Iranian Journal of Chemistry and Chemical Engineering
Year:2025 | Volume:44 | Issue:6|Papers Count:15

Bicrystal structures, composed of two distinct crystal orientations within a single material, have received significant attention due to their exceptional mechanical and structural properties, making them vital for diverse industrial applications. Their adaptability drives advancements in electronics and energy technologies, enhancing performance, efficiency, and sustainability. Defect evolution is a key determinant of their practical performance, which significantly influences their mechanical behavior. This study utilizes Molecular Dynamics (MD) simulations to analyze temperature-dependent dislocation defects and amorphization processes in silicon carbide (Si-C) bicrystals. Simulations were conducted in two phases: equilibrium and deformation. During the equilibrium phase, the total potential energy stabilized at -40476.152 eV after 1 ns, confirming system stability. In the deformation phase, external shear stress of 4.56 GPa induced 12 atomic dislocations at 300 K. Increasing the initial temperature intensified defect formation, with dislocation counts rising to 27 atoms at 1800 K. These results highlight the critical role of temperature in modulating the mechanical behavior of Si-C bicrystals. By fine-tuning temperature conditions, atomic-scale properties can be optimized to improve reliability and durability, facilitating their effective application in advanced technologies.

In this study, Zn-doped NiO nanofibers (NFs) were prepared using the electrospinning method. These nanostructures were prepared with different zinc concentrations (1, 3, 6, and 12 mol%). Their physical properties were studied by different characterization methods such as XRD, SEM, EDS, PL, and UV-Vis spectroscopies. Also, the electrical properties of these nanostructures were investigated by impedance spectroscopy (IS). The XRD and EDS analysis results showed the formation of the Face-Centered Cubic (FCC) phase of NiO nanofibers and the presence of Ni, Zn, and O in the final product. The morphological studies obtained from SEM images demonstrated that introducing Zn into the NiO lattice has given rise to an increment of nanofibers' diameters. Also, the absorption spectra were measured in the range of 200-900 nm, revealing that they were displaced to lower wavelengths. In addition, Tauc plots showed that the energy band gaps were in the range of 1.63 to 2.12 eV. PhotoLuminescence (PL) spectra indicated that increasing the concentration of Zn caused shifts in emission bands and, as a result, in their intensity. Impedance spectroscopy showed reduced impedance with increasing Zn concentration, enhancing charge separation. Furthermore, photocatalytic experiments for Methylene Blue (MB) degradation revealed that NFs with 12 mol% Zn exhibited the highest degradation efficiency of 96%. These findings suggest that Zn-doping effectively enhances the structural, optical, and photocatalytic properties of NiO NFs, offering the potential for advanced photocatalytic applications.

Supercritical carbon dioxide (scCO2) has the remarkable ability to penetrate graphite layers with significant force and low viscosity, effectively overcoming Van der Waals (VdW) forces and converting graphite into mono/bilayer graphene. By utilizing data from Design Expert software (version 7.0) and conducting laboratory experiments, it has been demonstrated that various parameters such as temperature (T), pressure (P), initial amount of graphite, surfactant and co-solvent addition, duration of sample placement in the cell, CO2 gas release duration, ultrasonic and centrifuge operation time, and power can significantly enhance the exfoliation process. The graphene produced was meticulously analyzed using advanced techniques such as RAMAN spectroscopy, High Resolution Transmission Electron Microscopy (HRTEM), Fourier Transform InfraRed (FT-IR) spectroscopy, Zeta potential analysis, and Atomic Force Microscopy (AFM). The results conclusively showed that under optimal conditions, mono/bilayer graphene was successfully achieved. This was confirmed by the presence of the G-Band at 1581 cm-1 in the RAMAN spectroscopy. The HRTEM images clearly displayed the formation of graphene layers under the applied conditions, while FT-IR results indicated that graphene sheets were successfully synthesized after applying appropriate conditions, with a thickness of 1.49 nm as observed in the AFM. The zeta potential value for this nanofluid was measured at -39.7 mV, indicating excellent stability. This innovative method offers a straightforward and cost-effective approach that eliminates the need for toxic or expensive chemicals, positioning it as a highly lucrative alternative to more complex graphene production methods, such as heating silicon carbide.

Graphene synthesis is essential for industrial applications due to its unique properties, such as high electrical conductivity, mechanical strength, and large surface area. Developing cost-effective and scalable production methods, like fluid exfoliation, enables the mass production of graphene materials for diverse applications, including electronics, energy storage, and water purification. Magnetic water is a promising fluid used in the graphene production process through exfoliation techniques. This study outlines the process of producing graphene nanosheets using magnetic water in the presence of supercritical carbon dioxide (scCO2). Computational simulation methods and a Molecular Dynamics (MD) approach were employed over 11 ns to achieve this. The simulation results indicated a favorable conversion of pristine graphite to graphene using our proposed method. Specifically, 91% of graphite atoms transformed into graphene nanosheets under optimal conditions. The number of graphene nanosheets produced increased to 38, with an average distance of 2.88 nm after 10 ns in the optimal condition of the system. These results were calculated with atomic precision through structural dumps of MD simulations. Additionally, the graphene nanosheets produced in magnetic water and scCO2 are suitable for various practical applications. The combination of magnetic water with scCO2 significantly enhances the conversion of pristine graphite into graphene.

The study introduces Carthamus tinctorius (safflower) extracted with sustainability and environmental care alternative for arsenic removal, promoting the use of natural products in environmental remediation. The current research presented the synthesis of Poly Vinyl Chloride (PVC) membrane with the presence of Carthamus tinctorius extract in its structure and as a green absorbent for the Clearing of arsenic (As) from water.  Investigating the extract for its dual role as an absorbent and an ionophore to facilitate ion transport could provide insights into a new mechanism for targeting heavy metal removal, especially in complex contaminated systems. Liquid Chromatography-Tandem Mass Spectrometry (LC/MS-MS), InfraRed (IR) spectroscopy, UltraViolet-Visible (UV-Vis) spectroscopy, Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray (EDX) spectroscopy techniques used for characterizing of the Carthamus tinctorius extract and confirmation of as removal. SEM image of the membrane surface after the adsorption process confirmed as removal. The EDX plot also presents the electron transition of an atom in the electronic energy level. Besides, additional investigations were conducted on the isotherm and kinetics of arsenic removal. The Langmuir and Freundlich models were the most appropriate for the obtained data, supporting the Adsorption efficiency of around 90 mg/g. In addition, the adsorption kinetics exhibited consistency with the pseudo-first-order kinetic model. Therefore, the use of herbal extract in PVC membrane structure indicated acceptable absorbent to remove arsenic from water. Carthamus tinctorius plays a good role as an ionophore in PVC membrane and has Nernstian behavior with a +59 mV slope.

This research delves into the dissolution kinetics of ulexite, a mineral characterized by its high boron content, in ammonium hydrogen sulphate (NH₄HSO₄) solution. Considering Turkey's pivotal position in the global boron market, the study is geared towards discovering a greener and more cost-effective alternative to the conventional sulfuric acid process for producing boric acid. Dissolution experiments were systematically performed under varying conditions, including temperatures of 30°C to 80°C, NH₄HSO₄ concentrations ranging from 0.2 M to 1 M, solid-to-liquid ratios of 0.02 to 0.1 g/mL, stirring speeds between 200 and 600 rpm, and particle sizes from 53 to 600 micrometers. The findings revealed that the dissolution rate increased with rising temperatures, higher NH₄HSO₄ concentrations, and smaller particle sizes. Specifically, at 80°C and NH₄HSO₄ concentration of 1 M, the dissolution rate was considerably higher than under lower temperature and concentration conditions. In contrast, a higher solid-to-liquid ratio resulted in a reduced dissolution rate, indicating that an optimal balance must be struck for efficient processing. Kinetic analysis, employing the shrinking core model, revealed an activation energy of 42.98 kJ/mol, signifying that the process is governed by chemical reactions. These insights suggest that NH₄HSO₄ could serve as a promising alternative solvent for boric acid production, offering potential environmental and economic advantages. Nonetheless, further research is essential to assess its feasibility for commercial use. Kinetic dissolution with ammonium hydrogen sulphate provides more efficient and faster results compared to dissolution with conventional solutions.

An intriguing novel complex, [ZnCl2(Ph3POH)2], containing two equivalents of triphenylphosphanol (Ph3POH), was synthesized by reacting anhydrous ZnCl2 with triphenylphosphine in methanol, yielding a dichlorobis(triphenylphosphanol)-zinc(II) complex with the chemical formula C36H32Cl2O2P2Zn. The synthesized zinc complex was fully identified by molar conductivity, magnetic susceptibility, FT-IR, UV-Vis spectroscopy, and single-crystal X-Ray Diffraction (XRD). The single-crystal X-ray diffraction study proves that the complex possesses a metal-to-ligand ratio of 1:2, with each Ph₃POH ligand coordinating to the Zn(II) center in an unidentate mode via its oxygen atom. Spectroscopic analyses, along with single-crystal XRD results, validated the mononuclear configuration of the Zinc(II) complex. Calculations were carried out utilizing Density Functional Theory (DFT) at the B3LYP/6-311G level for the ligand and the B3LYP/LANL2DZ level for the Zn(II) complex. These computations evaluated the kinetic stability and reactivity of the ligand and its zinc complex by measuring the HOMO-LUMO electronic energy levels and generating the Molecular Electrostatic Potential (MEP) map. The Natural Bond Orbital (NBO) analysis revealed that the charge on the zinc ion decreased from +2.0 e to +0.989 e upon complexation. According to the Hirschfeld surface study, measured over dnorm, shape index, and curvedness, the main intermolecular interactions contributing to crystal packing are H... Cl/Cl...H, C...H/H...C, and H... H. 

Researchers are currently focusing on renewable energy as an alternative to fossil fuels. Anaerobic digestion is being utilized to reduce greenhouse gas emissions and create a sustainable energy supply. Hydrogen production from renewable sources is one of the most important ways to provide sustainable and clean energy, and today, hydrogen production is considered one of the most profitable transitory investments in green energy. Utilizing biogas for steam reforming is an effective method for hydrogen production. This method, referred to as tri-reforming of methane (trm), enables the transformation of methane, CO2, Steam, and O2 to synthesis gas (a blend of CO2 and H2) while considering the composition of the biogas utilized, which includes oxygen in addition to methane and carbon dioxide. Trm combines methane, Partial Oxidation of Methane (POM), Steam Methane Reforming (SMR), and Dry Methane Reforming (DMR) in a single stage; biogas reforming: water vapor and purified biogas are fed into the reforming reactor. They are both maintained at 16 bar and 909 °C. 80% methane conversion is required. This section first explains how the PSA separation unit allows for hydrogen production with exceptional purity, reaching 75%, and the validation of the Aspen Plus model using experimental data and a biogas production rate per day in the experimental test was 175 liters, which was obtained in the simulation for a loading rate of 19 liters per day, and the validation of the Aspen Plus model using experimental data, food waste as the base material, and carried out at a comparable concentration (CH4%) of 70%. The figure indicates that the industrial partner's hydrogen separation yield was 79%.

With the depletion of conventional energy resources, Fuel Cells (FCs) have emerged as a promising clean energy technology, and each step towards efficiency and power production improvement would be effective in their commercialization. FCs offer several advantages, including high efficiency, portability, ease of installation and maintenance, high power density, and the flexibility to operate with different fuels. Despite these benefits, the commercialization of FCs faces challenges such as performance limitations, reliability concerns, durability issues, and high costs. Among these challenges, thermal management plays a critical role in maintaining FC longevity and performance. Inappropriate thermal management can lead to uneven temperature distribution, increased degradation rates, and reduced overall efficiency. To address this issue, this study explores the potential of Heat Pipes (HPs) as an effective cooling solution for FCs. HPs present a cost-effective alternative to conventional cooling systems due to their passive operation, eliminating the need for additional components such as pumps and valves, which not only simplifies the system but also reduces weight. Furthermore, HPs contribute to a more uniform temperature distribution within the fuel cell stack, expand the operational temperature range, enhance power generation, and improve overall system efficiency. These advantages make HPs a promising solution for improving the durability and performance of FCs, thereby accelerating their commercialization.

Distillation columns are essential in the chemical and process industries for separating liquid mixtures based on differences in the volatility of their components. Achieving the desired product compositions requires effective modelling and control strategies. This work focuses on developing a dynamic mathematical model for the UOP3CC Armfield binary distillation column used in the laboratory. The model incorporates mass and energy balance equations and considers key factors such as heat transfer in the condenser and reboiler, tray hydraulics, and vapor-liquid equilibrium. The model parameters are estimated and validated using real-time experimental data. The control strategy aims to regulate the temperature profiles to maintain the desired ethanol composition in the top product. This work explores the implementation of Proportional-Integral (PI), Model Predictive Control (MPC), and Robust setpoint Tracking Disturbance rejection with Aggressiveness (RTD-A) controllers to optimize process performance. Model order reduction techniques simplify the complex process dynamics, while a decoupler is used to manage interactions between control loops. The performance of the PI, MPC, and RTD-A controllers is compared using metrics like setpoint tracking, disturbance rejection, and computational efficiency. Experiments are conducted to establish the relationship between top tray temperature and distillate purity, leading to the identification of a temperature setpoint that maximizes ethanol purity. This setpoint is validated in a closed-loop system, with the physical model achieving a steady-state error of just 0.19%. The results emphasize the significance of accurate modelling in improving the performance of the UOP3CC distillation column.

In recent years, in order to preserve food and destroy vegetative microorganisms, foods have been thermally processed, which can cause physicochemical changes and reduce the absorption of some nutrients. The present research was to evaluate and compare the physicochemical properties and microbial quality of pomegranate juice pasteurized by the cold plasma method (at 20, 40, and 60 kV, for 5,10, and 15min under air gas) with those of pomegranate juice pasteurized by the thermal method (at 95°C for 5sec) without any process. The results showed that the cold plasma procces had a significant effect (p≤0.05) on physicochemical properties (acidity, pH and Brix), bioactive compounds (anthocyanin, total phenol and vitamin C), color indexes (a*, b* and L*) and microbial load (mold, yeast, aerobic bacteria and coliforms). As the voltage increased from 20-60 kV, time increased from 5-15 min, the acidity, Brix, and color indexes a* and b increased significantly (p≤0.05), and the pH value, bioactive compounds, index L, and microbial load decreased significantly (p≤0.05). Results showed that pomegranate juice pasteurized by the cold plasma method at 20kV for 5min under air gas had the most similar physicochemical properties (acidity, pH, and Brix), bioactive compounds, and color properties (a*, b* and L*) to control sample (without any process) and was introduced as the superior treatment. Therefore, it was found that plasma treatment was effective in inactivating the microorganisms, and this new non-thermal method could be used for the pasteurization of pomegranate juice instead of heat treatment.

Probiotics and prebiotics have recently gained attention in functional food production and the food industry. This study investigated the effect of isomaltulose (ISO) addition after 48 hours of fermentation on the characteristics of milk fermented with Lactobacillus helveticus PTCC1930 and Lactobacillus (L) paracasei ssp. paracasei PTCC1945 during 19 days of cold storage. The impact of ISO on physicochemical properties, microbial population, functional attributes (antidiabetic and antioxidant activities), and sensory characteristics of fermented milk was evaluated. Additionally, the antidiabetic activity of ISO in sodium phosphate buffer (PBS) was assessed based on α-amylase and α-glucosidase enzyme inhibition. The results indicated that the addition of ISO to fermented milk produced with both strains had no significant effect on physicochemical, microbial, antioxidant, or sensory properties. However, in milk fermented with L. helveticus, ISO increased the proteolysis rate from 2.28 to 2.39 mg leucine/mL and enhanced hypoglycemic properties (p<0.05). ISO supplementation increased the inhibitory activity of α-amylase from 15% to 21% and α-glucosidase from 11% to 35% compared to the control by the end of storage (p<0.05). A key advantage of this product was its sustained hypoglycemic activity throughout the storage period. Furthermore, milk fermented with L. paracasei ssp. paracasei containing ISO exhibited stronger α-amylase inhibition (25%) compared to the control (15.49%) (p<0.05). Additional findings demonstrated that ISO in PBS effectively inhibited α-amylase activity, with Line weaver–Burk plot analysis indicating a competitive inhibition mechanism. Overall, ISO in PBS and fermented milk positively influenced hypoglycemic properties. The application of ISO as a hypoglycemic agent in food products shows promise. Additionally, the combination of ISO and L. helveticus in fermented milk presents a novel, nutrient-rich functional beverage with potential applications in diabetes management.

Biodiesel is a renewable fuel made from animal fats and vegetable oils. Heterogeneous nanocatalysts are increasingly used in production due to their efficiency and ability to reduce processing costs. This study aims to maximize biodiesel production from waste cooking oil by developing a stable mixture of oxide catalysts (ZnO-CaO). The ZnO-CaO nanocatalyst was produced by applying a mixture design. The morphology and vibrational energies of the nanocatalysts were analyzed using SEM-EDS and FT-IR, respectively. To identify optimal transesterification conditions, the Box–Behnken design was employed as a statistical tool for process optimization. It was found that a maximum yield of 97.1% was achieved under the following optimal conditions: an ethanol/oil ratio of 10.83:1, a catalyst concentration of 3%, and a reaction time of 3 hours. It was also found that the biodiesel produced from WCO met ASTM D6571 standards, indicating a highly efficient catalytic process using mixed oxide catalysts with moderate basicity. It was additionally determined that the process was environmentally friendly with low E-factors (0.57 with useful glycerol, 0.31 as waste). High RME (80%) and close-to-unity MPI indicated efficient and green production. Ethanol and glycerol were the main waste contributors, but glycerol can be repurposed for valuable products, enhancing waste management.

The present study was conducted to evaluate the adhesion of Porphyromonas gingivalis (P. gingivalis) biofilms formed on Self-Ligating (SL) and Conventional-Ligating (CL) brackets and their bacterial viability after treatment with 0.12% chlorhexidine (CHX) mouthwash. In this experimental study, 48 commercial metal brackets were divided into two equal groups based on their types (CL with elastomeric ligature and SL). The brackets were first coated with saliva, then placed in the suspension of P. gingivalis for 3 days to grow bacterial biofilms on their surfaces. Half of the brackets in each group were randomly treated with CHX mouthwash or Phosphate-Buffered Saline (PBS) for one minute. Quantitative analysis was performed by counting the number of Colony-Forming Units (CFUs). Data were analyzed using ANOVA and the Tukey test (α=0.05). There was a statistically significant difference between the two types of brackets in biofilm formation, SL brackets were colonized more than CL brackets (P <0.024). In both groups, CHX-treated brackets exhibited a significant reduction in P. gingivalis viability compared to PBS-treated brackets (P <0.001). Comparison of the antimicrobial activity of CHX in two types of brackets showed that more bacteria survived on the surface of SL brackets (P <0.001). The number of P. gingivalis CFUs on SL metal brackets was significantly higher compared to CL brackets with an elastomeric ligature. CHX significantly reduced the bacterial viability of P. gingivalis. However, more bacteria survived significantly on the SL brackets after treatment with CHX.

Pipes have been used for many years to transport fluids safely. Historically, pipes have been used in many different ways; however, many internal and external parameters affect the use of pipes, such as leakage, chemical corrosion, fatigue, and sediment. Additionally, pipe environments and soil components, such as humidity, can cause problems. All these factors are sources of risks that affect the installation and maintenance costs of the pipelines. This paper provides pipelines, users with a comprehensive description of pipe defects, their type, and their potential cause, which can be used as a reliable reference to recognize and predict pipe defects and make proper arrangements to avoid catastrophic incidents.  Therefore, pipelines and their inspection methods are examined from multiple perspectives, including material composition, design, applications, and overall performance. Besides, pipelines, defect causes visual changes, making visual inspection methods valuable to the manufacturing sector and inspectors. However, in all inspections, the pipe length, size, internal diameter, location, and toxic environment around the pipes are the main limitations of assessments. To improve defect recognition, completely categorized defect types, shapes, and pipelines, defect diagnostic systems are introduced and compared to the concept of defect shape and diagnostic platforms. As stated in this review, steel, concrete, and PVC are the most commonly used pipeline materials, with welding defects, cracks, and corrosion as major concerns. Vision-based robotic inspection, AI-driven analytics, and advanced modeling improve defect detection and predictive maintenance. Integrating these technologies enhances pipelines, monitoring, safety, and longevity. Additionally, vision-based inspection systems can leverage defect categorization to develop a standardized image database, expanding the capabilities of existing systems. Finally, a review of recent and essential analytical research and some areas that still need more work are presented. In particular, they can offer researchers opportunities for their future research.