A comprehensive study on by-products of food processing industry pyrolysis using a thermobalance reactor coupled to GC-FID/TCD: Mass, atomic and energy balances, thermokinetic modeling, product distribution, and characterization

Abstract

The current study aims to investigate the pyrolysis process and bioenergetic potential of pineapple peel and passion fruit shell wastes (by-products of food processing industry) by the physicochemical characterization, mass balance, energy balance, atomic balance, and kinetic study. Pyrolysis was performed at low heating rates (5, 10, and 15 °C min−1) in an argon atmosphere in a thermobalance reactor coupled to GC-FID/TCD. The pyrolysis showed a higher yield of non-condensable gases that had low calorific value (<3.51 MJ kg−1gas) due to the high concentration of CO2, which are from oxygenated functional groups. The fraction of solid and liquid had calorific value greater than 26.84 MJ kg−1, where biochar is favorable for application in steam gasification due the ash composition. For the energy balance, it was observed that the pyrolysis condition in the current study provided little exothermic characteristics for global process of both biomasses. Thermogravimetric data showed two main regions of pyrolysis (active pyrolysis and passive pyrolysis). The high release of CO and CO2 with high weight loss rate were observed in active pyrolysis (<370 °C), while the release of CH4 and H2 with low weight loss rate were observed in passive pyrolysis (>370 °C). For the kinetic study, it was assumed the presence of four pseudo-components, which were extracted from thermogravimetric data using the deconvolution tool. The kinetic parameters obtained from the Vyazovkin method, compensation effect, and mater plot could satisfactorily describe the pyrolysis process of both biomasses, with a determination coefficient greater than 0.9.