A method based on the use of microemulsions with urea or ethylenediamine was developed by Carrillo and Laine [183] as a pulp pretreatment. It reduces the energy consumption, due to the ability of microemulsions to penetrate the capillary structures of wood. Urea and ethylenediamine were used due to their ability to loosen the hydrogen bonds between cellulose nanofibrils and to solubilize cellulose under certain conditions.Ionic liquids (IL) are organic salts with very interesting and valuable properties such as nonflammability, thermal and chemical stability, and infinitely low vapor pressure. Li and Wei [81] combined the used of 1-butyl-3-methylimidazolium chloride as IL with high-pressurehomogenization to isolate CNF from sugarcane bagasse.