The director of the Atomic Center at Pennsylvania State University in the United States and researchers from Shinshu University in Japan have developed a graphene-based desalting membrane that is more robust and more efficient than current filter membranes. This technology can be used in desalination, protein separation, wastewater treatment, pharmaceutical and food industries in the future.
“Our dream is to develop a smart membrane that has the characteristics of high throughput, high efficiency, long life, self-repair, etc. It can provide solutions for eliminating biological and inorganic pollution and obtaining clean water in water-deficient areas.” Mauricio Terrones, professor of physical chemistry and materials science engineering at Pennsylvania State University, said, "This research work is moving in this direction."
The hybrid membrane developed in this study employs a simple spraying technique to coat graphene oxide and a small amount of layered graphene in solution on the skeleton support membrane of polyvinyl alcohol modified polysulfone. The support membrane enhances the robustness of the hybrid membrane, allowing it to withstand strong cross-flow, high pressure and chlorine contact. Although the technology is still in the early stages of development, membrane samples have been able to filter out 85% of the salt, and the produced water, although not yet drinkable, is already available for agricultural irrigation. The membrane developed can also filter out 96% of the dye molecules, so it can be used in wastewater treatment in the textile industry to prevent the direct discharge of wastewater into the river to pollute the environment.
Chlorine is commonly used to degrade bioactive components in wastewater, but it can also rapidly degrade the performance of current polymer membranes. This new type of graphene-based film has a very strong chlorine resistance.
As we all know, graphene has high mechanical strength, porous graphene has a strong filtration capacity, almost 100% can filter out the salt in water, is a potential ideal desalting membrane material. However, there are many challenges in extending graphene to industrial quantities, including the need to control defects and handle two-dimensional materials that require sophisticated transfer techniques. Research teams are trying to overcome scalability issues and provide inexpensive, high-quality membranes on a production scale.
This result was published in the "Nature Nanotechnology" magazine published on August 28. The first author of the paper, Aaron Morelos Gomez, said: "The filter membrane we developed overcomes the water solubility problem of graphene oxide and uses polyvinyl alcohol as a binder to make it resistant. Strong water flow and high pressure impact. By mixing graphene oxide with graphene, we can also significantly improve the corrosion of its corrosion-resistant chemicals (such as chlorine)."