**1. Introduction**

Energy has established itself as an input of fundamental importance for economic growth and for raising the standard of living of modern society. Energy generation is overly dependent on petroleum derivatives. On the other hand, the gases emitted by gasoline, diesel and other derivatives have strongly contributed to environmental degradation, causing climate change, global warming, melting of the polar ice caps, rising sea levels, environmental disasters and destruction of the ozone layer. These events have negatively impacted the economy and public health policies. The limitation of oil reserves and the degradation of the environment are factors responsible for the incessant search for renewable energy sources to redeem and/or eliminate the impacts caused by fossil fuels to the environment [1, 2].

Biodiesel has become in the last decades, an alternative fuel capable of meeting the growing demand for energy. The increased demand for energy due to the world population growth has contributed to a possible depletion of fossil energy resources and logically raised the level of atmospheric pollutant emissions, causing environmental degradation [3]. In the current context, most of the energy produced in the world comes from fossil sources such as oil, coal and natural gas, which are directly associated with environmental issues and are responsible for the interest of biodiesel as a renewable fuel, capable of redeeming the emissions of greenhouse gases [4, 5].

Biodiesel is a clean-burning fuel, originating from natural and renewable sources such as vegetable oil, saturated edible oil generated from cooking and frying food, animal fat and a shortchain alcohol in the presence of a catalyst. This energy input has properties such as freedom from sulfur and aromatic compounds, high cetane number, average oxygen content, higher flash point, lower emission of hydrocarbon particles, carbon monoxide and dioxide, non-toxic and biodegradable character, which overlap in relation to the properties of petroleum derivatives [6–8].

The biodiesel production route most used today in Brazil and in the world is called transesterification. In this process, the triacylglycerides (TAG) present in the fatty raw materials, vegetable and animal oils and/or fats interact chemically with a monoalcohol (methanol or ethanol) in the presence of a basic Brönsted type catalyst (proton receptor chemical species) to be converted into a mixture of esters (methyl or ethyl) of fatty acids (biodiesel) and glycerin as a byproduct [9, 10]. **Figure 1** below shows the overall reaction process of the traditional transesterification process in the light of chemistry.

Transesterification occurs in three consecutive and reversible steps. To achieve relevant results in the course of traditional transesterification, excess short-chain alcohol is added, since the presence of water in the reaction medium (this occurs very often) even in small amounts (the reactants are hygroscopic). The basic catalysts are very sensitive by means of free fatty acids (FFA) from the fatty feedstock or formed by hydrolysis of the esters. In this system, the FFA react with the alkaline catalyst (NaOH or KOH) contributing to the formation of fatty acid salts (soaps), which in turn, at the end of the reaction, form emulsions and make it difficult to separate the product (biodiesel) from the by-product (glycerin). The use of Brönsted basic catalysts in the production of biodiesel by homogeneous catalysis requires the use of high quality grease raw materials. The acquisition of these raw materials results in a high cost and account for more than 85% of biodiesel processing expenses, as it requires the use of anhydrous alcohol and food grade oils and fats [11, 12]. Due to the basic catalysts, proton receptors (Brönsted), present high catalytic activity and are low cost and little aggressive of the equipment of the transesterification process are the most used in the biodiesel industry. The use of high purity raw materials in biodiesel production processes is one of the main

*Processing of Gong Oil (*Pachymerus nucleorum*) to Obtain Biodiesel by Methyl Route DOI: http://dx.doi.org/10.5772/intechopen.97721*

**Figure 1.** *Global reaction of triacylglycerides alcoholysis.*

factors that make it difficult for biodiesel to be more competitive in relation to petroleum derived fuels. In view of the above, the search for alternative feedstocks capable of reducing the costs of the alkaline transesterification process has led to studies aimed at the use of materials generated from renewable resources to make the production of biodiesel ecologically sustainable and economically viable, which meets the needs of the industrial sector and puts an affordable fuel on the consumer market. Among the raw materials with potential to overcome the limitations of traditional transesterification are oils and fats from oilseed plants, animals and residual raw materials, since they can be acquired at low cost and contribute to the sustainable production of biodiesel. On the other hand, these feedstocks have high acidity index and water content, the main factors that increase the costs of the process and consequently biodiesel becomes less competitive in relation to petroleum diesel. To adapt them to basic homogeneous catalysis technology, it is necessary to previously submit them to the degumming or esterification process by acid homogeneous catalysis to reduce the intrinsic drawbacks of these feedstocks [13, 14].

Due to its territorial extension and the variety of climates and soils, Brazil performs the biodiesel processing in a decentralized way at laboratory scale level, valuing the abundant raw materials in each of its regions. Thus, new alternatives for obtaining biodiesel are constantly being tested. This means that different routes and scales of production, different raw materials and inputs should be studied, whose purpose is to evaluate the quality of biodiesel produced [3]. In this context, an attractive alternative for the production of biodiesel in the Meso Region of Alto Turi, specifically in the municipality of Zé Doca (Maranhão, Brazil), lies in the transesterification of oils extracted from numerous oleaginous plants and animal fats. This locality presents conditions to generate different biofuel production routes. Among the various species with potential for the production of biodiesel, the gong or coconut bug (Pachymerus nucleorum) stands out. When subjected to heating, it decomposes, originating an oil equal to that extracted from the seeds of oilseed plants. It 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 (*Orbignya speciosa*) and carnauba (*Copernicia prunifera*) until the adult stage [3, 15, 16].

The adult female lays her eggs on the palm seeds at the time of infructescence, when the shell is forming and is less hard. The eggs hatch about 10 days later and the larvae penetrate the fruit. In this larval stage, lasting up to 90 days, the coleopteran (beetle) has a white color, black ocelli at one end of the body, along with the mouthpiece and is about 2 cm long as can be seen in **Figure 2** [16].

It is believed that the production of biodiesel from the oil extracted from the gong is an innovative idea and with relevant potential for society. In the literature,

**Figure 2.** *Visual aspect of the gong. Legend: a: tucum coconut, b: gong in tucum endocarp and c: gong. Source: [17].*

so far, no work has been found on this energy input and its use in the production of biodiesel. The production of biodiesel in Brazil, besides being an alternative for energy self-sufficiency, can also generate employment and income opportunities and contribute to the settlement of people in the countryside.
