Plastics recycled into acetic acid using sunlight

Plastic waste is a global problem, and researchers worldwide are looking for solutions to tackle it. Canadian researchers aim to convert old plastics into acetic acid using sunlight.

The team at the University of Waterloo in the Canadian province of Ontario has devised a cascade photocatalysis inspired by biological processes. The goal is to solve the problem of plastic waste while simultaneously converting it into a high-value product, said project leader Yimin Wu. The process can be applied to various common plastics.

It uses a catalyst consisting of iron atoms embedded in a carbon nitride support material. Under the influence of sunlight, hydroxyl radicals, very reactive hydrogen-oxygen molecules, are formed. These break down the long plastic chains into intermediates, which are then reduced to acetic acid in the same way.

The process is similar to how some types of fungi break down organic matter. The reaction takes place at room temperature and ambient pressure and occurs in water. This means the process should also be well-suited for breaking down plastic waste in water.

Tested on various plastics

The team has successfully tested the process with common plastics. These included, for example, polyethylene (PE), polyethylene terephthalate (PET), polypropylene (PP), and polyvinyl chloride (PVC). The yield varied, being best with PVC.

"This process allows us to break down plastic waste using abundant and freely available solar energy without releasing additional carbon dioxide into the atmosphere," said Wu. Acetic acid can be processed in the food industry or in the chemical industry, for example, as a flavoring agent, in solvents, or adhesives.

The team led by Wu has described the process in the journal Advanced Energy Materials. According to the researchers, it is currently still in the laboratory stage. However, they expect it to be scalable for industrial applications.

(wpl)