Nashrieh Shimi va Mohandesi Shimi Iran
Year:2022 | Volume:41 | Issue:1 (103)|Papers Count:30

In this research, we investigated the growth path, relative stability, surface energy, sphericity, and structural analysis of Au-Ag nanoalloys created during gas condensation methodology via molecular dynamics MD simulation. In good agreement with the experiment, the position of silver atoms at the clusters' surfaces whereas the gold atoms place at the cores of the clusters. Our results also indicated some ordered structures such as hcp-and fcc-like structures within the created nanoclusters. The thermal behavior of nanoclusters indicated that the clusters become more spherical by the temperature to arrange the more stable morphology. The Au atoms also tend to migrate to the cluster surface by increasing the temperature.

In this study, nanostructured Cu2O powder was produced by the mechanical milling of micron-size Cu2O powder, and then a Cu2O/ZnO nanocomposite powder with different ratios of Cu/Zn was prepared by a chemical method. The effect of various Cu/Zn ratios of 5, 10, and 20 on the structure, morphology, optical properties, and photocatalytic performance in the degradation of methylene blue pollutant solution by composite nanopowder was investigated. The results of X-ray diffraction showed that the final product has a crystalline structure with relatively broadened peaks, which indicates a fined structure. The scanning electron microscope images showed that in the nanocomposite with the Cu/Zn ratio of 5, ZnO covered almost the entire surface of the Cu2O particles. The optical properties of nanocomposites were studied by diffuse reflection spectroscopy and the minimum band gap energy was related to the nanocomposite with Cu/Zn ratio of 5, 1. 9 eV, and this was in the visible light range. This sample showed the maximum photocatalytic activity in the degradation of the pollutant under visible light and exhibits 98% degradation of neutral aqueous solution methylene blue at a concentration of 2 mg/L after 240 minutes of irradiation under visible light.

In the present study, with the knowledge of the properties and advantages of various nano-porous materials, nanoparticles of manganese oxide (II) were exchanged on the zeolite-Y surface (covalent bond) and its structure was characterized by using various techniques such as FT-IR, XRD, BET, FESEM, and EDX analyses. In the following, the manganese oxide/zeolite (MnO2@zeolite-Y) as a green active nanocatalyst for the synthesis of ethyl 2-((1H-benzo[d]imidazole-2-ylamine)(ariyl)methylthio) acetate were used via a one-pot multicomponent reaction of aryl aldehydes, 2-amino benzimidazole, and ethyl 2-mercaptoacetate in a water-ethanol solvent and room temperature. This catalytic method has many advantages, such as the use of non-toxic, low-cost, available, and recyclable acidic nanocatalyst (Lewis), the short reaction time, the ease of separating pure products, the use of green solvents, and mild conditions. The present method also promises that in the future it can be used as a convenient synthetic route for the preparation of new sulfur-bearing peptide derivatives based on 2-amino benzimidazole core under moderate conditions.

In this study, the possible pathways for the catalytic reaction of hydrogenation of alkenes using GaCl3. H2O catalyst in dichloromethane solvent with the presence of 1 and 4-cyclohexadiene were computationally performed using Density Functional Theory (DFT). The best way to undertake this reaction is to use an organic molecule as a hydride donor in the presence of a metal catalyst instead of working with hazardous hydrogen gas. The most commonly used metal in the field is platinum, whose high price has led scientists to look for a suitable replacement. The 13th group complexes, including gallium, can be good substitutes for platinum to catalyze this reaction. In this regard, three possible pathways were considered: two ways without the interference of the water molecule, including the catalyst binding to the hydride-donor species and the other one through the alkene binding to the catalyst, and the last pathway through the water molecule interference. All calculations have been conducted using Gaussian 2009 software and various computational methods and also, considering the solvent effects in accordance with the practical research that led to the elucidation of the mechanism of hydrogenation of alkenes.

With growing concerns about environmental pollution, the oil industry has begun to look for ways to reduce fuel pollution. Catalytic isomerization is a method in which the fuel octane number is increased without producing air pollutants. In the present work, three composite catalysts with one mesoporous silica and zeolite sections were prepared and used in the normal heptane isomerization reaction in the temperature range of 200-350 °, C. The catalysts were identified using various tests such as XRD, XRF, UV-Vis DRS, nitrogen adsorption-desorption, FT-IR, NH3-TPD, and TG/DTA. The kinetics of this reaction was also investigated using two models the power law and the Langmuir-Hinshelwood. According to the obtained results, the Pt/XH catalyst showed the highest reaction yield (23. 9%) and selectivity to isomerization products (51. 8%) and the Langmuir-Hinshelwood model presented the best correlation (more than 0. 9) with the experimental data.

In this research, various types of MOFs with different metal nodes such as iron, chromium, vanadium, and strontium were synthesized using benzene-1, 3, 5-tricarboxylic acid as an organic linker through a hydrothermal crystallization method. In continuation, the effect of pH, temperature, and reaction time on the properties of obtained MOFs have been studied. The synthesized nanocrystalline MOFs were systemically characterized using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Fourier Transform InfraRed (FT-IR) spectroscopy. Therefore, synthesized catalysts were successfully carried out in the esterification reaction of oleic acid with methanol for the production of biodiesel. In addition, the operating conditions such as temperature and time of reaction, the molar ratio of methanol to oleic acid, and the amount of catalyst were studied. It was found among the prepared catalysts MIL-100(Fe) is the most appropriate catalyst for the esterification reaction of oleic acid with a yield of 78. 8% upon the optimum operating conditions. The catalytic activity of catalysts decreased in this order: Sr-BTC (52%), Cr-BTC (44%), and V-BTC (42%).

Due to the important role of the binder of compound engines, many studies have been done to improve their mechanical and thermal characteristics. Glycidyl azide polymer is used as an energetic binder in compound engines. The aim of this research is to improve the thermal properties and glass transition temperature of this energetic binder by copolymerizing it. So, the energetic triblock the copolymer of polypropylene glycol-glycidyl azide polymer-polypropylene glycol (PPG-GAP-PPG) (Mn = 1800 g/mol) was synthesized. For this purpose glycidyl azide polymer (GAP) (Mn = 1006 g/mol) was synthesized by poly epichlorohydrin The GAP was used as the initiator. The GAP triblock copolymer was synthesized by ring-opening polymerization of polypropylene oxide in the presence of boron trifluoride etherate (BF3•, OEt2) as the catalyst. The synthesized triblock copolymer was characterized by Fourier-transform infrared (FT-IR) and nuclear magnetic resonance spectroscopy. The glass transition temperature (Tg) of the triblock copolymer was characterized by differential scanning calorimetry (DSC). The DSC result showed that the glass transition temperature (Tg) of the triblock copolymer (Tg = −, 63 °, C) is lower than the neat low molecular weight GAP (Tg = −, 53 °, C). The thermal stability of GAP and PPG-GAP-PPG triblock copolymer was investigated using differential thermogravimetric analysis (DTG). The result indicated that the triblock copolymer is more stable than the GAP. To optimize the synthesis conditions of the triblock copolymer PPG-GAP-PPG synthesis condition, the effect of temperature and catalyst on molecular weight, and copolymerization efficiency were investigated. The best mood for the synthesis of the triblock copolymer was the yield (86%) at 10-15 º, C, and 1% by weight of the catalyst. The DSC result showed that the glass transition temperature of the copolymer (Tg =-63°,C) was lower than that of low molecular weight glycidyl azide (Tg =-53 °,C). In order to optimize the synthesis conditions of PPG-GAP-PPG triblock copolymer, the influence of temperature and catalyst variables on molecular weight and copolymerization efficiency was investigated. The highest yield (86%) was obtained at 10-15 °,C and 1% of catalyst.

In this study, the effect of changes in plasma generator voltage on the partial oxidation reaction of methane in a DBD plasma reactor and in three states without catalyst, plasma with nickel oxide catalyst, and plasma with copper oxide catalyst was investigated. The results showed that increasing the device voltage from 6 to 10 kV with nickel catalyst increased the molar percentage of methanol from 0. 37 to 0. 76% and for C₂,+ hydrocarbons from 0. 55 to 1. 8%. Plasma and copper catalyst testing decreased the production of precious hydrocarbons as the voltage increased. Hence, the molar percentage of methanol declined from 0. 3 to 0. 18, and the molar percentage of C₂,+ diminished from 0. 82 to 0. 23. Calculation of energy consumption when increasing the device voltage showed that the experiments were performed at 6 kV voltage with a higher energy efficiency of 0. 17 mmol/ kJ. At this voltage and in the presence of a nickel oxide catalyst, the selectivity of carbon monoxide was 37% and hydrogen was 58%, which was higher than the other two and the amount of H₂,/ CO in the synthesis gas was closer to 2. To sum up, the choice of nickel catalyst in the DBD plasma reactor to produce precious hydrocarbons or synthetic gas with lower energy consumption is better than copper catalyst and non-catalyst plasma.

A tetraaza macrocyclic Schiff base complex of Zn(II) was synthesized by the reaction of ortho-phenylenediamine, acetylacetone, and anhydrous ZnCl2 in the ratio of 1: 2: 1, respectively. We adopted one pot template synthesis. The synthesized Zn(II) complex was characterized by repeating conductivity measurements, elemental analysis, decomposition point determinations, and spectroscopic methods such as FT-IR, 1H NMR, and UV-Vis studies. The interaction between the above Zn(II) complex (bis(acetylacetone-o-phenylenediamine)Zn(II) chloride) with calf thymus-deoxyribonucleic acid (CT-DNA) and bovine serum albumin (BSA) was studied by ultraviolet-visible absorption spectroscopy. The values of the binding constant suggest that the interaction affinity of the metal complex to CT-DNA is more as compared to BSA. The concentration of Zn(II) complex at the midpoint of the transition from native to interacted with CT-DNA is lower as compared to BSA. Moreover, the Hill coefficient, h, has a value of 1. 1 which confirms the non-cooperativity in the binding of Zn(II) complex with BSA. Furthermore, in order to investigate the interaction between Zn(II) complex and DNA as well as BSA, the docking simulation was performed with the optimized structure of the complex.

In this research, the pyrolysis of waste in the tires has been investigated in the vicinity of biochar catalysts that are produced by the gasification process of poplar. For this aim, 25 grams of sample were loaded in a laboratory-sized reactor and pyrolysis of the samples was carried out at 500°, C at atmospheric pressure. The results showed that the biochar catalyst can change the characteristics of the products produced. In the case of gaseous products, the catalyst had no significant effect on the amount of CO, CO2, and H2. However, it increased C3H8 and decreased C2H6 contents. Biochar catalysts reduced the content of aromatics while increasing the linear compounds, indicating the tendency of biochar catalysts to convert aromatics into linear compounds such as alkanes and alkenes. It also had a strong tendency for the deoxygenation of the tar. By using biochar as a catalyst, the char obtained included high content of aromatics. The DTG analysis of the char samples showed that the char molecular structure of the catalytic pyrolysis process is heavier and tidier. XRD analysis of the catalyst also showed that a layer of carbon material (coke) was sitting on the catalyst surface, which was resulting from the polymerization of aromatic compounds present in the volatiles produced in the pyrolysis process.

In this study, the structural, electronic, and optical properties of InN in three phases of zinc, vortexite, and NaCl have been studied. The calculations have been performed using the pseudopotential method in the framework of Density Functional Theory (DFT) by Quantum espresso package with LDA, GGA, and PBE0 approximations for the exchange and correlation potential terms. The results show that the band gap for InN in the hexagonal phase is a semiconductor with a direct band gap while it is indirect in the NaCl phase. The mostly contributed in the valence band and in the conduction band of the s-orbital nitrogen atom and orbital s and p indium atoms. The result of the compressibility shows that the structural phase of the NaCl is less dense than the two structural phases. Also, the optical properties of the compound including dielectric function, refractive index, electron energy loss Spectroscopy, and the results are consistent with other available data.

In this study, the Quantitative Structure-Property Relationship (QSPR) was proposed to predict the Upper Flammability Level (UFL) of 588 organic compounds including hydrocarbon compounds, halogenated compounds, alcohols, ethers, esters, aldehydes, ketones, acids, amines, amides, nitriles, and nitro compounds. A variety of molecular descriptors were calculated for each molecule. The Memorized-Ant Colony Algorithm (M-ACO) combined with multivariate linear regression (MLR) was used to select the best subset of descriptors that have a significant contribution to the UFL property. Different variable transformations were performed on both dependent and independent variables to obtain better multiple linear regression models. The best model was a four-variable model obtained by using the calculated descriptors as independent variables and the logarithm of UFL values as the dependent variable. This model has a very wide applicability range of UFL from 2/7 to 100 vol %. The training and test errors of the model were found to be 0/1 log UFL unit (R2 = 0. 80) and 0. 12 log UFL unit (R2 = 0. 75), respectively. Therefore, the model has good accuracy and can be used to predict the UFL of a wide range of organic compounds.

Increasing greenhouse gases, especially carbon dioxide, are a serious threat to the environment and rising global temperature. One of the methods of separation and reduction of greenhouse gases is based on physical and chemical absorption by nanofluids. The main goal of this study is to investigate the effect of aqueous base nanofluids containing activated carbon nanoparticles synthesized from agricultural waste at different concentrations on CO2 absorption. For this purpose, the activated carbon nanoparticles were first synthesized from walnut shells, and the physicochemical properties of the synthesized nanoparticles were determined by FESEM, FT-IR, and BET analyses, and then the nanofluids were prepared at different concentrations of nanoparticles including 0. 02, 0. 05, and 0. 1 wt. %. The effect of prepared nano-fluids on the carbon dioxide absorption at 35°,C and pressures of 20, 30, and 40 bar were investigated in a high-pressure equilibrium cell with a magnetic stirrer and results are compared with CO2 absorption by pure water. The results showed that carbon dioxide uptake increased with increasing nanoparticle concentration and initial pressure. The maximum CO2 absorption occurred at 40 bar and 0. 1 wt. % of nanoparticles, in which the CO2 absorption was 29% higher than pure water.

There are some drawbacks and limitations in conventional CO2 capture technologies including low mass transfer area. Therefore, it is necessary to provide a new absorption technology that does not have this limitation. The use of high-frequency ultrasonic waves is a method to produce fine droplets by atomizing the solvent. These droplets provide a large surface area for the mass transfer process. In this research, absorption was carried out utilizing high-frequency ultrasonic waves. The results indicated that the CO2 absorption rate in water was increased up to 20 times in comparison to the case without ultrasonic irradiation at 8. 64 watts. In addition, a magnetic stirrer was applied instead of the ultrasonic transducer to compare these methods. In this condition, the mass transfer coefficient by the ultrasonic system was approximately 4. 4 times more than the magnetic stirrer, which indicates better performance of the ultrasonic waves compared to the stirrer.

In this research, the adsorption of phosphoric acid from an aqueous solution was investigated at different temperatures (298, 308, and 318 K) by using different adsorbents such as wheat bran and banana peels, in a batch system. FTIR and SEM analysis were used, in order to determine the functional groups in the structure of adsorbents and the surface characteristics of adsorbents, respectively. In the adsorption experiments, the effect of important parameters such as the effect of contact time, the amount of adsorbent temperature, and initial acid concentration was investigated. Equilibrium time was determined 40 and 50 minutes for wheat barn and banana peels. The highest percentage of adsorption for banana peel and wheat peel was measured at 71% and 59. 8% for 1 g /L phosphoric acid, respectively. The optimum amount of adsorbent was determined 3g. Investigation of the temperature demonstrated that the percentage of removing phosphoric acid decreased by increasing the temperature. Different models of adsorption isotherms such as Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich models were applied to analyze the equilibrium data at different temperatures and Langmuir and Temkin isotherm have the most agreement with experimental data for absorbents. Different kinetic models such as pseudo-first order, pseudo-second order, Elovich, and intra-particle diffusion model were chosen to describe the kinetic of adsorption, and the pseudo-second-order model for wheat barn and Elovich for banana peels have the best agreement with experimental data for each adsorbent. Thermodynamic parameters like standard Gibbs free energy changes of adsorption (Δ, G oads), standard enthalpy changes of adsorption (Δ, H oads), and standard entropy changes of adsorption (Δ, S oads) were calculated by using equilibrium constant values at different temperatures. The negative value of (Δ, G oads) demonstrated that adsorption of phosphoric acid by adsorbents is a spontaneity process and negative values of (Δ, H oads) showed that adsorption of phosphoric acid on adsorbents is exothermic. The absorption capacity of banana peel and wheat bran was achieved20 and 11 mg/g, respectively. As a result, banana peel was the appropriate absorbent in this work.

In this study, the two novel modified structures of MCM-41 with furan ring were synthesized for the removal of Cu(II) ions from water. These novel adsorbents were synthesized by amination of MCM-41 using 3-Amino-propyltrimethoxy-silane and 3-(2-aminoethylamino) propyltrimethoxy-silane in the first step, and then using a furfural compound And the condensation reaction, the MCM-41 modified with furan groups, abbreviated as MCM-41@NO and MCM-41@N2O. Characterization and investigation of the adsorbent structure was performed using XRD, FT-IR, and BET. The concentration of soluble ions with Flame Atomic Absorption Spectrometry (FAAS) was determined. The adsorbent efficiency in removing copper ions was studied by examining variables such as adsorbent dose, pH, contact time, and soluble temperature. The equilibrium of adsorption of both absorbents fits into the Freundlich isotherm model. The kinetics study of adsorption shows the second order of kinetics for both absorbents. The study of the adsorption of Cu2+(aq) on the MCM-41@NO by using Monte Carlo molecular mechanics is the innovation of this work. The results of these calculations are compared to experimental results. The results of calculations show that the Cu2+ ions at 1. 63Å,from the surface of absorbent with 0. 75 kcal/mol energy have the maximum probability of distribution.

In this research, the ability of economically sawdust adsorbent coated by polypyrrole, a semiconductor polymer, for uranium sorption from aqueous solutions was studied in a batch system. The experiments were performed to investigate the effect of operating parameters such as pH, contact time, adsorbent amount, initial concentration, and temperature on the sorption of uranium, and optimum operating conditions were determined. The adsorption amount of 54. 65 mg/g was obtained at operational conditions, i. e., absorbent dosage 1 g/L, 100 mg/L of uranium initial concentration, 15 minutes as equilibrium contact time and pH of 5. The results showed that the rate of uranium sorption increases with the increase in temperature, which indicates the adsorption process is endothermic. The experimental results have been fitted with the Langmuir and Freundlich isotherm models, and the experimental data were in better agreement with the Langmuir model. Based on the Langmuir model the maximum adsorption capacity 93. 46 mg/g was obtained. Kinetics analysis of the adsorption process showed that the pseudo-second-order model has a better fit with the experimental data. The thermodynamic parameters such as Δ, H0, Δ, S0, and Δ, G0 were investigated so that the results show the adsorption process is endothermic and spontaneous.

The goal of this study is to synthesize TiO2(10)/MCM-41 nanocomposite via the hydrothermal-impregnation method and compare its performance with bare TiO2 nanoparticles with the aim of assessing the role of silica support in the removal of tetracycline antibiotics. The physicochemical properties of synthesized photocatalysts were investigated using various analyzes. The results of XRD and EDX analyses indicated the successful synthesis of TiO2(10)/MCM-41 nanocomposite. FESEM and EDX images showed the existence of nanosized small surface particles with uniform size distribution and dispersion over the structure of TiO2(10)/MCM-41. FESEM images also revealed that nanoparticles size decrease and the formation of agglomerations are prevented as a result of nanoparticle immobilization. The PL and DRS techniques confirmed that the TiO2 immobilization results in a decrease in electron-hole recombination and surface nanoparticle size. The N2 adsorption-desorption analysis showed that the synthesized nanocomposite has a high specific surface area (972 m2/g). According to the performance results, the tetracycline degradation over TiO2(10)/MCM-41 was 67. 7% higher than that of the bare TiO2 nanoparticles. This enhancement can be due to the suitable crystalline structure of TiO2, smaller size and uniform distribution of TiO2 nanoparticles, high specific surface area, the decrease of charge carriers recombination, and prevention of photocatalyst aggregation as a result of the existence of MCM-41. Based on the kinetics consideration, the degradation rate of pollutants over immobilized nanoparticles is higher and follows the second-order reaction. Also, a degradation efficiency of 68% was obtained under operation conditions of 20 mg/L tetracycline concentration, 1. 5 g/L photocatalyst dosage, and 2 h irradiation. The relatively high and constant activity after the first cycle of reuse refers to the suitable separation and thereupon, appropriate reusability of TiO2(10)/MCM-41 sample. Therefore, it can be concluded that in addition to easier and better separation, TiO2 immobilization over MCM-41 improves the optical and structural properties, and finally, increases the performance of the photocatalyst.

The role of great industries such as oil, gas petrochemical is essential in the world economy, however, the most problem of these industries is the abandoned pollutants in the environment. In this study, the removal of two major oil pollutants, benzene, and toluene was investigated in the presence of two new and native fungi called Aspergillus terreus and Exophiala xenobiotica. The factors affecting the removal process consist of temperature, time, concentration and pH. The results showed that the highest adsorption of pollutants occurs at 25 ℃,within 10 days of contact time with fungus A. terreus and 25 days for fungus E. xenobiotica in a way that both pollutants have a concentration of 5 ml/lit and pH=7. A comparison of the performance of two fungi on the removal of pollutants showed that in the condition in which the effect of concentration, contact time, and the temperature was investigated E. xenobiotica is successful in removing benzene and A. terreus showed better performance when the effect of pH was evaluated. In contrast, in the removal of toluene, the A. terreus showed better performance in all conditions. Finally, based on the result of this research, it could be concluded that the bioremediation process using new fungi is a promising and environmentally compatible solution to eliminate oil pollution. In general, based on the results obtained under the optimum conditions of all four parameters, A. terreus had the best performance for benzene and toluene contaminants with the removal of 68. 35% and 84. 27%, respectively.

In this research, the biosorption of tellurium from aqueous solutions by Pseudomonas putida was investigated. One Factor at a Time (OFAT) method was used for the investigation of the pH effect, and Response Surface Method (RSM) based on the Central Composite Design (CCD) was used for the investigation of initial tellurium concentration, biosorbent dosage, and contact time on biosorption. Based on the results, the second-order polynomial regression model with correlation coefficient R2=0. 937, by proper prediction of process behavior, determined initial Te concentration 109 mg/l, biosorbent dosage 1. 17 g/L, contact time 94 minutes optimized as the optimum point at pH=8. 5. The adsorption capacity of the biosorbent was 10. 1 mg/g at the optimum conditions. The experimental data were analyzed using Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherm. Moreover, the Kinetic of biosorption was determined. The equilibrium data were fitted well by the Freundlich model with a correlation coefficient R2=0. 996, which showed the biosorption of tellurium is multilayer, and the biosorbent surface is heterogeneous. The maximum biosorption capacity of tellurium was 19. 63 mg/g using D-R isotherm. The kinetic studies showed that the tellurium biosorption is very fast and the biosorption capacity reached a maximum of 15 minutes. Finally, the present research precisely confirmed that RSM is a suitable method to predict tellurium biosorption by Pseudomonas putida.

In the present research, an optical sensor based on bacterial cellulose nanofibers (BCNF) film containing silver nanoparticles (AgNP) was fabricated and used for the determination of 2-mercaptobenzoxazole (MBO), which is considered a poisonous and pollutant agent of water. To fabricate nanocomposite, the effective variables in the fabrication process such as pH of the solution, AgNO3 concentration, the mass ratio of Ag to nano paper, temperature, and reaction time was optimized. The results obtained from Field Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive x-ray Spectroscopy (EDS), Thermal Gravimetry Analysis (TGA), and UV-Vis spectroscopy showed that AgNPs have been successfully synthesized and fixed in the structure of BCNF film. The changes in peak absorption of local surface plasmonic of AgNP to the increase of MBO concentration were considered as an analytic sign. The prepared sensor has a linear range of 5-150 μ, g mL-1 and a limit of detection of 1. 7 μ, g mL-1 for the determination of MBO. To evaluate the selectivity of the sensor, its performance was investigated in the presence of interference compounds. To investigate the practical performance of the sensor to detect MBO, a water sample of Tejan River was evaluated. The results confirmed that the sensor has selectivity ability in the presence of other probable troublesome compounds and is suitable to detect MBO in real samples.

In the present study, a simple method as name dispersive liquid-liquid microextraction was developed for the thorium extraction. In this extraction method, acetone as a disperser solvent and chlorobenzene as an extraction solvent was used. Extraction and separation of thorium with complexing agent cyanex 272 in an acidic environment were performed. Some of the effective parameters on the extraction of thorium such as type and volume of extraction and disperser solvents and concentration of ligand and type and concentration of acid were studied and optimized. Under the optimum conditions, good linearity was observed in the range of 1. 0-5000 µ, g/L with the correlation coefficient (r2) > 0. 997. The limit of detection (LOD) was 0. 3 µ, g/L. Repeatability for five replicate measurements in the concentration level of 20. 0 µ, g/L was 6. 5% and extraction recovery 78% was obtained.

In this study, experimental findings related to the efficiency of a solid-liquid extraction were modeled through Response Surface Methodology (RSM) and Artificial Neural Network (ANN). Anethole is the main active pharmaceutical ingredient in the essential oil of fennel seeds, and it was extracted in contact with 70% ethanol as a solvent in a new modified Rotating Disc Contactor (RDC) column. The extraction yield of Anethole was considered as a response factor on which the impact of three variables was investigated, including fennel particle size, rotor speed, and solvent-to-solid ratio. The experiments were conducted with finely chopped fennel particles in sizes of 1. 7, 1, and 0. 3 mm, the rotor speed of 90, 135, and 180 rpm, and solvent-to-solid ratios of 10, 15, and 20. The obtained yields were modeled through RSM and were also simulated with the ANN method. The result of GC-MS and GC analyzers as well as simulation findings showed that by decreasing the size of fennel seeds, increasing the solvent-to-solid ratio, and rotor speed, the yield of the extraction process was enhanced. In addition, the correlation coefficient for the RSM and ANN were 0. 9604 and 0. 9955, respectively,which proves a high accuracy of ANN modeling in comparison with RSM.

The olive oil extraction industry generates large amounts of two by-products solid residue and an effluent known as olive mill wastewater that is currently considered olive mill waste. However, they have a great potential to be used as preservatives (single or combined with synthetic ones) of Biodiesel. Biodiesel is an alternative diesel fuel obtained by transesterification of vegetable fats and oils, using alcohol in the presence of a catalyst, but its drawback is of being more prone to oxidation than petroleum-based diesel fuel, can cause the fuel to become acidic and form insoluble gums and sediments and consequently increase its viscosity In this study, in order to increase the stability of biodiesel-based sunflower high oleic acid against the oxidation process during storage and distribution of water after extraction, we added 100 ppm of halo and 200 ppm of antioxidants (BHT + USM) together. Evaluate the effect of synthetic BHT antioxidants. The oxidative stability of biodiesel will determine using the Rancimat method to evaluate. the greater efficiency of the best combination used gas chromatography.

Alginate is a polysaccharide isolated from seaweed. This polymer is relatively biocompatible and has a negative charge. As a biochemical substance, it is widely used in drug release, wound production, printing, dyeing, and completing textiles. One of the most important methods for producing this biochemical polymer is the wet spinning method. In the present study, for the production of laboratory-scale alginate fibers, the wet spinning method, a chemical-based method, was used. After examining the behavior of polymeric polymer rheology that plays an important role in determining the membrane performance, adding olive oil to the spinning solution increased viscosity from 0. 55605 [Pa. s]to 2. 0542 [Pa. s]. The fibers produced had an integrated and uniform diameter. The strength and the structural properties of the fiber were examined. The results showed that the effect of the olive oil was to increase the stability of the spinning and elasticity of the fiber. An increase in strength was observed with an increase in porosity in the fiber structure. Multiple maps were prepared from the results of linear analysis and analysis was done using Energy Dispersive x-ray Spectroscopy(EDS). The presence of olive oil was confirmed in the linear analysis and the images of the alginate showed samples containing olive oil.

The aim of this study was to apply an artificial neural network to predict the degradation temperature of polyamide 12 under the influence of several factors such as environment, biofuels, and temperature over time. In this modeling, a three-layer perceptron (MLP) neural network is used. The perceptron neural network consists of three input layers, a hidden layer, and an output layer. The inputs of this network are three variables related to ethanol concentration, temperature, and time and its output is the temperature of polyamide degradation. The perceptron neural network was designed with a linear transfer function at the output layer for modeling. A comparison of experimental results and network modeling results showed R2 = 0. 99. Also, using experimental data, the mean squared error and absolute percentage error of system error were 0. 09 and 0. 03, respectively. Then, the degradation temperature and the effects of several factors such as ethanol percent and temperatures (20, 40, and 60) degrees Celsius on the physical properties of polyamide 12 during times (0, 900, 5000, 3000, 6000, and 7000) hours are predicted and the results show the high accuracy of the neural network in estimating the degradation temperature.

In the present study, carbon dioxide mass transfer flux in the reactive absorption process was modeled by three solutions of methyldiethanolamine (MDEA), monoethanolamine (MEA), and piperazine (PZ) using the film theory model and all governing equations solved simultaneously. The effects of all components' concentration during film and mass transfer flux with and without film displacement were investigated and predicted values were compared with experimental data of the carbon dioxide absorption process in the desired solutions. The influence of various dimensionless parameters including film and loading parameters as well as the effects of reaction, diffusion, film velocity, and eddy on mass transfer in the proposed model has been studied. The deviations were calculated from the experimental data for the mass transfer flux by calculating the average relative deviation (ARD). The values of ARD were obtained at about 5. 30%, 8. 24%, and 6. 56% for PZ, MEA, and MDEA solutions respectively. Moreover, based on the film displacement, the mass transfer flux was affected and the average relative deviations decreased. For PZ solution, 0. 1% and for MEA and MDEA solutions, 0. 6% and 1. 1% error reductions were observed, respectively. Furthermore, the results show that the effects of reaction and diffusion on the mass transfer flux are on average more than 35% than the effects of film velocity and eddy influence.

In the present study, the effect of Tarragon (Artemisia Dracunculus) extract as a green corrosion inhibitor on st37 carbon steel in 1M sulfuric acid and 0. 5M hydrochloric acid was investigated using potentiodynamic polarization, electrochemical impedance spectroscopy, and scanning electron microscopy. Potentiodynamic polarization measurements showed that the inhibitor is a complex type and, with an increase in the concentration of inhibitor the corrosion rate was decreased. The results of the potentiodynamic polarization and electrochemical impedance methods were in agreement. The results of TOEFL and EIS measurements revealed that the adsorption of Tarragon extract on carbon steel in 0. 5 M hydrochloric acid solution and 1M sulfuric acid was followed with the same temperature. Furthermore, the inhibition efficiency of the extract was higher in sulfuric acid rather than that in hydrochloric acid medium.

The aim of this experimental study is to investigate the thermal and hydrodynamic performance of graphene oxide and alumina nanofluids with two types of nanoparticle shapes in a plate heat exchanger. The nanofluids with a weight fraction of 0. 1% were prepared by dispersing nanoparticles in pure water via a probe ultrasonic apparatus and a vigorous mechanical mixer. Then, the thermo-physical properties of the nanofluids including thermal conductivity and viscosity were analyzed and compared. For the thermal test, a heating system including a brazed plate exchanger equipped with two pumps, two flowmeters, four thermometers, two storage tanks, and insulated steel tubes was set up. The flow rate of hot fluid (pure water) was fixed and the nanofluid was used as cold fluid to cool the hot fluid at flowrates of 1. 5, 2, 2. 5, 3, and 3. 5 L/min. Thermal and hydrodynamic performance was investigated by calculating heat transfer rate, Nusselt number, friction coefficient, pressure drop, pumping power, and finally the performance coefficient criterion (the ratio of heat transfer obtained to pumping power consumed). In comparison with water, the highest enhancement in heat transfer was obtained at the lowest flow rate of graphene oxide and alumina nanofluids to the extent of 46% and 18 %, respectively. This study showed that the maximum performance index was related to the graphene oxide nanofluid at flowrates less than 2. 5 L/min, while at flowrates higher than 2. 5 L/min, the performance index of graphene oxide nanofluid showed a significant drop and was lower than alumina nanofluid.

The current study investigated the accuracy and stability of an improved inter-particle interaction force term by incorporating force methods and different equations of state. In order to evaluate, eight schemes for incorporating the force term and five equations of state, Shan and Chen (S-C), Carnahan-Starling, Peng-Robinson (P-R), Van der Waals (VdW), and Soave-Redlich-Kwong (SRK), are utilized. Furthermore, affections of relaxation time and reduced temperature on accuracy, stability, and amount of spurious velocities are considered. Among several methods of incorporating the force term, the exact difference method with an improved model and Carnahan-Starling equation of state is shown to have better accuracy and stability and can give more accuracy with spurious velocities which have been greatly reduced. Compared with existing models, the improved model for the inter-particle interaction force term reduced the error of simulation, The minimum error rate accrued for the improved model with the exact difference method of incorporating force term and Carnahan-Starling equation of state and its value is equal to 0. 4% while in the identical condition this error rate for equation (9) inter-particle interaction force term is 3. 6%. Subsequently, in different relaxation times, a maximum range of stability and accuracy occurred for the exact different method which has better operation in a range of 0. 8 to 1 relaxation time. The minimum error of this method with the Carnahan-Starling equation of state in relaxation time 0. 8 and reduced temperature 0. 54 is 1. 8%. By comparing the variation of spurious velocities in the range of 0. 57 to 2 relaxation time is demonstrated spurious velocities are increased when temperature decreased.