Nashrieh Shimi va Mohandesi Shimi Iran
Year:2018 | Volume:37 | Issue:1 |Papers Count:27

Metal-organic frameworks due to their unique properties have many applications. Before using, metal-organic frameworks should be activated and there pores should become empty. ZnO nanoparticles can be prepared by calcination of non-active or activated metal-organic frameworks. In this paper, we wish to have a review on our recent research results in the field of using metal-organic frameworks as new precursors for the preparation of ZnO nanostructures. The results show that non-active metal-organic frameworks are appropriate precursors for the preparation of spherical ZnO nanoparticles but in their active forms, they tend to form agglomerated nanostructures. It can be said that if the number of organic components used in the structure of a metal-organic framework is greater; ZnO nanoparticles with a smaller size will result from it.

In recent years, research on mesoporous materials and different methods of preparation and synthesize of them is developed. These materials have had rapid and successful growth in different applications of various processes. Among mesoporous materials, regular mesoporous silica materials have attracted the attention of biotechnology researchers. In fact, the most widely used mesoporous materials in different industries and processes. These materials are used as adsorbents for the separation of biologically active molecules in food, as a preservative to stabilize enzyme, as a carrier in a drug delivery system and as a catalyst in the petroleum industry, etc. Controlled release systems are based-on mesoporous silica nanoparticles, capable of carrying different types of host molecules. Usually, drug loading is about 100 mg per gram of MSN. Mesoporous silica nanoparticles for drug delivery in the site-specific and controlled delivery of drugs, genes and other therapeutic factors such as antioxidants can be used. In this review article, the synthesize of mesoporous silica nanoparticles from materials, methods of structural properties control, and functionalization of them for applying in biological drug and biotechnology and also, advantages of mesoporous silica nanoparticles, biocompatibility and their uptake mechanism by host cells In vitro are described.

Phenol is among toxic pollutants with a resilient degradability behavior the total removal of which via traditional techniques is impossible. In this research, Carbon-doped TiO2 nano-photocatalyst is produced via sol-gel technique. Various techniques are used to characterize TiO2 nano-photocatalyst such as XRD, FT-IR, EDX, and FE-SEM. Based on the results, the carbon introduced into titania structure has led to response towards visible light. The synthesized catalyst was implemented for photocatalytic removal of phenol in a fluidized bed reactor under UV and visible light. The effects of several significant parameters were investigated such as phenol concentration, pH, time, C/Ti molar ratio and catalyst content. The degradation of Phenol using this nanocomposite is 84 % under UV irradiation during a 180 min period and 70 % under visible irradiation during a 420 min period.

Considering the importance of the fuel cells, we are up to developing an appropriate and efficient electrode system in this project so that we may take a step forward in this field. Besides, the significance of nanostructure compounds in electrochemistry led us to use a nanoporous silicate zeolite (MCM-41) along with silver nanoparticle in electrode fabrication. Characterization of the synthesized nano zeolite was carried out using X-Ray Diffraction (XRD), Fourier Transform InfraRed (FT-IR) spectroscopy and Field Emission Scanning Electron Microscopy (FESEM) techniques. Then, the synthetic nano zeolite containing Ag nanoparticle were employed in the fabrication of the modified carbon paste electrode and was used in the electrocatalytic oxidation of formaldehyde. The mechanistic and kinetic studies of the reactions were undertaken based on cyclic voltammetry and chronoamperometry techniques. The results revealed that the modified electrodes with MCM-41 nano zeolite and Ag nanoparticle exhibited much higher current densities and fewer overpotentials than that of bare carbon paste electrode for use in the fuel cell.

Advanced Oxidation Procedure (AOPs) and semi-conductive photo-responsive Titanium Dioxide (TiO2) catalysts have proven to be effective in degradation of antibiotic pollutants in aqueous matrices despite the minor issues that currently exist for their industrial application. As to address the current catalytic inefficiencies, silver doped TiO2 nanoparticles have been synthesized from commercial Degussa TiO2 in order to enhance the efficiency of TiO2 photocatalyst in comparison with the commercial TiO2 product in degradation of Erythromycin antibiotic and also to make degradation plausible in the visible irradiation range through optical precipitation. XRD, FE-SEM and DRS methods were implemented to characterize the as-synthesized nanoparticles. The efficiency of the as-synthesized photocatalyst was also investigated to measure the effect of silver doping and also to optimize operational parameters under UV irradiation. As with the improvement in photocatalytic activities, degradation efficiency at optimal operational conditions under UV irradiation was proved to be 76. 8% for Ag/TiO2while commercial TiO2 exhibited a 43. 7% efficiency under the same conditions. The effect of strong oxidant like H2O2 was further examined through the addition of H2O2 to the reaction medium and prove to have 89. 3% efficiency for Erythromycin degradation at optimal H2O2 concentrations. Positive results from UV experiments as well as H2O2 experiments and the minor antibiotic activity of Erythromycin degradation products exhibits Ag/TiO2 to be a promising future candidate for the treatment of Erythromycin containing Pharmaceutical wastewater.

One-pot synthesis of 3-substituted coumarins using Red mud (RM) which emerges as a by-product from the alumina producing process as a catalyst via Knoevenagel condensation of 2-hydroxybenzaldehyde derivatives and malonate derivatives are investigated. Reaction carried out under various conditions and the best results are obtained when the reaction is done under microwave irradiation. RM showed an efficient catalytic activity in this reaction. The catalyst can be used for at least four times after reactivation without remarkable losing in its efficiency. Finally, some of the thermochemical properties such as enthalpy and Gibbs free energy of formation for the synthesized coumarins are calculated using quantum chemistry, and also an electrostatic potential map of some of the synthesized coumarins was obtained using computational chemistry software which could be so helpful for the analysis of active reaction sites of coumarins.

Commercialization of Polymer Exchange Membrane (PEM) fuel cells needs to make CO resistance anode catalyst. Recently some researchers use the multi-layer catalyst, which oxidizes the CO molecules by ruthenium on the outer layer and prepares pure hydrogen for the inner platinum layer. In this work, we studied the Sn and Co Bi-metallic catalyst for CO electro-oxidation. Three samples with different composition ratio are synthesized on the carbon Vulcan support. Electrochemical tests conducted in homemade half-cell hiring new test procedure we developed in the previous article. Results show the high capacity of these non-noble metals for CO electro-oxidation in low potentials whereas CO oxidation on commercial Pt/C occurs at potentials above 0. 7 volts. In addition, the catalyst containing Sn50%-Co50% has the best results for CO and H2 electro-oxidation in fuel cell working condition.

Microbial Fuel Cell (MFC) is of the renewable energy in which microorganisms play the role of biocatalysts in Ox/Red reactions of a substrate like glucose. In MFC electrode is a key component. In this work, a porous nano-biocomposite electrode based on Bacterial Cellulose (BC) and polyaniline as continuous and dispersed phases respectively were synthesized by in situ chemical polymerization of 4 various concentrations of aniline. The synthesis was studied by FT-IR andFE-SEM. Then it was applied in MFC as an anode. Performance of MFC was examined in presence of new anodes. The resistance of electrodes and produced power and current densities were measured. The maximum power of 375mW/m3 and current of 617 mA/m2 were recorded for the system for the anode with maximum aniline concentration.

In this study, Ag-TiO2 and Ag-TiO2/GO nanomaterials were prepared and then characterized via different analysis methods such as XRD, SEM, EDX, Raman, and BET. The adsorption capacity of prepared samples was investigated by removal of methyl orange, as a model organic pollutant, from aqueous solutions. Based on results, Ag-TiO2-GO nanocomposite demonstrated an excellent activity over Ag-TiO2 sample. To understand the nature of the adsorption process, the equilibrium adsorption isotherms were studied. Based on results, for Ag-TiO2 and Ag-TiO2/GO, Freundlich and Langmuir isotherm models with a correlation coefficient of 0. 989 and 0. 993 fitted the experimental data, respectively. According to the Langmuir isotherm model, the maximum adsorption capacity of Ag-TiO2/GO nanocomposite for adsorption of methyl orange was about 69. 44 mg/g, which was about 3 times the adsorption capacity of Ag-TiO2. Furthermore, negative Δ G0 and Δ H0 values resulted from thermodynamic investigation suggested that the adsorption of methyl orange onto Ag-TiO2/GO nanocomposite was simultaneous and exothermic in nature, respectively.

Magnetic core-zeolitic shell structures modified with 3-Glycidyloxypropyl-trimethoxysilane (GPTMS) organic agents prepared by the hydrothermal method. The samples were characterized by X-Ray Diffraction (XRD), Thermo Gravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), and nitrogen adsorption-desorption isotherms (BET). The results of the XRD patterns confirmed the successful growth of aluminosilicate crystals on the surface of the magnetic cores. Furthermore, the SEM images indicated that structures were spherical and the particle size was below 100 nm. The sorption activity of the samples was evaluated by removal of lead and cadmium ions from the wastewaters and according to the results, the final sorbent was enabled to decrease the concentration of cadmium ions selectively. The sorption routes and the effect of the presence of organic agents on the sorption efficiency were mechanistically discussed. The effect of the acidity of the medium on the sorption capacity of the prepared structures was studied and the obtained results were discussed in terms of the chemical structure of the surface.

Whey, as a strong environmental pollutant, is produced along the production of cheese and contains about 50% of the valuable nutrients of milk. The membrane-based separation process is one of the most fascinating technologies for concentration and purification of whey proteins in the dairy industries; using this technology makes fewer damages to the nutrients of whey. In addition, separation of the valuable compounds of whey makes less environmental problems. In this study, three different nanostructure PES hollow fiber membranes with different characterization and pore sizes have been used and their intrinsic resistances were measured; the effect of temperature and pressure on fouling resistances and the effect of temperature on the permeation flux, protein rejection, and lactose permeation were studied. The results showed that permeation flux increases with increase in temperature. The intrinsic resistance and fouling resistances of the membranes increase with a decrease in pore size. The fouling resistance increases by pressure even though the intrinsic resistance of the membrane doesn't change.

Membrane systems are widely used due to their many advantages. The membrane is used for gas separation. In this study, improvement of gas separation properties in the alloy membrane of polyacrylonitrile (PAN) and polysulfone (PSF) was studied by adding aluminum oxide nanoparticles. By addition polysulfone to polyacrylonitrile membrane, the best combination of alloy membranes percentage was obtained. Then, a sol-gel method for making Nano-composite membranes was studied. All membranes were prepared using the solvent evaporation method. The ratio of polymers in the mixed matrix was considered at the rate of PAN 100%, PSF 100 %, (PSF 5%-PAN 95%), (PSF 10%-PAN 90%), (PSF 15%-PAN 85%). Aluminum oxide nanoparticles were placed on the membrane with weight percentages of 2. 5, 5, 10, 15, and 20. To study the membrane, SEM and FT-IR analyses were used. By adding aluminum oxide nanoparticles to the membrane at the weight percentage of 10% and measuring the rate of leakage, it was observed that the leakage rate of carbon dioxide, oxygen, nitrogen, and methane gases increased by 146%, 159%, 166%%, and 54%, respectively, compared to the membranes without aluminum oxide nanoparticles. Tests showed that the optimal amount of adding aluminum oxide to improve the properties of the membrane is 10% of the weight percentage.

Trivalent nitrogen compounds are almost tetrahedral so that the lone pair occupies one of the tetrahedral positions. This, in turn, causes the inversion of these tetrahedral molecules. In this study, N-inversion in N-phenylaziridines (without substituent and with a substituent group (F, Cl, Br, CN, NH2, NO2, OH, and Me) in both para and meta positions of the phenyl ring) was studiedby the Gaussian 09 program. The optimum geometric structures of initial and transition states were obtained using ab initio calculations at the MP2\6-31G* level of theory and in both the gas phase and CH2Cl2 solvent. The effects of the different substituent groups on kinetic parameters were studied and then Hammett curves were plottedthrough the Hammett equation. With respect to the obtained rate constants and Hammett curves, it can be concluded that the electron-withdrawing substituents increase the rate of inversion due to withdrawing of nitrogen lone pair towards themselves, and therefore, generating a stabilizing resonance current. Conversely, the electron-donating substituents decrease the rate of inversion. The transition state in an inversion of a n-phenylaziridine molecule with para-substituted NO2group has the lowest activation energy.

In this research, ternary electrolyte system “ KCl + H2O + Serine” was investigated as thermodynamics aspect and based on Pitzer ion-interaction model. For this reason, determination of mean activity coefficients was performed by a potentiometric method and using galvanic cell without a liquid junction. The galvanic cell used was type as K+-ISE | KCl (m), Serine (%wt. ), H2O (100-%wt. ) | AgCl-Ag and the ion selective electrodes used were potassium ion selective electrode based on PVC and Ag-AgCl electrode that both of them were created in our laboratory. Measurements were carried out at T = 298 K and ionic strength range from 0. 0017 to 2. 5 molal for different percentage mass fraction of serine (%wt. = 0, 2, 4, 8 and 10) in solution. Thermodynamic investigations were performed by correlation of experimental potentiometric data with Pitzer ion-interaction model. In this work, by determination of mean activity coefficients of KCl electrolyte and comparison of them with the calculated amounts by Pitzer ion-interaction model, the application of the pair electrodes was investigated. Then, by correlation of mean activity coefficients determined with the mode, the adjustable Pitzer parameters (β o, β 1, and CØ ) were determined. In the long run, thermodynamic properties such as osmotic coefficient (Ø ) and excess Gibbs free energy (GE) were calculated by using the adjustable parameters based on Pitzer ion-interaction model. The results showed that the Pitzer ion-interaction model was successfully for a description of the investigated system.

In this research work the effect of droplets size on drop-drop and drop-interface coalescence of sunflower oil in water emulsion in a non-uniform electric field has been in two systems “ drop-drop and drop-interface coalescence” under ramp-ac and square-ac waveform types investigated. In this work, the process was operated with the utilization of a batch cylindrical separator under high voltage condition. In this experimental work were of a constant frequency (60 Hz) and constant amplitude magnitudes 200 V/mm studied. Using a speed camera two patterns of coalescence for both drops-drops and drops-interface was observed: complete coalescence, incomplete coalescence. The middle size of droplets was observed between 200 and 650 micrometers using “ Photron Fastcam viewer and image-pro software” .

In this study, firstly bentonite from Tang-e Quchan mine was collected, and its montmorillonite content was mostly separated from impurities. Montmorillonite was used in the synthesis of Al-PILC to investigate the influence of pH during the intercalation process on properties of pillared clays. The pH of intercalation was initially 4. 1, and Al/Clay ratio was determined 4 mmole/g clay. The pH of the intercalation stage was changed by adding some droplets of dilute hydrochloric acid. Al-PILCs were heated at 400 ° C and were characterized using X-ray diffraction and adsorption/desorption isotherms of nitrogen. The results showed that at pH values between 3. 7 and 4. 1, Al-PILCs had an acceptable basal spacing and surface area. The highest surface area and the basal spacings were 18. 04 0A and 160 m2/g, respectively which was obtained for pillared interlayered clay with intercalated pH of 3. 8

In order to determination of flotation kinetic and particle size effect on it, flotation tests were conducted on a Gilsonite sample of Kermanshah state. Therefore, rougher and cleaner flotation tests through the oil collector-MIBC (Methyl Iso Butyl Carbonyl) frother, Gasoline collector – Pine oil frother and one test without any collector and frother, was done. Concentrates obtained from the tests weighted and ash analysis was taken from them, also all of the concentrates were grading, in different intervals. Then, for each test, drawn recovery – time graph and were fitted by using different first-order kinetics model. According to the graph observed that the results of all tests have high compliance with first order classic model. Kinetics constant calculated with the classic model are as follows, the rougher tests, oil collector – MIBC frother 0. 0303, Gasoline collector – pine oil frother 0. 0301 and test without any collector and frother is 0. 0161. Also, the amount of k respectively the above collector and frother 0. 0168, 0. 048, 0. 013 was calculated in cleaner tests, then the retention time and flotation cell volume according to k calculated. In this research, studied the relationship between flotation rate constant, maximum recovery and particle size too. The results show that maximum flotation recovery and flotation rate in rougher tests belongs to flotation test without any collector and frother with a particle size in rang-850, +500 µ m. as well as, in the cleaner test, maximum flotation recovery and flotation rate related to the test with Gasoline collector and pine oil frother with-850, +500 µ m particle size.

Cyanide is the most commonly depressant for pyrite and sphalerite in lead flotation. Although cyanide is a common and strong depressant, but its usage causes environmental pollution and serious hazards. In this study the performance of three chemical substances include sodium sulphide, sodium metabisulphite and sodium sulphite were investigated in lead flotation of Irankooh ore. Since in Bama plant, sequential flotation is being done and the tailing of lead circuit goes to zinc circuit, the effect of cyanide alternatives on zinc flotation was also investigated. After finding the optimal amount of each chemical substance and comparing its performance with cyanide, it became clear that sodium sulphite can be a suitable alternative for cyanide. In natural pH (8. 5) with using 600 g/ton sodium sulphite instead of cyanide in lead flotation of Irankooh ore, lead recovery has increased 2. 5% and zinc recovery in lead concentrate decreased 0. 7%, against iron recovery increased 1. 2% and lead grade decreased 1. 5%. In this condition, sodium sulphite had positive effect on zinc flotation and in comparing with the optimal amount of cyanide, Zn recovery and Zn grade increased 1. 5% and 1. 2% respectively. If lead flotation is done with this amount of sodium sulphite and in pH=9. 5, the performance will be quite better and in comparing with current plant performance, in addition of increasing 2. 8% in lead recovery, lead grade will be increased 2%.

In this study, optimization of a waste heat recovery system (WHRS) that works by an organic Rankine cycle (ORC) from a cement plant is investigated. Energy and economic models of the system are presented. The energy model and thermo-economic model are developed according to the first law of thermodynamics and specific exergy costing method respectively. To design ORC, there are two major issue that are considered here. One issue with recperator and another without that. The first law of thermodynamic as an objective function to maximize the efficiency and economic objective function to minimize the total cost of electricity produced are used. Optimization methodology is based on genetic algorithm and performed by EES software. Also in order to determine the effect of the fluids on the cycle, three fluid included R245fa, R123 and n-pentene are examined and their results is discussed. The results showed that in the case of thermodynamics optimization without recuperator, R123 with 17. 76% has the highest efficiency compared with the other fluids and with recuperator versus R123 with 20% is the best fluid. Moreover in thermoeconomic optimization R123 has the lowest total production cost compared with the other fluids with 0. 199€ /hr and 0. 315€ /hr in cycle without recuperator and with recuperator respectively. Here, it can be concluded that for the thermal recovery of medium-temperature sources, in thermodynamic optimization and thermoe-conomic optimization, R123 can be identified as a good choice for ORC cycles.

Development of Carbon Capture and Storage (CCS) technologies in saline aquifers is a tool to reduce environmental effects of CO2 emissions and climate change. Dissolution of CO2 in water provides an option for storage in saline aquifers. When CO2 dissolves in the water, the density of the solution increases. Then it may cause natural convection which in turn, increases the rate of dissolution and safety of the storage. In this paper, dissolution process and storage of CO2 in saline aquifers is studied. Here, the main purpose is to investigate the effect of porosity and permeability and anisotropicity of reservoir rock on dissolution process, onset of natural convection, time of maximum Sherwood number. To this end, numerical simulation of convective mixing in both isotropic and anisotropic reservoirs has been reported. The results show the three effective period of CO2 storage in aquifers. Comparisons of the results reveal that permeability has significant effect on the onset of convection and convection mixing process. Therefore it is one of the main factors that should be considered in choosing the storage site.

Biofouling is a process in which microorganisms grow and proliferate on the surface. Biofouling is a problem made by biofilm. This kind of fouling occurs in a wide range of industrial process and causes problems for the high-priced process, in particular. In different industries, it has been worked out to deal with this issue, separately. In all of them, the main problem is the biofilm formation. These days, many marine autonomous environment monitoring networks are set up in the world. Owing to the intense technological development of in situ autonomous monitoring systems, the biofouling problem for such systems has been a technological one which needed to be solved. Consequently, such systems without efficient biofouling protection are hopeless. Localized electro-chlorination biofouling protection is actually a promising and an advanced solution for in situ oceanographic sensors since many successful in situ results have been obtained and sensor manufacturers can integrate into their instruments a compact, simple, robust and low energy requiring a solution. This protection must be applied to the sensors and to the underwater communication equipment based on acoustic technologies. This paper presents the results obtained in the laboratory and at sea, with various instruments, protected by a localized chlorine generation system.

In this study, the conversion of standard synthesis gas to linear hydrocarbons is investigated in a single tube Fischer-Tropsch reactor using computational fluid dynamics. For this, a precise two-dimensional pseudo-homogeneous model includes momentum, mass, and energy conservation equations along with species and reaction kinetics relations was developed and numerically solved by computational codes. The shell and tube reactor was filled with spherical cobalt-based catalysts. The operating condition was as follows: coolant temperature: 555 K, pressure: 17 bar and inlet synthesis gas molar flow rate: 0. 0355gmole/s. The values of carbon monoxide and hydrogen conversions, hydrocarbon productions, pressure drop and fluid temperature on the reactor axis was analyzed. The simulation results were validated by comparison with experimental data. The implemented mathematical model predicted the conversion of carbon monoxide and hydrogen equal to 46% and 49%, respectively that was overpredicted in comparison with experimental ones. In the case of reaction products, maximum error was occurred in the propane production rate, 14%, which indicates a good agreement between mathematical results and experimental data.

In this study, the Scanning Mobility Particle Sizer (SMPS) was constructed and used to determine the particles size distribution of submicron aerosols. SMPS Spectrometer is widely used as the standard method to measure airborne particle size distributions. This particle sizer is also routinely used to make accurate nanoparticle size measurements of particles suspended in liquids. The SMPS consists of the constant output atomizer, the particle charge neutralizer, Differential Mobility Analyzer (DMA) and Condensation Particle Counter (CPC). Each part of this system was designed and constructed separately and then primary experiments were done. In the next step assembling of all devices was done to create a SMPS system. In this system, the Polydispersed aerosols were created from the atomizer inside the diffusion drier tube to eliminate their humidity. The polydispersed aerosols exiting the drier were passed through the neutralizer to obtain a known charge distribution. Then the aerosol stream was classified by the DMA at a selected voltage to extract a known particle diameter. The exiting particles from the DMA were led to the CPC in order to count particles number and to measure the size distribution. Calibration of SMPS performance by monodispersed particles with 100 nm size. This method is independent of the refractive index of the particle or fluid and has a high degree of absolute sizing accuracy and measurement repeatability. High-resolution data up to 250 channels, broad size range (from 1 nm to 1, 000 nm), fast measurements (complete size distributions in 10 minutes) and wide concentration range from 1 to 107 particles/cm3 are some advantages of this instrument over the existing systems.