Kinetics of catalytic pyrolysis of polyethylene terephthalate (PET) plastic polymer with zeolite

Polymer of synthetic Polyethylene terephthalate is recognised as the main chemical in water bottle could triggered the formation of micro plastic in harsh environmental condition. The aforementioned particles dissolved quickly in stream of water and inevitably would increase the intensity and possibility of gradual posing human in long time period. To address the issue, Pyrolysis is suitable technique to study the rate of decomposition of waste due to the acquisition of activation energy. The ultimate objective of the present work is to characterize the PET waste in terms of the ideal activation energy in sample of pure PET in the presence of zeolite catalyst, the relationship between crystallite structure and chemical composition of the PET which corresponds to the pyrolysis kinetic reaction. Thermogravimetric Analysis (TGA) is employed to characterise the material in terms of evaluation the thermal degradation. Sample A (Pure PET) with heating rate of 5⁰C/min experiences double stage mechanism to decompose the material over the temperature range 180-287⁰C. Sample B (PET+20%NaOH+Zeolite) has similar trend in terms of changing mass over temperature 450-800⁰C. Whilst, all peaks of sample C (PET+40%NaOH+Zeolite) have triple step mechanism at smoothly decomposed around 400-800⁰C. On the other hand, the FTIR spectrogram of the sample is match to the reference PET FTIR Spectrogram. Addition of higher concentration 20% w/w NaOH will cause absorption of 1738 and 1013 cm^-1 of terephthalic acid and 40% w/w NaOH of isophthalic acid at 3293 and 1641 cm^-1 appears. The two peaks appear due to hydrolysis of PET in the present of strong alkali. The X-Ray Fluorescence spectroscopy suggests the composition of zeolite of SiO2 (64.3%), K2O (10.03%) and Al2O3 (9.95%). The crystallite size samples are 214.61 nm for PET sample A. However, after the PET submerged in the presence of basic sodalite octahydrate, the final crystallite size decreases to 1.062 nm and 4.019 nm. The kinetics character of the decomposition of PET plastic bottle through TGA is reflected as the amount of activation energy of the sample. The value of a versus activation energy is described as iso-conversional Friedman and Flynn-Wall-Ozawa equation. The methods used to study the kinetics character of the decomposition of PET plastic bottle. The activation energy of the reaction in pure PET is 272.67 kJ/mol. This value is greater than the value of activation energy PET + 20% w/w NaOH+ Zeolite and PET + 40% w/w NaOH+ Zeolite, 134 kJ/mol and 12.04 kJ/mol, respectively.