Valorização da biomassa lignocelulósica: estudo da estrutura, composição e digestibilidade enzimática da biomassa vegetal após ser submetida a diferentes etapas de pré-tratamento

Bioenergy has been proposed as one way to significantly meet global energy demand and prevent environmental problems using renewable energy resources. The valorization of lignocellulosic biomass as a renewable feedstock for producing bioethanol and biomaterial has attracted much attention. However, efficient lignocellulosic biomass conversions require the development of strategies and technologies safe and inexpensive. Sugarcane is an agricultural crop produced in several tropical countries, notably Brazil. This work has investigated sugarcane wastes as potential raw materials to produce second-generation biofuels and nanomaterials. Different configurations of two-stage pretreatments were applied to sugarcane wastes (SCC, SCB, SCL) to produce fermentable sugars after enzymatic hydrolysis as well as nanocellulose via enzymatic hydrolysis and mechanical disintegration of cellulose-enriched material. Enzymatic hydrolysis yields of raw and pretreated sugarcane wastes were determined and correlated with structural, morphological, and composition changes after pretreatments. Overall, after combined pretreatments, enzymatic convertibility was highly efficient for all studies, reaching over 97% for SCC after acid-alkaline pretreatment (NaOH2% / H2SO42%), 91.2% for SCL acid-alkaline (H2SO41% / NaOH1%), 99.57 % for sugarcane bagasse after liquid hot water - alkaline sulfonation (H2O / Na2SO3 +NaOH). This efficiency was correlated to the removal of amorphous parts of lignocellulosic biomass, lignin, and/or hemicellulose, which also justify high crystallinity indices and crystallite sizes of pretreated biomass. An efficient carbohydrate extraction from sugarcane bagasse occurred during alkaline pretreatment using NaOH + H2O2, with a maximum delignification. Thermally and colloidally stable cellulose nanofibers were obtained. The enzymatic hydrolysis stage facilitated the defibrillation of blanched SCB, and the sulfonation introduced sulfonic groups in the CNF. The introduction of surface charges to CNF promotes their functionalization and widens their fields of application.A bioenergia tem sido proposta como uma forma de atender significativamente a demanda energética global e prevenir problemas ambientais, utilizando recursos energéticos renováveis. A valorização da biomassa lignocelulósica como matéria-prima renovável para a produção de bioetanol e biomaterial tem despertado muita atenção. No entanto, a transformação eficiente da biomassa lignocelulósica em açúcares fermentescíveis requer o desenvolvimento de estratégias e tecnologias para rupturas da biomassa lignocelulósica. A cana-de-açúcar é uma importante cultura agrícola produzida em vários países tropicais, notadamente no Brasil. Este trabalho investigou resíduos de cana-de-açúcar como potenciais matérias-primas para a produção de biocombustíveis e nano materiais de segunda geração. Diferentes configurações de pré-tratamentos de duas etapas foram aplicadas aos resíduos de cana-de-açúcar (SC, SCB, SCL) para produzir açúcares fermentáveis após hidrólise enzimática, bem como nanocelulose via hidrólise enzimática e desintegração mecânica do material rico em celulose. Os rendimentos de hidrólise enzimática de resíduos de cana-de-açúcar não tratados e pré-tratados foram determinados e correlacionados com alterações estruturais, morfológicas e de composição após os pré-tratamentos. No geral, após pré-tratamentos combinados, a convertibilidade enzimática foi altamente eficiente para todos os estudos (capítulo 4-6, atingindo mais de 97% para SCC após pré-tratamento ácido-alcalino (NaOH2%/H2SO42%), 91,2% para SCL ácido-alcalino (H2SO41% / NaOH1%), 99,57 % para bagaço de cana após LHW- sulfonação alcalina (H2O/Na2SO3+NaOH). Essa eficiência foi correlacionada com a remoção de partes amorfas de biomassa lignocelulósica, lignina e/ou hemicelulose, que também justificam a alta cristalinidade índices e tamanhos de cristalitos da biomassa pré-tratada. Um eficiente fracionamento do bagaço de cana-de-açúcar ocorreu durante o pré-tratamento alcalino com NaOH+H2O2, com máxima deslignificação. A etapa de hidrólise enzimática facilitou a desfibrilação da biomassa branqueada, e a sulfonação da biomassa branqueada melhorou sua digestibilidade enzimática. A introdução de superficiais no CNF promove suas funcionalizações e amplia seus campos de aplicação

Evaluating the Potential of Culms from Sugarcane and Energy Cane Varieties Grown in Argentina for Second-Generation Ethanol Production

The efficient transformation of lignocellulosic biomass into fermentable sugars is essential for building bioeconomies. Sugarcane is an important agricultural crop in a number of Latin American countries, including Brazil and Argentina. Herein culms from two different sugarcane (SC384 and SC724) and two energy cane varieties (EC3116 and EC3118) bred in Argentina were evaluated for sustainable production of second-generation biofuels and green chemicals. Changes in the biomass crystallinity, structure, and morphology introduced by pretreatments were investigated using X-ray diffraction (DRX), confocal laser scanning microscopy (CLSM), and scanning electron microscopy (SEM) techniques. Enzymatic hydrolysis yields of untreated and pretreated sugarcane and energy cane culms were determined and correlated with physical analyses and chemical composition characterizations. Overall, after combined acid and alkali pretreatment, enzymatic convertibility was highly efficient for all studied sugarcane and energy cane varieties, reaching over 97% of theoretical conversion yields. High crystallinity indices and crystallite sizes of pretreated culms and SEM results and CLSM were consistent with the removal of lignin, solubilization of hemicellulose, and amorphous parts of lignocellulose imprinted by the pretreatments. High potential of culms from sugarcane and energy cane varieties cultivated in Argentina for sustainable production of renewable lignocellulosic sugars and their transformation into green chemicals and fuels was demonstrated. Graphic Abstract: [Figure not available: see fulltext.]Fil: Kane, Aissata Ousmane. Universidade de Sao Paulo; BrasilFil: Pellergini, Vanessa O. Arnoldi. Universidade de Sao Paulo; BrasilFil: Espirito Santo, Melissa C.. Universidade de Sao Paulo; BrasilFil: Ngom, Balla Diop. Universite Cheikh Anta Diop; SenegalFil: Garcia, Jose Maria. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Tucuman-Santiago del Estero. Estación Experimental Agropecuaria Famaillá; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; ArgentinaFil: Acevedo, Alberto. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires; ArgentinaFil: Erazzú, Luis Ernesto. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires; ArgentinaFil: Polikarpov, Igor. Universidade de Sao Paulo; Brasi

Leaves from four different sugarcane varieties as potential renewable feedstocks for second-generation ethanol production: Pretreatments, chemical composition, physical structure, and enzymatic hydrolysis yields

Development of Bioeconomy is impossible without establishing efficient technologies of lignocellulosic biomass valorization via transformation into fermentable sugars. Sugarcane is a valuable agricultural crop in several Asian, African, and Latin American countries. Here, leaves from two sugarcane and two energy cane varieties were evaluated for sustainable production of second-generation sugars, and their enzymatic hydrolysis yields were compared. Structural, morphological, and chemical composition changes in sugar and energy cane leaves submitted to acid, and acid-alkaline pretreatments were analyzed using X-ray diffraction, scanning electron microscopy, confocal laser microscopy, high-performance liquid chromatography, and low-field solid-state NMR techniques. Enzymatic hydrolysis assays were conducted to evaluate saccharification yields of untreated and pretreated leaves. Jointly, our results revealed the significant potential of leaves from two commercial sugar cane cultivars currently bred in Argentina as possible lignocellulose substrates for the 2G ethanol industry.EEA FamailláFil: Espirito Santo, Melissa. University of Sao Paulo. Sao Carlos Institute of Physics; BrasilFil: Ousmane Kane, Aissata. University of Sao Paulo. Sao Carlos Institute of Physics; BrasilFil: Arnoldi Pellergini, Vanessa. University of Sao Paulo. Sao Carlos Institute of Physics; BrasilFil: Thema, Force Tefo. Botswana University of Agriculture and Natural Resources; BotswanaFil: García, José María. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Famaillá; Argentina.Fil: García, José María. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Acevedo, Alberto. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Suelos; ArgentinaFil: Erazzú, Luis E. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Famaillá; Argentina.Fil: Guimaraes, Francisco E.G. University of Sao Paulo. Sao Carlos Institute of Physics; BrasilFil: Azevedo, Eduardo R. de. University of Sao Paulo. Sao Carlos Institute of Physics; BrasilFil: Polikarpov, Igor. University of Sao Paulo. Sao Carlos Institute of Physics; Brasi