Iranian Journal of Chemical Engineering (IJChE)

Abstract Objective: C-Phycocyanin (C-PC) is a blue-colored protein antioxidant produced in the microalgae Spirulina platensis (S. platensis) that is used in the food, cosmetic and pharmaceutical industries. The purification methods are often time-consuming and expensive. In this study, Foam fractionation (FF) was used as a simple, rapid, cost-effective, and environmentally friendly method for the purification of C-PC.
Methods: The C-PC pigment solution was extracted from dry S. plantensis biomass in phosphate buffer. The FF method for the purification of C-PC was optimized using the response surface methodology (RSM). A UV-Vis spectrophotometer was used to determine the identifying absorbance peaks of the C-PC solutions.
Results: RSM obtained an optimal setting at the pH = 6, aeration rate of 3.5 vvm, and operation time of 21 min for achieving the highest purification fold (PF), purity index (PI), and C-PC recovery percentage (R) of about 1.56 ± 0.02, 0.59 ± 0.02, and 45.59 ± 0.72% respectively.
Conclusion: In the FF method there are no additional chemicals, also it is fast and has low operating costs, which make it an attractive method.

Abstract The synthesized polystyrene has weaknesses in terms of mechanical, physical and thermal properties which limit the use of this polymer. Therefore, the use of the mixtures of polymers can improve these properties. Different parameters like the mixing speed can affect the quality of the properties of the polymer being prepared from the mixture of several polymers. In this study, different percentages of nanocomposites in different stirring speeds have been added to polystyrene. Different tests have been performed on the prepared polymer and investigating the tests shows that in different stirring speeds the values of the tensile strength and impact resistance of the prepared polymer can be increased while the values of the Vicat Softening Temperature (vicat) and Melt Flow Index (MFI) test numbers remain constant. The obtained results from the laboratory data have been simulated by Artificial Neural Networks (ANNs) in order to predict the results for the points which have not been tested and the simulated results show that the laboratory data covered the simulated data perfectly. The results of tests show that by increasing nanoparticles, the resistance of the polymer against impacts will be increased and in addition, increasing the rate of the stirrer causes all other values of tests to increase.

Abstract In this work, the effect of the Si/Al ratio on the activity of zeolite supported bimetallic (Ni-Co) catalysts for Dry Reforming of Methane (DRM) has been studied. Samples are prepared with impregnation and sol-gel methods and then calcined at 550 °C for 2 h. The catalysts were characterized by XRD, XRF, FESEM, BET and TGA. All samples were tested in a micro reactor at three different temperatures (i.e. 700, 750, and 800 °C). Micro reactor test results showed that 800 °C was the proper temperature for DRM. The catalyst with 5 wt % of Ni and 2.5 wt % of Co supported on γ-Alumina have shown a higher H₂/CO ratio than other samples. For the zeolite supported catalysts when Ni/Co=2/1, the surface area and pore volume decreased but the H₂/CO ratio increased by increasing the Si/Al ratio. Reverse the Water Gas Shift (WGS) reaction was not very active when the catalyst and support showed a basic property. Also, the stability of the catalysts has been tested for 30h on stream.

Abstract Bone tissue engineering requires approaches to provide a suppression/promotion environment for the bone growth. Scaffold biomaterials have profound regulatory effects on the functionality of mesenchymal stem cells (MSCs). In the present study, the three-component bioceramic of selenium/reduced graphene oxide/hydroxyapatite (Se/RGO/HA) was developed and its performance to repair bone defects was compared to that of HA. The Se/RGO/HA nanocomposite scaffold was synthesized using the chemical bath technique, characterized by the X-ray diffraction spectra, field emission scanning electron microscopy, energy dispersion X-ray spectrometery, and Fourier transform infrared spectroscopy analyses. Human adipose-derived MSCs (hAD-MSCs) were used to investigate the in-vitro osteogenic properties of the Se/RGO/HA scaffold. The effect of the combined scaffold on the cell proliferation was analyzed by the MTT assay. Cell adhesion behaviors were evaluated using the optical microscopy and SEM. The osteogenic properties of the Se/RGO/HA scaffold were examined by the measurement of the alkaline phosphatase (ALP) activity and western blotting technique. The hAD-MSCs proliferation for HA and the Se/RGO/HA nanocomposite were 2 ± 0.1 and 1.1 ± 0.05 respectively. The Se/RGO/HA nanocomposite had cytotoxic effects on the KHOS-240S cancer cells. Additionally, good cell attachment and osteoblast-like morphology were characterized on the designed scaffold. The ALP activity and mineralization potential of cells seeded on Se/RGO/HA were higher than those seeded on HA. The Osteocalsin protein for Se/RGO/HA and HA were 64 ± 1 and 12 ± 0.1 respectively. Furthermore, the expression of Osteocalcin, a bone-specific protein, was synergistically increased by the incorporation of Se and RGO into HA. In conclusion, the presence of RGO inside Se could significantly increase the positive effects of HA on the osteogenic potential of hAD-MSCs.

Abstract Constructed wetlands have been increasingly used as an effective method for removing heavy metals from wastewater. This study aimed to investigate the combined effect of sawdust and Hydraulic Retention Time (HRT) on the performance of vertical-flow constructed wetlands cultivated with Phragmites Australis to remove Pb and Co from oily wastewater. To this end, nine barrels were used to construct the wetlands, which were filled with coarse gravel, polluted soil, and varying percentages of sawdust (0%, 20%, and 40%). Phragmites Australis cuttings were then cultured inside the barrels and irrigated with heavy metal-contaminated oily wastewater for three different hydraulic retention times (5, 10, and 15 days). After the vegetation period, plant, soil, and wastewater samples were collected and analyzed for Co and Pb concentrations, from which transfer factor (TF), bioconcentration factor (BCF), and removal efficiency (%) were derived. Results showed that while both Pb and Co removal efficiencies were affected by HRT and sawdust, the removal efficiency of Pb (36.66%) was higher than that of Co (30.83%). TF was less than one and was not affected by HRT and sawdust, but the effect of HRT and sawdust on increasing BCF was significant. However, Phragmites Australis demonstrated suboptimal performance in the uptake and transfer of metals from the root to stem.

Abstract The size and lifetime of evaporating sneeze droplets in the indoor environment were studied experimentally and theoretically. The effects of indoor temperature T_∞ and indoor humidity RH_∞ on evaporating droplets with the initial diameters of 4.9, 8.1, 17.2, and 29.7 μm were investigated. The size distribution and mean size of droplets were obtained by a laser particle sizer. The experimental data showed that the possibility of aerosolized droplets increased from 25.5 to 36.1 % by increasing T_∞ from 18 to 30 °C and decreased from 36.1 to 13.6 % by increasing RH_∞ from 30 to 60 %. A one-dimensional droplet evaporation model was used to estimate the lifetime of the droplet. A critical RH_∞ of 40 % was found; above it, the lifetime of the droplet exponentially increases. The effect of the initial diameter of droplets was higher than that of RH_∞ and also the impact of RH_∞ was higher than that of T_∞ on the lifetime of the aerosolized droplet nuclei. A significant effect of environmental conditions on the lifetime of the droplet was found over the range of 26 °C ≤ T_∞ ≤ 30 °C and RH_∞ ≤ 40 %, while the effect decreased in the range of 18 °C ≤ T_∞ ≤ 22 °C and RH_∞ > 40 %, where a minimal shrinkage of droplets took place because of the hygroscopic growth of droplets. The results of this study do not imply that the COVID-19 virus will be deactivated at the end of the lifetime of the droplet, but it represents that controlling the indoor environment is important for droplets to carry the virus.

Abstract Most of the reactions that occur in microreactors take place on the surface, so it is important to keep the reactants close to the reactive wall. One effective technique in this field is the single-phase hydrodynamic focusing. However, this method has a drawback: a high percentage of reactants penetrate into the sheath fluid. To address this issue, the concept of the two-phase hydrodynamic focusing is introduced in this study. The main idea is to use a highly viscous sheath fluid to create a barrier against reactant penetration into the sheath flow. To demonstrate the effectiveness of this method, a 3D numerical simulation was performed with an irreversible second-order reaction. The results show that the two-phase hydrodynamic focusing increases reaction rates, particularly in downstream regions where the Sherwood number can increase by several orders of magnitude with the use of a highly viscous sheath of liquids. Additionally, it was observed that the use of the two-phase hydrodynamic focusing improves the efficiency, which is defined as the ratio of the solute in the sample flow to the total solute in each cross-section..

Abstract A new approach is proposed to evaluate various designs for gas-solid cyclone separators. This approach uses single-phase flow simulation results to find a quantitative measure of flow symmetry in a given cyclone. Flow symmetry is computed by averaging imbalances of   non-axial velocities throughout the cyclone. Using this approach, two standard design methods are evaluated and the cyclone with a more symmetric flow pattern is chosen as a starting point for further design improvements by reducing the diameter of its vortex finder. Two-phase computational fluid dynamics (CFD) simulations compute 90.2 % collection efficiency for the improved design. CFD simulations reveal using a cascade of four cyclones results in an overall 99.98 % collection efficiency. Once installed in the actual industrial setting, the cyclone cascade achieves a 98.56 % collection efficiency and a particle size distribution which is in good agreement with CFD computed results.

Abstract MXene membranes perform well in biofuel separation due to their excellent hydrophilicity, flexibility, and mechanical strength. For the first time, computational fluid dynamics was used to model the dehydration of ethanol through the pervaporation system by the MXene membrane. We discretized the momentum and continuity equations using finite element methods and predicted the mass transport. Experimental results and model data were in good agreement (less than 10 %). The feed velocity, feed concentration, and membrane thickness all had positive effects on the separation factors while the temperature had a decreasing effect. This model's efficiency has decreased by 35 % after increasing the feed flow rate by 10 times. In addition, the separation factor increases tenfold when temperature is raised from 25 to 70 °C.

Abstract The preparation of ethylcellulose (EC) nanofibers (NFs) by the electrospinning method was optimized by Taguchi design. A Taguchi design was performed for electrospinning parameters such as EC concentration, voltage, ethanol/water ratio in the solvent, and feed rate in four levels (array L16).  EC solutions with a certain concentration were prepared in ethanol-water solvents with a certain ratio. The solutions were then stirred at a constant temperature for four hours and left overnight. Electrospinning parameters such as temperature 30 ˚C, distance between syringe needle and collector 10 cm, aluminum foil 20 micrometers as collector, collector speed 400 rpm, and electrospinning time 2.5 hours are constant in all electrospinning experiments, but voltage and feed rate were changed according to the experimental design. The resulting EC fibers were imaged by scanning electron microscopy (SEM). The SEM images of EC fibers were processed by Image J software, and the average diameter of EC fibers in each experiment was calculated. The results of the diameter of the electrospun EC fibers showed that all the fibers had a diameter of less than 100 nm. Also, the results of the diameter of EC fibers were analyzed based on the analysis of variance, and it was found that the ethanol/water ratio in the solvent (34.9%), the feed rate (23.5%), the voltage (22.1%), and the EC concentration (17.5%), respectively, had the greatest contribution to the diameter of EC fibers. Under optimal conditions, EC fibers with a diameter of 41 nm were prepared.
 

Abstract It is crucial to design and develop new polymers with desirable characteristics. Aromatic polyimides have been attracted more attention in comparison with other polymeric materials, because of their excellent properties, such as the high thermal stability, mechanical strength, and chemical resistance. In this work, two semi-aromatic polyimides (BCDA-mPDA and BCDA-Durene) were successfully synthesized from bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarbocylic dianhydride (BCDA), 1,3-phenylenediamine (mPDA), and 2,3,5,6-tetramethyl-1,4-phenylenediamine (Durene) to investigate the effect of methyl functional groups on the physicochemical and structural properties of the synthesized polyimides. The synthesized polyimides were characterized by the proton nuclear magnetic resonance (¹H-NMR) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) spectroscopy, inherent viscosity measurement, and solubility test. FTIR and ¹H-NMR results confirmed the chemical structure of the synthesized polyimides. XRD results showed that the presence of bulky methyl groups has led to increasing amorphous regions in the polymer structure. In addition, these new polymers were soluble in various organic solvents such as dimethylformamide (DMF), dimethylsulfoxide (DMSO), and N-methyl-2-pyrrolidone (NMP). The inherent viscosity of the synthesized polyimides was 0.65 dl/g for BCDA-Durene and 0.96 dl/g for BCDA-mPDA, which indicates the moderate molecular weight of the polymers.

Abstract  



Electrospun nanofiber is one of the promising alternatives for use in tissue engineering and drug delivery due to its controllable characteristics. However, choosing an appropriate biomaterial for a specific tissue regeneration plays a significant role in fabricating functional tissue-engineered constructs. Heart extracellular matrix (ECM)-derived electrospun nanofiber which mimic the physicochemical and structural characteristics of cardiac tissue is advantageous for cardiac tissue engineering. In this study, acellular calf heart ECM has been investigated as a potential biomaterial to be electrospun in a novel combination with poly vinyl pyrrolidone (PVP), gelatin (Gel) and polycaprolactone (PCL) for cardiac tissue engineering. The obtained fibers were aligned, uniform, and bead free. After fabrication, the scaffolds were cross-linked in glutaraldehyde vapor to become mechanically stronger and dissoluble in the aqueous environments. Considering surface topography, biocompatibility, hydrophilicity, and mechanical properties, the fabricated hybrid electrospun ECM/PVP/Gel/PCL fibers can be proposed as a biomimetic scaffold for heart tissue engineering applications.

Abstract In the presented research, the selective hydrogenation of benzene in a mixture of benzene and normal heptane (5 vol % of benzene) over different kinds of heterogeneous catalysts was investigated. For this purpose, a series of catalysts with various supports such as Pd/ZSM-5, Pd/13X and Pd/  was developed. To prepare Pd supported catalysts, the modification of supports was conducted by a specified amount of palladium nitrate in the aqueous solution. Experimental catalyst evaluation tests were performed in the catalyst assessment set-up. The characterizations of the physicochemical properties of the prepared catalysts were performed by XRD, NH₃-TPD and BET. It can be found that the conversion of benzene was promoted under the optimized reaction conditions of 200 °C, 1 MPa, H₂/HC = 1.3 (molar ratio) and the weight hourly space velocity (WHSV) = 25 hr^-1. Among these catalysts, Pd/13X exhibited the maximum conversion of benzene (90 %) and the minimum light-cut production under the optimum conditions. The study on the stability of catalysts shows that, the decline activity of Pd/13X catalyst is more than that of the other catalysts (from 90 % to 81 %) in the specified 20 h time on stream, but so far the activity of this catalyst is the highest in comparison with that of other catalysts at the end of the defined time (20 h).

Abstract The Mixed Matrix Membrane (MMM) concept consists of incorporating suitable polymers with inorganic or organic fillers. The majority of polymeric membranes maintain a trade-off between permeation and selectivity, which restricts their development in separation applications. In this paper, less reviewed challenges on development of MMMs, such as the preparation of mix-matrix resistant membranes for industrial gas separation applications, as well as the use of appropriate and compatible fillers for different types of polymers were discussed. The MMMs comprising Metal Organic Framework (MOF) fillers were extensively studied. The importance of MOFs includes finely tunable structures, excellent compatibility with polymer matrices, and molecular sieve action. MMMs are considered promising structures that combines the advantages of polymeric and inorganic membranes. They exhibit the potential to upgrade the separation performance of pure polymer membranes using filler materials, whereas the cost remains relatively lower than that of pure inorganic membranes. The development of novel filler materials makes a substantial contribution in terms of role-playing.

Abstract The purpose of this research is CFD modeling of the fluid flow inside an industrial valve in order to discover the areas with high shear stress and to determine the effect of hydrodynamic on the erosion rate. CFD results are compared with the existing experimental data in a valid reference and the model is verified with high accuracy. The impact of the pressure at inlet and the disc angle on the erosion is investigated. By increasing inlet pressure, maximum velocity, turbulence intensity, wall shear stress and particle erosion increased. However, the wall shear stress, turbulence intensity, and particle erosion are clearly reduced as the disc angle decreases. When the disc angle is less than 50o, the range of dependent parameters changes has a small value. Reducing the disc angle or increasing the inlet pressure led to an increase in cavitation. Therefore, to prevent the erosion of the butterfly valve, it is necessary to increase the disc angle or reduce the pressure at inlet. Erosion of the butterfly valve significantly occurred at the front and rear of the disc. Depending on the disc angle, the shear stress of wall for the modified configuration is 10 to 80 times lower than the original butterfly valve. Therefore, it can be stated that the modified geometry can reduce the wall shear stress and consequently the erosive for all the disc angles of the studied butterfly valve.

Abstract In this work, nanoparticles of the metal fuel Zirconium (Zr) and nanoscale oxidizer BaCrO₄ are synthesized considering their unique nanoparticle characteristics like mixing homogeneity and high surface/volume ratio. Using the synthesized fuel and oxidizer, the pyrotechnic mixture of Zr/BaCrO₄ was developed under 4 different conditions and analyzed in terms of the thermal behavior and burning rate. In the synthesis stage, the oxidizer nanopowder BaCrO₄ was developed through precipitating Barium Nitrate and Chromate Potassium in the vicinity of Dodecyl benzene sulfonate sodium (DBSS) stabilizer. Also, Zr nanopowder was prepared using direct reduction of Zr (NO₃)₂ by N₂H₂ and was coated by a 4% Collodion. Then, the pyrotechnic mixture Zr/BaCrO₄ was charged and pressed in the constructed combustion chamber. The burning rate of the mixture was captured by the direct footage of the combustion process using digital cameras with 60 frame-per-second capabilities. The fastest burning occurs when both the fuel and the oxidizer are nano-scaled. The thermal behavior of the mixture was studied using the simultaneous thermal analysis (STA) machine within the temperature range of 25 to 1000 °C. Results of the thermal analysis show that the thermal decomposition temperature of the Zr/BaCrO₄ mixture in the micron size is higher than in the nano size and the amount of destruction is lower. Increasing the concentration of zirconium in the nano-size from 10 to 50% leads to a decrease in the decomposition temperature from 565 to 437 °C, while the pyrotechnic mixture destruction rate increases from 39% to over 63%.

Abstract The properties of the Nanoclay-corn starch film were studied in the presence of Nanostarch. Nanostarch was synthesized through nanoprecipitation and characterized using the Particle Size Distribution Analysis, Field Emission Scanning Electron Microscopy (FESEM), X-ray diffraction Analysis (XRD), and Fourier Transform Infrared Analysis (FTIR). The XRD analysis of nanostarch particles revealed a distinctive V-type diffraction peak, with particle diameters ranging from 25 to 100 nm. The impact of introducing nanostarch into the starch-nanoclay film was investigated in terms of the thickness, transparency, morphology, wettability, and mechanical properties of the nanocomposite film. The results indicated that adding nanostarch particles improved the optical transparency of the film along with its hydrophobicity and flexibility. The film having a weight ratio of 0.769 (nanoclay to nanostarch) showed the maximum hydrophobicity (107.85°), and elongation at break (58.6%). This suggests that the appropriate incorporation of nanostarch can enhance the film's flexibility. The maximum tensile strength (5.88 MPa) was obtained for the film with a weight ratio of 1 (nanoclay to nanostarch).

Abstract In this research, a mixed matrix membrane based on polysulfone and zinc nitrate-methylimidazole fillers was synthesized to improve the ability of the polymer membrane for the separation of CO₂ and CH₄. The membranes were fabricated using the solution casting technique and characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR-ATR), energy dispersive spectroscopy (EDAX), and gas permeability tests. The FTIR-ATR analysis confirmed the presence of the functional groups. XRD results demonstrated an even dispersion of the additives throughout the polymer matrix, by the quantitative analysis revealing a reduction in the crystal size and percentage. The EDAX analysis confirmed the consistent spread of ZIF-8 particles in the polymer. The gas permeability tests showed a significant increase in the permeability and selectivity of the mixed matrix membrane compared to that of the pure polysulfone membrane. The presence of ZIF-8 particles enhanced the permeability of CO₂ by expanding the available space within the polymer and promoting the solubility of CO₂. Additionally, the increased free volume improved the diffusion coefficient of CH₄ and led to a slight increase in its permeability. The permeability of CO₂ increased from 76.72 GPU for the pure polysulfone membrane to 322.95 GPU for the mixed matrix membrane, while the permeability of CH₄ increased from 31.21 GPU to 61.27 GPU. The selectivity of CO₂/CH₄ exhibited a notable increase from 2.46 to 5.27. This improvement in selectivity can primarily be attributed to the significantly higher increase in the solubility coefficient of CO₂ compared to that of CH₄.

Abstract The Fe₃O₄/MW-CNT composite was prepared for a hybrid photo-catalyst-assisted electrochemical process for the removal of BTX contamination from wastewater. Oxidation of multi-walled carbon nanotube was conducted by different treatments including acid treatment and hydrogen peroxide. The XRD, FTIR, SEM, TEM, and BET analyses were performed to characterize both the MW-CNT and the synthesized composite. Simultaneous photo-catalyst and electrochemical processes were conducted to evaluate the performance of a new hybrid process for wastewater treatment. The effect of current density, photo-catalyst loading, and BTX initial concentration was investigated experimentally. The characterization results of the synthesized composite show that a mixture of strong nitric acid and sulfuric acid treatment at a high exposure time and low temperature is the best route for MW-CNT oxidation. The removal efficiency of BTX compounds from wastewater using the hybrid photo-electrochemical process was found to be in the range of 28 to 43% for different conditions. The optimum condition for maximum removal of BTX was found by mathematical modeling of experimental data. The results indicate that a combination of photo-catalyst and the electrochemical process can enhance the BTX removal efficiency.

Abstract The SrO-CaO-Al₂O₃ nanocatalysts were prepared and optimized using the co-precipitation method. In this work parameters affecting the catalytic performance for the production of biodiesel from sunflower oil have been investigated. Thev response surface methodology (RSM) has been used to assess the impact of operational conditions on the production of biodiesel, with the biodiesel yield as the response variable. The catalyst was found to be calcined at 600 °C, with a 5-hour calcination time, 75 minutes of the aging time, and a precipitation temperature of 50 °C as optimal conditions for the production of biodiesel. The results showed that the optimal reaction conditions were CH₃OH/oil=12/1 at 60 ˚C with the concentration of 6wt.%of the catalyst and reaction time of 3 h at stirring speed of 600 rpm. Furthermore, the biodiesel yield reached 99% under optimal operational conditions. The SrO-CaO-Al₂O₃ nanocatalysts were characterized by using transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transforms-infrared spectroscopy (FT-IR), and N₂adsorption–desorption measurements methods. The kinetic study has been done and the first order kinetic model was found  in agreement with experimental results (R²= 0.998). From the kinetic studies, E_a=41.57 kJ.mol^–1 and A= 5.25×10⁵ L.mol^-1s^-1 were obtained.

Abstract Plant fiber composites are currently experiencing strong development, particularly due to the growing interest in them in the automotive industry. These fibers are an excellent alternative to glass fibers from the environmental point of view due to their biodegradability and their much more neutral combustibility in terms of the release of harmful gases or solid residues. However, the incorporation of cellulosic materials into the thermoplastic matrix affects a large number of properties. Many factors, such as the nature and rate of the incorporated filler, can influence the properties of the composites. The present work involves studying the effect of the particle size of a natural fiber on the properties of a polymer matrix. The plant fibers used are DISS fibers ground into a powder with a particle size of less than 63µm. Different formulations based on HDPE/Diss were prepared with different amounts of the filler (10%, 20% and 30%). The HDPE/Diss composites were first processed using a calender, then molded into samples of various shapes with a thickness of 3 mm by compression at 190 °C. These were characterized by various techniques: physical tests, mechanical tests, rheological and morphological tests.

Abstract This study presents a neuro-fuzzy inference system for predicting the pressure loss in coiled flow inverter (CFI) tubes. Computational fluid dynamics (CFD) simulations were conducted to obtain the amounts of the pressure loss across nine distinct configurations of CFI. The neuro-fuzzy model utilized three key input parameters of the Reynolds number (Re), number of 90° bends (N), and tube-to-coil diameter ratio (L/D). Following CFD validation, the dataset was partitioned into training (two-thirds) and testing (one-third) subsets. The model achieved an outstanding mean relative error (MRE) of 0.549%, demonstrating its high predictive accuracy and reliability for the estimation of the pressure loss in coiled flow inverter systems. These results highlight the neuro-fuzzy approach as a suitable tool for optimizing CFI designs in industrial applications. This study ultimately demonstrates how the strategic combination of numerical simulation and machine learning can accelerate development cycles while maintaining rigorous accuracy standards, providing engineers with a powerful tool for system design and optimization. 

Abstract Heavy metals are among the most hazardous pollutants released into the environment through industrial activities. In recent years, adsorption has been recognized as an effective method for the removal of metal ions from wastewater. Ultrasonic irradiation is a promising technique for intensifying mass transfer during adsorption. In this study, the effect of high-frequency ultrasonic waves on the enhancement of the removal of nickel (II) ion from aqueous solutions using Fe₃O₄ nanoparticles was investigated. The influence of the dosage of adsorbenst, contact time, and pH on the removal efficiency was examined to optimize the removal efficiency using the response surface methodology (RSM). The maximum removal efficiency, achieved with the ultrasound-assisted process, was 84.3% at the contact time of 60 minutes, 8 g of Fe₃O₄, and pH = 5, while the conventional stirring (shaker) method resulted in a maximum efficiency of 79.54% at 100 minutes, 10 g of adsorbent, and pH = 9. The use of ultrasound significantly accelerated the adsorption rate at the initial stages by generating cavitation and microstreaming, which increased the availability of active surface sites on the nanoparticles. These findings demonstrate that the combination of Fe₃O₄ nanoparticles and ultrasonic irradiation offers a rapid, efficient, and environmentally friendly approach for the removal of nickel (II) ions from industrial wastewater.

Abstract Sulfur compounds pose significant challenges for environmental pollution. This issue has led to the application of various methods for sulfur detection and removal, which differ depending on the sulfur content. Among these methods is oxidative desulfurization, which has attracted considerable attention due to its mild operating conditions, ambient pressure, and relatively low temperature. In this study, a combination of chromium and nickel metals supported on ZSM-5 zeolite was used for oxidative desulfurization. Initially, nickel (3–8 wt.%) and chromium (1–8 wt.%) were separately loaded onto the zeolite to investigate the effect of each metal individually. Subsequently, a combination of 5 wt.% nickel and 1–8 wt.% chromium was simultaneously loaded onto the zeolite. The material containing 3 wt.% chromium and 5 wt.% nickel exhibited the highest efficiency within two hours. The synthesized catalysts were thoroughly characterized using FTIR, XRD, FESEM, EDX, and BET techniques. ZSM-5 zeolite with 5 wt.% nickel and 3 wt.% chromium showed 63% sulfur removal in the oxidative desulfurization process over two hours, indicating the favorable performance of this catalyst for the process.

Abstract This research aims to study the mixing dynamics of granular materials in the Triaxe mixer and compare the effect of operating conditions on the quality of mixing. The discrete element method was used to simulate the mixer and track the motion of particles. The Johnson-Kendall-Robinson model was used for the simulation of the contact of cohesive particles. The results indicate that the most influential parameter on the mixing performance is the rotational speed since raising the rotational speed increases the transferred momentum to the grains. In the specific design of the mixer, the dead zones are reduced, so the fill-level does not have a considerable impact on the homogeneity. Also, the quality of mixing of large particles in this blender is better than the same for smaller particles. The mixer's performance for blending cohesive grains was similar to that for the non-cohesive particles. For both types of solids, the relative standard deviation reached approximately 35% after 70 s. Mixing performances of two sizes of the mixer were compared based on two criteria, the constant impeller speed and constant power per volume of the mixer. The results show that the case of the constant impeller speed can predict the mixing performance of the larger mixer more accurately.