Processing of Gong Oil (Pachymerus nucleorum) to Obtain Biodiesel by Methyl Route

Abstract

Brazil is a large world producer of vegetable oils. This condition puts it in the vanguard of the use of renewable fuels on the planet, and may constitute an excellent opportunity for scientific and technological development of the country. The most widely used method for producing biodiesel is basic homogeneoustransesterification. Its disadvantage is the use of high quality raw materials, which raises the final cost of the process by about 85%. The final cost of biodiesel production can be reduced considerably with the inclusion of raw materials of low added value containing high content of free fatty acids (FFA), the great challenge is the development of different routes and production scales capable of making the production process of this energy input viable. In addition, the valorization of different raw materials and implementation of innovative technologies to make obtaining biodiesel ecologically sustainable and more competitive in relation to fossil diesel is of fundamental importance. Among the several species with potential for biodiesel production in Brazil, the gong (Pachymerus nucleorum) stands out, which, when heated, decomposes, originating an oil equal to that extracted from the seeds of oilseed plants. This is the larval stage of a coleopteran of the family Bruchidae, a beetle, which lives inside fruits of buriti (Mauritia flexuosa), tucum (Bactris setosa), babaçu (Attalea speciosa) and carnauba (Copernicia prunifera) until the adult stage. This work aimed to extract the oil from the larvae of Pachymerus nucleorum and adapt it to obtain biodiesel. The physical–chemical characterization of this raw material in natura revealed high FFA content (1.63% and 1.74%). The gong oil was submitted to esterification by acid catalysis, aiming to adapt it to the basic homogeneous transesterification process. The results indicated a significant reduction of FFA (0.85% and 0.55%). The infrared spectra (FTIR) of the esterified oil and biodiesel indicated the presence of methyl esters and low moisture content. Gas chromatography (GC-FID) revealed that the composition of the biodiesel consists of saturated fatty acid methyl esters (FAME). The esterification reaction of gong oil when pretreated provided evidence that the feedstock may be suitable for biodiesel production. At present, there are no studies involving the extraction and suitability of gongo oil for the specific production of biodiesel. This issue needs to be addressed so that we can advance in the esterification-transesterification processes of feedstocks with high acidity index.