Kinetic studies on the pyrolysis of plastic waste using a combination of model-fitting and model-free methods. (May 2020)

• Record Type: Journal Article
• Authors: Yao, Zhitong; Yu, Shaoqi; Su, Weiping; Wu, Weihong; Tang, Junhong; Qi, Wei
• Is Part Of: Waste management & research. Volume 38(2020)Supplement 1
• Page Start: 77
• Page End: 85
• Publication Date: 2020-05
• Subjects: Plastic waste -- acrylonitrile-butadiene-styrene -- pyrolysis kinetics -- model-free method -- model-fitting method; Factory and trade waste -- Periodicals; Refuse and refuse disposal -- Periodicals; Municipal engineering -- Periodicals; Déchets industriels -- Périodiques; Déchets -- Élimination -- Périodiques; Génie urbain -- Périodiques; 628
• DOI: 10.1177/0734242X19897814
• Languages: English
• ISSNs: 0734-242X

Abstract

In this work, the pyrolysis behavior of plastic waste—TV plastic shell—was investigated, based on thermogravimetric analysis and using a combination of model-fitting and model-free methods. The possible reaction mechanism and kinetic compensation effects were also examined. Thermogravimetric analysis indicated that the decomposition of plastic waste in a helium atmosphere can be divided into three stages: the minor loss stage (20–300°C), the major loss stage (300–500°C) and the stable loss stage (500–1000°C). The corresponding weight loss at three different heating rates of 15, 25 and 35 K/min were determined to be 2.80–3.02%, 94.45–95.11% and 0.04–0.16%, respectively. The activation energy ( Ea ) and correlation coefficient ( R 2 ) profiles revealed that the kinetic parameters calculated using the Friedman and Kissinger–Akahira–Sunose method displayed a similar trend. The values from the Flynn–Wall–Ozawa and Starink methods were comparable, although the former gave higher R 2 values. The Eα values gradually decreased from 269.75 kJ/mol to 184.18 kJ/mol as the degree of conversion ( α ) increased from 0.1 to 0.8. Beyond this range, the Eα slightly increased to 211.31 kJ/mol. The model-fitting method of Coats–Redfern was used to predict the possible reaction mechanism, for which the first-order model resulted in higher R 2 values than and comparable Eα values to those obtained from the Flynn–Wall–Ozawa method. The pre-exponential factors (ln A ) were calculated based on the F1 reaction model and the Flynn–Wall–Ozawa method, and fell in the range 59.34–48.05. The study of the kinetic compensation effect confirmed that a compensation effect existed between Ea and ln A during the plastic waste pyrolysis.