title: Current Pretreatment Technologies for the Development of Cellulosic Ethanol and Biorefineries.
abstract: Lignocellulosic materials, such as forest, agriculture, and agroindustrial residues, are among the most important resources for biorefineries to provide fuels, chemicals, and materials in such a way to substitute for, at least in part, the role of petrochemistry in modern society. Most of these sustainable biorefinery products can be produced from plant polysaccharides (glucans, hemicelluloses, starch, and pectic materials) and lignin. In this scenario, cellulosic ethanol has been considered for decades as one of the most promising alternatives to mitigate fossil fuel dependence and carbon dioxide accumulation in the atmosphere. However, a pretreatment method is required to overcome the physical and chemical barriers that exist in the lignin-carbohydrate composite and to render most, if not all, of the plant cell wall components easily available for conversion into valuable products, including the fuel ethanol. Hence, pretreatment is a key step for an economically viable biorefinery. Successful pretreatment method must lead to partial or total separation of the lignocellulosic components, increasing the accessibility of holocellulose to enzymatic hydrolysis with the least inhibitory compounds being released for subsequent steps of enzymatic hydrolysis and fermentation. Each pretreatment technology has a different specificity against both carbohydrates and lignin and may or may not be efficient for different types of biomasses. Furthermore, it is also desirable to develop pretreatment methods with chemicals that are greener and effluent streams that have a lower impact on the environment. This paper provides an overview of the most important pretreatment methods available, including those that are based on the use of green solvents (supercritical fluids and ionic liquids).
authors.affiliation: CEPESQ, Research Center in Applied Chemistry, Department of Chemistry, Federal University of Paraná, Curitiba, PR, 81531-970, Brazil.
authors.forename: Marcos Henrique Luciano
authors.identifier: http://orcid.org/0000-0001-5680-1278
authors.initials: MH
authors.lastname: Silveira
authors.affiliation: Unit of Bioenergy, National Laboratory of Energy and Geology, 1649-038, Lisbon, Portugal.|LAQV/REQUIMTE, Department of Chemistry, Faculty of Science and Technology, New University of Lisbon, 2829-516, Caparica, Portugal.
authors.forename: Ana Rita C
authors.identifier: http://orcid.org/0000-0002-3216-1533
authors.initials: AR
authors.lastname: Morais
authors.affiliation: Unit of Bioenergy, National Laboratory of Energy and Geology, 1649-038, Lisbon, Portugal.|LAQV/REQUIMTE, Department of Chemistry, Faculty of Science and Technology, New University of Lisbon, 2829-516, Caparica, Portugal.
authors.forename: Andre M
authors.identifier: http://orcid.org/0000-0001-8855-6406
authors.initials: AM
authors.lastname: da Costa Lopes
authors.affiliation: Department of Chemistry, Regional University of Blumenau, Blumenau, SC, 89012 900, Brazil.
authors.forename: Drielly Nayara
authors.initials: DN
authors.lastname: Olekszyszen
authors.affiliation: Unit of Bioenergy, National Laboratory of Energy and Geology, 1649-038, Lisbon, Portugal. rafal.lukasik@lneg.pt.
authors.forename: Rafał
authors.identifier: http://orcid.org/0000-0002-7805-5744
authors.initials: R
authors.lastname: Bogel-Łukasik
authors.affiliation: Department of Chemistry, Regional University of Blumenau, Blumenau, SC, 89012 900, Brazil. jandr@furb.br.
authors.forename: Jürgen
authors.identifier: http://orcid.org/0000-0001-8124-6528
authors.initials: J
authors.lastname: Andreaus
authors.affiliation: CEPESQ, Research Center in Applied Chemistry, Department of Chemistry, Federal University of Paraná, Curitiba, PR, 81531-970, Brazil. luiz.ramos@ufpr.br.|INCT Energy and Environment (INCT E&A), Department of Chemistry, Federal University of Paraná. luiz.ramos@ufpr.br.
authors.forename: Luiz
authors.identifier: http://orcid.org/0000-0002-4349-4990
authors.initials: L
authors.lastname: Pereira Ramos
mesh_terms: D056804:Biofuels; D018533:Biomass; D000431:Ethanol / Q000737:chemistry*; D008031:Lignin / Q000737:chemistry*
chemical_list: D056804:Biofuels; C036909:lignocellulose; D000431:Ethanol; D008031:Lignin
keywords: biomass; carbohydrates; pretreatment; sustainable chemistry; synthesis design