Comparison of Calcium Magnesium Ferrite Nanoparticles for Boosting Biohydrogen Production.

Dark fermentation (DF) is an eco-friendly process that simultaneously achieves organic matter degradation and obtains hydrogen (H2). Nonetheless, low H2 yield mainly caused by poor activity of key microbes, is still a problem that requires being resolved. In this work, MgFe2O4 and Ca0.5Mg0.5Fe2O4 nanoparticles (NPs) were synthetized and served as additives to boost H2 form from DF. H2 productivity gradually increased with the rise of NPs, and declined when NPs exceeded their optimal dosages. The highest H2 yield was 183.6 +/- 3.2 mL/g glucose at 100 mg/L of MgFe2O4 NPs, being 35.2 % higher than that of the control yield (135.8 +/- 3.1 mL/g glucose). However, the highest H2 yield of 171.9 +/- 2.5 mL/g glucose occurred at 400 mg/L of Ca0.5Mg0.5Fe2O4 NPs, increasing by 26.6 % over the control. Interestingly, the two NPs favored the butyric acid pathway for H2 synthesis. This provides guidance for multi -element oxide NPs used in DF.