Processo de produção e purificação do biodiesel de amendoim

Abstract

The concern about fossil fuel reserves depletion, pollution due to extensive use of conventional fuels and stricter standards for emission are the forces that drive research on alternative fuels. Amongst these are the biodiesel in which the use of vegetable oils has become an attractive to replace diesel from petroleum because of its physico-chemical characteristics and no toxic emissions. This work aimed to study the effect of diferente variables on conversion of peanut oil to biodiesel; determine the influence of temperature and pH in the purification process in order to optimize the amount of water used and study the thermodynamic equilibrium of the system biodiesel-glycerine-alcohol (decreasing the production of effluents). The process of production and purification of peanut biodiesel obtained by transesterification was studied. In this reaction was used sodium hydroxide (NaOH) as a basic catalyst, anhydrous ethanol and peanut crude oil (non-degummed) in a pilot production unit. In the purification process was used sulphuric acid diluted in distilled water and drying agent (magnesium sulphate). A 22 factorial design was performed to determine the influence of chemical variables on the amount of water required for thepurification. The variables for the production process were: temperature (30o, 70oC), stirring speed (150 rpm, 350 rpm), molar ratio oil/alcohol (1:4 and 1:10), amount of catalyst (0,5% and 1,5%) and reaction time (0,5 h, 2 h). For the purification process the variables analysed were: temperature (30o and 70oC) and pH (2 and 5). For the study of the system´s thermodynamic equilibrium was used purified biodiesel, jacketed glass reactor with circulating water, titration with biodiesel and glycerine. The evaluation parameter for the production process is the conversion to biodiesel determined by gaseous chromatography and for the purification process were the amount of water utilized and the determination of the influence of the temperature on the system´s thermodynamic equilibrium. The conversion to biodiesel varied between total saponification to a conversion of 87%. In the purification was observed that the effect of the pH variable could be ignored and the effect of the temperature and the interaction of the temperature and pH can be considered. The thermodynamic equilibrium of the system biodiesel/glycerine/alcohol and the tie lines did not have its behaviour influenced by the different temperatures, not influencing the miscibility of the mixture.