Biodiesel production from waste oils by using lipase immobilized on hydrotalcite and zeolites

In this work, hydrotalcite and four different types of zeolites were used as immobilization metarial. The size and type of the zeolite particles did not effect the amount of protein adsorbed. It was found that hydrotalcite is more efficient than zeolites studied. The amount of protein adsorbed (Pg) on hydrotalcite 13 mg/g was higher than that of zeolite as 9 mg/g. The amount of protein adsorbed on hydrotalcite was the highest at pH 8.5 and 4^ ◦C. The immobilization of enzyme on hydrotalcite reached steady state after 5 h. Immobilized lipase retained 36% of the initial activity at 45^ ◦C and 14% of initial activity at 55^ ◦C, after the seventh cycle. Immobilized lipase on hydrotalcite was found to able to catalyse the transesterification of waste cooking oil with methanol to produce methyl esters. Lipase immobilized on zeolites did not show significant yields at the same reaction conditions.