An international group of researchers, including scientists from Shinshu University in Japan and Penn State’s ATOMIC Center, created a graphene and graphene oxide-based coating for desalination membranes which are said to be more scalable and sturdier than current nanofiltration membrane technologies available.
The result of this creation would hopefully be a filter for clean water solutions, protein separation, wastewater treatment, as well as pharmaceutical and food industry applications. This membrane uses a simple spray-on technology to coat a mixture of graphene oxide and graphene in solution onto a backbone support membrane of polysulfone that is modified with polyvinyl alcohol. The team reports that even in the early stages of the development of the membrane, it can already reject 85% of salt, which is sufficient for agricultural purposes, and 96% of dye molecules.
The researchers explain that chlorine is usually used to mitigate biofouling in membranes. However, chlorine rapidly degrades the performance of polymer membranes that are currently available. The team found that adding a few-layer of graphene makes this new membrane highly resistant to chlorine.
However, there are still many challenges to overcome with using this material, including scaling up to industrial quantities as well as controlling defects and the need for complex transfer techniques that are needed to handle the two-dimensional material. Currently, the researchers are attempting to overcome scalability issues so as to provide an inexpensive and high quality membrane at manufacturing scale.
According to the team “our membrane overcomes the water solubility of graphene oxide by using polyvinyl alcohol as an adhesive making it resistant against strong water flow and high pressures. By mixing graphene oxide with graphene we could also improve significantly its chemical resistance”. The team further stated “our dream is to create a smart membrane that combines high flow rates, high efficiency, long lifetime, self-healing and eliminates bio and inorganic fouling in order to provide clean water solutions for the many parts of the world where clean water is scarce. This work is taking us in that direction.”