Scientists 3D print graphene aerogels that purify water on a large scale

Researchers at the University of Buffalo (UB) have developed a new 3D printed water-purifying graphene airgel that could be scaled up for use in large wastewater treatment plants.

Composed of an airgel type expanded polystyrene, lattice graphene and two bio-inspired polymers, the new material is able to remove dyes, metals and organic solvents from drinking water with an efficiency of 100% . Unlike similar nanosheets, the scientists’ design is reusable, leaves no residue and can be 3D printed in larger sizes, they are now aiming to bring it to market for industrial scale deployment.

“The goal is to safely remove contaminants from the water without releasing problematic chemical residues,” said study co-author and assistant professor of environmental engineering at UB, Nirupam Aich. “The aerogels we have created retain their structure when placed in water treatment systems, and they can be applied in a variety of water treatment applications.”

Graphene purification potential

With a high specific surface area and the ability to simultaneously exert electrostatic and hydrophobic interactions, graphene nanomaterials have recently emerged as a promising means of absorbing contaminants from water. In particular, the graphene oxide (GO) derivative of the material has been tested extensively for water purification purposes, but the recovery of GO devices from industrial processes has proven difficult.

Recently, scientists have experimented with assembling nanosheets into macroscopic aerogels, giving them a higher absorption capacity and making them more recoverable. However, such graphene aerogels are rarely deployed in processing facilities due to processing restrictions, which prevent them from being incorporated into industrial reactors, columns and scrub filters.

In contrast, direct ink writing (DIW) gives users precise control over the size, shape and architecture of the parts produced, while the repeatability of the process makes it highly scalable. Already, 3D printing has been deployed to create graphene thermal, energetic and biomedical devices, hence Buffalo scientists speculated that it could also be used to develop a mass-fabricated water purification system.

An evolving water-purifying airgel

In order to produce aerogels quickly and consistently, researchers first had to create an ink based on graphene, with the properties of allowing water absorption while preventing particle agglomeration. To achieve this, the Buffalo team added bio-inspired polydopamine (PDA) and bovine serum albumin (BSA) to a GO powder, producing a new 3D printing material optimized for viscoelasticity.

Relying on a modernized Ultimaker 2 GO 3D printer, the researchers then fabricated a 12mm (D) x 4mm (H) cylindrical test sample, before freezing and freeze-drying, leaving a G-PDA airgel. -BSA. During subsequent testing, the team repeatedly exposed their material to water loaded with organic solvent, in order to assess its ability to remove contaminants.

Each time, the graphene airgel was able to remove 100% of the solvents, while reducing the contamination of colored dyes by up to 20%. In subsequent design iterations, scientists even managed to reconfigure their airgel, so that it could remove heavy metals like lead and chromium, alloys that remain difficult to remove in water decontamination facilities. current.

With further development, scientists believe their evolutionary approach could also be applied to create other reusable functional nanomaterials, with potential end-use applications in water filtration plants in the form of devices such as adsorbents, reactors or filters.

“We can use these aerogels not only to contain graphene particles, but also nanometallic particles which act as catalysts,” Aich concluded. “The future goal is to have nanometallic particles embedded in the walls and surface of these aerogels, and they would be able to degrade or destroy not only biological contaminants, but also chemical contaminants.

3D printed purification devices

Considering the low cost and design flexibility that 3D printing allows, it is increasingly used to create new devices that make drinking water more readily available to those who need it. Last year, Cambridge University spin-out Blue Tap received funding from Innovate UK for its 3D printed chlorine metering device, which can be installed on water systems in developing countries. in order to make it drinkable.

Likewise, researchers at the University of Bath have developed a 3D printed water purification “ slab, ” which uses heat from the sun and UV light to kill harmful microbes living in liquids. The technology is designed to help provide safe drinking water to less affluent Asian, African and Latin American communities.

On a more militaristic note, GE Research recently received $ 14.3 million from the Defense Advanced Research Projects Agency (DARPA) to 3D print a device that creates water out of thin air. The portable system is being built to provide water to up to 150 soldiers at a time, and could later be deployed to deal with the world’s water scarcity.

The researchers’ results are detailed in their article entitled “Emerging Investigator Series: 3D Printed Graphene-Biopolymer Airgels for Water Contaminant Removal: A Proof of Concept. The research was co-authored by Arvid Masud, Chi Zhoub and Nirupam Aich.

To stay informed of the latest 3D printing news, don’t forget to subscribe to the 3D Printing Industry Bulletin or follow us on Twitter or like our page on Facebook.

Are you looking for a job in the additive manufacturing industry? Visit 3D printing works for a selection of roles in the industry.

The image shown shows the scientists freeze-dried ultralight G-PDA-BSA airgel on top of a Kim wipe. Photo via University of Buffalo.