Uso de resíduos agrícolas para produção de biochar para captura de CO2

Abstract

The increase in energy demand and the use of fossil fuels has increasingly exacerbated climate change triggered by excess carbon dioxide in the atmosphere. Problems arising from these changes have led countries to develop new technologies for decarburization and a clean energy transition. Among them, biochar obtained from agricultural waste through the pyrolysis process has emerged as a potential product for carbon capture and storage. Its characteristics allow for applications ranging from soil application to gas treatment, among others. Thus, the objective of this study is to compare the CO2 capture potential from biochar production using six types of biomass derived from agricultural waste, subjected to chemical activation with KOH (1:1) and then pyrolyzed in a muffle furnace. The biochars were named after thermal treatment according to their respective biomass initials: rice husk (CA), coffee husk (CC), wheat straw (PT), soybean straw (PS), bean straw (PF), and corn straw (PM). The samples were chemically and structurally characterized by FTIR-ATR; TG/DTA analysis to determine thermal stability and adsorption kinetics; surface area determination was obtained by BET analysis and microstructural evaluation by SEM-EDS. It was observed that all biochar showed CO2 capture potential (0.12 and 0.39 mmol/g). PS (soybean straw) and CA (rice husk) exhibited the smallest BET surface areas (0.017 m²/g and 30.18 m²/g), but stood out with the largest adsorbed masses (0.39 and 0.23 mmol/g), respectively. It is proposed that chemical functionalization of the surface overcame the textural limitations of these materials, with the role of oxygen and nitrogen surface groups. Therefore, it is concluded that the chemical activation process with KOH was decisive in improving the adsorptive performance of biochars by promoting structural and chemical modifications favorable to CO₂ capture. These results reinforce the potential of activated biochar as a promising, sustainable, and economically viable material for application in carbon removal and sequestration technologies, aligning with global goals of mitigating emissions and decarbonizing the energy sector.