Page 19 - Plastics News August 2020

Indian Researchers propose solution
In June this year, the Economic Times reported how the All India Institute of Medical Sciences was grappling with
rising PPE waste – the institute was reportedly storing used PPE on its premises since the Covid-19 outbreak.
Several media reports have shown how biomedical waste, including PPEs and syringes, are found dumped in the
open and sometimes mixed with regular waste. This is dangerous. Garbage collectors come under greater risk of
infection and, over a period of time, the PPE waste damages the environment.
A pile of PPEs in landfills or oceans will mean decades before they are degraded in a natural way with much harm
to the surrounding ecosystem. According to estimates, some 80 lakh tonnes of plastics go into our oceans every
year – on top of the estimated 1,500 lakh tonnes already mixed in with precious marine ecosystems.
Clearly, PPE waste disposal needs a solution. Indian researchers from the University of Petroleum and Energy
Studies in Dehradun have proposed a possible way forward – turn it into useful biofuel.
PPEs are largely made up of polypropylene (plastic). Instead of leaving it to be decomposed by microbes over
decades or have them incinerated only to release toxic gas, the material can be chemically decomposed with the
application of heat.
“Chemical processing of polypropylene is one of the most promising method,” write the authors of the paper in
the journal Biofuels. What they propose is PPE waste treatment by “pyrolysis”. The term has a Greek etymology
which roughly translates as separating with fire.
Pyrolysis entails heating up an organic material in the absence of oxygen (no oxygen means no combustion) and at
a high temperature and pressure to bring about a change in its chemical make-up. How cooked does the material
need to be? Generally, in industrial settings, the temperature is cranked up to over 430 degrees Celsius. In the
proposed method for PPE material, however, researchers have suggested a temperature range of 300-400 degrees
Celsius in a closed thermal reactor for 60 minutes. That should do, they reckon.
There are three stages in the process – initiation, propagation and termination. First, free radicals are released
after the heat is turned up. These free radicals are then broken down into smaller radicals and molecules. Finally,
the unstable radicals are turned into stable molecules through coupling reactions. Pyrolysis is not new in the
context of environmental solutions. Its benefits are well studied and reported in research. To give one example,
pyrolysis has been used to turn discarded vehicle tyres – which would release hazardous stuff in the air if
incinerated in landfills (tyre fire is a menace too) – into more useful materials that could be upgraded further and
put to productive use elsewhere.
The idea with PPEs is similar – to turn its largely plastic waste into more valuable stuff. The result is a liquid fuel
that can be used to generate energy. “The transformation into biocrude, a type of synthetic fuel, will not just
prevent the severe aftereffects to humankind and the environment but also produce a source of energy,” said lead
author Dr Sapna Jain. Liquid oil coming out of pyrolysis already has various applications in gas turbines, boiler
systems, generators, and stirling engines.
Co-author Dr Bhawna Yadav Lamba said: "There is always a need for alternative fuels or energy resources to meet
our energy demands. The pyrolysis of plastics is one of the methods to mitigate our energy crisis.” The prospect,
therefore, is not just of proper PPE waste management but also production of liquid fuel, which, according to the
authors, is clean and has fuel properties similar to fossil fuels.

Your feedback matters...
Do let us know what you feel

about this issue of Plastics News .

Send us your thoughts at publication@aipma.net

Thank you, in advance.

August 2020 17 Plastics News