دوماهنامه مهندسی شیمی ایران
پیاپی 130 (آذر و دی 1402)

Water scarcity will become one of the biggest global challenges in the coming years and all available unconventional water resources must be used to produce water. Zero liquid discharge as an emerging system to minimize effluent (especially brines) and maximize water recovery from wastewater has been used by researchers and industries in recent years. Thermal evaporation is known as a common method for zero liquid discharge. However, the use of conventional and novel membrane processes of reverse osmosis, membrane distillation, forward osmosis, and electrodialysis in combination with thermal systems and crystallizers have been recently considered to reduce the volume of wastewater and influent flow rate of the thermal systems. In this article, after a brief introduction of thermal and membrane zero liquid discharge systems, the conducted research to improve the economics of these systems using thermal-membrane hybrid processes is reviewed. By comparing the performance of each of them, the potential and limitations of these systems have been explained. Although the use of zero liquid discharge systems increases the initial investment, operating costs, and water cost, due to the lack of water resources in water stress areas and also the harmful environmental effects caused by wastewater discharge, it can be expected to be widely exploited in the near future. It is a necessary solution for the sustainable management of unconventional water resources.

In this review article, the necessity of carbon dioxide separation, and its separation methods are introduced. Membrane technology is considered as the best method in carbon dioxide separation. Among the membranes, SSZ-13, Si-CHA, SAPO-34 and DD3R zeolite membranes have the best performance in carbon dioxide separation. Meanwhile, the DD3R membrane is the best target for future research, but the formation of non-zeolite pores causes a decrease in their performance. The methods of carbonaceous components deposition and creating coke, silane coupling agents, chemical vapor deposition, chemical liquid deposition and dip-coating are the important methods for zeolite membrane modification. The dip-coating is an effective method for a wide range of materials in surface modification due to the simplicity of the process. Among the different materials used for modification, polymers have performed well due to their favorable processability. Among the polymers, poly dimethyl siloxane (PDMS) has shown better performance in modification of zeolite layers, and has been able to significantly increase the performance of DD3R zeolite membrane. The important effective parameters in the modification process of the zeolite membranes by dip-coating method include polymer glass transition temperature (Tg), cross-linking property, type of solvent and dissolution temperature, concentration of polymer solution, permeability and selectivity of the polymer material over to the target gases. The study of these parameters shows that plastic polymers such as cellulose acetate (CA), polycarbonate (PC) and thermoplastic elastomer polyether block amide (PEBA) are effective polymers in the surface modification of zeolite membranes with the aim of separating carbon dioxide.

Thermal comfort is one of the important and effective parameters on the health and efficiency of the human body, and textiles play a significant role in providing this parameter. In this regard, many engineered textiles have been proposed by adjusting different thermal mechanisms. In the present study, the recent developments in the field of active and passive temperature control (heating, cooling and two-mode textiles) have been expressed with emphasis on the effective mechanism of heat transfer in the desired textile. Finally, the used methods are compared and the challenges and opportunities in this field are pointed out.

Until now, various chemical treatments (oxidation and electrochemical destruction), biological treatments (microbial cultures and anaerobic bioremediation systems) and physical treatments (such as adsorption and ion exchange) have been proposed to remove dyes as one of the most important water pollutants. In this study, hydrodynamic cavitation (bubble formation in a liquid) was considered as a new method for dye removal. The important advantages of this method are no need to use chemicals, low energy consumption and the ability to combine with other advanced oxidation processes. A literature review on dye removal focusing on combination with other advanced oxidation processes indicated that orifice plates and venturi tubes are often used and less than 2 h (in optimum operating conditions) more than 80% of dye was removed. Also, factors such as device geometry, inlet pressure, operating temperature, pH and liquid properties (like vapor pressure, viscosity and surface tension) are effective parameters in this process. The results of previous works imply excellent efficiency of this method in combination with other processes and methods such as Fenton, photocatalytic, ozonation, aeration and presence of various metal and non-metallic ions in the reaction medium. Also, flexibility in designing and combining with advanced oxidation processes, depend on the purpose, are another major and important advantages for replacing this method with conventional methods in the near future.

Contamination of soil and water with heavy metal ions poses serious dangers and threats to the environment and human health, therefore it is very important to find an effective solution to remove these heavy metals from water. In this study, surface modified magnetic nanoparticles by N-phosphono-methylamino - diacetic acid with a core-shell structure were first synthesized. These nanoparticles were characterized. The performance of this synthetic nanoadsorbent for removing nickel (II), lead (II) and vanadium (V) ions from aqueous solutions was evaluated by various parameters such as adsorbent amount, contact time effect on adsorption rate and pH effect. The results show that the adsorption efficiency increases with raising pH and the best adsorbent performance in the adsorption process of nickel (II), vanadium (V) ions at pH = 6-7 and lead (II) at pH = 5-5.5 was observed. Also, the adsorption data were analyzed by the Langmuir and Freundlich isotherm model. In addition, the recyclability and reuse of the adsorbent shows that the adsorbent can be easily separated by using a magnetic magnet without any significant reduction in activity that can be used in successive metal ion adsorption-desorption cycles.

In this study, computational fluid dynamics simulation of liquid-liquid extraction of zinc was performed using trifluoroacetylacetone as a solvent in the hollow fiber membrane contactor. Mass and momentum balance equations (Navier-Stokes) were used to express the transport of zinc solutes through the membrane contactor. After applying the conditions, the governing equations were simulated using the finite element method. After validating the results, simulation was performed to study the distribution of zinc concentration in two-dimensional and three-dimensional form, as well as to investigate the effect of different parameters such as distribution coefficient and current intensity on the extraction efficiency. The results showed that by increasing the partition coefficient from 1 to 10, the amount of single-pass extraction increased from 10 to 100 percent. Also, the extraction efficiency in the counter-current flow of pipe and shell is 9% higher than in the co-current flow. Furthermore, this study showed that computational fluid dynamics could be used as an effective tool for the development of membrane-based extraction processes.

Hot water injection is one of the common mechanisms to enhance the oil recovery from reservoirs. But, novel methods of enhanced oil recovery are used for oil recovery, and one of them is flooding polymeric solutions inside the reservoirs. The main purpose of this experimental study is to investigate the process of enhancing the recovery of viscose oil by injecting distilled water and polyacrylamide-based polymeric solution from a two-dimensional porous medium. In order to study the flow patterns during the injection of base fluid and polymer solution, injection of displacing fluids was performed at a constant flowrate of 0.4 mL/min. Also, to investigate the effect of injected fluid temperature on fluid-fluid displacement and enhanced oil recovery efficiency, displacing fluids were injected at temperatures of 25°C and 90°C. The results showed that by adding polyacrylamide to water, the viscosity of the displacing fluid increased significantly, which led to an increase in the capillary number, and enhanced oil recovery up to 65.2% when injected with 0.5%wt polyacrylamide at ambient temperature. Also, increasing the temperature and reducing the mobility ratio of displacing fluids and base oil, the efficiency of oil recovery by injecting 5000ppm polymer solution increased to 66.4%, which is the maximum rate of base oil recovery by injecting displacing fluids in present study.

The methanol steam reforming in a microreactor is simulated using Purnama’s reactions kinetic model. The simulation results were validated against published experimental data in terms of methanol conversion and product composition. A new concept for making the microreactor package more compact is evaluated by simulation. This idea consists of thermal and mass integration of the process, i.e., the required heat of methanol vaporization and methanol steam reforming be supplied by the heat of catalytic heat of combustion of a portion of methanol in an adjacent micro reactor to the reforming section of the package. The simulation results showed that by using this method, it is possible to obtain a product with a hydrogen purity of more than 60% and CO content of less than 2%. The effects of reactor temperature and residence time on the performance of the presented package was investigated and it was shown that the methanol conversion increases with increasing each of these parameters. Also, it was shown that adding small amount of water to the methanol feed stock leads to significant reduction in CO content of the product.

Propylene is an important feedstock for manufacturing various products such as polypropylene, polyacrylonitrile, acrolein, acrylic acid, and so forth. Formerly, propylene was typically produced by fluid catalytic cracking and steam cracking. Due to the significant demand growth for propylene, direct production methods of propylene from the propane dehydrogenation method have been highly noticed by industries. The process of propane dehydrogenation has been commercialized by different companies and the most critical differences among different technologies are the type of reactor and their used catalyst. Platinum-based catalysts are the most widely used ones in this technology, and due to their high price in new catalyst generation, it has been attempted to use the least amount of platinum in the catalyst. Therefore, this article discussed the process of dehydrogenation of propane to propylene in general, then the platinum-based should be examined in terms of active sites, bases used, and types of promoters to increase efficiency. In conclusion, the patents related to the production of platinum-based catalysts by UOP have been collected and discussed.