Thermovalorization of acerola industrial waste by pyrolysis in a continuous rotary kiln reactor

Abstract

Industrial processes of acerola juice generate a great amount of lignocellulosic waste biomass. This work studies the thermal conversion of this biomass into value-added products by the pyrolysis. The process was carried out in a continuous rotary kiln reactor, investigating the influence of temperature on the yields and in the chemical characteristic of the products, that were characterized through elemental analysis, TG/DTG, FTIR, EDX, BET and chromatography. The biochar yield decreased from 86.2% at 300 °C to 28.6% at 600 °C, while the maximum yield of bio-oil (7.6%) occurred at 500 °C. The results indicate an increase in carbonization and in the degree of aromaticity with a decrease in the polarity of the biochar produced at higher temperatures, leading to potential applicability of the material for agronomic purposes and carbon sequestration. The surface characteristics presented by biochars also give these materials the possibility of being used in adsorption processes, aiming the removal of organic and inorganic contaminants present in water and wastewater. The bio-oils obtained have similar compositions, but pyrolysis temperature influenced the intensity of the chromatographic peaks. The major compounds identified in the bio-oils were phenols and acids, demonstrating their use in the synthesis of important chemical compounds.