Scientists develop biodegradable plastic from cassava starch

A team of scientists in Brazil has developed a biodegradable plastic that could be used for food packaging or carrier bags, by applying ozone gas to cassava starch.

The ozone (O3) gas changes the molecular properties of the starch from the root vegetable to produce a bioplastic 30 per cent tougher than those made of the starch of potato, rice or maize, the researchers say.

The world currently produces around 300 million tonnes of plastic waste every year — equivalent to the weight of the entire human population — according to UN Environment.

“Our tests indicate that this new technique is able to generate a biodegradable plastic as strong as traditional ones made of petroleum,” Carla Ivonne La Fuente Arias, University of São Paulo’s Luiz de Queiroz College of Agriculture.

Carla Ivonne La Fuente Arias, a chemistry engineer at the University of São Paulo’s Luiz de Queiroz College of Agriculture, told SciDev.Net: “Our tests indicate that this new technique is able to generate a biodegradable plastic as strong as traditional ones made of petroleum.”

The ozone gas has also enabled them to improve the transparency of the cassava-based plastic, according to Arias, lead author of the study published in the International Journal of Biological Macromolecules.

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Arias said she and her team had requested the patent for their invention and were in talks with a number of companies about developing the technology, but production costs remain unclear.

“At the moment it will undoubtedly be higher than the cost of producing traditional plastics,” she said.. “However, it should drop when produced on a large scale.”

Bioplastics are considered less harmful to the environment because they may be decomposed by the action of living organisms, carbon dioxide (CO2), biomass or water.

Arias is confident that the new material has potential to help tackle the rampant consumption of plastics and pollution generated by their improper disposal.

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Alexander Turra, a biologist at the University of São Paulo’s Oceanographic Institute believes, however, that the issue of plastic waste is more complex and related to socioeconomic problems.

“The pollution caused by plastics is related to the way the global economy is structured and also the societies’ consumption logic, which is, in turn, related to the way garbage is discarded,” he said.

“It is essential to think about this in order to change consumer behaviours, even if it involves biodegradable waste,” he points out, although he recognises “this new technological solution is important, and it may act as a palliative measure for the environment.”

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An estimated 8.9 billion tonnes of virgin plastic (non-recycled) and secondary plastic (produced from recycled products) have been manufactured since the middle of the last century, when plastics began to be produced on an industrial scale.

About two-thirds of this total — 6.3 billion tonnes — has been discarded as waste, while 2.6 billion tonnes is still in use, according to a study published in 2017 in Science Advances.

The manufacture of virgin plastic so far in the 21st century is equivalent to the volume produced in the previous 50 years. In 2016, production reached 396 million tonnes, says a report by the World Wildlife Fund (WWF) published in March this year.

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WWF’s projections indicate that if the increase in production is not contained, the world will have to deal with about 550 million tonnes of the material by 2030.

“It is essential to prevent all sorts of waste, biodegradable or not, from reaching the environment,” added Turra.

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To do so, he said, governments should invest in reducing social inequality, tackling access to basic sanitation and efficient waste collection systems, and improving environmental education.

The study published in the International Journal of Biological Macromolecules is supported by FAPESP, a donor of SciDev.Net.

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