A simple liquid battery containing a methylene blue solution and a colorless methylene blue (right) colorless solution. Image credit: Meredith Forrest Kulwicki / University of Buffalo
A sapphire dye called methylene blue is a common ingredient in textile mill wastewater. But scientists at the University of Buffalo believe that this industrial pollutant may have a second life. In a new study, they The dye was found to be good for storing and releasing energy when dissolved in water.
This makes this compound a promising candidate for redox flow batteries - a flow battery that is a large rechargeable liquid battery that allows future wind farms and solar power plants to store electricity on sunny or rainy days.
The study was published online in the journal ChemElectroChem in August.
Methylene blue is a widely used dye. Dr. Timothy Cook, assistant professor of chemistry at the UB School of Arts and Sciences, said that it may be harmful to health, so it is not something you want to dump in the environment without treatment. Much work has been done on how to separate methylene blue from water, but the problem with many of these methods is that they are expensive and produce other types of waste.
But what if we can find a new way to reuse, not just purify water? The first author of the University of Buffalo, Ph.D., Anjula Kosswattaarachchi, said that this is the real motivation for this project.
Methylene blue solution (picture from the network) Upgrade and recycle methylene blue - and wastewater?
This study is only the first step in assessing how methylene blue is used in industrial wastewater and whether it can be used in batteries.
To achieve this goal, Cook said, we need to avoid the expensive process of extracting dyes from water. What interests us is whether there is a way to directly reuse the wastewater itself.
In textile manufacturing, wastewater contains salt. Usually, in order for the redox flow battery to work, you must add salt as a supporting electrolyte, so the salt in the wastewater may be a built-in solution. Now this is speculative: we I don't know if it will work, because we haven't tested it yet.
Cook and Kosswattaarachchi have so far proved that methylene blue performs well in important tasks related to energy storage. In the experiment, scientists built two simple batteries, using dyes dissolved in salt water, to capture, store and release. Electronics (all key work in the battery life cycle).
The first battery produced by the researchers was nearly as efficient as charging and discharging 50 times: most of the electrical energy charged by the scientists was released.
However, over time, when methylene blue molecules are trapped on membranes that are critical to the proper functioning of the device, the ability of the battery to store energy begins to decline.
In the scientist's second battery, a new membrane material was chosen to solve this problem. The device maintains near-perfect efficiency of the first model, with no significant energy storage capacity drop in 12 charge and discharge cycles. .
The results show that methylene blue is a viable material for flow batteries. With this, the team hopes to do further research by obtaining real wastewater from the textile mill using the dye.
Cook said that we want to evaporate the wastewater into a more concentrated solution containing methylene blue and salt, which can then be tested directly in the battery.
The textile industry is the pillar industry of Sri Lanka (picture from the network) Personal contact between Sri Lankan textile industry and researchers
From a personal point of view, the project is very important for Kosswattaarachchi: Before coming to UB, she worked in the textile industry and developed new fabric technology for the Sri Lanka Institute of Nanotechnology (SLINTEC).
The textile industry is one of the most important economic sectors in the country, and the industry has created many jobs. But pollution is a disadvantage, and wastewater can become an environmental problem.
Kosswattaarachchi said that we believe this work can lay the foundation for an alternative route for wastewater management and pave the way for green energy storage technology.
