Utilização do óleo das vísceras de Tilápia do Nilo (Oreochromis niloticus) na produção de biodiesel de segunda geração.

Abstract

The objective of this work is to study the production of second generation biodiesel from fish viscera oil (Oreochromis niloticus), optimize the transesterification, evaluating the temperature, reaction time, molar ratio (alcohol:oil) and the action of the antioxidants, synthetic and natural, in the process of biodiesel degradation, determining its kinetics and thermodynamic parameters. The oil was extracted by the cooking process and the biodiesel synthesized by the alkaline methyl route (KOH). The temperature, reaction time and molar ratio were evaluated by experimental design of central composite (CCD). The physicochemical properties were carried out according to the National Agency of Petroleum, Natural Gas and Biofuels (ANP). The simplex-centroid was used to assess the efficiency of the antioxidant mixtures butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and propyl gallate (PG) on biodiesel stability at different temperatures (110, 115, 120 and 125 °C). The kinetic and thermodynamic parameters of the biodiesel degradation process were carried out through accelerated oxidation tests at different temperatures (100, 105, 110, 115, 120 and 125 °C). The ethanoic extract of curcumin was evaluated to avoid the biodiesel oxidation of the samples. The results demonstrated that the physicochemical properties of biodiesel from fish viscera oil were in accordance with the rules of the ANP and that the molar ratio (alcohol:oil) was the most significant variable in the transesterification reaction. The mixture of synthetic antioxidants showed no synergism, being the propyl gallate the antioxidant that presented better efficiency against the biodiesel oxidation. The kinetic and thermodynamic studies of the biodiesel samples showed that the biodiesel oxidation process was not spontaneous (ΔG ≠ > 0). However, the activation energy was low, which shows that the biodiesel samples are quite susceptible to the degradation process. Therefore, biodiesel storage process should be considered as critical.