Evaluating the bioenergy potential of Chinese Liquor-industry waste through pyrolysis, thermogravimetric, kinetics and evolved gas analyses

Abstract

Baijiu (Chinese liquor) industry is the world-renowned industry to produce high-quality liquor using mixed biomass feedstocks including sorghum, wheat, and rice bran. A huge amount of Baijiu Diuzao (residual solid waste) is produced every 1–3 months after the fermentation. The present study was focused on evaluating the bioenergy potential of the Chinese liquor industry waste for the very first time. The collected sample was subjected to thermal degradation in an inert environment at three heating rates including 10, 30 and 50 Kmin-1. It was shown that pyrolysis of this waste followed a three-stage degradation pattern, with a loss of 7.49% of the mass during the first stage at T ≤ 130 °C. While the second stage showed two zones ranging from 130 to 373 °C with an overall 51.12% of the mass loss. The third stage occurred above 373 °C and showed 16.08% loss in the mass. The released gases were subjected to TG-FTIR-MS analyses to monitor the composition and abundance of the gases where CO groups (aldehydes, ketonic and carboxylic) and hydrocarbons were shown to be the dominating functional groups. Moreover, the data were subjected to kinetics, thermodynamics and reaction mechanism analyses using KSA (Kissinger-Akahira-Sunose), FWO (Flynn-Wall-Ozawa), Vyazovkin and CR (Coats-Redfern) methods. Where, the activation energies (70–195 kJ mol−1), Gibbs free energy (177–185 kJ mol−1) and lower difference of enthalpy (ΔH = ∼5 kJ mol−1) indicated remarkable bioenergy potential of this waste either through pyrolysis or co-pyrolysis. The artificial neural network (R2 = 0.99) and reaction mechanism analyses indicated that the best thermal degradation chemistry was performed and described. This study will lead to establishing a thermal transformation strategy of this abundant and low-cost biological resource into energy and valuable chemicals in the cleanest manner.