Good News in Plastics

Compiled illustrations of a nylon chain above and PET chain below, both thermoplastic polymers, or simply put, types of plastic. Via WikiMedia, created by users YassineMrabet and Jynto, respectively.

There’s some cause to celebrate from a couple findings published recently in two journals, Nature and Animal Conservation, related to plastics, though of very different sorts. The first paper deals with a new method of plastic production using carbon dioxide and agricultural waste rather than petroleum as the raw input for PET plastic, and the second article studies the feasibility of introducing biodegradable fishing nets to replace nylon ones.

Both stories come from Conservation, our daily source of environmental news on the web. First, let’s hear from Prachi Patel on the more ecoefficient plastics:

Researchers have come up with an efficient method to convert carbon dioxide and inedible plant material, such as grasses and agricultural waste, into plastics. The carbon dioxide required for the process could be obtained from power plant or factory emissions. This could represent a low-carbon alternative to the petroleum-derived PET plastics commonly used to make bottles.

Stanford University chemistry professor Matthew Kanan and his colleagues reported the new method in the journal Nature.

The material that they have made, called polyethylene furandicarboxylate (PEF), is not new. Others have made it before, but the production methods have been expensive and not sustainable.

That’s because PEF is made from two components: ethylene glycol and a chemical called furandicarboxylic acid (FDCA). Scientists previously used fructose from corn syrup to make the FDCA. But that requires a lot of land, energy, fertilizer, and water, not to mention the competition with food production. “It would be much better to make FDCA from inedible biomass, like grasses or waste material left over after harvest,” Kanan said in a press release.

This is precisely what he and his colleagues have done. They have found a way to make FDCA from furfural, a well-known compound made from agricultural waste, and carbonate. To produce FDCA, the researchers simply heat up carbonate, carbon dioxide, and a chemical called furoic acid that is made from furfural. All the materials are abundant and cheap, which means there should be a simple, low-cost way to manufacture FDCA—and with it the low-carbon plastic PEF.

Catherine Elton writes about the biodegradable gillnet study conducted in South Korea:

Researchers have found that biodegradable gillnets catch fish as well as conventional nylon nets—and more quickly lose their ability to entangle animals when discarded at sea. Even more, the degradable nets tend to trap fewer young fish and bycatch.

Fishing nets that have been lost, abandoned, or discarded at sea account for ten percent of all the marine litter circulating in the world’s oceans. These 640,000 tonnes of nets aren’t just a plastic pollution problem, however. Long after they are lost, they continue to fish at sea on their own, trapping not only fish but seabirds and mammals in a phenomenon known as ghost fishing.

To combat this problem, researchers have been developing gillnets made of biodegradable materials, but the challenge has been to make them as good at catching fish as conventional gillnets are. In one of the most comprehensive studies to date, researchers assessed the fishing performance of a biodegradable gillnet at sea and its degradability in the lab. The results, published recently in Animal Conservation, provide some good news.

“Using a biodegradable net didn’t have much impact on how many adult fish were caught, but when it came to young fish and bycatch of other species, they caught much less,” says co-author Petri Suuronen. “That was a positive surprise.”

The fishing performance of the biodegradable nets were tested during six outings of a commercial yellow-croaker fishing vessel in the waters off southwestern South Korea. The biodegradability of the nets was tested by placing 30 sets of net samples in plastic containers at sea. The researchers used a scanning electron microscope to assess the samples every two months for four years. They also measured the strength, flexibility, and other physical properties of the nets, comparing them to conventional nets.

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