Kinetic simulation and prediction of pyrolysis process for non-metallic fraction of waste printed circuit boards by discrete distributed activation energy model compared with isoconversional method

Abstract

Kinetic studies on the pyrolysis process for non-metallic fraction (NMF) of waste printed circuit boards (WPCBs) were conducted using both the isoconversional SKAS method and the discrete distributed activation energy model (discrete DAEM). The pyrolysis process of the NMF sample could be classified into three stages, and a large mass loss was observed from 98 to 570 °C, attributed to thermal degradation of epoxy resins in the NMF sample. The kinetic parameters, including activation energies (E _i), pre-exponential factors (A _i), and contributed fractions (f _i,0), were determined. It indicated that the discrete DAEM could predict the pyrolysis process of the NMF more accurately and completely when compared with the isoconversional SKAS method. In the discrete DAEM, E _i and A _i values were evaluated at 99 equally spaced intervals of conversion. The E _i and A _i (in the form of lnA _i) transformed with reaction progress, ranging from 80.9 to 240.5 kJ/mol and 19.07 to 39.55 s⁻¹, respectively, with the conversion increased from 0.01 to 0.99. The pyrolysis of the NMF of WPCBs could be accurately characterized as 17 dominating reactions from f _i,0 results.

Graphical abstract

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