Abstract:
The increasing number of non-degradable waste plastics is currently a common problem.
Therefore, degrading recyclable plastics is essential to environmental engineering research.
This experiment attempted to degrade three types of plastics: PET, PE, and PP. For decades,
researchers have applied several methods like photo, chemical degradation, and
biodegradation. Some studies have recently applied mechanical methods to degrade PET,
while biochemists have utilised cultivated specific enzymes to degrade PE and PP. After
reading relevant research, we planned to use a ball mill to hydrolyse PET and apply
commercial enzyme preparations to degrade PE and PP. Likewise, we intended to select a
suitable one amongst several methods like ultraviolet irradiation and microwave treatment as
the pretreatment method of the reaction and determine the pretreatment effect on plastic
degradation.
In this thesis, some creative methods have been used, including ball milling with enzyme,
microwave treatment with oxidation. Additionally, a new wet aging method has been
established in the experiment. The results indicate that PET can undergo hydrolysis by ball
milling with Novozym® 51032 and aging. Shifting the aging method to wet aging can
significantly improve degradation yield; meanwhile, when using PET pretreated by
microwave for hydrolysis reaction, the yield can reach 65%. In addition, the experiment
verified that an enzyme laccase from aspergillus sp. can realise PE degradation through direct
soaking.
