Biodiesel production from waste cooking oil

Abstract

Abstract Biodiesel production from waste cooking oil was obtained using Thermomyces lanuginosus (TL) lipase (E.C.3.1.1.3) anchored on Fe3O4/Au nanoparticles through physical interactions. A remarkable biodiesel yield of ∼90% was obtained without any pre-treatment and at a lipase concentration of 20%, 45°C reaction temperature, 1:6 oil/methanol molar ratio, after 24 h. The immobilized enzyme showed fast kinetic (the biodiesel yield was already of 34.6% after only 3 h) and activity slightly dependent on the length of the acid chains. The effect of the Au NPs sizes was monitored, to study the role of Au conduction centres in facilitating enzymes favourable orientation. The immobilized lipase activity stays above 74% after the first 3 cycles of use. In particular, the produced biodiesel presents an ester content of 97.8% ± 0.21 and a linolenic methyl ester content of 0.53% ± 0.03, in agreement with EN14214 requirements.