National Institute of Technology, Odisha,
developed a commercially viable technology for efficiently rendering common
polymer, low-density polyethylene (LDPE)
into a liquid fuel.
This discovery may lead to re-using discarded plastic
bags and other products to address growing demands for fuel globally. Study was
published in International Journal of Environment and Waste Management. LDPE is
used to make container, medical and laboratory equipment, computer components
and plastic bags.
The team heat up the plastic waste to between
400 and 500 degrees celsius over a kaolin
catalyst (a clay mineral containing aluminum and silicon).This caused the
plastic’s long chain polymer chains to break apart in a process known as
thermo-catalytic degradation. The process released large quantities of much smaller, carbon-rich molecules.
An analytical
method called Gas chromatography-mass spectrometry (GC-MS) was used to
characterise these product molecules and found the components of their liquid
fuel to be mainly paraffins and olefins 10 to 16 carbon atoms long. This makes
the liquid fuel very similar chemically to conventional petrochemical fuels.
Kaolin acts as a catalyst by providing a
large reactive surface on which the polymer molecules can sit and so be exposed
to high temperature inside the batch reactor, which breaks them apart.
Recycling initiatives are in place across the
world but much of the polyethylene waste ends up in landfill, dispersed in the
environment or in the sea. The process, if implemented on a large scale, can
reduce pressures on landfill as well as ameliorating the effects of dwindling
oil supplies in a world with increasing demands on petrochemicals for fuel.