Iranian Journal of Chemistry and Chemical Engineering
Volume:40 Issue: 1, Jan-Feb 2021

IIn this research, the cotton fabric was modified with nanosized zinc oxide (ZnO) by a simple and novel approach. The nanosized zinc oxide was prepared and deposited onto cotton fabrics by in situ method using zinc acetate dihydrate (Zn(OAc)2.H2O) as precursors and sodium hydroxide, with and without starch as a capping agent. The size and morphology of nanosized zinc oxide on cotton fabric in the presence and absence of starch were investigated. The samples were characterized by X-Ray Diffraction (XRD), Fourier Transform InfraRed (FT-IR) spectroscopy, Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray spectroscopy (EDS), Atomic Absorption Spectroscopy (AAS), and contact angle. The antibacterial activity of modified cotton was evaluated by measurement of the reduction of the gram-negative of Escherichia coli (E. coli) on the treatment of cotton. SEM images of treated fabrics were indicated that nanosized zinc oxide was well dispersed on the surfaces of samples. The results of the contact angle revealed the more hydrophobic character of treatment of cotton as compared with blank, which will have high potential applications in various fields.

Metal-Organic Frameworks (MOFs) are an important class of highly porous hybrid materials. A bismuth-based MOF was prepared under solvothermal conditions via the self-assembly of primary building blocks at 100 °C for 3 h. Bismuth oxide nanoparticles (Bi2O3 NPs) were prepared by calcination and thermal decomposition of a bismuth-based MOF at 550 °C for 5 h for the first time. The nanocomposite was prepared by poly (methyl methacrylate) (PMMA) as a polymer matrix and bismuth oxide NPs as fillers. The bismuth oxide nanoparticles were characterized by Fourier Transform InfraRed (FT-IR) for determination of functional groups, X-Ray powder Diffraction (XRD) for evaluation of crystal structure, Dynamic Light Scattering (DLS) for investigation of size and size distribution, Scanning Electron Microscope (SEM) for the presentation of morphology and size, and Energy-Dispersive X-ray Spectroscopy (EDS) for determination of chemical composition. Based on the results, the bismuth oxide nanoparticles were observed with spherical morphology and a particle size of 60 nm. The bismuth oxide nanocomposites were evaluated by X-ray dosimeter test in comparison to lead and aluminum and air adsorbents for X-ray shielding, Diffuse Reflection Spectroscopy (DRS) for UltraViolet (UV) blocking, and antibacterial activity against Salmonella bacterial. Based on the results, the X-ray shielding is 31.9% compared with the lead with a thickness of 0.25 mm and 81.53% compared with aluminum with a thickness of 3 mm for the bismuth oxide nanocomposite. This nanocomposite has 70% UV blocking with antibacterial activity and it can have a good potential for biomedical and industrial applications.

In this research, various organic additives (as a chelating agent) were used to prepare NiMo/ 𝛾-Al2O3 bimetallic catalysts. Then effects of additives and pH variation were studied on textural properties, morphology, and size of nanocatalyst particles, interaction, and loading of active metals on a support.  Additionally, this research evaluated the activity of catalysts and compared them with commercial and catalysts in the absence of additives. The metal oxide nanoparticles were prepared and impregnated on 𝛾-Al2O3 in-situ by using the wetness impregnation method, under conditions 60°C and calcination temperature 520°C. The supported nanocatalyst was calcined to remove the volatile materials and gases. The catalysts were characterized by TPR, BET, BJH, AAS, FT-IR, SEM, and XRD. The prepared nanocatalyst displayed the enhanced catalytic activity for the heavy oil hydrodesulfurization (HDS) containing 21 g/L sulfur. At the acidic pH, the activity of the catalyst was promoted by using EDTA compound as a chelating agent. The sulfur content of the feed was decreased up to 2 g/L at 380°C, 60 bar, and LHSV 1.5h-1 showing an efficient catalyst with the conversion of 90.47%.

In this work, polyvinylidene fluoride membranes were modified by introducing nanostructure TiO2/SiO2/POM hybrid fibers in the polymeric dope, to endow them with photocatalytic properties. For this purpose, initially, hybrid fibers were synthesized by electrospinning and calcination technique, and then these additives were incorporated into the membrane matrix. FT-IR and XRD analysis were used for the characterization of synthesized compounds. The FESEM manifests that the average diameter of the hybrid composite fibers is about 500 nm, and investigated membrane morphology. The properties of the prepared photocatalytic membrane were examined by several investigations such as pure water flux, contact angle, salt, and heavy metal rejection. Photocatalytic experiments confirm that membranes display a highly efficient and durable activity for the photodegradation of Methylene Bue (MB) and Humic Acid (HA). Experiments show that the prepared membranes have excellent stability under UV irradiation and can be used potentially for the separation of different components from water. The measurement accuracy and repeatability were determined by calculating the Standard Deviation and entered into Tables.

In this study, a simple and fast colorimetric assay based on the aggregation of gold nanoparticles (AuNPs) was achieved for the determination of μg/Lof tolyl triazole (TTA). The aggregation of AuNPs is due to the high affinity between gold surface and nitrogen atoms of TTA and intermolecular bonding formation between TTA molecules. The plasmon peak of AuNPs at 520 nm was decreased with the formation of a band about 620 nm owing to the aggregation phenomenon. The effective parameters on the peak shift such as ionic strength, pH of the sample, and AuNPs concentration was investigated. The proposed method is capable of determining TTA over a concentration range of 10-100 µg/L with a limit of detection of 5.0 µg L-1 based on the absorbance ratio at 620 nm to 520 nm. The relative standard deviation of the method was 3.0% and 1.5% for 20 and 80 µg/L, respectively. A comparison between the outlined method and the previously published methods for TTA determination has also been made. The obtained results from this study proved to be effectively successful in the determination of TTA in water.

In this work, stabilized Ni/Fe bimetallic nanoparticles (S-Ni/Fe NPs) were synthesized in the presence of starch as the stabilizing agent and characterized by FE-SEM, EDS, and XRD. The results showed that the S-Ni/Fe NPs were spherical in the shape and have a nearly uniform distribution with a particle size of 20-50 nm. Then, perchlorate as a persistent inorganic pollutant was destructed to chloride ion by the S-Ni/Fe NPs. The main factors controlling the removal of perchlorates, such as the initial pH of the solution, the dosage of the S–Fe/Ni NPs, initial perchlorate concentration, temperature, and reaction time were optimized by using an experimental design based on response surface methodology. Under the optimal conditions, perchlorate was destructed with an efficiency of nearly 100%. The kinetics for the destruction of perchlorate by the S-Ni/Fe NPs complied with pseudo-first-order characteristics. The rate constant (Kobs) and activation energy (Ea) for the destruction were obtained 0.0471 1/min at 343 K and 13.07 kJ/mol, respectively. Therefore, the present study offers a powerful bimetallic nanoparticle for the destruction of the environmental oxidant pollutants such as perchlorate from aqueous media.

In the present work, BaCe0.85Yb0.15O3-δ mixed metal oxide nanoparticles supplying strong acid sites and good hydrophilic nature were used for the first time to build organic-inorganic proton exchange membranes. Poly(vinyl alcohol) - BaCe0.85Yb0.15O3-δ (PVAYb) nanocomposite membranes were fabricated. Different analyses such as Scanning Electron Microscope (SEM), Energy Dispersive X-ray (EDX) spectroscopy, Fourier Transform Infra-Red (FT-IR) spectroscopy, and ThermoGravimetry Analysis (TGA) were used to characterize and study the structural properties of the obtained membranes. SEM and EDX analyses exhibited a homogenous dispersion of the nanoparticles in the nanocomposite membrane.  It was found that PVAYb1.5 had a better elemental distribution compared to PVAYb2.5 composite membrane. PVAYb nanocomposite membrane containing 1.5 wt.% of BaCe0.85Yb0.15O3-δ nanoparticles displayed a high proton conductivity value (64 mS/cm) at 70 °C operation temperature. The peak power density of 29 mW/cm2 was obtained with a peak current density of 210 mA / cm2 for as-prepared Proton Exchange Membrane Fuel Cell (PEMFC) equipped with PPYb1.5 nanocomposite membrane at 70 °C.

MgO doped ZnO and pure ZnO nanoparticles were successfully synthesized by the sedimentary method. The products were characterized by XRD, TEM, and EDX. XRD patterns showed that the doped nanoparticles had the same crystal structures as the pure ZnO nanoparticles. Pure ZnO nanoparticles had a larger lattice volume than MgO doped ZnO nanoparticles. The photochemical degradation of indole 3- butyric acid as a pollutant in aqueous solutions was investigated by both pure and MgO doped ZnO under UV light irradiation. The effect of different parameters such as indole 3- butyric acid concentration, photocatalyst amount, PH, oxidant concentration on degradation of I-3BA, and optimum condition was obtained.

The present work has for the main objective the elimination of the textile dye Maxilon Red (MR) by coupling two processes, adsorption on activated clay followed by photocatalysis over the wurtzite ZnO. The influence of the physical parameters like the initial pH, adsorbent dose of the activated clay, MR concentration, and temperature have been studied. The best adsorption yield occurs at neutral pH ~ 7 within 60 min with an adsorption percentage of 97% for MR concentration of 25 mg/L and an adsorbent dose of 0.5 g/L. The data were suitably fitted by the Langmuir model with a maximum adsorption capacity of 175 mg/g. To investigate the adsorption mechanism, the adsorption constants were determined from the pseudo-first-order, pseudo-second-order, and intraparticle diffusion models. It was found that the MR adsorption is well described by the pseudo-second-order kinetic. The thermodynamic parameters ΔH˚ = -17.138 kJ/mol, ΔS˚ = 32.84 J/mol.K, and ΔG˚=−6.419 to−7.329 kJ/mol with rising temperature from 25 to 50˚C indicated that the adsorption is exothermic and spontaneous. The second part of this work was devoted to the photocatalytic degradation onto ZnO under solar irradiation of the residual MR concentration, which remained after adsorption. In this respect, the effect of ZnO dose and MR concentration has also been investigated. The photodegradation rate reached 99% under irradiation within 90 minutes under the optimum conditions. The parametric study showed that the elimination is very effective by photocatalysis, based essentially on the in situ generations of free radicals •OH which are non-selective and very reactive. The present study shows that the activated clay is an effective low-cost adsorbent for the removal of Maxilon red from an aqueous solution.

Aqueous chlorination of Ponceau S dye (PS) was kinetically investigated through a classical method and under solar or UV radiations. For the classical method, the kinetics of PS chlorination was established by varying concentration ratios R = [Free chlorine (Cl(+I))]/[PS], pH, temperature, and bromide ions concentration. The decolorization reactions exhibited pseudo-first-order kinetics with respect to Ponceau S dye and their apparent rate constants (kapp ) increased when R increased, in fact, kapp reaches 0.205 min-1 when R=10. Important removal levels were obtained when pH= 10, 100% of decolorization obtained at only 5 minutes which means that the hypochlorite ion (ClO-) was more reactive than hypochlorous acid (HClO) for decolorizing PS dye. Otherwise, the apparent rate constant of PS disappearance increased with increasing medium temperature and led to the activation energy of 39.64 Kj/mol. When bromide ions were present in the medium, the decolorization of the PS solutions was more important than the simple chlorination when R=2.5 and at pH 7.20 following an oxidation result of bromide ions by sodium hypochlorite to hypobromite and/or hypobromous acid, the addition to the N=N double bond of dye is easier in the case of Br(+I) than Cl(+I). Under UV or solar radiations, and when R=1 and at pH 4.5, the decolorization rates of PS solutions were clearly increased in comparison with dark chlorination. Thus, the comparative order obtained in terms of apparent rate constant was kapp (Cl(+I)/UV)> kapp (Cl(+I)/Sunlight)> kapp (Cl(+I)). The disappearance efficiencies were 47.6%, 52.4% and 99.2% respectively when using dark chlorination, Cl(+I)/Sunlight and Cl(+I)/UV processes. Thus, it was clear that the advanced oxidation processes have proven to be more effective in terms of water treatment by chlorination. Thus, compared with dark chlorination, the enhanced decolorization of PS could be attributed to the formation of reactive radicals that adopt essentially radical mechanisms that are faster compared to molecular attack.

This study has been accomplished to investigate the efficiency of electrocoagulation (EC) in aqua and determine operative condition and the effect of elements (Iron, Aluminum as an electrode), as well as, different connections in the amount of removing the tartrazine color of aqua using DC sources in an electrochemical cell, including anode and cathode the effect of each of varieties like the density of electricity circulation, time of the electrolyze distance between two electrodes, the density of electrolytic and pH which can have the most effect on color destroy. For solution 500 ppm NaCl +50 ppm tartrazine, COD (the amount O2 in chemical activity) almost equals 40 ppm in pH about 6, the density of electricity flow was about 125 Am-2 and distance between two electrodes was 2 cm in 8 min from electrolyzing almost 100% color and 90% COD were canceled in next stage. We compared the efficiency of EC cells, including monopole electrodes in parallel connection and series with EC cells including polarize electrode along with one simple cell of EC. The result of this experiment demonstrated that EC cells including monopole electrode with series connection with sacrifices electrode of aluminum and cathode, anode iron had more efficiency and when using EC simple cells, including an ironic anode and cathodic aluminum. We could see better results rather than EC simple cells including ironic anode cathode.

In this work, the Cellulose MicroFibers (CMF) were produced by using Recycled Newspaper Paper (RNP). The two adsorbents (CMF) and (RNP) were used in the adsorption of the basic textile dye BY28.  RNP was characterized by X-ray diffraction and FT-IR spectroscopy while the morphology was visualized by SEM analysis. The chemical composition was determined by EnergyDispersive Spectroscopy (EDS); the characteristics showed a good extraction of cellulose from a newspaper pulp compared to cellulose alone. The release of RNP was followed by measuring both the absorbance and Chemical Oxygen Demand (COD) in water after washing and deinking. Alkaline pH medium has a positive effect on the release of various compounds of the pulp. The adsorption of BY28 on RNP and CMF according to various parameters such as biosorbent dose (1 - 8 g) and initial BY28 concentration (25 - 200 mg/L) was investigated. The adsorption isotherms were studied by using the Langmuir and Freundlich. Maximal RNP and CMF adsorption capacities of 91.21 and 52.67 mg/g respectively were obtained at 20 °C.

n this research, the capability of Granular Activated Charcoal (GAC) for adsorbing Valeric acid (VA) from an aqueous solution was investigated in a fixed-bed column. The effect of important parameters, such as flow rate, initial concentration, bed depth, and the temperature was considered. The maximum adsorption capacity was achieved equal to 750.93 (mg/g). Length of Mass Transfer Zone (MTZ), Length of Unused Bed (LUB), and Carbon Usage Rate (CUR) were calculated. Three dynamic models (Thomas, B-A, and Yoon-Nelson) were applied in different situations. The Yoon–Nelson and Thomas models were found suitable for predicting the initial part of breakthrough curves. The FTIR tests indicated that the adsorption of VA on GAC has mainly occurred physically. The feasibility of desorbing VA from saturated GAC was also determined. The column was regenerated by using deionized water in three cycles. The desorption percentage of Valeric acid in the second and third cycles were 73% and 35%, respectively.

Core/shell magnetic nanoparticles of Fe3O4/Mn0.75Zn0.25Fe2O4 were synthesized using the co-precipitation method; and characterized by inductively coupled plasma spectroscopy, Fourier-transform infrared spectroscopy, surface area and porosity analyzer, and transmission electron microscopy techniques. Fe3O4/Mn0.75Zn0.25Fe2O4 nanoparticles were used as an adsorbent to remove phosphate from water. The response surface methodology, central composite design, and Design Expert software version 10 were applied to model the process. The model was used to study the effects of the operating conditions such as pH, adsorbent dose, and phosphate initial concentration. The significance of the model was confirmed by a large F-value, and low p-value. The results indicated that the adsorbent dose had the largest effect on the response. The phosphate adsorption decreased with increasing pH. The adsorption isotherm followed the Langmuir model. The thermodynamic studies showed the endothermic nature of the process. The kinetics of the adsorption was studied, and the experimental data were better fitted to the pseudo-second-order model.

Removing low-concentration nitrate from water is desirable because it may cause eutrophication when discharged, but it is challenging using current technologies. Membrane photobioreactor (MPBR) technology (which is the combination of membrane and microalgae cultivation) emerges as a suitable option to efficiently reduce the nutrient load from wastewater. This study developed a high-efficiency microalgal-bacterial Membrane PhotoBioReactor (MPBR) to biologically remove nitrate from water. In order to obtain low-fouling membranes, TiO2 nanoparticles were entrapped in PVDF membranes prepared by the phase inversion method. Successful fabrication of composite membranes (PVDF/TNT) was confirmed by using XRD, FTIR,  DSC,  TGA,  SEM, and AFM. Membrane properties were studied using contact angle, tensile strength, pure water flux, Bovine Serum Albumin (BSA) rejection, antifouling properties, and porosity. Compared with the pristine PVDF films, the hydrophilicity, permeability, and antifouling performance of the proposed membrane were improved. A laboratory-scale MBR equipped with a synthesized membrane was used to evaluate the performance of mixotrophic denitrification under different Carbon Nitrogen (C/N) ratios, Hydraulic Retention Times (HRT), Nitrate loading, and Influent alkalinity. Methanol was supplied as a carbon source. Almost complete denitrification was achieved when the bioreactor was fed with 75 mg/L NO3−–N, 150 mg/L methanol at 4 h HRT without external alkalinity supplementation. The results as a whole indicated that the MPBR can be applied effectively to the removal of nitrate from real wastewater.

An economic process was developed via the batch scale for the uranium (VI) stripping in the presence of iron (III) from loaded alamine-336 by ammonium carbonate solution. The optimum conditions were assessed for the uranium (VI) stripping using the central composite design method, which is a subset of response surface methodology. The R-squared, U (VI), and Fe (III) stripping percentages with a value of equal 0.989, 72.61%, and 0.1% were obtained, respectively in the optimum conditions of the U (VI) and Fe (III) stripping from loaded alamine-336. The optimum stripping conditions led to the obtaining of the ammonium carbonate concentration equal to 0.64 mol/L, the phase ratio of 0.8 (O/A), the temperature of 53 , the contact time of 2510 seconds, and the shaking speed of 1100 rpm. Moreover, the stripping kinetics, equilibrium constant, and thermodynamic data were determined to describe the nature of the U (VI) and Fe (III) stripping from loaded alamine-336 by the ammonium carbonate solution. The temperature-dependent data showed that the U (VI) stripping was an endothermic process.

New Schiff bases derived by the condensation of isonicotinoylhydrazide and 2-hydroxy-3-methoxy-benzaldehyde and 2,4-dihydroxybenzaldehyde have been synthesized. Compounds were characterized on the basis of various spectroscopic techniques like IR, 1H, and 13C NMR studies, elemental analysis. The ligands were subjected to anti-microbial and anti-tubercular activity screening using serial broth dilution method and Minimum Inhibitory Concentration (MIC) is determined. The ligands were evaluated for their anti-microbial activity against Gram-positive bacteria (Staphylococcus aureus ATCC 9144) and Gram-negative bacterium (Escherichia coli ATCC 11303). Therefore, newly synthesized ligands showed good biological activity against tested bacteria. Compounds show high levels of activity against Mycobacterium tuberculosis

An extractive spectrophotometric method is developed for the trace determination of vanadium (V). 2-Methyl-8-quinolinol(MQ) reacts with vanadium(V) to form a 1:2 (V : MQ) light brown complex in an aqueous medium at 0.05 M CH3COOH concentration which is quantitatively extractable into chloroform exhibiting maximum absorbance in the range 397- 405 nm. The complex is synthesized in 1:2 ratio and the structure of the formed complex is elucidated on the basis of IR, NMR, and TGA techniques aided with computational studies. The formed V (V)-MQ complex is also screened for its in vitro antimicrobial activity. The method obeys Beer’s law up to 6.2 µg V/mL with molar absorptivity and  Sandell’s sensitivity of 2.449 × 103 L/mol.cm and 0.0208 µg V/cm2, respectively, at 400 nm. The method is simple, rapid, and has good reproducibility with a standard deviation of ± 0.0027 absorbance units.

Despite several studies towards anti-HIV therapy, HIV infections remain a challenge due to the resistivity of developed drugs. The emergence of new HIV-1 PR mutations has led to the drug resistance of the available FDA-approved drugs and lower activity towards the HIV protease. Based on this the molecular properties of 4-hydroxy-6-methyl-3-[(1E)-1-(2-phenylhydrazinylidene) ethyl]-2H-pyran-2-one (DHAA-PH) has been carried out using the hybrid Density Functional Theory (DFT) and Time-Dependent (TDFT) method at B3LYP/6-31+G(d,p) levels of theory. To substantiate the sensitivity of functional applied M06-2X/ 6-311++G(2d,2p) and mPWB1W/6-311++G(2d,2p) was used to calculate the geometric, IR, 1H NMR, and energy gap calculations.DFT calculations with M06-2X and mPWB1W were observed to agree with the experiment compared to B3LYP functional. The absorption spectra of DHAA-PH showed three distinct bands which were designated as S0 to S1, S0to S2, and S0 to S3 in order of increasing energy. The high intensity (oscillator strength) of S0 to S1 infers that the transition is quantum-mechanically allowed, while the low intensity of S0 to S2 and S0 to S3 transitions suggests quantum mechanically forbidden transitions. Molecular dynamics simulations revealed that the obtained MMGBSA binding energies are better compared to the experimentally reported binding energies for HIV-1 protease inhibitors. 3D QSAR and computational ADMET study were performed. Pharmacophore fragments of the compound were identified as well as the fragments determining its toxicity and metabolic properties. Based on the analysis of these fragments, the ways to further design promising HIV1-protease inhibitors were proposed.

Among the various methods for CO2 removal from the atmosphere, CO2 absorption is considered as the most applicable one. Although several studies have been performed on CO2 absorption by using chemical solvents, there are not many studies on using improved absorbents. Therefore, the aim of this study was to measure the solubility of CO2 in utilized aqueous blends of 2-amino-2-methyl-1-propanol (AMP) and hexamethylenediamine (HMDA). In the present research, the equilibrium set up for measuring CO2 solubility in aqueous solvents was assembled. CO2 solubility experiments were carried out over a various range of CO2 partial pressures (8.44, 25.33, and 42.22 kPa) temperatures (303, 313, and 323 K) and solvent concentration (0.4, 1.8, 2, and 3 M). The results showed that increasing CO2 partial pressure or decreasing the temperature would lead to an increase in CO2 loading. Furthermore, with increasing HMDA concentration, CO2 loading reached a maximum value before it followed a slight decrease. The experimental results were fitted to the thermodynamic Deshmukh Mather model and the required parameters in this model were generated. The results showed that there is a good agreement between theoretical and experimental results of CO2 loading.

The non-electrolyte NRTL-NRF model has been modified to study electrolyte solutions. The modified model for electrolytes is composed of short-range parts expressed by the modified nonelectrolyte NRTL-NRF and the Pitzer-Debye-Hückel equation to represent the long-range interactions of ions in the solution. In this work, a salt-specific parameter is used. Various types of experimental data including binary and ternary activity and osmotic coefficients, solid and gas solubilities in aqueous NaCl, and also aqueous Methyldiethanolamine  (MDEA) data at wide temperature and pressure ranges have been implemented to check the performance of the present model. The overall relative standard deviation of 0.046 has been achieved for 130 strong aqueous binary electrolytes by the new model in fitting the experimental data of activity coefficients. The percent of absolute average deviations of the modified model for CO2+ MDEA+ H2O andH2S+ MDEA+ H2O is 30.3% and 24.8%, respectively. The results show the good capabilities of the model for electrolyte solutions.

In this study, the effect of the mixture of two types of promoters including THF and SDS as well as the effect of temperature and pressure was studied on the methane hydrate formation. In order to investigate the effect of promoters, the induction time, as well as the amount of water, converted to the hydrate was reported; moreover, the percent of methane hydrate was calculated as results. According to the results obtained from experimentation, by adding SDS as surfactant the induction time decreases significantly in the presence of 0.243 mL THF. The results showed that for the condition where initial pressure was 40 bar and SDS concentration was chosen to be 1500 ppm the induction time decreases 59.5%. Also, the results declared that with the increase in the initial pressure the values of the induction time decline. For those that the initial pressure was set at 50 bar and the aqueous solution contains 250 ppm SDS the rate of hydrate formation was observed to be higher than those lower SDS concentrations were used. Furthermore for the condition where the initial pressure was set on 40 bars and the concentration of SDS was chosen to be 1500 ppm the rate of hydrate formation was found to be the maximum value. Finally, the results of experimentation and modeling showed that for the condition where initial pressure was chosen 50 bar the apparent rate constant of hydrate formation was maximum, for the solution with 250 ppm SDS. Also, this parameter would be 80% much higher than those of pure water was used at beginning of the hydrate crystals growth.

Catalytic reforming is a process known in the refining industry to improve the quality of gasoline by increasing the octane number, the production of aromas, and hydrogen production as a byproduct. The purpose of this research is to develop a kinetic model for naphtha catalytic reforming reactions with consideration of simple and reliable assumptions and also to provide a mathematical model using mass balance. In the kinetic model, 22 lamps and 48 reactions are present. Also, in the mathematical model, the superficial velocity of the fluid is considered variable in the axial direction of the reactor. In order to evaluate the proposed model, laboratory tests have been used in 24 different operating conditions, which according to the results of the analysis of the products, the yield of liquid is observed in the range of 0.701 to 0.952. Also, using experimental results, the model parameters are obtained through optimization with MATLAB software. Finally, the results of comparing the predicted product distribution through the model with their experimental values showed that the proposed model with acceptable accuracy could predict the distribution of the products.

Oil refineries are facing an ever-strict restriction in terms of fuel specification in view of the several policies by the environmental impact agency (EIA). Strict rules have been enforced on the gasoline product specification. Isomerization is one of the key processes for increasing the octane number of gasoline. Hence a case study has been performed using the concept of hydrogen once-through technology to analyze the process constraints for optimal operation of the process using Aspen HYSYS. In addition to this, a rigorous process model of isomerate stabilizer was also used to compare the results of the stabilizer model and optimize those various variables affecting the octane number of gasoline. The model was validated by observing the effects of constraints on the efficiency of the process by comparing it with the operational isomerization unit to further verify the authenticity of the case study. Furthermore, a calculator has been generated for the reactor temperature with respect to high benzene contents in the feedstock (benzene in feed Vs reactors ΔT).

In this paper, the effect of the feed size distribution was studied for a ball mill. Copper ore of 0.5% was tested using batch-grinding tests. Samples were carried out using three reconstructed feed size distributions in an experimental ball mill. The size distribution was reconstructed using the double Weibull formula, and modeled using the selection and breakage functions. Copper ore samples were grinding up to 15 min. A nanosize (-19+12.5), coarse (-19+6.3 mm), medium (-4.75+0.6 mm), and fine (+0.425-0.038 mm) particle size distributions were tested. The 0.32 m diameter test mill was run at 38% volume loading and Nc (critical speed) of 68% (50.85 rpm). Breakage rate parameters were calculated and simulated for each size distribution in an industrial mill. The results show that the change in the feed size distribution has an impact on the grinding kinetics. The curves show that the mono size fraction has the highest specific rate of breakage. It is also important to note that, as the size distribution F80 decreases the power consumption increases.

Residence Time Distribution (RTD) is a suitable method to find out the hydrodynamics of any industrial or lab-scale reactor. Radiotracer 198Au was used to trace the liquid phase of the industrial scale continuous three tube pulp digester. The radiotracer was injected instantaneously as an impulse input in the liquid phase and concentration versus time data were collected at the inlet and outlet of each tube using a data acquisition system. The flow modeling of continuous pulp digester has been done in two ways. Firstly, the whole digester was considered a single reactor. Secondly, each tube of the digester was considered a single reactor separately. For the second case, the convolution procedure was opted to deal with a non-ideal input signal for the second and third tubes. Axial dispersion model and tank in series with a back-mixing model were used to simulate the experimental data. Mean residence time and Peclet numbers were calculated for each tube and the whole digester.

The sonochemical activity of an oxygen bubble formed in an aqueous medium and oscillating under a dual-frequency excitation is studied in this paper. Several couples of frequencies are formed amongst 35, 140, 300, and 515 kHz, with a maximum acoustic amplitude of 1.5 atm. The molar yields of the emerging oxidants are analyzed in accordance with the combined frequencies and compared to the cases of mono-frequency excitations of similar maximum amplitude, i.e., 1.5 atm. Qualitatively, passing from a mono to a dual-frequency excitation demonstrated to be with no effect on the predominant species which remain, and. However, the results exhibited a very selective quantitative evolution depending on the combined frequencies. Some couples proved to induce a negative effect and reduce the production at the single bubble level, particularly with basic frequencies of 140 and 300 kHz, while some others demonstrated a noticeable enhancement such as the couples (35, 140 kHz) and (515, 35 kHz), as compared to mono-frequency fields.

The conventional models utilized to study flow behavior in a Non-Condensate gas reservoir did not consider the effects of gas slippage and different outer boundary conditions. For gas wells with a constant production flow rate in a bounded oil or gas reservoir, commonly, the outer boundary conditions are infinite boundary conditions or zero flux. In this study, the dimensionless pseudo pressure and dimensionless derivative of pseudo pressure in the presence of 4 different outer boundary conditions (infinite reservoir, constant pressure, exponential, and power-law) besides effects of gas slippage, wellbore storage, and skin factor are analyzed. To do this, the dimensionless pseudo pressure partial differential equation of radial flow was derived from the combination of continuity equation with Darcy’s law, the equation of state, compressibility equation, and dimensionless parameters. Then the derived partial differential equation is solved analytically in the Laplace domain. The obtained results of this work have important significance to understand the effects of different conditions on the transient pressure behavior of Non-Condensate gas reservoirs.

In this study, a low-cost feedstock was chosen for biodiesel production. Coconut fatty acid Distillate (CD) is the by-product collected from coconut oil refineries which contain lauric fatty acid as a major saturated fatty acid. The standard titration procedure was adopted to find Free Fatty Acid (FFA) content. The FFA was found to be 24.5% which requires esterification and transesterification processes to produce biodiesel. In the first stage, FFA was reduced to 1.8% by acid (H2SO4) esterification followed by transesterification to produce biodiesel. The CD BioDiesel (CDBD) production was optimized involving four parameters and three levels of L9 orthogonal array. The optimized parameters were reaction time (40 min), reaction temperature (50 °C), catalyst concentration (0.5%), and methanol to oil ratio (8:1). The order of significance of parameters was determined using ANOVA. The results showed that reaction time had more influence on the biodiesel production whereas methanol to oil ratio had the least influence. A linear regression model was developed to predict the yield and was compared with the experimental values. R2 value for the model was 95%, and the error value is less than 15% indicating a good fit of the model. A maximum yield of 92.9% was obtained utilizing the optimized, which was very close to the prediction. Thus, a low-cost feedstock, which is otherwise marketed as a low-value product, could be utilized in making biodiesel adding sustainability.

Analyzing and modeling causal factors of occupational accidents play an important role in planning prevention programs. The study aimed to explore the causal factors of occupational accidents in chemical industries in Iran. The reports of 1322 accidents from 2007 to 2016 were gathered from 22 chemical industries. First, the Accident Frequency Rate (AFR) was calculated and all the effective factors were reviewed and labeled as “dependent” and “independent” factors. Second, feature selection was conducted to find the important causal factors. Then, multiple linear regression analysis was employed to model the most frequent causal factors in accident occurrence.  The average accident frequency rate (AFR) was 87.75±74.82. A total of 30 independent casual factors were identified to be eligible for further analysis. Results of multiple linear regression analysis showed that 21 out of 30 important casual factors had the most important role in occupational accidents which are categorized into personal factors, organizational factors, HSE training, risk management, unsafe acts, and conditions as well as the type of accident occurrence. This study revealed that any preventive program should consider the importance of each casual factor in occurring occupational accidents. The higher level of importance needs the higher level of attention.