A Biomassa residual da casca da mandioca como matéria-prima para a obtenção de compostos furânicos: uma alternativa sustentável para o ensino de Química Orgânica

Abstract

The present work proposes the use of residual biomass of cassava bark from local crops as a propellant organic residue to obtain compounds or organic molecules of commercial value. And, through the use of these residues, a differentiated experimental class of Organic Chemistry is proposed. The peels used in this work were purchased at the street market in Amargosa-BA, washed and dried using the conventional method for 6 days in the sun and then for 18 hours in an oven at 100°C. Among the scenarios for obtaining organic compounds, this work discusses the characteristics of acid hydrolysis as well as the main mineral acids used during reactions that involve breaking glycosidic bonds in carbohydrates. In addition, it points out the main advantages and disadvantages when using aqueous systems and develops the reactions using biphasic systems through the relationship between FA (Aqueous Phase) and FO (Organic Phase). To study the cleavage reactions, the following concentrations of sulfuric acid were used (0.5 mol/L, 1.0 mol/L, 2.0 mol/L, 4.0 mol/L and 6.0 mol/L L) and, as the organic phase, Isobutyl Methyl Ketone (MIBK) was used in the proportions of 1:1, 1:2 and 2:1 (v/v) between FA and FO. After the reactions, the samples were filtered and properly stored in a freezer. Afterwards, the organic phases of all reactions were analysed using a spectrophotometer together with the addition of standard method in order to quantify the furan compounds, that is, the furfural obtained as a product of the cleavage reaction of hemicellulose with the reaction medium. In this study, it can be seen that the higher the acid concentration in the reaction medium, the higher yields in milligrams per gram of biomass will be obtained. In this way, high yields were found in reactions that employed the use of 1:2 FA/FO with acid concentrations of 4.0 and 6.0 mol/L. To evaluate the proposal for an experimental class, a semi-structured questionnaire was made available to teachers in Google Forms to validate the proposal and the experimental procedure developed.