Pyrolysis Kinetic Behavior and Thermodynamic Analysis of PET Nonwoven Fabric

Area of Science:

• Chemical Engineering
• Materials Science
• Environmental Science

Background:

• Polyethylene terephthalate (PET) is a widely used plastic, generating significant waste.
• Valorization of PET waste is crucial for sustainable resource management.
• Benzoic acid is a valuable chemical intermediate with diverse applications.

Purpose of the Study:

• To investigate the pyrolysis of PET nonwoven fabric waste for benzoic acid extraction.
• To characterize the pyrolysis products and understand the process kinetics and thermodynamics.
• To evaluate the efficiency of PET fabric waste as a source for benzoic acid recovery.

Main Methods:

• Thermogravimetric analysis (TGA) for thermal degradation studies.
• Fourier-transform infrared spectroscopy (FTIR) for functional group analysis.
• Gas chromatography-mass spectrometry (GC-MS) for product identification and quantification.
• Kinetic and thermodynamic modeling of the pyrolysis process.

Main Results:

• PET fabric waste yields 80 wt.% volatile matter and degrades by 84% below 490 °C.
• FTIR confirmed the presence of carbonylic C=O functional groups in the pyrolyzed vapor.
• GC-MS identified benzoic acid as the major product (75% abundance) at a 5 °C/min heating rate.
• Activation energy was determined to be in the range of 161-256 kJ/mol.
• Thermodynamic parameters (enthalpy, Gibbs free energy, entropy) were estimated.

Conclusions:

• Pyrolysis is an effective method for extracting benzoic acid from PET nonwoven fabric waste.
• This approach significantly enhances benzoic acid recovery compared to using PET bottle waste.
• PET fabric waste represents a promising secondary source for valuable chemical production.