrical conductivity of B12N12 improved significantly in the adsorption process and B12N12 is an appropriate sensing material for developing novel electrochemical sensor to nalidixic acid determination. The important structural parameters including chemical hardness, chemical potential, dipole moment, electrophilicity and maximum charge capacity were also computed and discussed in detail.

    Keywords: Nalidixic acid, B12N12, Adsorption, NBO, DFT, Sensor
  • Mahmoud Awad *, Tamer Wafy Pages 750-759
    Thermal insulators based on ethylene propylene diene terpolymer (EPDM) is an effective class of extreme temperature thermal insulators due to their outstanding heat, mechanical and ablative characteristics. This classed insulator is often reinforced by Kevlar pulp and fumed silica. Ammonium sulfate and antimony trioxide combination have been added as a flame retardant. To improve the elastomer ablative characteristics, multi-walled carbon nanotubes (MWCNTs) were added. We have studied different MWCNT concentrations. In this work, we investigated the effect of the MWCNTs content on the characteristics of the selected insulating formulation based on EPDM. The maximum improvement of tensile strength was 60%. Thermal stability increased by 27% through thermal gravimetric analysis (TGA-DTG), while the ablation resistivity was significantly increased by 60%. The weight loss of the 10 phr MWCNT sample decreased by 40% compared with that of the neat sample. Besides, an increase in ablation rate by 60% was recorded with the same sample.
    Keywords: EPDM, MWCNT, Thermal characterization, Oxy- acetylene torch test, Ablation
  • Bahareh Davarnia, Seyed Ahmad Shahidi *, Azade Ghorbani Hasansaraei, Fatemeh Karimi Pages 760-766

    Ag nanoparticle and 1-buthyl-3-methyl imidazolium bromide (1B3MIBr) carbon paste electrode(Ag/NP/1B3MIBr/CPE) amplified sensor was fabricated for determination of rutin in this project. The electro-oxidation of rutin occurs at a potential about 0.4 V at the surface of Ag/NP/1B3MIBr/CPE and this value is less positive than the unmodified CPE. pH = 7.0 was selected as an optimize condition for all of electrochemical investigations in this work and for evaluating electrochemical parameters such as diffusion coefficient (5.0 × 10-6 cm2/s). At the optimized condition for rutin analysis, the differential pulse voltammetry (DPV) peak currents of rutin show a wide linear dynamic range from 0.05-320 μM with a detection limit of 10 nM. Finally, the Ag/NP/1B3MIBr/CPE was used for determination of rutin in soy samples with good selectivity and high sensitivity.

    Keywords: Rutin analysis, Ag Nanoparticles, Electrochemical food sensor, Modified electrode
  • Maryam Abrishamkar *, Salma Ehsani Tilami, Sepideh Hosseini Kaldozakh Pages 767-776
    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.
    Keywords: Electrocatalyst, Nano-ZSM5, Cyclicvoltammetry, Chronoamperometry, Cefixime, Zeolite surface
  • Fahimeh Hooriabad Saboor *, Omid Hajizadeh Pages 777-788

    Separation of light hydrocarbons (LHs) is one of the most important and mostly energy intensive petrochemical processes. Several techniques have been developed industrially based on traditional separation methods such as distillation and extraction. However, they mainly suffer from high-energy consumption and low efficiency. Adsorptive separation using porous solid materials and membrane separation are the promising processes to separate the mixture of light hydrocarbons comprising paraffin/olefin mixtures of C1/C2/C3 hydrocarbons. Introducing and developing new porous adsorbents for selective separation of LHs is highly needed because of competitive adsorption and challenging separations that are arising from the similarity in some structural and physicochemical properties of LHs. In addition, separation under the mild condition is of great importance for the application in industry. In this review, we discussed some methods for separation of LHs mixtures and highlighted the recent advances in the separation techniques based on using porous structures especially metal organic frameworks in the form of porous adsorbents and membranes.

    Keywords: Light hydrocarbon, Separation, Adsorption, distillation, Membrane, MOFs, Zeolite
  • Bhawana Khatri, Armila Rajbhandari (Nyachhyon) * Pages 789-799
    BiVO4/Hydroxyapatite (HAP) composite was synthesized successfully by combining co-precipitation process and wet-chemical method. Three composites have been prepared by varying the molar concentration of BiVO4 and HAP and were named as 1:1-BHC, 1:2-BHC and 2:1-BHC respectively. These composites were characterized by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). SEM and TEM images of as prepared composites revealed the BiVO4 nanorods enclosed with HAP nanoflakes while XRD and FTIR results confirmed the formation of nano composites. The composites were then used as photocatalyst for the photocatalytic degradation of malachite green (MG) dye and the photocatalytic activities were compared with that of BiVO4. The 2:1-BHC showed best MG photodegradation, better than BiVO4 itself due to synergistic effects of adsorption of dye particles by HAP and subsequent photocatalytic degradation by BiVO4. The optimum catalyst dose for 2:1-BHC was found to be 0.1 g per 100 mL of 10 ppm dye concentration with initial pH of solution being 6. These results revealed that BHC-composite did possess the features of visible light active photocatalyst and could be used for the degradation of organic pollutants like dyes.
    Keywords: Photocatalysis, BHC-composites, MG photodegradation, Nanocomposite