Pirólise do resíduo de vinagre de maçã por termogravimetria: um estudo cinético considerando o processo em única etapa e múltiplas etapas

Abstract

The great climate changes alert about the need to renew the energy matrix. For this, it is essential to focus on using renewable energy sources, such as biomass, which present lower greenhouse gas emissions. The high disposal of wastes from agricultural and agro-industrial production has mitigated the interest in using residual biomass, especially the apple vinegar bagasse. This work sought to characterize and evaluate the energy potential of apple pomace biomass (BM) through the pyrolysis process in a thermogravimetric analyzer. The pulverized residue presented a low ash content, high content of volatiles, and carbon, besides a high HHV of 18,19 MJ kg-1. Pyrolysis was carried out at four heating rates, up to a final temperature of 900°C. Due to its well-diversified composition, the BM was evaluated using pyrolysis kinetics considering the single-step and multi-step mechanisms. The activation energy (Ea) was obtained from integral and differential isoconversional methods (FR, FWO, KAS, and STK), and the pre-exponential factor (A) was obtained by the Kissinger method. The single-step mechanism resulted in Ea values in the range of 165-183 kJ mol-1 and A above 1.25 1016 min- 1. All fitting methods provided R² values above 0.9993, indicating an optimal fit to the BM pyrolysis experimental data. The multi-step mechanism was studied using the deconvolution associated with the STK method, resulting in a good approximation of the complex thermal behavior of biomass (with R2 > 0,95). The econvolution curves satisfactorily represented the experimental data, indicating the presence of four pseudo-components: pseudo-extractives, pseudo-hemicellulose, pseudo-cellulose, and pseudo-lignin. The multistep mechanism resulted in average values of Ea in the range of 135-895 kJ mol-1 and A above 3.90 1014 min-1. Associated with the results of physical-chemical characterization, when compared to the literature, the results arising from this work indicate that the apple pomace has potential for application in conversion processes for bioenergy production.