No abstract

The present research aims to evaluate the effect on the stability of biodiesel during the storage period at 60°C and at low temperatures of the antioxidants from extracts of mango (biodiesel with extracts of mango), pitanga (biodiesel with extracts of pitanga) added at concentrations of 500, 2000, 4000 and 8000 parts per million to soybean biodiesel. All samples were characterized by the tests of acid value, kinematic viscosity, cloud point, pour point, pour point, cold filter plugging point and Fourier transform infrared (FTIR). Through the FTIR, it was observed that the CH and OH regions showed greater intensity for the non‐additive biodiesel (B100) in relation to the additive Biodiesel, which shows the antioxidant effect of the additives on the oxidative stability of biodiesel. The effect of the extracts on thermo‐oxidative stability follows the sequence: mango leaf extracts > pitanga leaf extracts > B100 after 504 h and at the low temperature the effect of antioxidant following sequence: pitanga extract > mango extract > B100 showing the effect of the antioxidant additives of leaf extracts on the stability of soybean biodiesel at regions of high and low temperatures. The mango and pitanga leaves extracts, are very promising as green antioxidant for biodiesel because it allows the longest storage time without deteriorating.

Biodiesel is a clean fuel, and an alternative to the environmental complications ascribed to fossil fuels. However, the forms of its production are still the object of research in the literature because some issues related to its process improvement and economical viability remain a challenge. Consequently, this research aims to produce biodiesel by the ethylic route from Ricinus communis L. oil extracted with a simple solid liquid extraction method without the use of the soxhled extractor and inspired from rural communities practices. In this sense, Ricinus communis L. was extracted by n-hexane as solvent, obtaining biodiesel through ethyl transesterification via alkaline catalysis. The characterization of biodiesel in terms of—acid value (AV), combustibility and corrosivity to copper. The results indicated that the yield of the extracted oil was 14% in relation to the mass of seeds used, the value of the AV was 0.96 mg NaOH/g, showing in this case that the oil can be used in the transesterification process to obtain biodiesel. The biodiesel yield obtained was 37% and the AV was 1.98 mg NaOH/g, being considered above the acceptable value for its use in diesel engines, and should be neutralized to at least 0.8 mg NaOH/g. Based on this work, biodiesel was obtained via ethyl esterification of Ricinus communis L. oil extracted from a simple and easy method.

Oxidation stability is one of the most important properties of biodiesel because it affects their stability during the storage period influence on engine performance. Current research tend to develop antioxidant additives to improve their stability. Some plants have antioxidant properties due to their chemical composition and may assist in this stabilization. The aim of this study was to oxidative term stability of soybean biodiesel and pure beef tallow and spiked with leaves and extracts of the leaves of cherry, soursop, mango and cherry front light, 60 ° C and low temperatures for 0, 168, 504, 1176 and 1848 h of storage in order to evaluate its framework within the ANP, ASTM, EN. The leaves used as an antioxidant additive were ground in a knife mill to 10 mesh and extracts of leaves were obtained by Soxhlet process. Soybean biodiesel was obtained by the ethyl route and beef tallow by methyl. The term oxidative stability was monitored by determining the acid number, kinematic viscosity, density, by infrared spectroscopy with Fourier Transform and thermogravimetry. The results showed that the biodiesel soya and tallow is stable against the light for 1848 h. The antioxidant effect of leaves on soybean biodiesel after 168 h of storage at 60 ° C follows the following order: leaves of soursop> sheets of cherry> mango leaves> acerola leaves while for the leaves of the statement we have: extract leaves acerola> extract of the leaves of soursop> extract of mango leaves> extract of cherry leaves after 504h. For the leaves beef tallow biodiesel showed the order: leaves of cherry> leaves acerola> mango leaves> soursop leaves and extracts the order: Mango leaf extracts> soursop leaf extracts> leaf extracts of cherry> acerola leaf extracts. The butylated hydroxytoluene (BHT), synthetic antioxidant, showed higher antioxidant effect on soybean biodiesel in relation to additivations with leaves and their extracts after 1176h. In beef tallow biodiesel BHT activity was similar to the extracts of the leaves of cherry, soursop and cherry after 504h and the sleeve after 1176h. The order of stability of soy biodiesel additive against low temperatures was: cherry extract> mango extract> acerola extract> soursop extract. The results of the tests indicate that low temperature soybean biodiesel additive or may not be used in any region of the country for all seasons. The effect of the extracts of leaves in front biodiesel stability at low temperatures was: extracts of mango leaves> acerola extracts> soursop extracts> cherry extracts. Biodiesel pure beef tallow has lower stability in low temperatures to soy biodiesel. The results of the AI, kinematic viscosity, density, FTIR and TGA show that the extracts of the leaves and fruits studied sheets can act as antioxidant additives in the oxidative stability of biodiesel.

Resumo: O biodiesel é suscetível ao processo de oxidação em relação ao diesel mineral durante a estocagem alterando suas propriedades como índice de peróxidos, viscosidade e índice de acidez, causando problemas ao motor. Sendo assim, faz-se necessária a adição de antioxidantes. Certos compostos naturais apresentam substâncias fitoquímicas (como flavonoides, vitamina C, carotenoides e polifenóis) com a capacidade de inibir o processo de degradação, aumentando assim o tempo útil dos biocombustíveis. A acerola, planta fartamente abundante no Brasil, exibe em sua composição diversas substâncias com ação antioxidante. Sabendo-se que os antioxidantes sintéticos são eficientes, porém tóxicos e não biodegradáveis e, aliado a isso pensando na sustentabilidade do homem no campo e a proteção do meio ambiente, é que se estudou a estabilidade do biodiesel de soja aditivado com folhas de acerola como agente antioxidante, em substituição ao antioxidante sintético. As amostras foram expostas a ação da luz ambiente e da temperatura de 60 ºC, no tempo zero, 168, 504, 1176 e 1848 h, avaliando seu tempo de estocagem. Observou-se que o biodiesel aditivado com 0,015 g da folha, exposto por 1176 h à luz ambiente manteve o índice de acidez dentro das normas nacionais e internacionais, assim como após 168 h à 60°C de exposição. Resultados de termogravimetria, espectroscopia de infravermelho com transformada de Fourier e de índice de acidez das amostras de biodiesel de soja puro e aditivados mostram-se concordantes e indicam que as folhas de acerola se prestam como aditivo antioxidante nas condições estudadas.