نشریه شیمی و مهندسی شیمی ایران
سال چهل و یکم شماره 2 (پیاپی 104، تابستان 1401)

Silver-iron oxide binary nanocomposites have attracted great attentions due to hybrid unique properties of silver (Ag) and iron oxide (Fe3O4) nanoparticles such as magnetic, optical and antimicrobial properties. Catalytic degradation of organic pollutants, electrochemical sensor and targeted antimicrobial agents are some potential applications of Ag/Fe3O4 nanocomposites. In this study, Ag/Fe3O4 nanocomposites were synthesized using starch as a stabilizer and linker between Ag and Fe3O4 nanoparticles. Their antibacterial and antibiofilm activities against E. coli, P. aeruginosa and S. aureus were evaluated and compared with Ag nanoparticles. The 15–20 nm Ag-nanoparticles adhered as single particles to the agglomerations of 2-10 nm Fe3O4 nanoparticles. MIC and MBEC of the nanocomposites, depending on cell types and producing conditions, were 2-14 ppm and 20-30 ppm, respectively. In the presence of nanocomposites at a half of MIC concentration, Lag phase of growth curve of E. coli and P. aeruginosa increased about 8h and 5h, respectively. Bare Fe3O4 nanoparticles have no significant effect on growth curve of gram positive and negative bacteria, while Ag/Fe3O4 nanocomposites showed more antibacterial activity against gram negative bacteria than Ag nanoparticles. Antibiofilm activity of Ag/Fe3O4 nanocomposites against P. aeruginosa and Methicillin-resistant S. aureus was significantly more than Ag nanoparticles. Unlike Ag nanoparticles, Ag/Fe3O4 nanocomposites at a MBEC concentration inhibited the increase of biofilm biomass. Amount of starch acted an important role on the nanocomposite antibacterial activity. Evaluation of bacterial death time exhibited that Ag nanoparticles killed tested gram- positive and negative species faster than Ag/Fe3O4 nanocomposites that may be attributed to involvement of Ag nanoparticles in the starch matrix and Fe3O4 agglomerations and subsequently, slow release of Ag ions.

In this study, two metal-organic frameworks of UMCM-150 entitled Fe1Cu2(BHTC)2 and Cu3(BHTC)2 were used to delivery and release of  acetaminophen  as a non-steroidal drug. These frameworks were synthesized using solvothermal method. The crystallinity of the synthesized metal-organic frameworks was confirmed by SEM and XRD analyses. The stability of particles was determined by DLS analysis and their thermal stability was evaluated by TGA analysis. Also, the surface area, volume and size of pores were also measured by BET analysis that indicated a particularly suitable surface area and porosity of the pores. After loading acetaminophen in carriers with 25.29% efficiency for Fe1Cu2(BHTC)2, and 10.82% for Cu3(BHTC)2, the release of drug was evaluated in saline phosphate buffer solution at pH = 7.4. The release efficiencies of Fe1Cu2(BHTC)2 and Cu3(BHTC)2, were obtained 41.45 and 57.5%, respectively. Also, various kinetic models (zero, first order, Higuchi and Korsmeyer-Peppas) were used to interpret the release data that the Korsmeyer-Peppas model (R2=) reasonably described the release results. Based on the obtained results, both synthesized metal organic frameworks are promising option for the delivery and slow release of acetaminophen.

In this research, three simple methods including thermal, ultrasonic irradiation, and high-speed milling method (HSBM) techniques for the preparation of pyrano[4,3-d]thiazolo[3,2-a]pyrimidine derivatives in the presence of MgO nanopowders under solvent-free conditions has been reported. MgO nanopowders were prepared in an aqueous solution containing freshly squeezed orange juice with pulp and characterized by XRD, FE-SEM, EDS, and FT-IR techniques.

In this study, the multi-walled carbonnanotubes (MWCNTs) were functionalized and then were characterized by the several techniques such as :Fourier-transform infrared spectroscopy analysis, X-ray powder diffraction ,scanning electron microscopy, Brunauer-Emmett-Teller and Barett-Joyner-Halenda analysis and particle size analyzer. Then, the functionalized multi-walled  carbonnanotubes were used for removing Cr (III) ions from aqueous media. Several adsorption experiments were carried out for evaluating the adsorption capacity of the synthesized FMWCNTs. For adsorbing Cr (III) ions from aqueous solutions. The experimental results showed that the synthesized FMWCNTs have a good capacity for Cr (III) ions adsorption. The effect of the initial concentration of the sorbate, sorbent dosage, temperature, pH  and contact time on the removal  percentage of Cr ( III) ions on to the FMWCNTs and the adsorption capacity of the prepared adsorbent was studied and the optimum value of each of them was determined.Based on the experimental results, the isotherm models evaluation was also performed and the obtained results revealed that the Langmuir, Freundlich, Temkin and Dubinin-Radushkevich models can be used for interpretation the experimental results. Kinetic study showed that the kinetic results of this research can be compared with the pseudo first order, Elovich and intraparticle diffusion kinetic models and selecting ones with the largest R2. In addition, adsorption thermodynamic study ,on the basis of the adsorption capacity dependence on the  temperature,was performed. The obtained results showed that the considered adsorption process at the used temperature range is exergonic G0ad<0 and exothermic H0ad<0 and with a decrease in the randomness (S0ad< 0). Based on the magnitude of H0ad, one can claim that the studied adsorption may be a physical adsorption one.

In this research, adsorption of Zinc ion was investigated at batch system using spirulina microalgae and Magnetic microalgae. The effect of important parameters such as pH of the solution, absorbent contact time, the initial concentration of Zn(II) ion, adsorbent dosage and temperature were investigated on The removal efficiency and  adsorption capacity. Also adsorbent features were studied by using SEM photographs and FT-IR spectroscopy. The maximum Zinc ion adsorption occurred in pH=6. The optimum adsorbent dosages were determined 0.03 g for spirulina microalgae and Magnetic microalgae. So at optimum pH and adsorbents dosage for 150 mg/l initial zinc ion concentration 84.43% and 96.56% of removal efficiency was obtained for spirulina microalgae and Magnetic microalgae, respectively. Removal efficiency increased by increasing contact time between adsorbent and solution and after passing 10 min for spirulina microalgae and Magnetic microalgae reached to equilibrium. Examining kinetic models showed that pseudo-second order kinetic model had best fit for adsorbents. In investigating Zinc ion initial concentration in range of 50-300 mg/l, results showed by increasing initial concentration, efficiency decreased. Also experimental data of spirulina microalgae and Magnetic microalgae solutions had best fit by sips and Langmuir, respectively. Investigating temperature effect showed, by increasing temperature, removal efficiency decreased for spirulina microalgae and Magnetic microalgae. The thermodynamic parameter was studied in 298, 303, 313 and 323 Kelvin.

In the present study, the natural convection heat transfer in a L-shape enclosure, filled with copper-water nanofluid is investigated by considering the effect of different factors such as aspect ratio, volume fraction of copper nanoparticles and Rayleigh number on the heat transfer coefficient, temperature and velocity distributions. All governing equations are solved by finite volume method. The results indicated that at high Rayleigh number, the dominant heat transfer mechanism will change from conduction to free convention and the maximum heat transfer coefficient will decrease. While at low Rayleigh numbers, the fluid in the horizontal part of the enclosure is approximately static and the predominant mechanism of heat transfer is conduction. The transition of conduction mechanism to free convection occurs at Rayleigh number in the range of 105 to 106. Also, the presence of copper nanoparticles, leads to significant enhancement in the heat transfer coefficient, for all values of Rayleigh number. In addition, the simulation results indicate that inclusion of a number of pins inside the enclosure has a significant effect on increasing the heat transfer coefficient. The achieved results indicated that inserting three fins in the structure of enclosure at aspect ratio of 0.4, nano particle volume fraction of 0.1 and Rayleigh number of 106 enhances the heat transfer coefficient from 984.3 to 1093.8 W/m2.K.

Solar energy is the most appropriate choice for human energy supplying. Because of, its renewable and No risk of environmental pollution. of course, there are problems to convert this form of energy into the others such as low thermal efficiency and how converting it. Flat plate solar collector is one of the most important solar thermal energy absorbers for industrial and household applications. In this research, we investigated the thermal performance of a flat plate solar collector using zinc oxide nanoparticles in water based fluid + ethylene glycol as the operating fluid. The purpose of this study was to improve the thermal performance and how to increase the thermal efficiency of flat plate solar collectors. Initially, experiments were performed in the presence of working fluid 65% water + 35% ethylene glycol without nanoparticles zinc oxide and thermal efficiency was obtained. Then thermal efficiency of solar collector was investigated in the presence of 0.05% and 0.1% volumetric zinc nanoparticles in the flow rate range 1–5 liters per minute. The effect of the nanoparticles and their concentration on the thermal performance of the solar collector were investigated by determining the amount of heat absorbed in the presence of nanofluid relative to the pure base fluid. The use of zinc oxide nanoparticles at 0.05% and 0.1% volumetric fraction resulted in a 4-20% increase in average thermal efficiency and 8-33% in maximum efficiency of flat plate solar collector. Although in nanofluids with higher volumes, about 5-7% was added to the average thermal efficiency of the solar collector, it also increased the sedimentation rate of the nanoparticles in the base fluid.

In this research, copper-reduced graphene oxide (Cu-rGO), graphene-palladium (Pd-rGO) and palladium/copper-graphene (Pd/Cu-rGO) nanohybrids were prepared and used as electrode materials towards electrocatalysis of hydrazine oxidation. For this purpose, firstly, GO was prepared by modified Hummer's method. In the following, for preparation of the Cu-rGO nanohybrid, GO and metallic precursor were reduced by hydrazine monohydrate, simultaneously. Then, Pd/Cu-rGO nanohybrid was obtained by chemical reaction between Cu-rGO nanohybrid and acidic palladium chloride solution via galvanic replacement of Cu nanoparticles with PdII. Morphology and nanoparticles size were investigated by field emission-scanning electron microscopy (FE-SEM). FE-SEM studies showed the formation of Cu and Pd/Cu nanoparticles with average size about 20 and 15 nm on the graphene surface, respectively. Elemental mapping of the prepared nanohybrids demonstrated uniform dispersion of Cu and Pd/Cu nanoparticles on the graphene substrate. Functional groups at GO and graphene were determined by Fourier transform infrared spectroscopy. By X-ray diffraction analysis, structure of the nanoparticles in nanohybrids was identified. The results of electrochemical impedance spectroscopy showed that the modification of glassy carbon electrode (GCE) with the synthesized nanohybrids effectively reduced the charge transfer resistance between the modified electrode and redox species. The capability of the modified GCE for electrocatalysis of hydrazine oxidation was studied in 0.1 M PBS solution (pH=7.0). The obtained results showed the acceptable electro-catalytic activity of modified electrode towards hydrazine oxidation. Also, Pd/Cu-rGO nanohybrid in addition of the high surface area, due to the synergistic effect between Cu and Pd showed higher electro-catalytic activity towards hydrazine oxidation.

In this study, polyethersulfone (PES)-based nanofiltration (NF) membranes were prepared by introducing synthesized oleic acid-titanium oxide (OA-TiO2) nanoparticles by phase inversion method. Various concentration of OA-TiO2 nanoparticles were used to the membrane fabrication. The OA-TiO2 nanoparticles were characterized by Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM), and X-Ray Diffraction Analysis (XRD). Moreover, the membrane morphology was investigated by FESEM, 3D surface images. The separation performance of membranes were studied by the contact angle, pure water flux (PWF), flux recovery ratio (FRR%), and the rejection of Na2SO4 and CrSO4. The best pure water flux (18.206 L/m2h) was revealed for M2 with 42% increase compared with neat PES membrane at operation pressure 4.5 MPa due to increase membrane hydrophilicity and better dispersion of OA-TiO2 nanoparticles. Furthermore, the best Na2SO4 rejection (81.5%) was obtained to M3 and the highest CrSO4 removal (80.4%) was revealed to M5 at operation pressure 4.5 MPa. The enhancement of salt rejection attributed to Donnan effects and adsorption mechanism. The incorporation of OA-TiO2 nanoparticles into the PES improved the anti-fouling properties and FRR% increased to 83%.

This study aims is to assess the tetraethylenepentamine-functionalized Rosa Canina-L fruits activated carbon prepared by microwave-assisted technique for the removal of Methylene Blue dye from an aqueous solution. The morphological and anatomical characterization of the developed adsorbent was carried out using various analytical techniques such as Fourier Transform Infrared Spectroscopy and Field emission scanning electron microscopy. The surface morphology and physical condition of the absorbent surface show a porous morphology that contains numerous deep holes suitable for dye absorption. Taguchi design of the experiment was used to find the best conditions for the removal of MB dye from the aqueous solution. The effects of different parameters such as pH, adsorbent dose, reaction time, initial dye concentration, and temperature at 3 different levels were considered using an L27 Taguchi method. Analysis of data was performed using one- way variance and calculation of signal-to-noise rate. Based on signal- to- noise ratios, the optimum process conditions were pH 4, adsorbent dose 0.03 g, contact time 30 min, initial MB concentration 25 mg/L and temperature 298 K. According to one- way variance results, the influence of the controllable factors in descending order is pH > adsorbent dose > temperature > initial dye concentration > contact time. Moreover, the adsorption behavior of this adsorbent fits well with the Langmuir isotherm and pseudo-second-order kinetic model. The whole process of adsorption of Methylene Blue dye onto this adsorbent was found to be spontaneous and exothermic under standard conditions.

In analytical chemistry, sample preparation before any instrumental measurement is one of the most important steps. Extraction is one of the most widely used methods of sample preparation, which concentrates the analyte and transfers it to a simpler and cleaner matrix media. Therefore, in the present work, electromembrane extraction method combined with UV–Vis spectrophotometric detection was proposed for the preconcentration and determination of methylene blue in cultivated fish samples. The optimized conditions for preconcentration step were: agarose amount 5.0% (w/v), acetic acid amount 0.10% (v/v), pH of donor and acceptor phase of 8.3 and 2, respectively, applied electric voltage 80V and extraction time of 25 min. In the optimum conditions, the precision according to relative standard deviation formula was found to be 2.3 and the linear range was 0.015-1.560 µM. Limits of detection and quantification were 4.7×10-3 and 15.4×10-3, respectively. The method validation was compared with the other methylene blue analysis techniques. The proposed method provided a rapid, sensitive, requires low sample volume, and short extraction time with high precision and accuracy which is applicable successfully for routine analysis of methylene blue contents in cultivated fish samples.

In this research, electrochemical measurement of propranolol drug on carbon paste electrode modified with chitosan grafting by glutaraldehyde magnetic nanoparticles was studied. Cyclic voltammetry and square wave voltammetry Techniques were used to study the drug. In order to characterize the modifier, FT-IR, XRD, SEM, EDX, and BET analysis were used. The effective factors on the performance of the electrode were investigated and optimum conditions were obtained as follows: pH = 7, absorption time of 10 minutes, and the amount of 10% modifier. At the optimum conditions, the dynamic linear range of propranolol was 1 to 14 μM and 14 to 284 μM and the detection limit was 0.3 μM. This electrode was investigated to measure propranolol in real samples. Compared to other measurement methods, ease of operation and reasonable price, without losing the detection limit, are other features of this electrode.

Recently, the high pressure injection technique has been introduced for hypochlorite treatment of hollow fibrous membranes. In this process, the hypochlorite solution is injected into the channels of fibers at a high pressure. Literatures show that this technique is more efficient than conventional methods of hypochlorite treatment. In this study, the effects of injection pressure (in the range of 10-30 psig) on the mechanical, pore sizes and hydraulic permeability of the polysulfone (PSf) hollow fibrous membranes have been investigated. The pore sizes and pore structures were analyzed by atomic force microscope (AFM) and scanning electron microscope (SEM) images. Results showed that the pore sizes and hydraulic permeability of the hollow fibers are increased with increase in injection pressure of sodium hypochlorite. On the contrary, the mechanical properties of the membranes dropped after an increase in injection pressure from 10 to 30 psig. This decrement could have been occurred due to removal of the polyvinyl pyrrolidone (PVP) from the polymer matrix of the PSf hollow fibers. These results can be useful for control and adjustment of the process parameters of hypochlorite treatment of the hollow fibrous membranes.

The paper, presents an analysis of the mechanism of thorium ions (IV) transfer in a polymer inclusion  membrane (PIM). A PIM membrane containing polyvinyl chloride (PVC) as the base polymer , and Di-(2-ethylhexyl) phosphoric acid (D2EHPA) as extracting agent (carrier) was used for the recovery of Th(IV) ions in nitric acid medium. First of all, the influence of the carrier concentration as an important parameter in the transport efficiency was investigated. Also, the aqueous phase parameters including the initial concentration of thorium (IV) and pH of the feed phase, the strippiing phase acid concentration were evaluated. Regardless of  the initial concentration of thorium (IV), for experimental conditions, 45% Wt of D2EHPA, was found as the optimal value of carrier concentration, for which the process was the most effective. Studies on the transport kinetics and transport mechanism of Th(IV) ions carried out and the results showed that the transport of Th(IV) across PIM was consistent with the first order kinetics equation and the “jumping” mechanism for the experimental conditions was concluded as the dominant transport mechanism.

In this study, the catalysts (HSAPO-34) were synthesized by the hydrothermal method using of n-poropyl amine as a meso structure-forming agent. Since the main problem of these catalysts is their short lifetime due to coke formation. Cokes are mainly aromatic and branched isomers, are formed inside the catalyst vacancies and is irreversibly absorbed into the acidic sites, thereby reducing the concentration of the catalytic acid sites. Therefore, using of various metals such as lanthanides as a modifier by creating new acidic sites improve the catalyst acidity and prolonged the catalyst lifetime. The combination of Ce and La metal salts was used to improve the acidity and prolonged the synthesized catalyst lifetime. The catalyst properties (Ce La / HSAPO-34) were determined by various methods such as XRD, FESEM, NH3-TPD and BET. Catalytic performance (Ce La / HSAPO-34) was studied in a fixed bed reactor in methanol to propylene conversion reaction. The catalytic test results showed methanol conversion above 90% and propylene selectivity (48.5%) and it took 8 hours for the catalyst to deactivation.

The CeO2-MnOx mixed oxides supported on ZSM-5 with different loading percent are prepared by sol–gel combustion method and their performances are evaluated in catalytic oxidation of ethyl acetate. The physico-chemical properties of prepared catalysts are characterized by X-ray diffraction (XRD), N2 adsorption by BET method and scanning electron microscopy (SEM). The XRD and SEM results proved that the nanocrystalline CeO2-MnOx with highly dispersed were performed on the support during the preparation of mixed oxide. The effects of CeO2-MnOx loading, reaction temperature and time and presence of water vapor on ethyl acetate conversion were investigated. The results showed that the ethyl acetate conversion increased by the increase of CeO2-MnOx loading, but its variation was negligible in loading above 20%. By the way, as the reaction temperature increased, the conversion increased, so that the highest conversion was obtained at 350 ºC. The 20% CeO2-MnOx/ZSM-5 had the grated performance (98% ethyl acetate conversion) at 350 ºC.

Iran is rich in gas resources, which is the most important source of hydrogen production. Purification of produced hydrogen is required for use in various processes. One of the applications of hydrogen in fuel cells is that the need for hydrogen purification and carbon monoxide concentration is as low as 10 ppm. This is due to the carbon monoxide poisoning of the fuel cell anode. The use of nanocatalysts, especially gold nanocatalysts, for hydrogen purification in processes is of particular importance. In this study, oxidation of carbon monoxide in the presence of rich hydrogen stream was investigated by coating gold nanoparticles, which had a significant effect on the rate of conversion of CO. In this work, FESEM, BET, XRD, TPR analyzes were used for characterization and FT-IR for catalytic performance testing for the preferential carbon monoxide oxidation process. Catalytic activity test result for synthesized catalysts: CeO2 < Cu5% IMP-CeO2 < Au-CeO2 < Au-Cu5% IMP-CeO2 indicating synergistic effect of gold and copper for preferential oxidation of carbon monoxide.

In this study, poplar wood pyrolysis in the vicinity of biochar catalyst produced from spruce wood gasification process has been investigated. For this purpose, in a laboratory-sized reactor, 30 g of the sample was loaded and the pyrolysis of the samples was performed at 500  and at atmospheric pressure. The results showed that the biochar catalyst did not have a significant effect on the bioavailability of pyrolysis, while the amount of gas product decreased (5.78 wt% decline) and the biochar increased (5.19 wt% increase); it also changed the specifications of the products. In the case of gas products, the summation of CO and CO2 levels increased in total (8.68 wt% increase), while the hydrocarbon gases with more than two carbon declined (16.10 wt% decline), but did not have a significant effect on CH4 levels. Biochar catalysts have increased the amount of aromatics and reduced linear compounds in bioavailability, indicating the tendency of Biochar catalysts to process the conversion of linear compounds to aromatics such as carboxylic acids. Biochar also had a strong tendency to de-oxygenate bioavailability, which led to improved bioavailability. The production quartet had less aromatics. DTG analysis showed that the solution from the catalytic pyrolysis process had a lighter and more regular molecular network. Catalyst XRD analysis also showed that a layer of carbon (coke) material from the polymerization process of the aromatic compounds in the vapors produced in the pyrolysis process was sitting on the catalyst. Considering all, the presence of biochar catalyst did not change the yield of bio-oil, while its quality such the aromatic content enhanced.

Coke formation is one of the most important reasons for the deactivation of petrochemical and refinery catalysts. This study investigates the coke formation in the structure of Pd-Ag/ α-Al2O3 catalyst. Various hydrocarbons as coke agents including xylene, toluene, benzene, propylene and green oil were investigated at different operating parameters including flow rate, temperature, pressure and coking time. The fresh and coked catalysts were investigated with FT-IR, FE-SEM and TGA methods. The obtained results revealed that this catalyst has a low tendency for the deposition of coke that could be according to the low surface acidity of it. In addition, the deposited coke in the case of green oil seems to be due to the cracking of heavy hydrocarbons in the pores of catalyst.

In this research, the interaction of methylated nucleobases of Adenine (m-A), Guanine (m-G), Cytosine (m-C) and Thymine (m-T) with five ionic liquids (ILs) ([Bmim][BF4], [Bpy][BF4], [Ch][BF4], [Bmim][CH3COO] and [Bpy][CH3COO]) was investigated by using Density functional theory (DFT) at the M06-2X level and 6-311++G(d,p) basis set. In this investigation, the nature and strength of interaction between the methylated nucleobases and ionic liquids were analyzed using four analysis methods of natural bond orbital (NBO), atoms in molecules (AIM), reduced density gradient (RDG) surfaces and energy decomposition analysis (EDA). The result of this research showed that the interaction between methylated nucleobases and ionic liquids is electrostatic in nature and is mainly caused by hydrogen bonds. In order to find out the strength of interaction between ionic liquids and methylated nucleobases, the binding energy (ΔEb) values were also evaluated for the ionic liquid…methylated nucleobase complexes. The result of DFT calculations showed that the interaction strength of methylated nucleobases with ionic liquids follows the order of m-G…IL > m-C…IL > A…IL > m-T…IL.

[2+3] cycloaddition reactions of a fullerene C20 with azomethine ylide derivatives (RHC-NH+-CHR‒) have investigated in order to design new pincer fullerene ligands. The negative values of [2+3] cycloaddition reaction energies indicate the exothermic character of formation of the considered pincer fullerenes. Exploring of the effects of nature of the flanking arms on fullerene pincer ligands based on the frontier molecular orbital analysis (FMO) indicate that reaction energies well correlate with HOMO of 1,3 dipoles. The pincer-ligated metal complexes obtained by the addition of transition metals to the pincer bites. Natural bonding orbital analyses (NBO) are performed to investigate the delocalization of the localized bonds and lone pairs of donor nitrogen atoms and the transition metals in the considered pincer-ligated metal complexes. Based on our results, the strongest interaction among all the interactions is due to the delocalization of electrons from lone pairs of central nitrogen atoms to the LP* of the transition metal, following by the lone pairs of nitrogen atoms in the flanking arms.

In this study, using density functional theory, atoms in molecules and natural bonding orbital’s analyses, the strength of individual hydrogen bonds and the total interaction energy in the thymine-adenine (TA) base pair containing deoxyribose(d) and phosphate(p) substituents, was evaluated. The results of the absolute electron energies show that the structures containing the substituents are more stable than the TA base pair. In addition, according to the results of the hydrogen bonding energy, the binding of deoxyribose to adenine increase the total hydrogen bond strength more than binding this substituent to thymine. In all structures, deoxyribose binding increases N-H…N hydrogen bond strength and decreases N-H…O bond strength. While phosphate group modulates the additive effect of deoxyribose on hydrogen bond strength. It is interesting to note that the C-H...O bond is weaker than the other hydrogen bonds, but the mentioned substituents affect this hydrogen bond more than others. Also, the hydrogen bond of N-H ...N is stronger than the other hydrogen bonds and the highest of the energy value of this bond belongs to the TA-d structure. It also has the highest total hydrogen bond energy. Moreover, four parameters were introduced as suitable descriptors for evaluating the hydrogen bonding of this system.

One of the significant challenges in synthesis  of electrospun scaffolds is the fabrication of highly porous scaffolds free from defects and beads,with uniform fibers. In this study, effects of applied voltage and distance on morphologies of electrospun pcl-KIT-6 composite scaffolds were investigated.Fibre morphology was observed under a scanning electron microscopy. The effects of operating parameters including applied voltage, and tip-target distance on the morphology of electrospun  pcl-KIT-6 composite scaffolds  were systematically evaluated. Results showed that The morphological structure can be changed by changing the applied voltage and distance.when the voltage was increased from 15to 18 kv, nanofibres with beades were observed. Furthermore, increasing distance from 15 to 20cm had a positive effect on the scaffolds' morphology and decreased the defects such as beads in the structure. Hence the optimum conditions for electrospinning the PCL/KIT-6 composite scaffolds were determined for voltage and distance in 15kv and 20cm.

 The determination of physical properties and the obtaining of parameters related to thermodynamic models are essential in the design and simulation of industrial units for gas absorption and desorption by amine solvents. In this work, the viscosity and density of the binary and ternary mixtures of Ethanolamine and 2-amino-2-methyl-propanol (AMP) and water were measured at a temperature range of (303 to 343) K. Appling the thermodynamic models, the excess volume of the binary mixtures was correlated with the Redlich-Kister model and the mean relative error was less than 3% for all data. The dynamic viscosity for binary systems were determined by Eyring-NRTL and Eyring-Wilson models and used to predict the ternary mixture behavior. The results showed that the Eyring-Wilson model had better prediction than Eyring-NRTL model. Ultimately, the kinematic viscosity was correlated by the Redlich-Kister expansions and its temperature-dependent parameters were determined.

The phase transition of pentiloxcycyano biphenyl (5OCB), heptiloxycyano biphenyl (7OCB) liquid liquid crystal and the different mixtures of binary mixture of 7OCB-5OCB was studied to behavior of phase diagram by using differential scanning calorimetry (DSC). For 5OCB and 7OCB the crystal phase (C) to the nematic phase (N) phase transition temperature of was observed at temperatures 321 and 327 K, respectively, Whereas, in the binary mixture, the C to N phase transition temperature has decreased compared to each of the pure components, the highest decrease in phase transition temperature was observed in the 40% of mole furcation 7OCB liquid crystal. Additional functions in the binary mixture 7OCB-5OCB system were also investigated using regular solutions. The value of excess function such as Gibbs and enthalpy excess was to predict the behavior of the binary mixture with a slight deviation from the ideal state.

Deposit formation on heat transfer surfaces in heat exchangers is one of the most chronic problems in many industries. It causes flow mal-distribution, increased pressure drop, excessive fuel consumption, and generally reduction of the exchanger thermal efficiency. It is therefore indispensable to investigate fouling mechanisms as well as the impact of various operating conditions. These would, in turn, help to develop mitigation strategies. Water is the most widely used as working fluid in heat exchangers due to its high heat capacity, redundancy, and low price. However, the presence of various ions, such as calcium, carbonate, and sulfate in water, causes the formation of calcium sulfate and/or calcium carbonate deposits in heat exchangers. In this study, the effect of operating conditions including fluid velocity, calcium sulfate concentration, and heat flux on the formation of calcium sulfate deposit has experimentally been investigated. For doing so, firstly, the impact of these parameters on deionized water was examined under clean condition. The results of fouling experiments showed that increased heat flux and concentration of calcium sulfate resulted in intensified deposit formation as well as increased surface temperature and thermal resistance, which all would give rise in reduction of heat transfer coefficient. In contrast, the higher that fluid velocity is, the lower would be the deposition, surface temperature, and thermal resistance.

Aim of this research is to investigate the effect of the flow regime on separation in the gaseous diffusion system, the effect of the Knudsen number on the separation factor, and the diffusion velocity of the particles. In the current research, firstly, a brief description of the theory that governs the system will be given. Then, with the simulation of an element, the effect of the type of flow regime and Knudsen number on the variation of enrichment, the separation factors and the diffusion velocity of the light and heavy components inside the pores are investigated. Results are compared by theoretical equations. It is also should mentioning that two light and heavy isotopes of UF6 gas have been used for separation by gaseous diffusion method. The results will show; separation does not occur in the continuous flow regime, and separation will be occurring only in the molecular and transient flow regime. Also, with the increment of the Knudsen number, the amount of changes in the enrichment in different parts of the system will increase compared to the incoming gas. In other words, with the increment of Knudsen number, more separation is formed and the separation factor of the system increases. For instance, for a Knudsen number of 0.1, the separation factor is equal to 1.00101, and for a Knudsen number of 0.8, this value will increase to 1.00333. Finally, the diffusion velocity of the particles inside the pores, which is criteria of the effective separation of the particles, has been investigated. The results show that the diffusion velocity of particles for the light component is higher than heavy component, and this is due to the higher intensity of the particles of the light component passing through the pores.

Keeping constant and reasonable production from oil reservoirs which are in the second half of their life has pushed scientists to consider enhanced oil recovery (EOR) methods and novel methods in this field are presented. Magnetized water flooding as a green and compatible method with the environment is one of the novel methods besides polymer flooding which has been applied many years ago. The main purpose of this paper is to combine the two mentioned methods to increase the efficiency of flooding operations. Therefore, magnetized water is utilized as a solvent for polymer powder, then surface phenomena including interfacial tension and contact angle were studied. Somehow the effects of four factors including; magnetization time, magnetic field intensity, time after magnetization, and polymer concentration on mentioned surface phenomena were evaluated. The results showed that all of the aforementioned factors except magnetization time have a great impact on interfacial tension and just magnetic field intensity has a significant effect on contact angle. These results prove that flooding of magnetized water-based polymer solution has a great impact not only on macroscopic efficiency but also on microscopic efficiency and can improve the efficiency of polymer flooding.

The crude oil contains various contaminants including water, gas and sediments which should be removed in desalination unit. In addition, the wastewater from desalination unit should be refined to remove the oil droplets. In this work, a mathematical model was presented for demulsification process of crude oil emulsions from wastewater of desalination plant. A nonlinear hyperbolic integral differential equation was obtained by population balance method. The population balance integral equation terms were simplified using fixed pivot method and a system of partial differential equation (PDE) were obtained. The partial equations were converted into systems of ordinary differential equations (ODE) using the method of line. The ODEs were solved by the application of MATLAB Software. The profile of volumetric distribution of oil droplets, mean droplet diameter (D4,3), and oil separation rate along the height of the system at different times were reported. The accuracy of the model was examined by comparing with experimental data of water dispersion in oil system obtained from literature. Then, the model was applied to predict the oil in water systems and the effects of viscosity and density crude oil on separation of dispersed phase and mean droplet diameter (D4,3) were investigated. Finally, adjustable coefficients in the equations were estimated. The results showed that, by reducing the density of crude oil the settling velocity increases. Furthermore, the decreasing in crude oil viscosity will lead to increase the frequency collision droplets and oil separation.

Due to the complexities of oil reservoir simulation models, there is a need to find an optimization method that can have good accuracy and speed while reducing computational costs. In this regard, in this study, a parallel genetic algorithm has been used to accelerate the optimizer in order to prevent the increase of the computational load of the well placement problem and the prolongation of the execution time. Instead of one population of chromosomes (i.e., the same optimization variables), this algorithm works with several populations, which exchange chromosomes with each other. The proposed mathematical model is a single-objective problem, which is to maximize the present value of the project in the location of wells. The price of oil and the cost of separating water and gas are considered in this economic function. In evaluating the objective function, the CPU of a single computer, or multiple networked computers, each in parallel, are responsible for calculating the chromosomes’ fitness of parallel populations. After calculating the target function or suitability of the chromosomes of all populations (in which each population has common genetic function), migration between populations takes place. A case study has been used to validate the implementation of this method. In the proposed model, the location of vertical wells in an oil tank has been verified. As a result of the optimization, the wells are located at five points, four injection wells at the corners, and one production well at the center of the model, and in addition to reducing optimization time, the number of simulator performances in parallel processing mode is significantly reduced. In this research, the performance of genetic and parallel genetic algorithms for location optimization on the same reservoir model is shown. The execution time of optimization between genetics and parallel genetics is 7100 seconds and 1800 seconds, respectively. As it is known, the use of PGA has quadrupled the execution time in the studied oil reservoir.