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Introducing membrane additives to enhance the desalination process in desalination systems.

 | Post date: 2024/06/9 | 
Introducing membrane additives to enhance the desalination process in desalination systems.
In a groundbreaking development, a team of researchers at Amirkabir University of Technology has introduced advanced membranes for the electrodialysis process in desalination systems, integrating graphene oxide to surpass conventional commercial membranes. Leila Ghadiri, a distinguished Ph.D. graduate and project manager, shed light on the pressing global issue of drinking water scarcity. With 72% of the Earth's surface covered in water, a substantial portion remains saline and unfit for consumption. Ghadiri underscored the imminent threat posed by water scarcity in specific regions of Iran, jeopardizing the well-being and health of inhabitants. She advocated for the urgent establishment of infrastructure to implement desalination techniques capable of addressing the challenges posed by high salinity water sources.
Numerous desalination methodologies have been proposed, with membrane-based technologies emerging as the preferred choice due to their user-friendly nature, cost-effectiveness, and adaptability across various applications and geographical locations. Ghadiri highlighted the limitations inherent in current ion exchange membrane processes, including intricate synthesis procedures, the generation of hazardous byproducts, perilous reactions under extreme pressure and temperature conditions, exorbitant costs, and restricted functionality at elevated temperatures.
In response to these challenges, Ghadiri proposed a strategic approach involving the synthesis and deployment of novel membranes to counteract the constraints associated with existing ion exchange membranes utilized in desalination processes. This innovative solution aims to revolutionize the field by enhancing efficiency, sustainability, and safety in water desalination practices, ultimately paving the way for a more secure and accessible freshwater supply for communities in need.
Dr. Naji introduced electrodialysis as one of the most widely used membrane methods for removing salts from saline water, emphasizing that the driving force of this method is the electric field applied to cationic and anionic exchange membranes, which are hydrophilic and placed consecutively between two metal electrodes. This process is considered one of the membrane desalination methods, in which the membrane plays a critical and fundamental role in salt removal and water desalination.
She highlighted the challenges associated with ion exchange membranes, such as low ion conductivity, selective permeability, low electrical resistance, and high energy consumption, especially in the context of the electrodialysis process. To address these challenges, incorporating graphene oxide into the membrane structure is considered one of the most effective methods. This incorporation can enhance hydrophilicity, increase mechanical strength, and improve ion conductivity.
Dr. Naji emphasized that in their research, they conducted functionalization of graphene oxide using sulfone and phosphorus groups. They studied the impact of the diversity and loading amount of cation exchange groups in the structure of the polyvinylidene fluoride polymer membrane, as well as the mechanism of attachment of hydrophilic and cation exchange groups. Furthermore, they investigated how these modifications affected the physicochemical, electrochemical, and separation performance properties of the membrane in desalination processes.

The researcher from Amirkabir University of Technology highlighted the high potential of cation exchange membranes in possessing desirable properties such as ion selectivity, chemical resistance, high thermal and mechanical stability, high ion conductivity, and selectivity towards specific ions. They mentioned that these membranes have various applications in electrodialysis processes, including separating different ions from aqueous solutions, water and wastewater treatment, ion exchange membrane separation processes, extraction of valuable metals from aqueous solutions, and utilization across a range of industries.
Dr. Naji's research is crucial for advancing the field of ion exchange membrane separation and enhancing the technical and functional properties of membranes. The optimization of processes, evaluation of membrane quality and efficiency, cost reduction, technology acquisition, and commercialization of membrane production are all key objectives of her work. By improving the capabilities and applications of these membranes in the electrodialysis process, there is potential for larger commercial utilization and a broader range of industrial applications.
Emphasizing the significance of ion exchange membranes in the electrodialysis system, Dr. Naji highlighted their structural and physical properties, which play a critical role in determining the amount of electrical energy required and the efficiency of ion separation from water. She noted that although these membranes are commercially available, their high cost is a limiting factor for expanding the application scope of the electrodialysis process, particularly in large-scale water desalination.
Given this, research centers worldwide have been focusing on developing low-cost ion exchange membranes with high separation efficiency. Dr. Naji's current research project, which involves the procurement and selection of raw materials, synthesis and functionalization of graphene oxide using sulfone and various phosphorus species, membrane synthesis and preparation, and the construction of necessary testing devices, has received support from the National Research Fund and the Special Nanotechnology Development Headquarters.
Dr. Naji explained that challenges in implementing this project included the preparation and identification of suitable raw materials for PVDF membrane production, as well as the synthesis of graphene oxide. Addressing these challenges required controlling the thickness and density of the membranes, distributing graphene oxide in the PVDF matrix, and increasing the loading amount of cation exchange groups in the graphene oxide structure to enhance ion conductivity capabilities and improve membrane performance. These challenges were tackled through detailed studies of resources and the control of influential parameters.
Dr. Naji highlighted that the achievements of this project are significant, as the cation exchange membranes made from polyvinylidene fluoride/graphene oxide loaded with agents have wide applications across various industries and technologies. These membranes can be utilized in water desalination and the removal of harmful ions and pollutants. Additionally, they can aid in the purification and recycling of chemicals, water softening, the production of demineralized water, the removal of metal cations from water, water recovery in metal industries, the recovery or separation of pharmaceuticals, and the retrieval of valuable metals in metal, medical, oil, gas, and petrochemical industries.
The project, titled "Preparation and performance evaluation of polyvinylidene fluoride/graphene oxide loaded cation exchange membranes for application in the electrodialysis process," was successfully carried out under the supervision of Dr. Leila Naji, a respected member of the faculty at Amirkabir University of Technology.