Integration of rare earth element stimulation, activated carbon adsorption and cell immobilization in ABE fermentation for promoting biobutanol production

Abstract

The objective of this work was to promote biobutanol production by integrating rare earth element stimulation, activated carbon adsorption and cell immobilization into acetone-butanol-ethanol fermentation. Among eight selected rate earth elements, the trace supplement of gadolinium (Gd(III)) into fermentation medium (1 × 10−5 M) could significantly stimulate cell growth and biobutanol biosynthesis. Subsequently, activated carbon particles had been used to alleviate biobutanol toxic effect for bacterial cells. The adsorption of biobutanol on activated carbon particles was coincident with Pseudo-first-order dynamics and Freundlich isotherm models. In order to prevent the competitive adsorption between bacterial cells and biobutanol on activated carbon particles, bacterial cells bad been immobilized on the surface of volcanic stones. After cultivating for 5 h, activated carbon particles were introduced into fermentation broth for performing biobutanol isolation. Finally, the total biobutanol yield using the developed strategy was 15.26 ± 0.43 g/L, which was 73.20 ± 12.69% higher than that of common fermentation with free bacterial cells.