دوماهنامه مهندسی شیمی ایران
پیاپی 123 (مهر و آبان 1401)

The type of mixed refrigerant components is one of the most important factors affecting the energy consumption of compressors in the natural gas liquefaction process. In the recent researches, various components have been used, which usually contain ethane or ethylene. So far, no comparison has been performed between the performance of these two components in the mixed refrigerant. In this research thermodynamic properties of ethane and ethylene were compared. Then PRICO process, as the most common small-scale liquefaction process, was simulated with three types of five-component refrigerants including ethane, and then optimized using the genetic algorithm tool in MATLAB 2019a. Then, the thermodynamic effect of ethylene replacement in these three refrigerants on the work consumption of compressors as an objective function was investigated. The results indicated ethane or ethylene presence in mixed refrigerant is necessary and their absence leads to work consumption of 3792.35 kW. This value is higher than all six case that contain ethane or ethylene. Also, results showed that the use of ethylene reduces the work consumption of compressors, and in refrigerants with nitrogen, methane, ethane, propane, and i-butane components, replacing ethane with ethylene reduces process work consumption by 11.28%.

The behaviors of biological scaffolds from the attack of their mechanical behavior are a function of their microstructure. In this research,an attempt is made to find the relationship between the microstructure and mechanical properties of the studied scaffolds. Therefore, electrospinning of 10% polyvinyl alcohol and 20% gum arabic solution was performed in different ratios (60-40, 30-70, 20-80, 10-90, 0-100), and the effect of gum arabic on physical properties, microstructure, and properties. The mechanical nature of the spun scaffolding was investigated. The structural properties of the solution and the association between its phases were investigated using a light microscope.The viscosity of the solution was also investigated to investigate the effect of gum arabic on the electrospinning process. Fourier transform infrared spectroscopy of production scaffolds was performed to investigate the presence of gum arabic in the structure of electrified fibers. A tensile test was used to evaluate the mechanical properties of production scaffolds. The results showed that the presence of gum arabic causes the production of thinner fibers with higher density in the scaffolds and as a result of these changes, the modulus and strength of biological scaffolds increase.

The skin is one of the largest organs of the human body that protects against physical, chemical and microbial damage of the external environment. This complex organ has the ability to regenerate and has the possibility of self-healing. However, severe skin wounds do not heal on their own in a short period of time and require the use of engineered scaffolds. In recent years, tissue engineering has made tremendous advances in the production of these skin repair structures. Among these structures, hydrogels are one of the most important and practical scaffolds for improving and repairing the skin. Based on the materials used in the construction of hydrogels, hydrogels are divided into two categories: natural and synthetic. A combination of natural and synthetic polymers is used to improve performance and accelerate the function of hydrogels in the wound healing process. The purpose of this review article is to focus on providing information on the types of polymers used to make functional wound healing hydrogels.

Chlorophyll and carotenoids are essential compounds in many everyday products. These substances are used not only as an additive in pharmaceutical and health products but also as a natural food coloring. In addition, they have antioxidant and anti-mutagenic properties. Extraction of these compounds is based on cell degradation methods and the chemical solubility of the compounds. Methods of separation of these compounds include chromatographic, solvent, supercritical, enzymatic, ultrasound, and microwave methods. One of the most important issues related to the extraction of chlorophyll and carotenoids from microalgae in the culture medium is the need for an efficient, cost-effective, and high-yield extraction process. The greatest limitation in the biological processing of pigments is related to the installation of equipment and operation. Therefore, the purpose of this study is to investigate the main methods for the extraction of chlorophyll and carotenoids from microalgae by considering the advantages and disadvantages of each method.

For the first time in this study, the effect of ionic liquids in different concentrations and properties on the growth and performance of microorganisms capable to be used for MEOR, biodegradation and bioremediation purposes has been investigated. In this regard, two ionic liquids with different characteristics and chain lengths, namely; 1-octadecyl-3-methylimidozalium chloride and 2-decyl-3-methylimidozalium chloride were synthesized in the laboratory and their effects were investigated in different concentrations (0, 10, 25, 50, 100, 200 ppm) on 5 different bacterial species (including Enterobacter and Bacillus families), isolated from oil or oil-contaminated soil. The results show an optimum amount of concentration on the top -down curve of the growth and performance of microorganisms in most cases. The maximum the growth rate was obtained for the most species, ranges between 10 and 25PPM and the antibacterial concentration of studied ionic liquids for all species was achieved in 50 ppm. Also, in most cases, 1-octadecyl-3-methylimidozalium chloride was shown to have a greater effect on the growth and yield of all microorganisms.

Desalination process of seawater by reverse osmosis method, has attracted more attention in recent years, due to its high efficiency, and about 62 percent of seawater is treated by this method. In this process energy recovery devices play an important role in reducing energy consumption and process costs, because on the one hand the energy consumption of high pressure pumps for feeding reverse osmosis membrane is high, and on the other hand 40 percent of feed water is treated with membrane and 60 percent is discharged as a high-pressure waste, which releases a lot of energy. The energy recovery device converts this hydraulic energy of the effluent into mechanical energy and transfers it to the feed pump as a shaft aid or uses it independently to transfer a part of the feed. The purpose of this research is to study energy recovery devices and compare them with each other to select a suitable energy recovery system.