نشریه شیمی و مهندسی شیمی ایران
سال سی و هفتم شماره 2 (پیاپی 88، تابستان 1397)

In this research, chiral nickel nanocomposite was synthesized, which has the property of stealth by the ability to absorb microwave waves. In the synthesis of this nanocomposite, the first, graphene oxide synthesized with the method of Homer with paraphenylenediamine was reacted and then using carbon dioxide salts, a carbon-carbon bond between modified graphene oxide and a single-walled carbon nanotube was established. Then, in the presence of this hybrid, aniline polymerization was carried out in acidic medium using ammonium peroxy sulfate as a primer, which resulted in the production of graphene oxide, a single-wall carbon nanotube, and polyaniline. The doping of this nanocomposite in ammonia solution, then washing and drying the doping of the nanocomposite with chiral tartaric acid, created the chiral nanocomposite. Afterward, nickel ions were loaded with hydrazine as a reducing agent on a chiral nanocomposite. All of the synthesized materials were identified by the infrared spectrum and the results indicated that the synthesis of chiral nickel nanocomposites was successful. Structural and morphological analysis of synthetic compounds were used for Scanning Electron Microscopy (SEM). The crystalline properties of synthetic compounds were also investigated by X-ray Diffraction (XRD). Ultimately, the microwave absorption spectra of the composite were investigated.

Catalytic ozonation has been used for the removal of pollutants in water and wastewater treatment. In this research, Mn3O4 nanocatalyst was synthesized by coprecipitation method by using Mn(CH3COO)2.4H2O and characterized by Field Emission Scanning Electron Microscope (FESEM), Fourier Transform InfraRed (FT-IR) spectroscopy, X-Ray Diffraction (XRD) and Energy Diffraction X-ray (EDX). According to the SEM image the morphology of Mn3O4 nanocatalyst has been nano spherical and an average diameter of about 10-20 nm. The Mn3O4 nanocatalysts were applied for degradation of phenol in aqueous solution.  The concentration of phenol in solution at 60 minutes was obtained 98.43 % where increase 16.98 % compared with single ozonation (without catalyst). Also, the mineralization of phenol by catalytic ozonation has been used synthesized catalysts amount 32.5 % increasing indicate the effects applied catalysts for degradation phenol.

In this study, Ni-Co/Al2O3-MgO nanocatalysts with two Al/Mg ratios of 0.5 and 5 were synthesized successfully using the impregnation method. The synthesized nanocatalysts were characterized by XRD, FESEM, BET, and FT-IR. The Ni-Co/Al2O3-MgO (Al/Mg=5) nanocatalyst showed high activity among other samples, which is due to its desired textural properties. XRD analysis illustrated that the Ni-Co/Al2O3-MgO (Al/Mg=5) nanocatalyst has smaller and well-dispersed NiO crystals. Also, the Ni-Co/Al2O3-MgO (Al/Mg=5) nanocatalyst due to BET analysis has a high specific area. According to the FESEM images, nanoscale particles with uniform surface size distribution have been observed in the Ni-Co/Al2O3-MgO (Al/Mg=5) nanocatalyst. During the 600 min stability test, feed conversion, and H2/CO molar ratio remained at constant values for the superior nanocatalyst.

Superparamagnetic Iron Oxide NPs (SPIONs), because of their multi-task capabilities, (e.g. magnetic labeling, cell isolation, hyperthermia, and controlled drug release) have been recognized as one of the most promising NPs for theranostic applications. When NPs come in contact with a biological medium, the surfaces of them are covered by biomolecules (e.g., proteins, natural organic materials, and enzymes). Therefore, what a biological entity, such as cells, tissues, and organs, sees when interacting with NPs is the different original pristine surface of the NPs and actually is hard protein corona. The shape of NPs has a great impact on proteins adsorb onto its surface and consequently on the way that cells interact with it. In this research, goethite (α-FeOOH) nanorods have been synthesized using homogenous co-precipitation of Fe2+ and Fe3+ ions using slow hydrolysis of urea at 90 °C. It is revealed that urea plays a crucial role not only as a base source but also as a soft template to form α-FeOOH nanorods. Cytotoxicity of nanorods was assessed using the MTT assay, which is a nonradioactive, colorimetric assay. The cell-SPION incubation time was selected 4, 8 and 48 h. According to the results, the biocompatibility of the polyethylene glycol coated particles is higher than bare. Influence of shape and aspect ratio of as-synthesis NPs in protein absorption profile on the surface of them has been investigated. One-dimensional sodium dodecyl sulphate polyacrylamide gel electrophoresis (1D SDS-PAGE) was used for separation of Fetal Bovine Serum (FBS) proteins absorbed onto NPs and demonstration of the shape and aspect ratio influences.

Polyethylene glycols, PEGs, with molar masses of 2000 and 6000 g/mol were dissolved in PEG with a molar mass of 400 g/mol to prepare the homogeneous solutions. Rheological properties and density values for these solutions have been measured. Nanoparticles of MgO were added to these solutions and dispersed by an ultrasonic bath for making homogeneous nanofluids. The UV-Vis spectroscopy, zeta potential, and dynamic light scattering have been used to specify the stability and particle size distribution of colloidal solutions studied. Density values of prepared nanofluids have been measured at different temperatures. The excess molar volumes were calculated from density data for highlighting the interparticle interactions occurred in nanofluids. Polynomial equation and Singh et al. model were used for fitting the excess molar volume values of binary and ternary systems, respectively. Fluid flow and suspense structure of MgO nanoparticles in solutions of PEG400, PEG400-PEG2000, and PEG400-PEG6000 were studied by measuring the rheological properties at T=298.15 K. Bingham plastic and Herschel-Bulkley equations have been used for modeling the dependence of shear stress on shear rate. Carreau-Yasuda model has also been modified for modeling the viscosity values.

In this research, a new image processing method has been developed to separate and measure the distribution of nanoparticles in TEM images. In the proposed method, the pre-processing procedures, including median filter and histogram equalization, have been used to improve the image quality, then according to the auto-defined threshold, the image has been binarized. In the consequent procedures, in order to distinguish and separate the nanoparticles, the labeled connected component has been applied to the binary image. To validate the proposed method, the algorithm has been applied in two TEM images. The results were compared with the manual measurement while agreeing well with manual measurements. The merits of the proposed method are: the ability to analyze accurately the nano-clusters with a very high number of the particle as well as a low computational cost and fast processing, which makes it suitable to process large stacks of images, such as those generated by TEM.

In this research, a novel generation of stoppers for in-service natural gas distribution and transportation pipelines was prepared on the basis of nanocomposite hydrogels for preventing the gas leakage during the welding operation. The nanocomposite hydrogel stoppers were prepared on the basis of polyvinyl alcohol as the matrix phase and montmorillonite nanoclay as the reinforcing phase. Some structural, physical and mechanical properties of the prepared stoppers were experimentally investigated and their dehydration kinetics and the stopping performances were also evaluated. The results showed that the nanocomposite hydrogel stoppers possibly had an exfoliated morphology and the presence of montmorillonite in their structures increases the crosslinking and improves the mechanical properties (up to 280% increase in the elastic modulus and a 43% decrease in the elongation at break). The results obtained from the dehydration tests demonstrated that the weights of prepared stoppers are reduced to 60-70 % of their initial weights during the first hour of the dehydration process. The results obtained from the stopping performance showed that the prepared nanocomposite hydrogel stoppers could undergo the gas pressure up to 9 psi. It was observed that the stopping ability and the maximum endurable pressure of the prepared nanocomposite hydrogel stoppers are increased by increasing the diameter and length of the stopper. The accomplished experiments for investigating the stopping ability of the nanocomposite hydrogel stoppers proved their unique performances in perfect sealing and preventing gas leakage in natural gas pipelines. In general, it can be expressed that the prepared nanocomposite hydrogels are suitable candidates to be used as novel stoppers during the welding operation in the natural gas distribution and transportation pipelines.

Linear alpha-olefins are one of the most important products of the petrochemical industry, which are widely used in the preparation of detergents, lubricants, plasticizers and also as co-monomer in the production of Linear Low-Density PolyEthylene (LLDPE). Ethylene oligomerization, especially ethylene trimerization (1-hexene production), is one of the most important methods used to produce these high-consumption materials, in which different catalysts are used in the presence of ethylene gas. In this regard, ethylene trimerization catalyst based on four-component system {2,5-dimethylpyrrole (DMP)/Cr(III)/Triethyl Aluminum (TEA)/hexachloroethane (HCE)} was prepared with high purity and the prepared catalyst was characterized using different analysis such as FT-IR, UV-Visible, CHNS, and ICP. The effect of ethylene pressure, the molar ratio of Al/Cr, ligand and solvent types and different injection methods on activity and selectivity was studied. Also, with increasing the ethylene pressure, the productivity of 1-hexane increased. The use of hexachloroethane as an accelerator in the presence of n-heptane aliphatic solvent increased the yield of the catalyst. The best way to perform the trimerization reaction was the production of dual catalyst-ligand and cocatalyst-hexachloroethane solutions separately and adding them to the reactor. Ethylene trimerization using this catalytic system at 27 °C, 90 °C, normal heptane solvent and Al/Cr ratio of 40 resulted in selective production of 1-hexene with a yield of 193850 (g L-C6/g Cr.h) and selectivity of 91.8 percent.

Imidazolium-based Ionic Liquids (ILs) with the dicyanamide anion, [N(CN)2]-, have low melting temperature, high thermal and chemical stabilities, high ionic conductivity and low viscosity making them ideal candidates in the different industrial applications. In this work, the structural and thermodynamic properties of two ILs based on 1-alkyl-3-methylimidazolium cation, [amim]+, (alkyl = methyl and ethyl) and [N(CN)2]-, are studied using molecular dynamics simulations. The non-polarizable all-atom force field was applied to investigate the influence of the effect of changing alkyl side chain from methyl to ethyl and temperature on the behavior of ILs. The quantities such as the radial distribution function, spatial distribution function, the density of IL, molar volume, isobaric thermal expansion coefficient, and enthalpy of vaporization were studied. The density of the [dmim][N(CN)2] is larger than that of the [emim][N(CN)2] at all temperatures because of the relatively higher symmetry and greater packing of [dmim]+ in the liquid state. With increasing alkyl chain length from methyl to ethyl, the electrostatic interactions between ions are weakened and the van der Waals interactions are strengthened, and consequently, the enthalpy of vaporization is decreased.

For long last time water has been considered as an inimical contaminant to pure Ionic Liquids (ILs) because the presence of a low amount of water drastically changes the properties of ILs. But, water is now a very important partner for ILs because mixing the IL-water is an easy strategy to control and access to unique properties of both of them. Applying this type of binary mixtures also provides a broad application in different fields. In this work, molecular dynamics simulations were used to study the details of the dynamical behavior of the binary mixture of 1-butyl-3-methylimidazolium nitrate ([bmim][NO3]) and water in different molar fractions in order to discover the influence of water addition on the properties of the ionic liquid. The dynamics of systems studied by the computing of mean-square displacement and self-diffusion coefficients of species. The presence of water causes significant enhancement of ionic self-diffusion coefficients. In neat IL and the concentrated IL solution, self-diffusion of the cation is higher than that of the anion; however, in the binary mixtures with the water molar fraction greater than or equal to 0.25, the anions diffuse faster than the cations.

In this research, we investigated the structural, electronic and optical properties of BaZrO3 ceramics and the effects of pressure on these properties were studied. The calculations have been performed by Full Potential Linearized Augmented Plane Wave (FP-LAPW) method in the framework of density functional theory and we used WIEN2k and Quantum Espresso packages. The exchange and correlation potential terms are calculated by LDA, PBE, PB Esol, GGA-WC, GGA+U, modified Becke–Johnson (mBJ) and GG Am BJ+U approximations. The calculated band gap for BaZrO3with the best approximation GG Am BJ+U shows that there is an indirect band gap at the Γ-L direction that it is equal to 5.30eV, so BaZrO3 is an insulator. The results of the band structure and the dielectric function show that the next probable transitions appear at W-L, Γ- Γ and K-K directions and by calculation of density of states we find that p orbital of O atom possesses the majority of contributions in the valence band and at the top of the conduction band, 3d orbitals of Ba and Zr atoms have the dominant contribution. This compound has low compressibility and high hardness. The maximum of absorption, the minimum of reflection and the Plasmon peak occur when the energy of photons is 20.53 eV.

Abstract-4-(3-(2,4-Dichlorophenyl)triaz-1-enyl)benzamide, CTB, was synthesized and characterized using IR and NMR (1H and 13C) spectroscopy. The optimized geometry, vibrational wave numbers, 1H and 13C chemical shift values and NBO parameters of CTB were computed with Density Functional Theory (DFT/PBE1PBE) and Hartree-Fock (HF) methods using 6-311+G(2d,p) basis set. The harmonic vibrational wavenumbers were calculated and their scaled values were compared with the experimental FT-IR spectrum. A detailed interpretation of the NMR spectra of CTB was reported. The calculated data are in reasonably good agreement with the experimental measurements. Moreover, the logP value and thermodynamic properties were estimated with ChemBioOffice Ultra 11.0, ACD/LogP and ALOGPS programs. The NBO analysis was carried out for CTB.

Quantitative Structure-Activity Relationship (QSAR) was developed for modeling and predicting of the PIM inhibitory activities a data set containing 39 structures of triazolopyridine derivatives with known biological activities. Segmentation the whole dataset into a training set and test set was performed randomly. StepWise (SW) and Genetic Algorithm (GA) techniques with Multiple Linear Regression (MLR) were used to select the most important descriptors and to create the best prediction model. Comparison of the results obtained for SW-MLR and GA-MLR models was showed that GA-MLR model is superior to the SW-MLR model. The robustness and the predictive ability of the final GA-MLR model validated by internal and external statistical validations including Leave-One-Out (LOO) cross-validation, Leave-Group-Out (LGO) cross-validation, Y-randomization and external test set. High agreement between experimental and predicted activity values indicated that GA-MLR model with five variables has good quality and it could be used in design novel compounds with higher PIM inhibitor activity.

Petroleum hydrocarbon contamination of groundwater has become a widespread environmental issue in developing countries. In recent years, various technologies have been applied to remediate petroleum pollutants from groundwater, such as Modified Fenton (MF). In the present study, treatment of benzene-contaminated groundwater is investigated. In the first step of the experiments, calcium peroxide nanoparticles were synthesized, then encapsulated using sodium alginate. Moreover, application of synthesized capsules in benzene removal from groundwater was evaluated in batch and column studies. In the batch experiments, 50 mg/L of benzene was removed completely within 70 days. Whereas, the pollution removal reached 100% after 4 days in the column experiments. In addition, the dissolved oxygen of the reactor with CaO2 capsules raised from 4 to 6 mg/L. The microbial count was increased to 106 CFU/mL, while the blank experiment was approximately 106 CFU/mL. Consequently, the results showed high efficiency and appropriate performance for encapsulated calcium peroxide nanoparticles for remediation of benzene from groundwater.

In this research, the formation constant (Kf) of some metallic ions complexes with 2,2- pyridine 2,6- diyil bis(nitrilo (E) methyliden Schiff base ligand in ethanol at 25°C have determined coductometrically, and the data showed good complex formation with Li+ ion. Thus this is used for modification of C18 disk for solid phase extraction (SPE) of Li+ from waters and brines samples and determination by flame photometer. Since the direct determination of lithium in brines by flame photometry is difficult, because of a large amount of interferences ions and high viscosity of the sample, thus the samples were diluted extremely. Then lithium has extracted by ligand modified C18 disk and determination by flame photometer. In the optimum condition, pH = 8, 4.0 mg of ligand, 5.0 mL 0.3M perchloric acid as an elution buffer, the detection limit of the method was 0.74 µg/L. The method has used for determination of trace amount of lithium ion in natural brines successfully.

In this work, the Modified Operation Line Method (MOLM) was used for modeling and simulation of the gas separation membrane process due to its simplicity and well compatibility with exact solution methods. This method reliability was verified by comparing the obtained results with the literature for both organic and inorganic membranes. Then, the verified model was applied to calculate the surface area of the membrane separation process, as a case study, for the separationof butane isomers produced in LPG unit of Tabriz refinery. The results showed that the MOLM method is not efficient for countercurrent flow pattern. But, this method can predict the required membrane area for cocurrent flow pattern accurately. Modeling results showed that high purity products can't be obtained using a single stage membrane. For this purpose, a processes design was performed to achieve products with a purity higher than 98% of normal and isobutane produced in LPG unit of Tabriz refinery by multistage membrane cascade using MOLM method and required membrane area was calculated to equal to 2910 m2. Also, the effects of the key parameters such as selectivity and ratio of feed pressure to permeate pressure on the membrane surface area were evaluated. and ratio of feed pressure to permeate pressure on the membrane surface area were evaluated.

This study presents a new thermodynamic equation for interfacial tension at the organic phase/water interface in the presence of anionic surfactant. The anionic Sodium Dodecyl Sulfate (SDS) is selected to check the validity of the derived equation. The temperature and pressure from the reference are considered as 25°C and 1atm, respectively. It is shown that the newly derived equation can properly describe the organic phase/water interfacial tension in the presence of a single surfactant. In this study, hydrocarbons including n-heptadecane, n-decane, n-nonane, n-octane, n-hexane, 1-octane, 1-hexene, n-cyclohexane, n-cyclohexene, n-butylbenzene, and benzene are considered as the organic phase. By curve-fitting of the experimental data, the following two parameters are obtained: 1) molar surface area, and 2) bulk-surface distribution coefficient of surfactant. In all cases investigated, errors for the proposed equation of this study are less than one of the latest previous works in the literature. The Mean Squared Error (MSE) ranges for the proposed equation and the previous work are 0.5-5.1 (mN/m)2 and 1.8-23.9 (mN/m)2, respectively. The results show a good agreement with the experimental data in the concentration region below and near the Critical Micelle Concentration (CMC).

In this work, hydrate formation conditions of ethane in the presence of THF as promoter and modeling of ethane hydrate formation were investigated. The Parrish-Prausnitz model was used because of its simplicity and accuracy, and SRK and PR equations of state were used in calculations. The mechanism of the experiment for finding the equilibrium point of hydrate formation is confliction of formation and dissociation curves. At first, pure ethane system and then system containing THF in three concentrations of 5, 8 and 10 mol% were hydrated in a stirred setup. In pure ethane system, experimental results were closer to reference results and the average error of modeling was low for both of equation of states. In the system containing THF promoter, there was more difference between experimental and modeling. The overall error of SRK equation of state was lower than PR. promotion effect of THF on ethane hydrate formation was more significant than reference additives. Also, in the concentration of 5 and 8 mol%, THF acted as a promoter but in a concentration of 10 mol%, it acted as an inhibitor.

In this study, a two-stage natural gas reciprocating compressor is simulated based on ideal and real models. To this end, a zero-dimensional numerical method based on the crank angle is developed. For this simulation, control volumes including compressor cylinders, suction, and discharge chambers with equivalent mass and energy equations along with piston movement, valve dynamic, and mass flow rate through valve and orifice equations and heat transfer equation for heat-exchanger are investigated. For real gas model, the AGA8 equation of state has been used for computing thermodynamic properties. Simulated results compared and validated with the previous experimental results for air reciprocating compressor. Then, the developed model is used to predict compressor behavior and performance parameters. It suction and discharge pressure was considered 4.122 and 9.795 MPa respectively. Predicted results show that intermediate pressure for simulation based on real gas (4.015 MPa) is lower than ideal gas (4.093 MPa). Furthermore, the mass flow rate based on the real model (730.67 kg/h) is higher than the ideal model (710.3 kg/h). In addition, discharge gas temperature prediction with the ideal model is lower than the real model.

β-Carotene is a strongly colored red-orange pigment. Microalgae are high of interest since they can be a great source to synthesized Beta-carotene. So far, the production of beta-carotene has been studied in pure cultures. Because of the practical problems with pure cultures, in this study, the high light intensity has been applied to mixed microalgae species obtained from the Caspian Sea and also a pure culture of Dunaliella salina and the amounts of beta-carotene, chlorophyll and proteins have been measured. Operating conditions in the light stress were the same for both samples: pH=7.5, temperature 26-28 °C and stirring at 160 rpm. On the 6th day, the stress was applied. Final beta-carotene concentration of microalgae Dunaliella salina was increased from 5.9 to 19.5 mol Beta-Carotene/g Protein. However, the concentration was reached from 7.3 to 22.7 mol Beta-Carotene/g Protein for Caspian Sea microalgae. The initial and final concentration of protein was 467.3, 1239.9 and 495.2 and 1131.3 mg/L for pure and mixed culture, respectively. The results of this study show the potential of Caspian Sea mixed microalgae culture as a viable alternative for Dunaliella salina microalgae for beta-carotene production in industrial scales. Therefore, mixed microalgae culture can be used for Beta-carotene production which is preferable and more economical than sterile systems and consequently the possibility of process industrialization will be increased.