Hidrólise enzimática de fibra de Caroá (Neoglaziovia variegata) visando à produção de nanocelulose e etanol
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Data
2016-02-03
Autores
Gonçalves, Daniele Fernanda Chiarelli [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
As fibras de caroá contêm elevado teor de celulose (≈ 65%), podendo ser utilizada como fonte renovável de energia para a produção de nanocelulose e etanol de segunda geração (2G). Desse modo, objetivou-se com esta pesquisa obter nanocelulose e etanol a partir da fibra de caroá, por meio de uma metodologia capaz de gerar menor impacto negativo ao ambiente. Ensaios de pré-tratamento hidrotérmico (160, 170 e 180 oC) foram realizados visando à remoção da hemicelulose da fibra de caroá. Com base nos resultados, o material pré-tratado em banho hidrotérmico a 160 oC foi deslignificado com NaOH 1%, para obtenção da polpa de celulose. O método organossolve com o uso da relação de água/etanol (50/50) a 180 oC também foi testado. A eficiência desses processos foi avaliada por meio da caracterização química (teor de celulose, hemicelulose e lignina) e da difração de raios-X (DRX). Por ter fornecido o melhor rendimento de polpa de celulose, o pré-tratamento com banho a 160 oC e deslignificado com NaOH 1% foi o método selecionado. Esse material foi submetido a análises de termogravimetria (TG) e microscopia eletrônica de varredura (MEV). Por meio dessas técnicas, notou-se que houve a remoção da hemicelulose e da lignina da fibra de caroá. Em uma segunda etapa, a endoglucanase comercial E-CELTM foi utilizada para hidrolisar a polpa celulósica e gerar nanoestruturas de celuloses. A nanocelulose obtida foi caracterizada por microscopia de força atômica (AFM). Os dados de AFM evidenciaram a presença de nanocelulose cristalina com razão de aspecto de 16 ± 5. O material residual desse processo foi usado em uma nova hidrólise com o coquetel enzimático “Accellerase 1500” para liberação dos açúcares fermentescíveis, que podem ser convertidos em etanol. A concentração de glicose obtida após 72 h de reação foi de 19,6 g L-1 e de etanol após a fermentação foi de 7,5 g L-1. Dessa forma, as fibras de caroá são potenciais fontes de nanocelulose e etanol 2G.
The fiber of caroa plants has a high quantity of cellulose (≈ 65%) that can be used as a renewable energy source to produce nanocellulose and second-generation ethanol (2G). The aim of this research was to obtain nanocellulose and ethanol from caroa fiber using methods with minimal detrimental effects on the environment. Hydrothermal pretreatment trials (160, 170 and 180 oC) were carried out to remove the hemicellulose from caroa fiber. Based on the results, the pre-treated material at 160 °C in liquid hot water was delignified with 1% NaOH to obtain cellulose pulp. The organosolv method using water/ethanol ratio (50/50) at 180 oC was also studied. The efficiency of these processes was assessed by chemical characterization (content of cellulose, hemicellulose, and lignin) and by X-ray diffraction (XRD). The best yield of cellulose pulp was obtained from the pre-treated material using liquid hot water at 160 °C and delignified with 1% NaOH and was selected for further analysis. This material was submitted to thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). After the material was pretreated a second process, commercial endoglucanase E-CELTM, was used to hydrolyze the cellulosic pulp and to produce cellulose nanostructures. The nanocellulose obtained was characterized by atomic force microscopy (AFM). The AFM data shows the presence of nanocellulose crystal with aspect ratio of 16 ± 5. The residual of these materials was used for a new hydrolysis with the enzyme cocktail "Accellerase 1500" for release of fermentable sugars, which can be converted into ethanol. The concentration of glucose obtained after 72 h of reaction was 19,6 g L -1 and the concentration of ethanol after fermentation was 7,5 g L-1 . Therefore, caroa fibers are potential sources of nanocellulose and ethanol 2G.
The fiber of caroa plants has a high quantity of cellulose (≈ 65%) that can be used as a renewable energy source to produce nanocellulose and second-generation ethanol (2G). The aim of this research was to obtain nanocellulose and ethanol from caroa fiber using methods with minimal detrimental effects on the environment. Hydrothermal pretreatment trials (160, 170 and 180 oC) were carried out to remove the hemicellulose from caroa fiber. Based on the results, the pre-treated material at 160 °C in liquid hot water was delignified with 1% NaOH to obtain cellulose pulp. The organosolv method using water/ethanol ratio (50/50) at 180 oC was also studied. The efficiency of these processes was assessed by chemical characterization (content of cellulose, hemicellulose, and lignin) and by X-ray diffraction (XRD). The best yield of cellulose pulp was obtained from the pre-treated material using liquid hot water at 160 °C and delignified with 1% NaOH and was selected for further analysis. This material was submitted to thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). After the material was pretreated a second process, commercial endoglucanase E-CELTM, was used to hydrolyze the cellulosic pulp and to produce cellulose nanostructures. The nanocellulose obtained was characterized by atomic force microscopy (AFM). The AFM data shows the presence of nanocellulose crystal with aspect ratio of 16 ± 5. The residual of these materials was used for a new hydrolysis with the enzyme cocktail "Accellerase 1500" for release of fermentable sugars, which can be converted into ethanol. The concentration of glucose obtained after 72 h of reaction was 19,6 g L -1 and the concentration of ethanol after fermentation was 7,5 g L-1 . Therefore, caroa fibers are potential sources of nanocellulose and ethanol 2G.
Descrição
Palavras-chave
Bioetanol, Bromeliaceae, Celulase, Hidrólise enzimática, Nanoestrutura, Bioethanol, Cellulase, Enzymatic hydrolysis, Nanostructure