Comparison of magnetite/reduced graphene oxide nanocomposites and magnetite nanoparticles on enhancing hydrogen production in dark fermentation

Abstract

Magnetite/reduced graphene oxide nanocomposites (Fe3O4-rGO NCs) and magnetite nanoparticles (Fe3O4 NPs) were added to enhance biohydrogen (bioH2) production in dark fermentation. Concentration of supplements from 10 to 100 mg/L was appropriate to enhance bioH2 production, and inhibition appeared once concentration exceeded 100 mg/L. The best bioH2 yield was 198.30 mL/g glucose at 100 mg/L Fe3O4 NPs and 225.60 mL/g glucose at 100 mg/L Fe3O4-rGO NCs, which was 42.97% and 62.65% higher than that in the blank group, respectively. Both Fe3O4 NPs and Fe3O4-rGO NCs could intensify butyrate-type fermentation and change the hydrogen-producing microorganism cells morphology, but the enhancement effect of Fe3O4-rGO NCs was superior. Microbial community structure analysis showed that Clostridium-sensu-stricto-1 became more dominant ultimately by Fe3O4-rGO NCs.