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Phenol
resins are synthetic polymers belonging to the family of
thermo-resistant polymers, with various commercial and
industrial applications. Compared to common plastics, these
resins present considerable difficulties for recycling, because
they cannot be melted or mixed with other plastics, as they are
incompatible. The difficulty of recycling or breaking them down
means that many end up in landfills.
So
there is growing interest in researching methods and techniques
for recycling these materials. One possible solution studied
recently involves mushrooms. Researchers found that wood fungi,
which are already known to decompose organic pollutants such as
DDT, TNT and PCB, can also break down phenol resins. The
researchers created cultures with eleven different types of
fungus and observed the most efficient decomposition with white
wood mushrooms. Biodegradation of phenol resins is demonstrated
by the change in colour of the mushroom as it absorbs the phenol
and formaldehyde, the monomers from which the resin is produced.
The presence of these substances in the mushrooms was then
verified
using laboratory techniques (gas chromatography and 13C
analyses). It is possible to hypothesise that the phenol and
formaldehyde could then be extracted from the mushrooms and used
to make new resins, thus providing a perfect example of a closed
circuit.
This
is undoubtedly an important discovery, which sheds new light on
the degradation of phenol resins and could make mushrooms an
important factor in large-scale recycling of these resins. On
the other hand this is only a first step: more advanced research
is needed to better understand the factors which influence the
degradation process and above all to translate the process to an
industrial scale, in order to demonstrate that it can be applied
to mass recycling.
In conclusion, degradation of phenol resins using fungi is
certainly an interesting alternative to dumping, and is well
worth following up, but its use for recycling of resins is
premature and needs further research.
(Hi-Tech Ambiente, Italy, www.pubblindustria.com)