TITLE:
Thermal Pyrolysis of Waste Disposable Plastic Syringes and Pyrolysis Thermodynamics
AUTHORS:
Adil Koç
KEYWORDS:
Plastic Waste Injector, Rate Constant, Thermodynamic Quantities
JOURNAL NAME:
Advances in Chemical Engineering and Science,
Vol.12 No.2,
April
11,
2022
ABSTRACT: In this study, the convertibility of disposable plastic waste injectors
made of HDPE and PP plastics into valuable chemical products by thermal
pyrolysis was investigated. While PP plastic wastes were decomposed in the
temperature range of 400°C - 445°C, HDPE plastic wastes were decomposed in the
higher temperature range (430°C - 475°C). Although the physical appearance of
the liquid products obtained in the thermal decomposition of PP plastic wastes
are lighter in color and fluid, it has been observed that the liquid
decomposition products of HDPE plastic wastes have a more dense and viscous
structure. By using the first-order kinetic model, kinetic expressions for both
plastic wastes were derived, reaction rate constants, k, and activation energy, Eact,
and thermodynamic quantities such as reaction enthalpy, △H≠, reaction entropy, △S≠ ve and Gibbs free energy, △G≠ were calculated. In the thermal pyrolysis of PP and HDPE plastic wastes, Eact, △H≠, △G≠, △S≠ values are 162.30 kJ/mol, 156.52 kJ/mol, 219.50 kJ/mol, -87.71 J/molK,
and 201.80 kJ/mol, 195.77 kJ/mol, and 229.14 kJ/mol, -46.48 J/molK,
respectively. These thermodynamic quantities calculated for both plastic wastes
show that the pyrolytic decomposition studies carried out in an inert gas
atmosphere have endothermic reaction behavior.