A recent discovery says a blue dye that’s usually found in wastewater can now power batteries. The dye is called methylene blue. Yes, you read that right. The dye you used for science experiments back in your school days is much more useful than you ever thought it would be. When it comes to battery materials, there’s a lot of talk about lithium and cobalt. But some chemists think methylene blue could power the batteries of the future.
The dye creates an intense sapphire colo, it looks good but can be extremely harmful. when it leaches into wastewater from textile mills. Anjula Kosswattaarachchi is a Ph.D. candidate in chemistry who used to work with textiles at the Sri Lanka Institute of Nanotechnology. She was familiar with the problem of methylene blue pollution.
At the University of Buffalo, she studies a type of liquid battery called flow batteries. Interestingly, she also worked on a project that focused on removing hazardous materials from wastewater. She once had the brilliant idea to combine the two concepts. And has been working on a project combining the two ideas ever since.
She says we use it because it’s really good at producing a particular color. It’s one of the most commonly used dyes. It can even be used as medicine when it’s at the perfect dose! But it’s hard to get that perfect dose, and when it’s not, it can be poisonous. It can cause diseases, including cancer and genetic mutations. It’s also damaging to the environment because the dye is quite visible even at very low concentrations. It’s probably the most-studied dye when it comes to research on how to remove it from the water.
What’s up with methylene blue, wastewater, and batteries? Good question.
The idea is to use wastewater with methylene blue in flow batteries. Instead of extracting the dye from the water we could just reuse the water to power the battery.
So what exactly is a flow battery?
Basically, there are two external tanks that hold liquid electrolytes. The electrolytes are pumped through the center, and a chemical reaction happens to power the battery. It’s a relatively new field of study, but the advantage of a flow battery is that they’re safe. They’re liquid, so they won’t catch fire. The tanks can be really big, so you can power a lot of things at a large scale. They can store power for longer.
Where does methylene blue come in?
Methylene blue is part of the liquid that could be used for storing and pumping in the tanks. Usually, salt must be added to the solution for the chemical reaction to work. Methylene blue in wastewater already has salt in it. In her experiments, she built small batteries that had the methylene dye in salt water. One charged and drained 50 times. It’s quite stable, too.
It’s calculated that we should be able to generate up to 9.6 kilojoules per liter with methylene blue as the battery component. In practice, methylene will have to be combined with another material, research is ongoing on that material. And we still need to use samples of real wastewater to test. That’s the next step. Soon into the future, we might very well be using these batteries in our daily lives.