Aplicação da análise termogravimétrica na avaliação da interação entre os componentes do bagaço e da palha de cana-de-açúcar
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Data
2020-02-20
Autores
Oliveira, Miriam Ricciulli de
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Universidade Estadual Paulista (Unesp)
Resumo
A biomassa apresenta-se como uma promissora alternativa aos combustíveis fósseis por ser renovável, de baixo custo e amplamente disponível. Esta pode ser obtida a partir de resíduos agroindustriais mostrando-se como um importante modelo de energia sustentável. Os principais componentes da biomassa são hemicelulose, celulose e lignina e, por possuírem diferentes propriedades químicas, influenciam diretamente na eficiência de um processo de conversão termoquímica. Metodologias convencionais atualmente aceitas na determinação dos principais componentes da biomassa requerem maior tempo e possuem alto custo. A análise termogravimétrica (TG) é uma técnica rápida e de baixo custo, resultando em curvas TG/DTG que fornecem uma indicação do percentual de cada um dos componentes da biomassa. Entretanto, não há uma metodologia aceita no sentido de substituir o método convencional por via úmida na determinação dos constituintes de materiais lignocelulósicos. Portanto, o objetivo deste estudo é avaliar o efeito da interação entre os componentes do bagaço e da palha de cana-de-açúcar (hemicelulose, celulose e lignina), isolados por diferentes tratamentos químicos, por meio da análise de sinergismo em ensaios termogravimétricos. Este estudo contribuirá para a elaboração de uma metodologia para determinação dos teores desses componentes por meio da análise termogravimétrica, com precisão similar aos métodos convencionais. Os resultados da caracterização química e a caracterização físico-química pela técnica de FTIR e DRX dos componentes isolados das biomassas mostraram que os tratamentos químicos foram adequados para o isolamento da celulose e lignina, porém para a hemicelulose verificou-se a necessidade de buscar uma metodologia mais adequada para seu isolamento. Pela TG, observou-se os eventos de decomposição de cada amostra em atmosfera inerte (N2) e oxidante (ar sintético) e realizou-se um estudo de sinergismo entre os componentes por meio de diferentes misturas preparadas entre eles. Ao comparar as curvas DTG experimentais (DTGexp) e DTG teóricas (DTGteo) das misturas, verificou-se efeito sinergético entre os componentes isolados, indicado pela diferença entre os perfis de decomposição, principalmente em temperaturas acima de 350°C, atribuindo o sinergismo a presença de lignina nas amostras. Ressalta-se que a diferença entre as curvas DTGexp e DTGteo é melhor evidenciado em atmosfera oxidante do que em inerte, onde os perfis de decomposição são muito semelhantes.
Biomass presents itself as a promising alternative energy source to replace or reduce the use of fossil fuels because it is renewable, low cost and widely available. This can be obtained from agro-industrial waste, showing itself as an important model of sustainable energy. The main components of biomass are hemicellulose, cellulose and lignin and, due to their different chemical properties, they directly influence the efficiency of a thermochemical conversion process. Currently, the accepted methodologies for determining the main components of biomass require time and are expensive. Thermogravimetric analysis (TGA) is a fast and low-cost technique, resulting in TGA/DTG curves that provide an indication of the percentage of each biomass components. However, there is no accepted methodology in the sense to replace the conventional wet method use to determining the lignocellulosic materials components. Therefore, the objective of this study is to evaluate the effect of the interaction between the components of sugarcane bagasse and straw (hemicellulose, cellulose and lignin), isolated by different chemical treatments, through the analysis of synergism in thermogravimetric tests. This study will contribute to the development of a methodology for determining the content of these components through thermogravimetric analysis, with precision similar to conventional methods. The results of chemical characterization and physico-chemical characterization by FTIR and DRX technique of the components isolated from sugarcane bagasse and straw showed that the chemical treatments were adequate for the isolation of cellulose and lignin. However, further studies should be performed to develop an adequate methodology for hemicellulose isolation. Through the thermogravimetric analysis, the decomposition events of each sample were observed in an inert atmosphere (N2) and oxidant (synthetic air) and a study of synergism between the components was carried out by means of mixtures prepared between them. When comparing the DTGexp and DTGteo curves of the mixtures, it was found that the pure components had a synergistic effect due to the difference between the degradation profiles, mainly at temperatures above 350 °C, attributing synergism to the presence of lignin in the samples. It is noteworthy that the difference between the DTGexp and DTGteo curves is better evidenced in an oxidizing atmosphere than in an inert atmosphere, where the degradation profiles are very similar.
Biomass presents itself as a promising alternative energy source to replace or reduce the use of fossil fuels because it is renewable, low cost and widely available. This can be obtained from agro-industrial waste, showing itself as an important model of sustainable energy. The main components of biomass are hemicellulose, cellulose and lignin and, due to their different chemical properties, they directly influence the efficiency of a thermochemical conversion process. Currently, the accepted methodologies for determining the main components of biomass require time and are expensive. Thermogravimetric analysis (TGA) is a fast and low-cost technique, resulting in TGA/DTG curves that provide an indication of the percentage of each biomass components. However, there is no accepted methodology in the sense to replace the conventional wet method use to determining the lignocellulosic materials components. Therefore, the objective of this study is to evaluate the effect of the interaction between the components of sugarcane bagasse and straw (hemicellulose, cellulose and lignin), isolated by different chemical treatments, through the analysis of synergism in thermogravimetric tests. This study will contribute to the development of a methodology for determining the content of these components through thermogravimetric analysis, with precision similar to conventional methods. The results of chemical characterization and physico-chemical characterization by FTIR and DRX technique of the components isolated from sugarcane bagasse and straw showed that the chemical treatments were adequate for the isolation of cellulose and lignin. However, further studies should be performed to develop an adequate methodology for hemicellulose isolation. Through the thermogravimetric analysis, the decomposition events of each sample were observed in an inert atmosphere (N2) and oxidant (synthetic air) and a study of synergism between the components was carried out by means of mixtures prepared between them. When comparing the DTGexp and DTGteo curves of the mixtures, it was found that the pure components had a synergistic effect due to the difference between the degradation profiles, mainly at temperatures above 350 °C, attributing synergism to the presence of lignin in the samples. It is noteworthy that the difference between the DTGexp and DTGteo curves is better evidenced in an oxidizing atmosphere than in an inert atmosphere, where the degradation profiles are very similar.
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Análise termogravimétrica, Biomassa, Isolamento dos componentes, bagaço de cana-de-açúcar, palha de cana-de-açúcar, Thermogravimetric analysis, Biomass, Isolation of components, Sugarcane bagasse, sugarcane straw, Termogravimetria, Bagaço de cana