Humanity has come to heavily rely on the benefits that plastics offer and their application can be found in almost every aspect of daily life. However, the major downside of this reliance on synthetic polymer-based materials is that it has been scientifically proven they are contributing to some of humanity's most-serious environmental issues.
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Now, a team of researchers at the Tokyo Institute of Technology have developed a chemical method that can help transform polymers into a fertilizer source which could revolutionize both plastic recycling methods as well as the food production industry.
One of the most surprising facts that the researchers highlighted was that only 14% of all plastic waste is actually recycled, globally. Another 14% is incinerated for energy recovery while the remaining 72% is simply discarded, which contributes significantly to environmental pollution and the destruction of resources.
Thus, the ‘plastic problem’ is an issue that should be addressed, including developing new circular systems for plastics as humanity is producing nearly 300 million tons of plastic waste each year.
Solving Multiple Problems
The Tokyo-based team initially set out to address the problems associated with polymer recycling by developing an innovative chemical recycling system. However, the innovation of the research can also be applied to provide solutions to the food-production industry as resources come under strain.
The study, which is to be published in the journal Green Chemistry, demonstrates the revolutionary process which converts bio-based polycarbonate into a fertilizer source. Thus, the concept uses plastics to address multiple problems humanity faces today.
The team led by Assistant Professor Daisuke Aoki and Professor Hideyuki Otsuka, used a process known as ammonolysis – an ammonia treatment in water – for “the chemical recycling of PIC, which is expected to be a promising alternative to petroleum-based plastics on account of its superior properties,” stated Aoki.
By evaluating the effectiveness of the ammonolysis of the bio-based synthetic polycarbonate in water at atmospheric conditions the team was also able to assess the ‘greenness’ of the method by eliminating the use of additional solvents and energy sources.
However, the results yielded demonstrated that after 24 hours the mild conditions did not produce any significant degradation of the polycarbonate – poly(isosorbide carbonate). In fact, there were still significant amounts of the isosorbide derivatives present which led to the team changing the temperature conditions of the experiment.
When increasing the temperature to 90 ℃ it was discovered the time taken for the material to break down was reduced to around 6 hours which, even with extra energy requirements, still offers a green approach to the method:
The reaction occurs without any catalyst, demonstrating that the ammonolysis of PIC can be easily performed using aqueous ammonia and heating. Thus, this procedure is operationally simple and environmentally friendly from the viewpoint of chemical recycling.
Daisuke Aoki, Assistant Professor, Department of Chemical Science and Engineering, Tokyo Institute of Technology
To confirm the results of their tests, the team evaluated the materials using a range of methods, including Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy.
“Bread From Plastics”
The team is resolute in its belief that the concept will make a major contribution to the current field.
We are convinced that the present study represents a milestone toward developing sustainable and recyclable polymer materials in the near future. The era of bread from plastics is just around the corner.
Daisuke Aoki, Assistant Professor, Department of Chemical Science and Engineering, Tokyo Institute of Technology
With such a strong stance on the outcome of their investigation, the Tokyo team is presenting an exciting chemical polymer recycling method that could address some of the major issues that world leaders and governments are facing today.
The announcement of this research comes at a time when the United Nations is holding its most important summit on the climate crisis, the COP26 2021 Climate Change Conference.
References and Further Reading
Abe, T., Et. Al., (2021) Plastics to fertilizers: chemical recycling of a bio-based polycarbonate as a fertilizer source. [online] Available at: https://doi.org/10.1039/D1GC02327F
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