Kinetic and thermodynamic studies of biomass pseudo-components under thermo-oxidative degradation conditions using asymmetric function of Bi-Gaussian as deconvolution technique

Abstract

This work aimed at investigating the kinetic and thermodynamic characteristics of components of pine sawdust (PS), edible fungi spent substrate (FVSS) and their blend during thermo-oxidative degradation. The novelty focused on applying deconvolution technique to distinguish an overlapped peak into three individual peaks corresponding to pseudo-hemicellulose, pseudo-cellulose and pseudo-lignin, respectively. Particularly, the function of Bi-Gaussian was employed to capture the asymmetric reaction shapes. Mass loss was recorded using a thermal analyzer at heating rates of 10, 20 and 30 K min−1 in air atmosphere. Methods of Starink and master-plots were used for estimating kinetic triplet. The average activation energies of FVSS are lower than PS, with an order of pseudo-lignin > pseudo-hemicellulose > pseudo-cellulose corresponding to the ranges of 211.70–342.78, 139.00–172.53 and 128.08–146.99 kJ mol−1, respectively. The pre-exponential factor are all higher than E+10 s−1 demonstrating some simple complex chemical reactions occurred. Models of D2 and A1 dominate the degradation of pseudo-hemicellulose and pseudo-cellulose, respectively, in PS and the blend. The average values of ΔS, ΔH and ΔG are −51.62-146.31 J mol−1, 122.99–335 kJ mol−1 and 78 144.87–216.59 kJ mol−1, showing the non-spontaneous process and need energy to maintain.