One of the main contributors to plastic pollution is the ubiquity of difficult-to-recycle plastic packaging such as plastic bags, milk bottles, and sachets. Because they are such a pain to recycle, most of these single-use plastics end up in landfills or waterways, polluting the environment as a result.
An interdisciplinary team of scientists, however, has found a way to put this non-recyclable type of waste to good use: turning it into a clean source of hydrogen fuel.
As study co-author Peter Edwards at the University of Oxford explains, the density of hydrogen in plastic bags is about 14 percent by weight, which offers a possible new source for countries eyeing cleanly produced hydrogen to tackle climate change.
Current approaches involve heating plastic waste to extremely high temperatures. This decomposes the plastic into a gaseous mixture of hydrogen and carbon monoxides, which are then separated in an additional step.
Edwards and his team, however, have figured out a more efficient way to extract the hydrogen. Their process involved pulverizing the plastic samples and mixing them with a catalyst of iron oxide and aluminum oxide.
Microwaving the mixture then heated the catalyst which, in turn, heated the plastic — recovering 97 percent of hydrogen in the plastic within seconds. The solid material left over was almost exclusively carbon nanotubes, which can also be used in many applications.
What’s particularly efficient about this single-step approach is that the microwaves are heating only the catalyst, not all of the plastic, resulting in less energy use, as the plastic does not absorb microwave radiation.
Happy with the results, the scientists now plan to test the method in larger experiments, with the hope to potentially develop a viable solution to both plastic waste and producing clean hydrogen. We call that a Win-Win!