Dot the carbon dot: NYU Abu Dhabi scientists recycle plastic bags and surgical masks with novel method

10 Mar 2023 --- A team of NYU Abu Dhabi (NYUAD) researchers has developed a single-step, organic process to convert PE-based plastic bags and PP-based surgical masks into carbon dots.

Carbon dots are carbon-based nanomaterials that have high stability, good conductivity, low toxicity and are considered environmentally friendly. These dots can be used as building blocks for a variety of packaging materials. 

The conversion of single-use plastic carbon dots, known as biocompatible carbon nanomaterials, can create applications in biological imaging, environmental monitoring, chemical analysis, targeted drug delivery, disease diagnosis, therapy and anticounterfeiting. 

“The new method our team has developed is cost-effective and safe and can be easily implemented to significantly reduce the amount of harmful plastic released into our ecosystems,” says the study’s senior author, Khalil Ramadi, assistant professor of bioengineering at NYUAD.

The study is titled High-yield, One-pot Upcycling of Polyethylene and Polypropylene Waste into Blue-Emissive Carbon Dots and was published in the journal Green Chemistry. 

Khalil Ramadi, assistant professor of bioengineering at NYUAD (Image credit: NYU Abu Dhabi). “Boundless” applications 
Existing methods to upcycle plastic into carbon dots involve multiple, time-consuming steps and toxic chemicals. The newly developed process by NYUAD is solvent-free and hydrothermal, separating it from current single-use plastic recycling methods. 

“In addition to providing a new tool to protect our ecosystems, this approach can efficiently and responsibly produce carbon dots, a versatile nanotechnology whose potential applications are nearly boundless,” explains Ramadi. 

The method uses oxidative degradation, which can upcycle plastics contaminated with organic waste such as food scraps. Recycling items with food remnants poses a significant challenge to traditional recycling technologies.

Carbon economics 
The study demonstrates a new synthesis method, which is “a simple, cost-effective and highly scalable approach to upcycling plastic waste.”

The scientists estimated the synthetic method’s economic feasibility by comparing the process’ variable costs to existing chemical recycling processes, considering the monetary value of the created carbon dots.

They observed that the global market value of carbon dots is expected to reach US$6.412 billion by 2025, up from US$2.496 billion in 2019. The researchers believe this high commercial value that more than justifies the associated processing costs.

Plastics circularization
Innova Market Insights has named “Plastics circularization” as this year’s top packaging trend. The market researcher states that the main focus for the industry should be on delivering recycle-by-design packaging and recycling systems that can help reestablish plastic within a circular economy.

“We’re delighted to support the UAE’s Circular Economy Policy further. Given that we are tackling the plastic waste crisis by creating a valuable product using a relatively easy-to-implement method,” says Mahmoud Elbeh, an NYUAD undergraduate student and researcher on the study. NYUAD turns plastic bags into environmentally friendly carbon dots for multiple applications. 

“We’re looking forward to more collaborations not only to scale up this project but also utilize the produced dots for further development and applications.”

Environmental impact
A primary reason for the research was the high volume of single-use plastics consumed during the pandemic, particularly surgical masks and medical waste, which the researchers say presents an increased need to find a solution for managing non-biodegradable waste. 

NYUAD states that approximately 26,000 metric tons of pandemic-related plastic waste – from medical waste to online shopping packaging – have been released into the world’s oceans.

The scientists add that an estimated 14% of eligible plastic packaging is recycled, with the rest ending up in landfills and oceans. They say these materials can be consumed by organisms or fragmented into micro- and nano-plastics that can threaten terrestrial, marine and freshwater ecosystems and, ultimately, human health.

By Sabine Waldeck