Advanced characterization of hemp biomass pyrolysis: Bioenergy recovery and environmental implications

Abstract

This paper investigates the high-temperature pyrolysis of wild hemp, focusing on converting into valuable gaseous products, bio-oil (BO) and biochar (BC), which can be explored for energy and environmental applications. The pyrolysis products were characterized through various advanced techniques to identify the product composition, physicochemical properties and their suitability in further applications. The yield of the pyrolysis process resulted in 55.68 % gaseous products, 11.11 % BO and 31.86 % BC. The composition of gaseous products include hydrogen (H₂), methane (CH₄), and carbon monoxide (CO). Whereas, the BO contains phthalates and fatty acid esters that are relatively in higher quantity. The physicochemical properties of BC revealed the d-spacing of graphitic (d₀₀₂ = 3.0 Å) and calcite peaks (d₁₀₁ = 2.12 Å), as well as exhibiting the porous structure. Moreover, the Density Functional Theory (DFT) of BC revealed that the sum of Mulliken charges is 0.00 in the armchair model. Given that all free-edge carbon atoms have negative charges, they were particularly susceptible to the chemisorption of oxygen atoms and molecules from the reactant gas, leading to the formation of the semi-quinone structure, which contains oxygen content. Finally, based on the characterization and DFT, the potential application of BC in energy and environmental prospects is revealed.