World’s thinnest graphene filter and its use in carbon capture

Significance 

One of the main culprits of global warming is the vast amount of carbon dioxide pumped out into the atmosphere mostly from burning fossil fuels and the production of steel and cement. In response, scientists have been trying out a process that can sequester waste carbon dioxide, transporting it into a storage site, and then depositing it at a place where it cannot enter the atmosphere. The problem is that capturing carbon from power plants and industrial emissions isn’t very cost-effective. The main reason is that waste carbon dioxide isn’t emitted pure, but is mixed with nitrogen and other gases, and extracting it from industrial emissions requires extra energy consumption—meaning a pricier bill.

Scientists have been trying to develop an energy-efficient carbon dioxide-filter. Referred to as a “membrane,” this technology can extract carbon dioxide out of the gas mix, which can then be either stored or converted into useful chemicals. However, the performance of current carbon dioxide filters has been limited by the fundamental properties of currently available materials.

Now, Professor Kumar Varoon Agrawal at École Polytechnique Fédérale de Lausanne in Switzerland led a team of chemical engineers to develop the world’s thinnest filter from graphene. But the graphene filter isn’t just the thinnest in the world, it can also separate carbon dioxide from a mix of gases such as those coming out of industrial emissions and do so with an efficiency and speed that surpasses most current filters. The work is now published in Science Advances.

The authors made carbon dioxide-sized holes in graphene, which allowed carbon dioxide to flow through while blocking other gases such as nitrogen, which are larger than carbon dioxide. The result is a record-high carbon dioxide-capture performance. For comparison, current filters are required to exceed 1000 gas permeation units (GPUs), while their carbon-capturing specificity, referred to as their “carbon dioxide/nitrogenseparation factor” must be above 20. The membranes that the EPFL scientists developed show more than ten-fold higher carbon dioxidepermeance at 11,800 GPUs, while their separation factor stands at 22.5.

In a nutshell, EPFL chemical engineers successfully developed a graphene filter for carbon capture that surpasses the efficiency of commercial capture technologies, and can reduce the cost carbon capture down to $30 per ton of carbon dioxide. The research team is now working on scaling up the process by developing a pilot plant demonstrator to capture 10 kg carbon dioxide per day, in a project funded by the Swiss government and Swiss industry.

World's thinnest graphene filter and its use in carbon capture - Advances in Engineering
1 / 1An illustration of the graphene carbon dioxide filter. Credit: KV Agrawal, EPFL

About the author

Kumar Varoon Agrawal is the GAZNAT Chair of Advanced Separations and Assistant Professor at the Institute of Chemical Sciences and Engineering (ISIC) at the École Polytechnique Fédérale de Lausanne (EPFL). His research group is developing synthetic routes for realizing the two-dimensional nanoporous membranes with a precise control of nanopore size and functionality.  Kumar received his undergraduate degree in Chemical Engineering from IIT Bombay in 2005.  Following this, he joined the global R&D division of Procter & Gamble in Kobe, Japan working on the product design (2005-2008). Subsequently, Kumar joined the group of Michael Tsapatsis (University of Minnesota) for a Ph.D. in chemical engineering (2008-2013). His thesis work led to the development of two-dimensional zeolite nanosheets (refer to Varoon (Agrawal) et al., Science 334, 72-75, 2011).

Kumar joined Michael Strano group at the Massachusetts Institute of Technology (MIT) as a postdoctoral researcher (2014) where he studied the effect of nanoconfinement on the phase transition behavior of fluids (refer to Agrawal et al., Nature Nanotechnology, 12, 267-273, 2017). Kumar is the recipient of several awards including North American Membrane Society (NAMS) Young Membrane Scientist Award (2018), AIChE Separations Division Graduate Student Research Award (2013), Sigma Xi Award (2013), University of Minnesota Doctoral Degree Fellowship (2012), IIT Bombay Institute Silver Medal (2005), and Manudhane Best Undergraduate Student award (2005).

Reference

Shiqi Huang, Shaoxian Li, Luis Francisco Villalobos, Mostapha Dakhchoune, Marina Micari, Deepu J. Babu, Mohammad Tohidi Vahdat, Mounir Mensi, Emad Oveisi, Kumar Varoon Agrawal. Millisecond lattice gasification for high-density CO2– and O2-sieving nanopores in single-layer graphene. Science Advances,  2021-02-24 , DOI: 10.1126/sciadv.abf0116.

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