Pyrolysis characteristics, kinetics, and biochar of fermented pine sawdust–based waste

Abstract

Pyrolysis characteristics, kinetics and modified biochar derived from pine sawdust after fermentation (FPD) were determined by Fourier Transform Infrared (FTIR), Thermogravimetric analysis (TG) and Scanning Electron Microscopy (SEM), and comparison was established with pine sawdust (PD). The pretreatment i.e. fermentation changed the properties of raw materials and improved the pyrolysis properties.The variation range of CPI values of FPD was 6.51×10 -7 -16.38×10 -7 % 2 •min -2 •°C -3 , significantly higher than that of untreated samples determined under the same experimental conditions. The average activation energy of FPD was 367.95 kJ/mol attained by Flynn-Wall-Ozawa (FWO) method, 389.45 kJ/mol by Kissinger-Akahira-Sonuse (KAS) and 346.55 kJ/mol attained by Starink method much higher than PD. Additionally, fermentation could enhance the adsorption capacity for methylene blue of biochar from 0.76 mg/g to 1.6mg/g due to the abundant surface functional groups and three-dimensional internal pore structure.The adsorption pattern of fermented pine wood shifted from chemisorption dominated to the synergetic adsorption of surface functional groups adsorption and intragranular filling. Pyrolysis kinetics and biochar determination provide an in-depth understanding of fermented pine sawdust pyrolysis behaviors and product characteristics, which is the basis for designing pyrolysis process and re-using fermentation residues.