However, the increased usage has exacerbated the issue of CFRP’s waste disposal. The currently used techniques pose environmental risks; therefore, there is an urgent need to look for more sustainable recycling options.  

To overcome this issue, researchers at the Korea Institute of Science and Technology (KIST) have come up with a novel recycling method. 

“As the amount of carbon fiber reinforced plastics (CFRPs) waste is increasing globally, we have developed a technology to upcycle it in an eco-friendly way,” said Yong-chae Jung, director of the RAMP Convergence Research Center.

Use of supercritical water

Dealing with CFRP trash is highly taxing. It has a highly non-degradable nature, which requires the development of cutting-edge methods. 

Some currently used techniques include high-temperature incineration methods, which subject CFRP waste to intense heat in controlled conditions. However, this high-temperature incineration approach releases harmful chemicals into the atmosphere, polluting the surrounding environment. 

The KIST team sought to develop an alternative, highly efficient, and sustainable technique. For this purpose, they harnessed the unique properties of “water in a supercritical state” to recycle over 99% of CFRP within tens of minutes.

As per the press release, supercritical water occurs “under conditions of temperature and pressure above a certain level.” This extensive process creates unique properties that make it highly effective for industrial recycling processes.

When water reaches supercritical conditions, its polarity rises. This means that it is strongly attracted to other polar molecules, such as the epoxy resin commonly used as the matrix in CFRP. 

Moreover, supercritical water also exhibits high diffusivity and density. 

These unique properties allow supercritical water to remove epoxy from CFRP while preserving recycled carbon fiber selectively. Interestingly, this recycling process was established using only water without needing catalysts, oxidants, or organic solvents. 

Upcycled carbon fiber

The researchers further experimented with supercritical water by introducing glycine. This process converted upcycled CFRP into recycled carbon fiber doped with nitrogen atoms.

The upcycled carbon fiber displayed greater electrical conductivity than typical recycled carbon fiber from previous processes. 

The authors point out that this is the first time a single recycling technique has been employed to recycle and upcycle CFRP in a fraction of the time.

These recycled carbon fibers might serve as electrodes in e-mobility batteries.

 “It is a meaningful research achievement that not only dramatically reduces carbon emissions, but also presents a virtuous cycle of resources that can be converted into battery electrode materials for E-mobility,” Jung concluded in the press release. 

If applied on a larger scale in the near future, this eco-friendly solution has the potential to break the cycle of CFRP waste.

The findings were published in the journal Carbon.