Likewise, in all tests with the reaction mixture directly ultrafiltered, the percentage of glycerol was below the value specified
by the ANP for free glycerol, which is 0.02% in mass. Compared to the works in the literature using membrane technology in the purification of biodiesel [18,24–28], the methodology used herein has the advantage of eliminating the step of separation by settling and provide a biodiesel with a very low content of glycerol after a single processing step.