Graphene Ink and 3D Printing for Aerogel Water Purification Filters
A graphene-based ink suitable for Direct Ink Write (DIW) 3D printing of uniquely structured water purification filters.
Graphene aerogels are incredibly light weight 3D versions of 2D graphene. In many respects they make an ideal filter for purifying water with their high surface area, re-usability, and binding ability. Typically aerogels are made with graphene oxide (GO) to increase porosity. Unfortunately GO needs to be cast and will leach into water. To allow 3D printing of free-standing aerogel structures many groups mix GO with polymers to provide support during the printing process. However the polymers are difficult to remove after printing without damaging the aerogel structure.
In a procedure pioneered by the inventors, a specialized GO/biomolecules/water mix is printed on a frozen surface with the resulting ice acting as a support scaffold. The ice is removed by freeze drying and subsequent heating removes the oxygen leaving the graphene aerogel in the shape it was printed. The filter’s large surface area (shown in the pictured SEM micrographs) binds dyes, organic solvents and heavy metals from water. In addition, the graphene is encased in the non-toxic biomolecules and does not leach into treated liquid. The printed structure can be geometrically optimized to improve filtration or convenience.