4. Conclusion

Through the analysis of total carbon, it can be observed that the methodology used in the purification of Magnesol® is satisfactory, as approximately 3.90% carbon was found after the washing process with THF. This was proven through infrared analyses which showed the absence of signals around 2900 and 2700 cm-1 in the purified Magnesol® as well as a decrease in the signal at 1000 cm-1, resembling virgin Magnesol®.
After the Magnesol® was purified with THF (r.t., 30:1 solv./Magnesol®; 3 stages, duration of 10 min. for each wash), we observed different behaviors depending on whether it was used with virgin oil or frying oil. For the Magnesol®used in the purification of biodiesel from the virgin soybean oil, we found it can be used at most two times without losing its efficiency, whereas the Magnesol® used in the purification of biodiesel from soybean oil used in frying can be used at least 2 times, as no loss of efficiency was observed. These results were verified in the glycerol analyses presented in this study.
After the acidity, glycerol, flash point and density tests, it was found that biodiesel after being purified with Magnesol® is in good condition to be used in industry with less glycerol, the main impurity.