Some Scientific Research on Membrane Filters
The traditional filter layer usually blocks large-sized particles to pass small-sized objects. Pennsylvania State University has developed a non-traditional self-healing liquid filtration membrane that can act like “reverse filtration.” The same function acts to block small particles when a larger object passes through the filter. The invention is said to have been inspired by biological cell membranes, a study published in the journal Science Progress. This self-healing, stable liquid material mimics the function of biological cell membranes. The most basic reason is that these liquid films have a ring-fixed, like soapy liquid that blows bubbles. Since the large particles of kinetic energy passing through the liquid film can pass through, the surface tension of the liquid can be self-repaired after passing through, and the small particles cannot pass due to insufficient kinetic energy.
Chemical engineers at the Ecole Polytechnique Federale de Lausanne (EPFL) have worked tirelessly to demonstrate for the first time that atomic-thick graphene can efficiently separate gas mixtures. This “ultimate” membrane can also be expanded and expanded, which will become a breakthrough in industrial gas separation. The process of separating mixed gases (such as air) into their individual components can be used in a variety of industrial applications, including biogas production, air enrichment in metal processing, removal of toxic gases from natural gas, and ammonia and refinery Hydrogen recovery. Synthetic membranes made of polymers such as cellulose or other materials are often used in gas separation processes. In recent years, research has turned to a monoatomic thickness graphene film called the “ultimate” film, which has proven to be the thinnest molecular barrier and therefore the most effective film with excellent permeability, strength and scalability. However, two bottlenecks have been encountered in the development of graphene: first, the lack of a method of incorporating molecular-sized pores into the graphene layer; and second, the lack of a method for fabricating high-strength, defect-free, large-area graphene films.
Now the research has ushered in a major breakthrough that can solve the above problems. The team of Kumar Varoon Agrawal of EPFL Valais Wallis has developed a large-area single-layer graphene film that efficiently separates hydrogen and methane (with a separation factor of up to 25%) with porosity only 0.025%, with unprecedented hydrogen permeability. This unique membrane has nanopores that allow hydrogen to permeate through it, the “gas screen”. The film is stable at industrial pressures and temperatures (at least up to 7 bar and 250 ℃ ). More importantly, the team was able to produce a 1 square meter surface defect-free film that far exceeds the previously reported few square microns. Agrawal’s team is now working to incorporate higher density nanopores into graphene to achieve the true potential of graphene.
Agrawal said: “This is an innovative technology for producing defect-free graphene layers. There is still a long way to go to achieve the ultimate performance of atomic-thickness graphene films. In the future, it can be applied to many important separation applications. Includes carbon capture, hydrogen recovery and clean drinking water.”
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