نشریه شیمی و مهندسی شیمی ایران
سال چهل و دوم شماره 3 (پیاپی 109، پاییز 1402)

Porphyrins can be widely considered as active site biocomplexes, while biomimetic-based synthetic metal porphyrins can be used as pseudo-enzymes. A system consisting of a metal porphyrin-cysteine complex and a “polyethylene glycol (PEG)” polymer or a mixture of the active surfactants "sodium dodecyl sulfate and dodecyl triethyl ammonium bromide (SDS/DTAB)" was used for native-chloroperoxidase model. Native chloroperoxidase could have the function of peroxidase, ie oxidation of substrates at different pHs. In the absence of a suitable substrate, chloroproxidase decomposes hydrogen peroxide indicating catalase activity. Metal-tetra (2-pyridyl) porphyrin (M-TPP), which is more resonant, is more potent than heme (as the native-enzyme active site) in its pseudo-peroxidase and catalase activity. Fe-TTP has the highest peroxidase activity among metal-porphyrins with central metals including iron (III), manganese (III) and zinc (II). The triple component: "Fe-TPP-cysteine-PEG" is most effective by reducing the Michaelis-Menten (KM) parameter. It is observed that the hydrophobicity of porphyrin increases with the change of the central metal to iron (III), manganese (III) and zinc (II), respectively. In this case, the hydrophobicity of the active site of the peroxidase-like nanozyme is a potential for more hydrophobic substrate (guaiacol) to enter the reaction cycle, resulting in greater Fe-TPP activity and efficiency than other M-TPP complexes. In the next step, to design the catalase biocatalyst, Mn-TPP has the highest catalase activity among other metal-porphyrins mentioned. The triple component: "Mn-TPP-cysteine-SDS/DTAB " is most effective by reducing the Michaelis-Menten (KM) parameter. Transmission electron microscopy shows M-TPP-cysteine-PEG nanozymes as multi-holes hydrogel colloids, compared to M-TPP-cysteine-SDS/DTAB single-hole vesicle catalyst, which indicates a higher efficiency through the higher specific surface area for effective treatment of peroxidase nanozyme with organic substrate.

In this paper, Mn2+-doped iron oxide nanoparticles/reduced graphene oxide (Mn-IONs@RGO) nanocomposite are fabricated through an electrochemical synthesis procedure for the first time. The electrosynthesis procedure is based on the electrochemical growth of IONs onto the RGO plates electrophoretically deposited on the cathode electrode. X-ray diffraction pattern of the prepared nanocomposite revealed its magnetite crystal structure. For the prepared Mn-IONs@RGO nanocomposite, particle morphology of IONs, Mn2+ cations doping in their crystal structure and presence of reduced GO plates were confirmed through FE-SEM observations, EDS as well as FT-IR analyses. Mn-IONs showed spherical particles with 20-25 nm in size and elemental composition of 71.36 wt% iron, 7.71 wt% manganese and 20.93 wt% oxygen. It was also found that 59.15 wt% iron, 8.42 wt% manganese, 23.67 wt% oxygen and 8.76 wt% carbon are presents within the composition of the synthesized Mn-IONs@RGO sample. The presence of Mn and C in the composition Mn-IONs@RGO revealed doping of IONs with Mn2+ cations and formation of Mn-IONs particles onto RGO layers through electrochemical deposition route. The superparamagnetic nature of the fabricated nanocomposite was confirmed through M-H curve and magnetic data obtained by vibrating sample magnetometer (VSM) analysis. The Mn-IONs@RGO nanocomposite showed magnetic properties of Ms=31.86 emu g–1, Mr=0.07 emu g–1 and Hci=2.29 G.

Magnesium ion rechargeable batteries are useful for storing electrical energy because the abundance and energy density of magnesium is higher than lithium. In this research, the primary structures of the (4, 4), (5, 5) and (6, 6) single-walled carbon nanotubes were optimized using the M06-2X method and the 6-31g(d,p) basis set using Gaussian 09 program package. Then, the interaction of magnesium ion with these structures was studied to evaluate their ability to make magnesium batteries. The results show that the complexes created from these structures have good binding energies and the larger the outer diameter of the nanotubes, the more favorable the binding energy. In fact, the energy gap of these nanotubes decreases with the increase of the diameter of the nanotubes and affects their binding strength to magnesium ions. On the other hand, boron nitride nanotubes corresponding to carbon type were also optimized with a similar method and the interaction of magnesium ion with these structures was also investigated. The results show that boron nitride nanotubes with smaller outer diameters form complexes with higher binding energies with magnesium ions. In general, both types of these nanotubes are good options for preparing the anode material in magnesium ion batteries. Finally, increasing the binding energy of their complexes with magnesium ions is associated with increasing battery voltage.

In this study, films consisting of TEMPO-oxidized cellulose nanofibers (TOCNF) prepared from eucalyptus and graphene oxide (GO) were prepared by casting-evaporation method. The morphological structure, thermal stability and mechanical properties of the nanocomposite films were investigated by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and tensile mechanical tests. The results obtained from the X-ray diffraction spectrum, FTIR spectrum and SEM observations revealed that TOCNF and graphene oxide were able to form nanocomposite films with homogeneous structure in low-weight percent of graphene oxide. Compared with films of Tempo-oxidized cellulose nanofibers (TOCNF/GO0%), the mean tensile strength of nanocomposite films consisted of 1.5 wt% of graphene oxide (TOCNF/GO1.5%) increased to 19%, which was not statistically significant. In addition, the mean tensile strength of nanocomposite films consisted of 3wt% of graphene oxide (TOCNF/GO3%) decreased to 14.5%, which was not statistically significant. The results of TGA showed that the thermal degradation temperature of TOCNF/GO0.5%, TOCNF/GO1.5% and TOCNF/GO3% nanocomposite films compared to the film of TOCNF/GO0% slightly changed towards lower temperatures.

Biodegradable films based on corn starch and bovine gelatin were produced using a co-rotating twin screw extruder and water and sorbitol, both as plasticizers. To enhance hydrophobicity, two reactive methods were employed: one, chemical bonding of paraffin wax via maleic anhydride, and the other, acetylation through acetic anhydride. In both methods, the extruder served as a reactor. Next, biodegradable films were cast from binary starch/gelatin, and ternary starch/gelatin/paraffin-grafted starch, as well as starch/gelatin/acetic anhydride-grafted starch blends, with the same extrusion process. The films were evaluated and compared in terms of mechanical and barrier properties against moisture, contact angle, water absorption, and water vapor permeation. Results revealed that introducing paraffin-grafted starch into the starch/gelatin blend improved hydrophobicity according to three criteria: a 28° rise in water contact angle, a 9 percent decrease in water absorption, and a 4.2 percent lessening in water vapor permeation, while the mechanical properties were comparable to the binary starch/gelatin blend. On the other hand, in films from starch/gelatin/ acetic anhydride-grafted starch compared to starch/gelatin, the contact angle increased by 21° and water absorption decrease by 4.5 percent, but the mechanical properties were deteriorated, and water vapor permeation elevated by 3.5 percent.

One of the solutions proposed with the development of nanotechnology and electrospinning for the development of a new generation of membranes is the use of nanofibers for the preparation of porous membranes. These nanofibers can also be prepared as nanocomposites and the performance of membranes is greatly improved by adding nanoparticles. In this study, nanofiber nanocomposite membranes were made of polyphenylene sulfone by the electrospinning method. Graphene oxide and polyacrylamide-modified graphene oxide were used as additives in nanofiber membranes. To modify graphene oxide, acrylamide monomer was polymerized on the surface of graphene oxide using the live radical polymerization method. According to the studies, graphene oxide modified with polyacrylamide has not been used as an additive in the electrospinning method and its effect on membrane performance has not been studied. Graphene oxide and synthesized membranes were identified by various analyzes and it was found that the addition of modified graphene oxide to the membrane improves properties such as hydrophilicity and pure water flux, so that the contact angle of water in membranes containing 0.5 The percentages of graphene oxide and modified graphene oxide decreased by 9 and 21 degrees, respectively, relative to the membrane without additives. The swelling in these membranes increased by 110 and 175% compared to the blank membrane, respectively. Pure water flux was obtained in these membranes 221 and 187, which was higher in the empty membrane. The efficiency of the membranes was studied by removing salts, dyes, and heavy metals, and the results showed that nanocomposite membranes can remove these species more effectively. To. In the removal of salts and heavy metals, the membrane with 0.1% of graphene oxide had an optimal performance and the removal of optimum membrane dyes with 1% of graphene oxide was modified.

A variety of polymer inclusion membranes (PIMs) based on the poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), cellulose triacetate (CTA) and poly(vinyl chloride) (PVC) polymers with different proportion of dicyclohexano-18-crown-6 (DC18C6) as extractant, 2-nitrophenyl octyl ether (NPOE) as plasticizer were fabricated. PIM containing 45% PVC, 20% DC18C6 and 35% NPOE was selected as the optimum PIM composition because of their satisfactory physical, mechanical and extraction properties. The effect of parameters affecting the extraction process such as pH, extraction time, type and concentration of electrolyte and initial concentration of Cr(VI) were investigated and its shown that the PIM were able to extract 57% of chromium ions from 50 mL solution containing 2×10-4 mol/L of chromium(VI) and 1.2 mol/L HCl in 22 h. The maximum capacity of the selected PIM for extraction of chromium ions was 7 mg of of Cr per 1 g of membrane. The selectivity of the PIM towards Cr(VI) was tested in the presence of Zn(II), Cu(II), Fe(II), Cd(II), Ni(II) and nitrate ions and indicated that the PIM can extract selectively V(V) from the mixtures containing these heavy metal ions. The PIMs were used successfully for extraction of Cr(VI) from various water samples. The isotherms and kinetics of the processes were well described by Dubinin Radushkevich and pseudo second order models, respectively. These analyses revealed the process might be chemical processes.

In this research, 32 layered reduced graphene oxide (rGO) nanosheets with carbon-defects, as a nano-adsorbent, were designed through the one-pot sono-solvothermal method. The properties of this nano-adsorbent were determined using various analyses such as XRD, Raman, FESEM, 3D analysis, TEM, EDS, FTIR and UV-Vis spectroscopy analyses. The results revealed that rGO nanosheets well formed during sono-solvothermal process due to the efficient reduction of graphene oxide. So that, according to the results of Raman analysis, the reduction of GO to rGO as well as the creation of structural defects were confirmed. Besides, in view of the UV-Vis upshots, it was observed that a shoulder peak around 300 nm of graphene oxide spectrum, belong to the electrons transition from n to π* of C=O band which is existed in the functional groups, was disappeared in the rGO spectrum. This nano-adsorbent was evaluated in the elimination of the ciprofloxacin (fluoroquinolone antibiotic) as a model pollutant of emerging contaminants category. On the basis of experimental outcomes, the maximum adsorption efficiency of ciprofloxacin antibiotic was obtained by rGO (98.9%) during 120 min. Moreover, the study of adsorption isotherms showed that the adsorption process is consistent with the Friendlich adsorption isotherm.

In this study, processed chicory leaf powder was used as a natural adsorbent to remove cobalt ions from aqueous media. Natural adsorbents were characterization by several methods include X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform spectroscopy (FTIR), Brunauer-Emmet-Teller (BET) and Particle size analyzer (PSA). A set of experiments was performed to detect the optimal conditions and to investigate the effects of various parameters such as initial concentration, contact time, adsorbent dose, solution pH and temperature on the percentage of removal. The optimal conditions for cobalt removal were: pH = 6-8, contact time 20 min, adsorbent dose 20 mg and initial concentration 15 (mg L-1). Adsorption data showed that the adsorption process is more compatible with Langmuir's isotherm. The kinetic data were consistent with the quasi-second-order model with a valid correlation coefficient. Calculation of thermodynamic values ​​showed that the adsorption process is spontaneous, with decreasing entropy and exothermic. Finally, the introduced sorbent was compared with a strong adsorbent such as carbon nanotubes doped with silver nanoparticles (Ag2O-MWCNT). The optimal conditions for the removal of cobalt ions by the processed synthetic adsorbent were: initial concentration of 10 mg L-1, contact time of 40 min, amount of adsorbent 30 mg and pH = 7. Adsorption data showed that the adsorption process for cobalt ions is compatible with Freundlich's isotherm. The kinetic data were consistent with the quasi-second-order model with a valid correlation coefficient. Calculation of thermodynamic values ​​showed that the adsorption process was spontaneous and exothermic. The results of this comparison show that the introduced natural adsorbent performs even better than the synthetic and expensive adsorbent and provides a promising outlook if further processing and modifications are performed on this adsorbent.

In this study, TiO2 and Fe2O3 nanoparticles were used in enhancing CO2 absorption and stripping. For this regards, mentioned nanoparticles at different concentration were applied to 10 wt.% MDEA solution for CO2 absorption/desorption at a bubble column. Also, the Zeta potential analysis were studied to evaluate of all nanofluids stability and the experimental results of CO2 absorption and stripping was reported in presence nanoparticles. The results reveals that all nanofluids had better capability for CO2 absorption, TiO2 nanofluid with 0.1 wt.% concentration can increased CO2 absorption up to 28.4%, that it had highest performance than the other nanofluids due to more stability. In addition, the experimental tests of regeneration were shown lower ability of Fe2O3 nanoparticles on CO2 stripping than the TiO2 due to lower stability. Accordingly, TiO2 and Fe2O3 nano fluids at 0.05 wt.% concentration and 70oC regeneration temperature were lead to raising CO2 desorption as 25.8% and 24.5%, respectively.

In this research, the interaction of boron nitride (6,6) nanotubes with a length of 8 nm with vitamin B6 (pyridoxal phosphate) was theoretically investigated and the effects of electron destabilization, dipole-dipole interactions and steric repulsions on the structural and electronic properties and The reactivity of vitamin B6 (pyridoxal phosphate) in the presence of single-wall boron nitride (6.6) nanotubes with a length of 8 angstroms was studied using density functional theory quantum mechanical calculations at the B3LYP computational theoretical level and G* 31-6 basis series. . In order to determine the electrical conductivity and chemical behavior of boron nitride nanotubes in reaction with vitamin B6, electron energies, dipole moments, energy gap of homo-lomo molecular orbitals, chemical hardness (η), electron chemical potential (μ) And Mulliken's electronegativity (χ) and adsorption energy (EAd) were investigated in the gas and solvent phases. The results showed that the adsorption energy in the gas and solvent phases is -12.962 and -7.895 kcal/mol, respectively, which shows that the adsorption reaction is feasible in both phases in terms of energy. In the gaseous phase, the energy gap in the encapsulated vitamin B6-boron nitride nanotube mixture (3.517 Eg= electron volts) has decreased compared to the energy gap in the vitamin B6 molecule alone (4.561 Eg= electron volts). In the vitamin B6-boron nitride nanotube encapsulated mixture, with the reduction of the Eg energy gap, the hardness parameter has decreased, the softness parameter has also decreased, and the electronegativity and electrophilicity values ​​have increased.

Superparamagnetic iron oxide nanoparticles (SPIONs) with Fe3O4 molecular composition were considered for the study of protein interactions and drug delivery. Considering that SPIONs play a significant role in nanomedicine and drug delivery systems, investigating the interaction between SPIONs and a model protein and its structural and functional changes can be enlightening in scientific research. SPIONs with sizes of 20, 50, and 100 nm were selected. The UV-visible spectroscopic study showed the interaction between protein-nanoparticles. Rotational exponential imaging was used to measure the changes in the secondary structure of lysozyme in interaction with SPIONs. A significant reduction in the helical structures of the protein was observed. Protein fluorescence quenching analysis was used to understand the nature of protein-nanoparticle interaction. The interaction of SPIONs and lysozyme showed a combination of dynamic and static quenching. The activity and enzymatic properties of lysozyme attached to SPIONs were measured compared to free lysozyme. The activity decreased dramatically in all sizes of SPIONs, but the Km changed under different reaction conditions.

In this study, the antioxidant activity of alpha-tocopherol, α-TOCO, one of the eight forms of vitamin E with CCl3O2 radical using density functional theory, DFT, and conductor-like polarizable continuum model, CPCM, at the B3LYP/6-31G** level of theory and three different phases of gas, oil and water have been studied. Interaction energy calculations show that there is a gravitational force between the radical and α-TOCO and their values in the oil and water phases are more than the gas phase. Mechanisms study of electron transfer, hydrogen atom abstraction, and radical addition show that the radical addition process is more thermodynamically desirable than other reactions and that the oil and aqueous phases are both suitable for this type of process. The values of the calculated reactivity quantities show that α-TOCO tends to oxidize against radicals, that this tendency is more in the aqueous phase than the others. Also, by radical adsorption on α-TOCO in each phase, the antioxidant property of α-TOCO decreases and its electroaccepting increases. The results of TD-DFT calculations show that the maximum absorption wavelength, λmax, and the corresponding oscillator strength, fmax, for α-TOCO in the oil phase are greater than those in the gas and aqueous phases. λmax and fmax change significantly by radical adsorption on α-TOCO, and in the oil and water phases, λmax of the complex is approximately equal to the wavelength of red light. The results of calculations of atoms in molecules, AIM, show that the interactions between α-TOCO and radical in all three phases are of the type of hydrogen bond and van der Waals, with the difference that the number of bonds and the strength of the bonds are reduced from the oil to water phase and from water to gas phase, respectively. This result corresponds to the calculated values for the interaction energies.

Rising global warming and the growing need for energy are important issues that lead to the proliferation of renewable energy. The aim of  this project was to investigate the effect of adding Cadmium sulfide and Zinc sulfide in Copper(II) sulfide and Lead(II) sulfide to improve the sensivity by Successive ionic layer adsorption and reaction method in light and dark conditions. The best sell made during this project Cu sheet /8CuS/2CdS / 8 PbS  (0.5 M). The largest difference between the current intensity in the dark and  light for this cell in the potential of one volt is 14 mA. SEM images of the cell showed that the semiconductor particles were in the nanometer range. The photoelectrochemical properties have been investigated using electrochemical techniques of chronoamperometry, cyclic voltammetry and chronopotentiometry.

In this research, the activity and potential energy effect of ring pressure in simple 10-7 membered cycloalkynes in reaction with nitrile oxides, nitrile sulfides and triazoles have been studied by DFT method. Structural properties, thermodynamic and kinetic data such as reaction free energy changes (ΔrG), transition state free energy changes (ΔG*) and reaction rate constants (k) were obtained at 298 K temperature and the effect of substitution groups (R) in dipoles (R- CNO, R-CNS, R-N3) have been investigated on the reaction rate. The results show that by reducing the size of the ring and the bending of the triple bond and as a result of increasing the potential energy of the ring pressure in cycloalkynes, ΔG* of the zygotic ring reaction decreases. Also, the rate constants and free energy changes of the reactions increase with the reduction of the ring size.

A highly efficient and sustainable procedure was described for the production of amidoalkyl naphthols using graphene oxide substituted 2-aminobenzothiazole which was activated by phosphoric acid (GO@ABTZ.H3PO4), catalyst. The synthesis was achieved using aldehydes, 2-naphthol, and acetamide (or urea) in the presence of catalyst through a one-pot three-component process without solvent. This eco-friendly catalyst managed to efficiently proceed organic synthesis processes. The proposed catalyst exhibited several advantages including cost-effectiveness, being non-metallic, providing green and environmentally-benign conditions, easy storage, facile handling, and durability. Moreover, the applied procedure has several priorities such as short reaction times, solvent-free conditions, simple work-up, and high yields. The stability and recoverability of the catalyst were also examined in five cycles which showed no considerable loss of activity.

The addition of aromatic substrates to electron-deficient alkenes, which in many respects may be considered a Friedel– Crafts type alkylation, is a key reaction in synthetic organic chemistry for the formation of new C-C bonds. Indole and many of its derivatives are relevant units in many naturally occurring compounds, because of their pharmacological and biological properties. Due to the increased nucleophilic reactivity of C3 position of indole ring, it is often used for the subsequent transformations leading to different indole alkaloids. Here I report an efficient catalyst that can catalyzes the electrophilic substitution of indole with electron deficient alkenes. First, Cobalt tris(2-guanidinobenzimidazole), tri chloride (Co(GBI)33+, 3Cl-)  is prepared and then the reaction of indole with beta - nitrostyrene has studied. No product was detected, so the reaction conditions such as the solvents and the amount of catalyst were changed, but the results were the same. After that the chloride moiety of the complex were replaced with tetrakis[(3,5-trifluoromethyl)phenyl]borate (Barf-)anion and the reaction has run on different condition. Our results showed that Cobalt tri(2-guanidinobenzimidazole), tetrakis[(3,5-trifluoromethyl)phenyl]borate (Co(GBI)33+, 3BArf- ) catalyzes the reaction of indole with β - nitrostyrene and afforded the product in high yields. It is noteworthy to mention that using lipophilic anions such as BArf- [(B(3,5-C6H3(CF3)2)4-] , the catalyst could be solubilized in nonpolar solvents that do not compete with substrates for the hydrogen bonding sites.

A theoretical study at the B3LYP/6-311++G (d, p) level on tautomerization of 3,4-dihydropyrimidin-2(1H)-imine(3,4DHP) into 1,6-dihydropyrimidin-2-amine(1,6DHP) and 1,4-dihydropyrimidin-2-amine(1,4DHP) was performed at 298.15K. Two mechanisms have been considered for these processes: (i) one in which the hydrogen is directly transferred, mechanisms A, through TS13 and TS24 in two different pathways, called P(a) and P(b), respectively and (ii) another one in which a double hydrogen transfer takes place via TS1133, TS1234 and TS2244 by formation of the corresponding dimer, mechanisms B. The results associated with the gas phase reveal that overcame to TS13 and TS24, need high activation free energies of 38.31, 40.29 kcal/mol, respectively as a consequence of the strain associated with the formation of the four-membered transition state, while overcame to TS1133, TS1234 and TS2244, require much lower activation free energies, 7.01, 8.19 and 8.98 kcal/mol, respectively. To investigate the effect of solvent on the kinetics and thermodynamics of the tautomeric process in p(a) and p(b) paths, Implicit, explicit, and a combination of both implicit and explicit solvation models in various media (protic and aprotic polar solvents) have been considered. The results show that the use of a protic polar solvent reduces the energy barrier of the corresponding transition states in a very significant amount.

Domestic companies in metal and alloy production have faced many problems in providing the required energy. These companies often use traditional industrial furnaces, which consume a lot of energy, have a very negative impact on the environment. For this reason, the use of modern low-consumption processes for metal oxide reduction will be of great interest. In this research, the carbon bed of a new metal oxide reduction system operated under microwave heating is modeled. In this system, the carbon bed is responsible for the heating process and converts electromagnetic waves into heat. In this system, because the metal oxide granules are imbedded inside the carbon bed that converts almost all electromagnetic waves, the heating effects of metal oxides were ignored. Comparison of the modeling results with experimental data related to carbon bed temperature rising trend showed that the used model has good accuracy and the average error is less than 5%. Based on the modeling, it was found that the carbon bed temperature (excluding metal oxide granules) increased around 9% by increasing the microwave power from 1000 w to 1200 w. In addition, SiC had better performance compared to the carbon bed in terms of the rate of generated heat. It was determined that the maximum temperature decreased by increasing the carbon emissivity parameter and the final bed temperature increased by 9% after 15 minutes by changing the emissivity parameter from 0.95 to 0.65.

Protein products are currently one of the most perishable food sources that require the use of modern packaging methods such as smart packaging that can perform intelligent functions to increase shelf life, control changes and maintain product quality. The aim of this study was to provide a pH-dependent color sensor, simple, inexpensive and non-toxic to detect spoilage of protein materials during storage. Experiments were performed on the samples at both ambient and refrigerator temperatures. Watman paper impregnated with aqueous extracts of fruits and plants was used to make this sensor. The growth of microorganisms during storage of protein materials leads to the breakdown of chicken meat sausage proteins and the production of volatile amines, which accumulate in the packaging, causing the environment to become alkaline and change the color of the filter paper impregnated with the aqueous extract. These color changes were evaluated using CIELab imaging and thiobarbituric acid index measurement, total volatile nitrogen, total phenol, and changes in the appearance of the samples, all of which were consistent with the color change of the sensor as the decay process progressed.

Natural gas, petrochemical and some refinery feed streams have trace of mercury which threats the environment and human health. Moreover, brazed aluminum heat exchangers are susceptible to corrosive attack by this component. This study discusses adsorption performance of elemental mercury sorbents from simulated natural gas (SNG) by copper sulfide pported active alumina. All sorbents were characterized through XRD, BET, TEM, XRF, LECO carbon/sulfide analyzer. The simulated natural gas creates by evaporating the liquid mercury contained in a thermostat glass saturator at temperature of 60oC into a stream of pure nitrogen. These sorbents were loaded in a fixed-bed reactor and sulfided with a nitrogen gas containing 8 % mol of H2S at the temperature of 285oC overnight. Then, the effect of sorbent samples for removing mercury was tested at the temperature of 60oC, pressure of 1atm and SNG flowrate of 220 cm3/min, and in several steps in terms of time the results were reported. The characterization results of suitable sorbent showed its meso pore is higher and capacity is larger than other sorbent. Experiments have showed the suitable sorbent removed approximately 19 percent of mercury exist in SNG with respect to sorbent's weight.

In this study, the points of view of complete kinetics method, approximation of linear driving force and equilibrium method in the simulation of gas adsorption systems with the numerical calculation of differential quadrature element-increment method were investigated. So that, in the method of complete kinetics, all mechanisms including Knudsen diffusion, viscous flow, slip flow, molecular diffusion and surface diffusion are considered. In linear driving force approximation, mass transfer is expressed by a general mass transfer coefficient instead of all mass transfer resistances, and as a result, elapsed time of calculations is reduced. However, the approximation of the linear driving force is highly dependent on the average radius of the particle adsorbent, and increasing the particle radius causes more deviation from the complete kinetic point of view. In the equilibrium method, adsorption kinetics is not considered and concentration changes in the system are determined based on the equilibrium adsorption isotherm. The results show that with the increase in the radius of the adsorbent particles, the complete kinetic view will be a more appropriate method to describe the adsorption behavior. It was also observed that the overall mass transfer coefficient changes in the adsorption process, depending on the temperature and pressure conditions, so that an increase in temperature causes it to increase, and this dependence is more sensitive at low pressures. In addition, with increasing pressure, the overall mass transfer coefficient passes through a minimum value and then increases.

In this research, a hybrid renewable system based on the use of solar and oceanic thermal energy to produce power and hydrogen by using a flat plate solar collector was investigated from a thermodynamic and economic point of view. The objective functions investigated in this research were exergy efficiency and cost rate. Collector mass flow rate, collector area, turbine inlet temperature, and solar radiation intensity were considered as four decision variables, and the effect of these parameters on system performance and system exergy loss was investigated. The optimization of objective functions was done by the Nelder-Mead method. From single-objective optimization, it was concluded that the best system exergy efficiency rate is 7.31% and the system cost rate is 27.48 $/hour in the optimal state. From the sensitivity analysis, it was concluded that increasing the parameters of the collector area, solar radiation intensity, and turbine inlet temperature had a positive effect on the system performance, and increasing the mass flow rate parameter of the solar collector had a negative effect on the system performance. Also, from the analysis of the exergy loss of the system, it was concluded that the increase in the intensity of solar radiation, the area of the collector, and the mass flow rate of the collector increase the overall exergy loss of the system, but the increase in the inlet temperature to the turbine decreases the exergy loss of the system.

In this work, Fe3O4 and Al2O3 nanoparticles were used to investigate their effects on wax formation, morphological characteristics, and rheological behavior in a crude oil sample. For this purpose, differential scanning calorimetry, cross-polarized microscopy, and viscometry have been utilized as the main experimental techniques. It was observed that Fe3O4 and Al2O3 nanoparticles had the most positive effect on the wax appearance temperature (WAT) of the crude oil by reducing the WAT from 24 0C to 14 and 17.5 0C at 100 ppm, respectively. Addition of the nanoparticles into the crude oil caused deformation of wax crystals to more spherical and regular structures. In addition, presence of the nanoparticles prevented formation of the strong three-dimensional lattice of wax structures at high temperatures. However, superior size-dependent properties of the nanoparticles are responsible for controlling the growth of wax crystal nuclei and reduction of the WAT. Findings of this work reveal the potential of Fe3O4 and Al2O3 nanoparticles as efficient and low-cost additives for production, storage, and transportation of waxy crude oil.

With the existence of several natural gas perfuming systems, such as the bypass system and the injection system, for some reasons including the problems and limitations of the existing systems, it seems necessary to introduce a new perfuming system with less limitations. Currently, in the gas distribution system in the country, only the above two systems are used for gas aromatization. Since the injection system has a high maintenance cost and also the bypass system is limited to low capacities, it is very necessary to introduce a new system to aromatize the consumed natural gas. In this article, a new gas perfumer system has been introduced. The desired system is created by combining an ejector with a bypass system. In this article, the modeling of the combined system under study has been done and the effect of important parameters such as gas pressure (gas pressure in the upstream), mass flow rate of the odorant, gas temperature (temperature in the upstream), nozzle diameter and number of nozzles are also on the amount The compressed gas has been carried out to enter the mercaptan tank and absorb the required amount of fragrance according to the conditions. The results show that the diameter of the nozzle and the number of nozzles have no effect on the mass rate of gas flow required for the fragrance system. But the gas mass flow rate required for the aromatizer system is affected by the gas pressure and gas temperature upstream of the aromatizer system

CO2 injection processes are among the effective methods for enhanced oil recovery. A key parameter in the design of CO2 injection project is the minimum miscibility pressure (MMP). From an experimental point of view, slim tube displacements test routinely determines the MMP. Because such experiments are very expensive and time-consuming, searching for fast and robust methods for determination of MMP is usually requested. The Neural Network (NN) and Support Vector Machine Regression (SVM) were used to designs networks for estimation MMP. The Networks Trained by trusted data including independent variables. The validity of these new models were successfully approved by comparing the models results to the pure and impure experimental slim-tube CO2-oil MMP and the calculated results for the common pure and impure CO2-oil MMP correlations. The average accuracy of the predicted values for the neural network in terms of coefficient of determination (R2) and mean square error (MSE) are 0.9863 and 0.0018. These values for the SVM regression are 0.9870 and 0.0017, respectively. In addition, the new models could be used for predicting the impure CO2-oil MMP at higher fractions of non-CO2 components (Up to 100% for methane and 50% for hydrogen sulfide).

Ethylene is one of the most important basic materials in petrochemical industries. It is used as raw material in the production of many chemicals, such as polyethylene and ethylene glycol. The thermal cracking of hydrocarbons, such as ethane, is the most commonly used process for ethylene production. Thermal cracking furnaces provide the required energy for cracking ethane to ethylene. In this research, the cracking furnaces of the Morvarid petrochemical complex was simulated and controlled and sensitivity analysis were performed. For this purpose, firstly the unit was simulated in steady state using Aspen Plus® and after ensuring simulation accuracy, the results were used as the starting point for dynamic simulation in Aspen Dynamic® and the dynamic behavior of the unit was studied. The accuracy of this simulation was satisfactory in dynamic and steady-state forms, so that the average error of stream information compared to the design data were 0.42% and 1.15% for steady-state and dynamic simulation, respectively. Then the feed flow rate stepwise increased to 6.6% of the initial flow rate while the ethylene conversion was controlled at 38.5%. In order to achieve this conversion, the temperature of the thermal cracking furnaces increased to 1131℃ with increasing feed flow rate. With this changes, change of ethylene product flow rate was 0.86 of feedstock changes. Then, the change in the feed composition was investigated whilst the propane concentration in the feed stream was increased gradually as well as the ethane concentration was decreased by 10%. In this case, the mass fraction of propane in the feed flow was changed from 2.52% to 12.52%. Due to these changes and without changing the unit operating condition, finally, the ethylene flow rate decreased 3.3% compared to the primary state.

Control of the distillation tower is one of the main concerns in the design of chemical processes due to its high importance. Operational errors may occur in distillation towers for various reasons, leading to serious disruptions in process performance or the occurrence of undesirable incidents. In this research, an attempt has been made to use one of the existing validated models for the Tennessee-Eastman Process distillation tower in the MATLAB software to identify potential malfunctions in the tower's operation related to this process. Hotelling's T-squared test is employed for error detection. After detecting errors using the proposed diagnostic method, the type of fault can be determined. The presented method can accurately detect potential model errors within a short period (up to 0.1 hour).

Large-scale use of hydrogen requires precise risk control, which can be achieved through investing in a reliable risk analysis method. In the present study, to investigate the hazards caused by hydrogen with high pressure and temperature in the sorbitol production plant, the concept hazard analysis method and the qualitative risk analysis were used to identify the main hazards in this plant. Then PHAST 8.22 software was used to model the consequences of high-risk scenarios. Moreover, the risk assessment data of the International Association of Oil and Gas Producers was used to estimate the frequency of scenarios. The event tree analysis was used to estimate the frequency of the consequences of the defined scenarios. Finally, the vulnerable areas were recognized, and the number of casualties in the event of any of these consequences was estimated. Using the frequency vs. number of fatality (F-N) curve based on the risk acceptance criteria for hydrogen document, areas with unacceptable risk were identified. According to this diagram, the risk of the reactor and the compressor are in an unacceptable area. Therefore, the necessary measures in terms of structure, performance, or organization should be prioritized to reduce the risk associated with this two equipment.

In the last two decades, environmental pollution by heavy metals has increased, and the accumulation of these pollutants in aquatic ecosystems has brought many risks to the health of humans, animals, plants, and the environment. Cadmium and nickel can be mentioned as metals that have very toxic and carcinogenic properties. In this research, the isolation of bacteria from the steel industry factory in Sari, the effluent of the sausage factory in Golestan province, and the Lavij hot spring in Mazandaran, which have the ability to uptake heavy metals cadmium and nickel, were investigated. In the following, the optimization process of biological adsorption (the effect of parameters such as: temperature, concentration of metals, dosage of bacteria, pH...) was investigated. Based on the above results, the best isolate was used to remove these metals. Biochemical, morphological, and molecular findings have shown the closeness of the selected isolate to the genus Bacillus. According to the minimum inhibitory concentration test of the selected Bacillus bacteria, this isolate was resistant to a concentration of 1500 ppm of cadmium and 2200 ppm of nickel. The optimum pH for the removal of cadmium and nickel metals by the selected bacteria was 6.5 and 5.5, respectively, and the adsorption efficiency of cadmium and nickel metals was 0.72 and 0.63 mmol/g, respectively. The temperature for the removal of cadmium and nickel by Bacillus bacteria was about 45 degrees Celsius. The adsorption isotherm for both metals is similar to the Langmuir isotherm, which shows that the surface adsorption process is single-layer, and its kinetics is according to the second-order kinetic model, and the optimal amount of Bacillus bacteria biomass is about 1.5 g/liter. The selected isolate has suitable characteristics for use in real and industrial scale containing the mentioned metals.