Purificação de biodiesel por adsorção

Abstract

NaOH as the catalyst. The reaction occurred at 30°C for one hour with oil:alcohol molar ratio of 1:7,5. From this mixture was evaporated the ethanol excess at 65°C and the glycerol excess was removed by decantation. For the separation of residual glycerol from biodiesel it was used an adsorption process with bone activated coal modified with nitric acid. The acid solution for treating the coal was defined by analyzing the percentage of glycerol adsorbed by this coal and, according to the results, an nitric acid solution of 1% was sufficient to treat the coal that, at 5% mass in biodiesel, adsorbed 96,83% of glycerol. The major modification undergone by the adsorbent were the increase of superficial area, from 104,3m2/g to 235m2/g. For comparative purposes, it were used for adsorption two solutions containing glycerol, one artificial solution with PA glycerin and distillated water prepared in laboratory, called solution 1, and the other one, the biodiesel produced by ethylic transesterification of degummed soybeal oil, called solution 2. The results showed that the adsorption was efficient, solution 2 showed glycerol content within the limits specified by ANP and ester content of 94,95%. The glycerol adsorption was affected by biodiesel for the kinetic experiments, but it was not possible to obtain the adsorption isotherm for solution 2.