Obtenção de ésteres metílicos a partir da borra de café

Abstract

The use of biomass as energy matrix have intensified increasingly around the world. Brazil, because it is a producer country of several agrobusiness products, is favored in the generation of feedstock to achievement of biofuel. One of this products is the coffee, which Brasil is the major producer and the second main consumer. The preparing of coffee as drink generates a residue known as coffee grounds, that holds elevated content of lipid material, feedstock to producing of biodiesel. The present searching aimed the obtainment of methyl ester (biodiesel) from coffee grounds. For this it was developed the extraction, of lipid material of the biomass, using the Soxhlet method (adapted) and the extraction to cold using ultrasound and etanol as solvent. The extractions presented results of 12,04% ± 0,04 and of 11,32% ± 0,02 using Soxhlet and ultrasound, respectively. After extraction of coffee oil, it was made analytical determinations and the chemical description of fatty acids. The identification of fatty acids presente in the oil extracted was realized through of use of gas chromatography and the method of normalization of the área of the peaks of the chromatogram, getting up, thus, the profile of the fatty acids present in the lipid fraction of coffee grounds. For achievement of the methyl esters of fatty acids it was realized a multivariate experimental study based on factorial planning of experiments (22), ranging the reaction time and catalyst concentration. The mass results obtained to biodiesel were about 75% (m/m) and all the variables studied present significant difference. Lastly, it were evaluated the parameter of biodiesel quality, according current legislation: humidity content, density and acidity index. The humidity content was the only parameter in disaccord to legislation. In this way, the coffee ground proved to be a feedstock of high potencial and low costs to achievement of a biofuel.