Like your whisky straight, no color? Graphene turns aged spirit transparent

whisky filtering graphene 87671472 l
Kichigin Aleksandr/123RF

Looking for a geeky magic trick to show your friends? All you need is a supply of all-around wonder material graphene and some booze. A membrane made of graphene oxide (GO), aka the world’s thinnest material, can filter the color out of whisky — leaving it as a transparent liquid you could potentially sip from a water glass throughout the day, with no one being the wiser. Well, the alcoholic beverage does retain one crucial telltale trait — its smell.

While the whisky component of the experiment is its most eye-catching element, the most exciting part of the work is actually the development of the ultrathin membrane itself. These new graphene-oxide sheets are assembled in such a way that pinholes formed during the assembly process produce an atomic-scale sieve, which can carry out incredibly fine grain filtering.

“Using GO membranes, we filtered several dye molecules — as small as 1 nanometer — dissolved in organic solvents, and found that the GO membrane only allows solvents to permeate, while blocking the dye molecules depending on their molecular size,” Professor Rahul Nair from the U.K.’s University of Manchester told Digital Trends. “The absence of dye molecule permeation was apparent even from the color of the solution after filtration. The original dye solution is colorful, while after filtering through the GO membrane, the solution lost its color and became a pure solvent.”

As to how this could be used in the real world, Dr. Yang Su, who also worked on the project, said: “Many chemical-related industries could [benefit] from this research — from [the] pharmaceutical and petroleum industry to food production. For example, in pharmaceutical manufacturing, most of the active ingredients are dissolved in organic solvent. Our research would enable efficient, stable extraction of the pharmaceutical ingredients from their organic solvents.” This could help reduce the costs of molecular extraction.

The team tested various dye molecules in addition to whisky and cognac. After filtering the whisky through the graphene-oxide membrane, its amber color (the result of small molecules leached from the oak barrels during production) was removed. As to how this affects the taste, Nair said, “We haven’t tested the flavor yet, due to safety rules in the lab.”

A paper describing the work was recently published in the journal Nature Materials.