Despite the growing plastic pollution on our planet, petroleum-based polymers have turn into a integral part of contemporary lifeThey make cars and airplanes lighter and more energy efficient. They are a core material of contemporary medicine, helping to maintain equipment sterile, administer drugs, and make prosthetics, amongst other things. And they’re a vital a part of the wiring and hardware that underpins our technology-driven civilization.
The problem is that after they’ve lost their usability, they turn into waste and ultimately pollute our oceans, rivers and soil. and body.
But latest research from a team of UC Berkeley chemists offers a glimmer of hope with regards to the thorny problem of plastics recycling—a glimmer of hope that might allow us to get the most effective of each worlds and perhaps even get a tiny piece of the pie in the method.
The group has developed a catalytic recycling process that breaks the chains of among the mostly used plastics – polyethylene and polypropylene – in order that the constructing blocks of those plastics may be reused, in some cases with an efficiency of over 90%.
The catalysts needed for the response – sodium or tungsten – are available and cheap, they are saying, and initial tests have shown that the method is prone to be scalable to an industrial level. It uses no water and uses less energy than other recycling methods – and is much more efficient than producing latest, so-called virgin plastics, the researchers say.
“So by making one or two products at very high yields and at much lower temperatures, we use some energy, but significantly less than any other process that mines polyolefins or converts petroleum resources into monomers for polyolefins,” said John Hartwig, a UC Berkeley chemist and co-author of the study recently published within the journal Science.
Polyolefins are a family of thermoplastics that include polyethylene – the fabric used to make single-use and “reusable” plastic bags – and polypropylene – the ever present plastic that makes up our yogurts, microwaveable dishes, and automotive bumpers. Polyolefins are made by combining small chain links, or monomers, of ethylene or propylene, which are often derived from oil and natural gas.
Polyethylene and polypropylene make up the bulk (57%) of all polymer resins produced, the study authors noted. They have proven to be a plague on the environment and have been present in the shape of microplastics in drinking water, beer and each organ of the human body, in addition to in blood, semen and breast milk.
Hartwig and RJ Conk, a graduate student who led the research, said that they had not heard of the plastics, recycling or waste industries. They said they kept their technology under wraps until they published their work and received a patent on the method.
A spokeswoman for the Plastics Industry Association declined to comment or request an authority to review the document.
Hartwig said there are some limitations to the work. For example, the plastic have to be sorted before the method may be used. If the products are contaminated with other plastics corresponding to PVC or polystyrene, the result just isn’t good.
“We haven’t any way of [plastics] back to the monomer and in addition they poison our catalyst,” said Hartwig. “So PVC is bad for us and principally for everybody else. It can’t be chemically recycled.”
He said other contaminants – food waste, dyes, glues, etc. – could also potentially cause problems, but researchers are still at an early stage of the process.
But Plastic bagssuch as those used in supermarkets to store fruit and vegetables are promising because they are relatively clean and “no person knows what to do with them”. He said plastic bags are problematic for recycling facilities because they are known to clog up machinery.
“There are places where these bags are collected. I don't know what they do with them. Nobody wants them,” he said.
Others, however, are less confident.
Neil Tangri, science and policy director at GAIA, an international environmental organization, said he was not a chemist or chemical engineer and therefore could not comment on the methods, but noted that there were broader “real-world” problems that could prevent such technology from being successful.
“Plastic recycling just isn’t something we do well … we only get about 5 to six percent a 12 months. So we're taking a look at latest technologies that can try this higher,” he said. “My general warning is that going from analyzing small amounts within the lab to having a working process at scale in real-world conditions … is a big, huge leap. So it's not like we're going to see a transition to business production in the subsequent 12 months or two.”
He noted that while the reaction temperature is lower than that used in pyrolysis – burning plastic as fuel – or cracking – when plastics are made from virgin material – it still requires a lot of energy and therefore potentially leaves a pretty large carbon footprint. In addition, he said, 608 degrees – the reaction temperature mentioned – is the temperature “at which dioxins are likely to form. So that might be a challenge.” Dioxins are highly toxic byproducts of some industrial processes.
But, Tangri said, even if all of those problems could be solved – as well as the sorting and contamination problems cited by Hartwig – “it's so low cost to make latest plastic that the gathering, sorting, cleansing… they talked about… all those steps, the energy consumption, you simply can't sell your plastic. [recycled material] at a price that justifies all of it… And that's probably not due to the engineering approach. It's due to the reality of today's plastics economy.”
Lee Bell, technical and policy adviser to IPEN, a global environmental group, shares this view.
“What seems promising within the lab rarely translates to commercial-scale success and high yields from mixed plastic waste,” he said. “Not only do you might have to cope with the devilish problem of inevitable plastic contamination [because chemical additives are in all plastic] but additionally competes with low cost latest plastic available on the market.
“In my view, this is another laboratory experiment with plastic waste that will ultimately be thwarted by contamination with mixed plastic waste and commercial realities,” he said.
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