Aproveitamento de biomassas de frutas tropicais e pré-tratamento com líquido iônico para produção de etanol

Abstract

The search for biofuels has intensified recent due to the environmental urgency of replacing fossil fuels with renewable alternatives. The investigation of biomass, especially that derived from waste, presents an excellent option for biofuel production, including second-generation ethanol (E2G), which can be produced from lignocellulosic waste. E2G production requires pretreatment and hydrolysis of biomass to break down cellulose, generate higher amounts of sugars, and consequently increase production yields. Ionic liquids (ILs), composed of organic and inorganic ions, have low melting points, vapor pressure, and the ability to solubilize cellulose, making them effective in breaking down cellulose, thus emerging as an efficient alternative in acid pretreatment. Therefore, this study aimed to evaluate the efficiency of triethylammonium hydrogen sulfate IL in the pretreatment of tropical fruit residues such as banana, orange, and mango. For this purpose, the biomass was characterized through sugar quantification analyses and determination of ash content, moisture, extractives, holocellulose, α-cellulose, and hemicellulose content. Two pretreatment processes for lignocellulosic biomass were conducted, one in an oil bath and the other in an oven. Additionally, yield analyses, Scanning Electron Microscopy (SEM), and infrared spectroscopy (IR) were performed on the products obtained from the pretreatments. Based on the characterization analyses of the raw materials, mango residue was identified as the biomass with the highest potential for bioethanol production, followed by orange and banana residues, due to their high sugar content, low ash and moisture content, and favorable cellulosic composition. Among the evaluated pretreatments, the oven method showed the best results in weakening the lignin-hemicellulose-cellulose complex and lignin precipitation, also indicating mango residues as the most promising in terms of cellulose pulp production and lignin removal.