New Hope for Cleaning Up Our Oceans?

By February 8, 2019 Research
Plastic is ubiquitous in our society, it is one of the most useful classes of materials we utilize in our everyday lives, and we are surrounded by it on more ways than one.  One of the most challenging problems with the extensive use of plastics is what to do with the waste–the very qualities that make plastic desirable also make them difficult to dispose of, and extremely persistent in the environment.
8.3 billion tons of plastics have been produced over the past 65 years, with about 12 percent incinerated, 9 percent recycled and almost 79 percent clogging up landfills or oceans; the United Nations estimates greater than 8 million tons of plastics flow into the oceans each year.  This crushing amount of plastic not only damages the ocean and marine creatures, it has begun to trickle down into people too–scientists have recently discovered up to nine different types of microplastics in the bodies of every single participant in a European study.  The long term effects of these microplastics are unknown.
The World Economic Forum predicts that by 2050 the oceans will hold more plastic waste than fish.
The question of what can we do about plastic waste may be one step closer to a solution.  A team of researchers at Purdue University, led by Professor Linda Wang, has developed a chemical conversion process that converts recycled shopping bags into oil. Using distillation, the oil is then separated into a gasoline-like and a diesel-like fuel.  The technology can convert more than 90 percent of polyolefin waste into different products, including pure polymers, naphtha (a mixture of hydrocarbons), fuels, or monomers. Now, the team is working to optimize the conversion process to produce high-quality gasoline or diesel fuels.

“Our strategy is to create a driving force for recycling by converting polyolefin waste into a wide range of valuable products, including polymers, naphtha, or clean fuels,” said Linda Wang, the Maxine Spencer Nichols Professor in the Davidson School of Chemical Engineering at Purdue University. “Our conversion technology has the potential to boost the profits of the recycling industry and shrink the world’s plastic waste stock.”   Initial results of Wang’s study were published Jan. 29 in ACS Sustainable Chemistry and Engineering.

The conversion process uses selective extraction and hydrothermal liquefaction to convert wet biomass into a crude-like oil  compound under moderate temperature and high pressure.  Once the plastic is converted into naphtha, it can be further separated into specialty solvents or other products. The clean fuels derived from the polyolefin waste generated each year can satisfy 4 percent of the annual demand for gasoline or diesel fuels.

“Plastic waste disposal, whether recycled or thrown away, does not mean the end of the story,” Wang said. “These plastics degrade slowly and release toxic microplastics and chemicals into the land and the water. This is a catastrophe, because once these pollutants are in the oceans, they are impossible to retrieve completely.”

Wang hopes her technology will encourage the recycling industry to increase their efforts at reducing the rapidly rising amount of plastic waste. She and her team are looking for investors or partners to assist with demonstrating this technology at a commercial scale.