Master's Thesis Defense by Ms Georgia Fragkou

"Microwave assisted co-pyrolysis of agricultural and plastic waste for the production of oil and char"

MSc Thesis Title: Microwave assisted co-pyrolysis of agricultural and plastic waste for the production of oil and char

Thursday 25 July 2019, at:11:00, Venue: Hall K1.119

Examination Committee

  • Professor Evangelos Gidarakos (advisor)
  • Associate Professor Dionysia Kolokotsa
  • Dr. Frantseska-Maria Pellera


The οbjective of the present study is to evaluate agro-industrial and plastic waste for the production of oil and char by microwave pyrolysis.

Orange juice residues and plastic polypropylene waste was pyrolyzed in a modified household microwave oven. The microwave oven was modified to collect the pyrolysis gases during reaction by drilling a hole on its top. The process took place in a reactor which had been fitted with a suitable adapter to allow the flue gas to be fed to the condenser. At its outlet, the condenser was connected to the condensate flask. Τhe produced gases were removed by means of a vacuum pump, before which a gas trap was inserted.

The parameters tested in the pyrolysis experiments were the type of absorber, pyrolysis time and the applied power. Lignite fly ash, residual slaughterhouse ash and activated carbon were examined as microwave absorbers. At first, orange juice residues were pyrolyzed, followed by a mixture of orange juice residues and polypropylene waste. Τhe low temperature and the small mass decrease in the case of pyrolysis but also in co-pyrolysis experiments indicated that the addition of microwave absorbers in the process is necessary.  At the end of each experimental test, the yields of oil, char and gas were evaluated. Among the absorbers, the activated carbon recorded the highest temperatures, the greatest mass reduction and the highest oil production. Therefore, for the further co-pyrolysis tests activated carbon was used as an absorber.

During the experimental procedure the main characteristics of the pyrolysis products were also determined. Specifically, the char was characterized by proximate and elemental analysis, high heating value, the concentration of metals and FT-IR analysis. The collected oil was characterized regarding elemental analysis and high heating value. Finally, according to the results obtained by co-pyrolysis using a microwave absorber, there was no increase in the production of the pyrolyzed products but there was an improvement of the pyrolysis products with respect to their main characteristics.