Pyrolysis of water hyacinth biomass parts: Bioenergy, gas emissions, and by-products using TG-FTIR and Py-GC/MS analyses

Abstract

This study aimed to quantify the pyrolytic bioenergy potential of water hyacinth roots (WHR), stems and leaves (WHSL) by assessing their physicochemical properties, pyrolysis performances, kinetics, and thermodynamics. Their gas emissions and other by-products were also detected using thermogravimetry-Fourier transform infrared spectroscopy and pyrolysis–gas chromatography/mass spectrometry analyses. The WHR and WHSL pyrolysis consisted of the three consecutive stages of the moisture removal, devolatilization, and the decomposition of residuals. The main pyrolysis temperature varied between 200 and 600 °C. The elevated heating rate raised both initial devolatilization and peak temperatures and shortened the reaction times of the thermochemical conversions of both samples. According to the comprehensive pyrolysis index, WHSL outperformed WHR. The average activation energy estimates pointed to a lower decomposition cost for WHSL (172.09–173.09 kJ/mol) than WHR (230.11–232.06 kJ/mol). The fluctuating thermodynamic parameters indicated a complicated pyrolysis mechanism for WHR and WHSL. The main gases evolved from the WHR and WHSL pyrolysis in decreasing order were CO2, CO, C–O, SO2, CC, H2O, CH4, and CO. The main pyrolytic by-products were phenols (19.2%), and furans (12.4%) for WHR and nitrides (11.9%), and phenols (10%) for WHSL. Our results provide insights into scaling-up bioenergy potential, value-added by-products, and emission controls based on the pyrolysis of the water hyacinth biomass parts.