Biodiesel production in a magnetically fluidized bed reactor using whole-cell biocatalysts immobilized within ferroferric oxide-polyvinyl alcohol composite beads

Magnetic whole-cell biocatalysts (MWCBs) constructed by immobilizing Bacillus subtilis cells within ferroferric oxide-polyvinyl alcohol composite beads were developed and employed to transesterify waste frying oil to biodiesel in a magnetically fluidized bed reactor (MFBR). Effective variables including biocatalysts concentra-tion, reactant flow rate, magnetic field intensity and temperature were evaluated to enhance the trans-esterification. By coupling MFBR with MWCBs, continuous biodiesel production was achieved. Response surface methodology and Box-Behnken design were employed to predict the optimal conditions and the maximum biodiesel yield reached 89.0 & PLUSMN; 0.6% after 48 h under the optimized conditions. Furthermore, MWCBs displayed satisfactory stability and reusability in MFBR and still maintained a biodiesel yield of more than 82.5% after 10 cycles. Lastly, the fuel properties of the obtained biodiesel met the ASTM and EN standards. The present study revealed that the route of producing biodiesel over MWCBs in the MFBR system showed great potential for industrialization.

Automated summary

In this study, magnetic whole-cell biocatalysts (MWCBs) were constructed and employed in a magnetically fluidized bed reactor (MFBR) for continuous transesterification of waste frying oil to biodiesel. The optimization of variables led to a maximum biodiesel yield of 89.0±0.6% after 48 hours. MWCBs exhibited satisfactory stability and reusability in the MFBR, and the fuel properties of the obtained biodiesel met international standards. The results indicate the great potential of MWCBs in the industrial production of biodiesel.