Model-Fitting Methods for Evaluation of the Kinetics Triplet during Thermal Decomposition of Poly(ethylene terephthalate) (PET) Soft Drink Bottles

• Published in: Industrial & engineering chemistry research Vol. 45; no. 23; pp. 7752 - 7759
• Main Authors: Saha, Biswanath, Ghoshal, Aloke K
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 08.11.2006
• Subjects: Applied sciences; Chemical engineering; Exact sciences and technology; Kinetics; Bottle; Thermal decomposition; Modeling
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/ie060282x

Different chemical reaction models (first-order, second-order, and nth-order) and six different model-fitting techniques (nth-order, Friedman, Freeman−Carroll, Chang, ASTM E689, and the standard deviation minimization technique (SDMT)) are used to evaluate the kinetics triplet (E, ln k 0, and n) for the thermal decomposition of waste soft drink poly(ethylene terephthalate) (PET) bottles (M/s Coca Cola). Nonisothermal experiments at four different heating rates (5, 10, 15, and 25 K/min) and isothermal experiments at four different temperatures (685, 693, 703, and 711 K) are conducted using thermogravimetric analysis (TGA). The experimental results are predicted through simulation of the kinetics models of decomposition. The model input parameters (i.e., the optimum kinetics triplet) are used as obtained from the different model-fitting techniques. Results show that the SDMT methodology with Agarwal and Sivasubramaniam approximation for the temperature integral is possibly the best and most versatile method to calculate the optimum kinetics triplet, because it, in contrast to other model-fitting methods, addresses multiple heating rates. The optimum kinetics triplet thus obtained for the thermal decomposition of the waste PET sample is E = 269.35 kJ/mol, ln k 0 = 44.94, and n = 1.