Synthesis of biodiesel from high FFA alperujo oil catalysed by immobilised lipase

• Enzymatic biodiesel synthesis from alperujo oil with and without neutralization.
• Comparison of r-ROL activity on different polymethacrylate supports.
• Positive effect of free fatty acids on initial rate and stability.

Synthesis of biodiesel was carried out through enzymatic biocatalysis by the transesterification of natural waste olive oil (alperujo oil) using a recombinant 1,3-positional selective Rhizopus oryzae lipase (rROL). The most relevant property of this uncommon substrate is the high content of free fatty acids (FFAs), making it impossible to produce biodiesel through basic catalysis. The synthesis reactions were carried out in a solvent-free media using a covalent immobilisation on a glutaraldehyde-treated polymethacrylate amino-epoxide carrier. Methanol was added by stepwise addition to avoid lipase inactivation. FFAs effects on the kinetics, yields and stability of biocatalysts were studied. It was concluded that the high free fatty acids content allows an increasing on the initial reaction rate and it gives more stability to the immobilised enzyme, demonstrating the efficiency of this new substrate for the biodiesel production.