Desenvolvimento de materiais carbonosos porosos a partir de precursores naturais para captura de CO2
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Data
2025-05-30
Autores
Garcia, Emily Fabre
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Universidade Federal do Espírito Santo
Resumo
Carbon dioxide (CO2) is one of the main greenhouse gases. The increase in anthropogenic activities results in higher CO2 emissions into the atmosphere, causing global warming. Carbon capture and storage are technologies capable of reducing atmospheric CO2 levels, contributing to mitigate the problems caused by global warming. Biochars have been widely investigated as adsorbents for CO2 capture due to their low cost and wide availability. However, research into CO2 capture followed by storage using biochars is still limited. Therefore, this work aimed to investigate the capture and storage of CO2 in physically activated biochars derived from coconut endocarp and chemically modified with calcium (Ca); for comparison, other biochars prepared from different precursors (such as coffee straw and babassu endocarp) and also modified with magnesium (Mg) were also investigated. The adsorption and carbonation performances were evaluated at different temperatures and humidity conditions. All the biochars analyzed were efficient at adsorbing CO2 at temperatures close to room temperature; the analyses carried out on the biochars derived from coconut endocarp showed that the adsorption capacity decreased progressively with increasing temperature. Among the samples derived from the endocarp of Cocos nucifera L. and babaçu coconut, and modified with Ca, the biochar with the lowest Ca content (3.5 %) had the highest specific surface area (577 m2/g) and the highest adsorption capacity (46.1 mg/g). The adsorption kinetics were evaluated using three kinetic models, with the Avrami model showing the best fit to the experimental data. Heat treatment at 510 ºC led to the formation of CaCO3 particles deposited throughout the porous structure of the biochar; the sample with the highest Ca content (23.9 %) and the lowest specific surface area (242 m2/g) showed the highest carbonation capacity. The carbonation of biochar modified with Ca was also affected by humidity, being significantly faster at room temperature in humid environments than in dry environments. The results of this study showed that Ca-modified coconut endocarp derived biocarbons are hybrid adsorbents capable of adsorbing and storing CO2 in the form of carbonates, and could serve as a sustainable alternative to help achieve the targets set by the Paris Agreement.
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Adsorção de CO2 , Análise cinética , Endocarpo de coco