It was found that a very
important fraction of the hydroxides, both sodium and potassium, are consumed by the saponification reaction,
thus decreasing the final acyl-glycerides conversion. Carrying out the reaction in two steps, it was
found that not improvement was obtained regarding the catalyst consumption and soap formation, what
indicates that the water fed to the system and the water formed by free fatty acid neutralization, determine
these values independently of the reaction strategy followed in the process.
The importance of this study is that in medium and small scale plants, the biodiesel production is often
carried out with crude oils, and consequently, the selection of the catalyst that minimizes soap formation
and its solubility in the biodiesel phase, is an important issue