Plastic oil

Ideal disposal for waste plastic bottles

Published: Saturday 04 July 2015

Oil-rich waste: non-biodegrada us scientists have found an ingenious use for empty plastic bottles. Instead of disposing them in landfills, the non-biodegradable waste can be used to make engine oil for cars, say researchers at the University of Kentucky and the Chevron Energy Technology Company. They converted the plastic bottles into high-grade oil, which, they say, could improve fuel economy and reduce the frequency of oil changes.

The study will appear in the July 20 issue of Energy & Fuels (Vol 19, No 4) , a peer-reviewed journal of the American Chemical Society. The technology could have significant environmental impact. It could make a difference in communities that want to do something positive about their waste plastic problem, especially if there is a refinery nearby where the processing could take place, says the study's lead author Stephen J Miller. The us generates about 25 million tonnes of plastic each year, of which barely one million tonnes are recycled. Most of this plastic is polyethylene, which the researchers showed can be broken down by heat into a wax that can be converted into a high quality lubricating oil.

Of the plastic used in the pilot study, about 60 per cent was converted into wax with the right molecular properties for further processing to make lubricating oil for uses such as motor oil or transmission fluid. These high quality oils derived from wax can assist auto manufacturers in meeting mandated fuel economy specifications, Miller says.

The process for converting wax to lubricating oil used in this pilot study was put into commercial use by Chevron in the early 1990s with waxy petroleum-derived sources. In the future, superior lubricating oils will be produced from wax using a process known as Fischer-Tropsch, Miller says. However, this new study suggests wax derived from recyclable plastic can produce lubricants of comparable quality, adds Miller.

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