Mechanism of waste biomass pyrolysis: Effect of physical and chemical pre-treatments.
To impart usability in waste based biomass through thermo-chemical reactions, several physical and chemical pre-treatments were conducted to gain an insight on their mode of action, effect on the chemistry and the change in thermal degradation profiles. Two different waste biomasses (Douglas fir, a softwood and hybrid poplar, a hardwood) were subjected to four different pre-treatments, namely, hot water pre-treatment, torrefaction, acid (sulphuric acid) and salt (ammonium phosphate) doping. Post pre-treatments, the changes in the biomass structure, chemistry, and thermal makeup were studied through electron microscopy, atomic absorption/ultra violet spectroscopy, ion exchange chromatography, and thermogravimetry. The pre-treatments significantly reduced the amounts of inorganic ash, extractives, metals, and hemicellulose from both the biomass samples. Furthermore, hot water and torrefaction pre-treatment caused mechanical disruption in biomass fibres leading to smaller particle sizes. Torrefaction of Douglas fir wood yielded more solid product than hybrid poplar. Finally, the salt pre-treatment increased the activation energies of the biomass samples (especially Douglas fir) to a great extent. Thus, salt pre-treatment was found to bestow thermal stability in the biomass.
Department of Biological Systems Engineering, Washington State University, Pullman 99164-6120, WA, USA; Department of Civil and Environmental Engineering, University of Auckland, Auckland 1142, New Zealand.
Oisik
O
Das
Department of Civil and Environmental Engineering, University of Auckland, Auckland 1142, New Zealand. Electronic address: a.sarmah@auckland.ac.nz.
Ajit K
AK
Sarmah
D017745:Incineration / Q000379:methods*; D014866:Waste Products
D014866:Waste Products
Activation energy; Biomass; Pre-treatment; Torrefaction; Waste