Three
sub-group lipases of Burkholderia cepacia lipase
(BCL), Rhizomucor miehei lipase (RML), and Candida rugosa lipase (CRL) were covalently immobilized
on dendrimer functionalized magnetic carbon nanotube and used as catalysts
to catalyze biodiesel production. The effects of imprinting molecule,
organic solvent, water, methanol, temperature and time interval of
methanol addition on the yield of biodiesel were optimized. The results
showed that bioimprinting could greatly enhance catalytic performances
of the three immobilized lipases. The obtained lipases were then employed
to catalyze biodiesel production, and the achieved optimum conditions
were: for BCL, water content 5 wt. %, reaction temperature 35°C,
and with t-butanol as reaction medium, methanol :
oil molar ratio 4:1, its highest biodiesel yield attained 96.4%; for
RML, water content 10 wt. %, reaction temperature 50 °C, n-octane as the reaction medium, methanol : oil molar ratio
of 5:1, the utmost biodiesel conversion rate was up to 96.2%; and
for CRL, water content 7.5 wt. %, reaction temperature 40 °C,
isooctane as the reaction medium, methanol:oil molar ratio of 4:1,
the best yield reached 85.1%. It was borne out that the effect of
time interval of methanol addition on the biodiesel conversion was
more obvious for the immobilized RML and CRL than BCL. Furthermore,
waste vegetable oil was also explored for biodiesel preparation vs
soybean oil. It reveals that the immobilized RML exhibited best catalysis
toward both feedstock in its corresponding solvent systems.