Journal of Applied Research in Chemistry
Year:2016 | Volume:10 | Issue:3|Papers Count:11

The Photocatalytic processes can be used as an efficient method for the purification of wastewaters containing heavy metals. The goal of present study was the synthesis of ZnO nanoparticles immobilized onHZSM-5 and investigation of its photocatalytic properties in efficient reduction of Cr (VI). ZnO/HZSM-5 nanocomposite was synthesized by hydrothermal/ impregnation method and characterized by XRD, FESEM, BET and EDX techniques. The XRD analysis confirmed the existence of ZnO andHZSM-5 as crystalline phases in the nanocomposite structure. Also, FESEM images illustrated that fine nanoparticles of ZnO were uniformly dispersed overHZSM-5 support. The effects of pH and initial concentration were evaluated. The results indicated that the removal rate of chromium was increased with decreasing pH value and initial concentration of chromium. Finally, in order to obtain the kinetic information, the experimental results indicated that with increasing pH from 3 to 7 the reaction rate constant was decreased from 0.019 to 0.007 (1/min) and the photo-reduction of chromium process was fitted with a pseudofirst-order. Therefore, the photocatalytic process that uses ZnO/HZSM-5 nanocomposite can be employed as an effective and eco-friendly process is excellent candidate for treatment of the wastewater containing high levels of hexavalent chromium.

RuO2 coating was fabricated by two different methods including thermal decomposition of RuCl3 at 400°C and electrochemical deposition from RuCl3 bath-heat treatment at 120°C on the Ni substrate. Electrocatalytic activity of prepared coatings were investigated toward hydrogen evolution reaction (HER) in a 1 mol.L-1 solution of sodium hydroxide by electrochemical techniques including cyclic voltammetry, electrochemical impedance spectroscopy, and electrochemical polarization. The results revealed the better kinetics of HER on electrochemically deposited coating so that the charge transfer resistance and tafel slopes are lower and current densities are higher at the surface of the same coating. SEM micrographs, EDX analysis, and XRD patterns were provided in order to investigate the morphology and structure of the surfaces. These investigations were showed that the electrochemically prepared coating has amorphous structure with higher roughness at the surface, while thermally prepared coating has a smooth and uniform state.

Olive (Olea europaea) is a medicinal plant that has medicinal properties, in addition of its use in food. All body of the plant olive has active constituents. This plant has various cultivars.The aim of this study is to identify the volatile components of leaves of olive varieties (Manzanillo and Koroneiki) by GC/MS, and GC/FID due to the genetic proximity of the two plants, and evaluating the antioxidant capacities in accordance with a change in extraction conditions, for the first time.The results showed that Ethyl acetate, 2-Hexenal and n-Octyl acetate had the highest percentage of essential oil components of Koroneiki cultivar and the major components of the essential oil of Manzanillo cultivar include: Geranyl acetate, p-Cymene and Valeric acid.The studies also indicated that all extracts of these leaves have a noticeable inhibitory power on 2, 2 -diphenyl-1-picrylhydrazyl (DPPH) free radical and this ability increases with increasing polarity of the solvent used to extract, and the extraction method showed a significant effect on the amount of antioxidant capacities of these extracts.According to these results, it seems that extracts of this plant can be used as a rich source of antioxidants in medical and related industries.

In this study, design and construction of a preconcentration system for determination of trace impurities in ultra pure hydrogen were performed. Preconcentration of impurities was done by adsorption of impurities on silica gel (as adsorbent) in liquid nitrogen temperature (77K). Expriments were carried out by a gas chromatograph equipped with TCD and FID detectors, molecular sieve 5 A, and propack Q columns, for optimization of theoric values from calculations. The optiumum conditions have been determined by expriments: as adsorbent (silica gel 70-230 mesh, chromatography grade, 1 g), preconcentration column: 1.4 inch×5 cm copper tube, hydrogen flow rate in preconcentration process: 100 ml/min.

In this study, magnetic nanocellulose/halloysite nanotubes (M-NC/HNT) composite was fabricated and studied as a nanoadsorbent for the removal of Zinc (II) from aqueous solutions.The HNT as a mineral nanotube with unique properties along with NC after magnetization were used as nanocomposite. The nano-adsorbent was characterized using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and X-ray diffraction analysis (XRD). The magnetization values of magnetic nanoparticles were measured by vibrating sample magnetometer (VSM). The effects of various parameters like pH, initial Zn (II) concentration, temperature, amount of adsorbent, and contact time on the efficiency of Zn (II) removal were studied and their values were then optimized. The adsorption equilibrium data fitted well with Freundlich isotherm model. The results showed that the (M-NC/HNT) composite could remove the Zn (II) from industrial wastewater with an efficiency of 94.4 % The results of this study indicated that the proposed nanoadsorbent with high stability can be easily recovered and reused.

The catalytic performance of Mn (NO3) 2.4H2O as an environmental friendly and mild catalyst for one-pot and eco-friendly synthesis of highly substituted tetrahydropyridines via fivecomponent reaction of amine derivatives, b-ketoester, and aldehyde derivatives have studied. The present methodology has numerous benefits such as non-toxicity and being inexpensive. Besides available catalyst, environmental friendly conditions, easily separated catalyst, and high yields of products makes it more feasible.

One of the main carcinogenic pollutants occurring in in the wastewater of some chemical industries is ortho toluidine (OT). In this project the removal of OT was investigated by UV/H2O2 and UV/US/H2O2 processes in batch recirculated reactors. The effect of three main factors including initial concentration of OT, H2O2, and pH was investigated as an influencing variables on UV/H2O2 process at 25°C and the optimum conditions were obtained as 40 mM of hydrogen peroxide, 50 mg/l of OT, and pH at 9. The rate constant of the reaction was increased by addition of ultrasonic waves to UV/H2O2 process. The UV/US/H2O2 process was investigated at 25, 30, and 35 °C and the maximum efficiency was found at 35 °C. Through kinetic studies, the psudo first order rate constants were obtained as 0.0442 min-1 (at optimum conditions) and 0.0593 min-1 in UV/H2O2 and UV/US/H2O2 processes, respectively. The removal of total organic carbon (TOC) was obtained as 38 and 52.5% in UV/H2O2 and UV/US/H2O2 processes. Also, the effect of volume and volumetric flowrate of the circulated wastewater and kinetic reactions were explored so that the efficiency of the processes was reduced by increasing in the volume of the wastewater and it was decreased by increasing in the volumetric flowrate of circulated waste water.

In this study, magnetite/ aminopropyltriethoxysilane/ glutaraldehyde (Fe3O4/ APTES/GA) nanoadsorbents were synthesized, and their applications for the adsorption of thorium ions from aqueous solutions were studied in a batch sorption process. The magnetite nanoparticles were synthesized with an average diameter of 20 nm by co-precipitation method. Then surface modification of Fe3O4 nanoparticles was carried out with 3-aminopropyltriethoxysilane and glutaraldehyde. The influence of the several variables, such as pH (1-5), Th (IV) initial concentration (50- 300 mg/L), and adsorbent dose (1- 5 g/L) on the Th (IV) adsorption was investigated by response surface methodology (RSM) based on Box-Behnken design. The results of analysis of variance (ANOVA) showed adsorbent dosage, initial concentration of thorium, and pH were the most effective factors on adsorption of thorium. The results showed that the highest absorption capacity (q) was 107.23 mg/g at pH=4.5, initial concentration of 250 mg/L, and adsorbent dosage of 1 g/L for 90 minutes. Also thermodynamic parameters (DGo, DHo, DSo) declared that the Th (IV) adsorption was endothermic and spontaneous in temperature range of 25 to 45°C.

Determination of crystallinity in nanocomposites is so important by using multiscale modeling method that relates macroscopic and microscopic temperatures and crystal morphology to each other. The purpose of this study is to present a multi-scale modeling and a multi-scale computational method to simulate crystallization during cooling in polypropylene and nanocomposite based on polypropylene/ graphene. Based on multi-scale model, algorithms are combined with finite volume method and pixel coloring. The finite volume method on a coarse network is used to calculate the macroscopic temperature and pixel coloring method on a small network to find the crystal morphology. Also the cooling rate is studied. It was also found that the pseudo isothermal region will further increase the temperature at the core; this area represents the latent heat released of crystallization. The latent heat released in the nanocomposite happens in less time. This is the first time that a multi-scale modeling is combined with a multi- scale algorithm to model the crystal structure of nanocomposites.

In this study, after coating of polyester and carbon fabrics with nickel-phosphorous via electroless method, their properties were studied. Surface resistance, morphology, coating thickness and chemical composition, and stability against environmental factors (washing and ultraviolet radiation) of fabrics were investigated. The coating led to a decrease in surface resistance of polyester and carbon fabrics to 20 and 1.9 W/cm2, respectively. Investigation of the morphology and coating thickness of fibers by scanning electron microscopy showed that the nickel particles with an average thickness of 1.3 m were coated uniformly with a nodular structures on the surface of fibers. According to X-ray spectral energy distribution analysis, the percentage of nickel in polyester and carbon fabrics was evaluated to be 75.48 and 67.28%, respectively. The investigation of return loss of waves at various frequencies showed that the nickel-phosphorous coated carbon fabric at the frequency of 10.75 GHz with return loss -33 dB can attenuate these waves up to 99.95% and also nickel-phosphorous coated polyester fabric at the frequencies of 11.9 GHz with return loss-18.5 dB can attenuate these waves up to 98.59%. The results showed that the coated fabrics have advantages such as uniformity of the coating layer and high stability against environmental factors in addition to having high performance in the attenuation of waves.