New recycling technology breaks down mixed plastics

A team of American scientists has developed a novel method for transforming non-recyclable plastic mixtures into useful chemicals. Scientists managed to recycle plastics found in mixed materials, including a fabric made of 40% polyester and 60% cotton, in a single chemical reaction. The research results were published in the journal Materials Horizons.

The vast majority of mixed plastics end up in landfills because they are very difficult to recycle. The shirt is made of 40% polyester and 60% cotton and has plastic and cotton fibers very tightly woven together. To separate them, the fibers must be unwound or subjected to a series of energy-intensive chemical reactions to make them reusable.

Scientists have developed a catalyst that can effectively break down the polymers that make up plastics while leaving other components intact. The catalytic converter leaves behind a mixture of carbon-based chemicals that can then be converted back into plastic or other materials.

The catalyst is TBD:TFA – an “organocatalyst” composed mainly of carbon and hydrogen atoms, but without precious metals, on which many catalysts are based. Once the catalyst is heated to a specific temperature (100-200°C, depending on the mixtures being decomposed), it can decompose four different plastics tested by the researchers: polycarbonate, PET, polyurethane and polyamide in less than 2 hours.

In each case, “monomers” of each plastic were obtained – individual molecules that, when combined, form long polymer chains that give the plastic its properties. These monomers can be turned back into plastics or used to produce other chemicals such as dyes or pharmaceuticals. The catalyst left behind other polymers, such as cellulose, from which cotton is made. It can also be easily reused.

The researchers estimate that using their catalyst could lead to “more than 80% reduction in energy consumption and carbon footprint.”

Source: www.pubs.rsc.org
Photo: www.pixabay.com