These results are justified by the absence of acidity in the oil, which prevented the agglomeration of the dispersed phase in the final mixture. Saleh et al. [26] studied biodiesel purification using membrane process and demonstrated that at lower soap concentrations, the increasing amount of water promotes the generation of larger glycerol rich particles. In this present work, soaps formed in the reaction, when there are free fatty acids in the oil, along with salts from the neutralization with acidified water, contribute to the formation of a dispersed phase containing glycerol, which can be retained by the membrane