title: Alkaline-sulfite pretreatment and use of surfactants during enzymatic hydrolysis to enhance ethanol production from sugarcane bagasse.
abstract: Sugarcane bagasse is a by-product from the sugar and ethanol industry which contains approximately 70 % of its dry mass composed by polysaccharides. To convert these polysaccharides into fuel ethanol it is necessary a pretreatment step to increase the enzymatic digestibility of the recalcitrant raw material. In this work, sugarcane bagasse was pretreated by an alkaline-sulfite chemithermomechanical process for increasing its enzymatic digestibility. Na2SO3 and NaOH ratios were fixed at 2:1, and three increasing chemical loads, varying from 4 to 8 % m/m Na2SO3, were used to prepare the pretreated materials. The increase in the alkaline-sulfite load decreased the lignin content in the pretreated material up to 35.5 % at the highest chemical load. The pretreated samples presented enhanced glucose yields during enzymatic hydrolysis as a function of the pretreatment severity. The maximum glucose yield (64 %) was observed for the samples pretreated with the highest chemical load. The use of 2.5 g l(-1) Tween 20 in the hydrolysis step further increased the glucose yield to 75 %. Semi-simultaneous hydrolysis and fermentation of the pretreated materials indicated that the ethanol yield was also enhanced as a function of the pretreatment severity. The maximum ethanol yield was 56 ± 2 % for the sample pretreated with the highest chemical load. For the sample pretreated with the lowest chemical load (2 % m/m NaOH and 4 % m/m Na2SO3), adding Tween 20 during the hydrolysis process increased the ethanol yield from 25 ± 3 to 39.5 ± 1 %.
authors.affiliation: Departamento de Química, Biotecnologia e Engenharia de Bioprocessos, Campus Alto Paraopeba, Universidade Federal de São João Del-Rei, CP 131, Ouro Branco, MG, 36420-000, Brazil.
authors.forename: Jéssica Faria
authors.initials: JF
authors.lastname: Mesquita
authors.affiliation: Departamento de Biotecnologia, Escola de Engenharia de Lorena, Universidade de São Paulo, Lorena, SP, 12602-810, Brazil.
authors.forename: André
authors.initials: A
authors.lastname: Ferraz
authors.affiliation: Departamento de Química, Biotecnologia e Engenharia de Bioprocessos, Campus Alto Paraopeba, Universidade Federal de São João Del-Rei, CP 131, Ouro Branco, MG, 36420-000, Brazil. andrepiranga@yahoo.com.br.|Instituto de Recursos Naturais, Universidade Federal de Itajubá, CP 50, Itajubá, MG, 37500-903, Brazil. andrepiranga@yahoo.com.br.
authors.forename: André
authors.initials: A
authors.lastname: Aguiar
mesh_terms: D002482:Cellulose / Q000737:chemistry*; D006868:Hydrolysis; D031786:Saccharum / Q000737:chemistry*; D012972:Sodium Hydroxide / Q000737:chemistry*; D013447:Sulfites / Q000737:chemistry*; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D013447:Sulfites; D013501:Surface-Active Agents; D012972:Sodium Hydroxide; D002482:Cellulose; C027433:bagasse; C025026:sodium sulfite
keywords: Cellulose; Ethanol; Lignin; Semi-simultaneous hydrolysis and fermentation; Tween 20