Influência de líquidos iônicos na extração de fenóis da fração aquosa do bio-óleo da semente de goiaba (Psidium guajava L.) por ultrassom e micro-ondas

• Autor(a) principal: Cerqueira, Solange da Conceição Almeida
• Data de Publicação: 2020
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da UFS
• Texto Completo: https://ri.ufs.br/jspui/handle/riufs/14819
• topic: Química; Fenóis; Líquidos; Micro-ondas; Ultrassom; Pirólise; BMIM.NTF2; BMIM.PF6; Micro-ondas; Fração aquosa da pirólise; Phenols; Microwaves; Ultrasound; Aqueous pyrolysis fraction; CIENCIAS EXATAS E DA TERRA::QUIMICA

The present work sought to develop a method of extracting phenolic compounds present in the aqueous fraction of bio-oil arising from the pyrolysis process of guava seeds. The separation between the organic phase and the aqueous phase was carried out by decantation, after the pyrolysis process of approximately 300 g of biomass at 600 ° C and nitrogen flow of 100 mL min-1 . The conventional liquidliquid extraction method (LLE) was applied using ethyl acetate as a solvent, and methodologies for ultrasound-assisted liquid-liquid extraction (UALLE) and microwave-assisted liquid-liquid extraction (MALLE) were developed. The experiments to study these systems were carried out in batches, according to a statistical factorial design (22 ). Initially, a previous study of the variables temperature and potency in UALLE and volume of solvent and potency in MALLE was carried out to determine the extraction conditions, whose variable evaluated was the concentration of phenol monomers. Finally, a second planning was carried out for both methods in order to evaluate the percentage of ionic liquid (LI) and pH for the extraction of phenols present in the aqueous fraction. By gas chromatography/mass spectrometry it was possible to quantify 12 phenol monomers in this study (phenol, o-cresol, m-cresol, p-cresol, 2,5 dimethylphenol, 4-ethylphenol, guaiacol, o-catechol, 4-methylcatechol, m-catechol, 2,6 dimethoxyphenol and eugenol) and by UV-vis the analysis of total phenols. MALLE proved to be more efficient in relation to LLE and UALLE, with extractions greater than 125% and 53%, respectively. In the study of the extraction of phenols using ethyl acetate combined with LIs, the ionic liquid bis (trifluoromethylsulfonyl) imidate of 1-butyl-3-methylimidazolium (BMIM.NTF2) showed to be more efficient for the extraction of phenols in relation to hexafluorophosphate of 1-butyl-3- methylimidazolium (BMIM.PF6). The extraction of phenols was influenced by the pH of the aqueous fraction, with greater extraction at pH ≤7 and showed recoveries above 80% in both techniques. The microwave assisted extraction process used 6 times less time than ultrasound extraction to obtain extracts with similar concentrations.