Improved biohydrogen evolution through calcium ferrite nanoparticles assisted dark fermentation.

Area of Science:

• Biotechnology
• Green Chemistry
• Nanotechnology

Background:

• Dark fermentation (DF) is a promising method for green hydrogen (H2) production.
• Current H2 yields via DF are significantly lower than theoretical maximums.
• Enhancing microbial activity and metabolic efficiency in DF is crucial for increasing H2 production.

Purpose of the Study:

• To investigate the effect of calcium ferrite nanoparticles (CaFe2O4 NPs) on H2 yield in dark fermentation.
• To determine the optimal concentration of CaFe2O4 NPs for maximizing H2 production.
• To elucidate the mechanisms by which CaFe2O4 NPs influence the DF process and microbial community.

Main Methods:

• Synthesis and characterization of calcium ferrite nanoparticles (CaFe2O4 NPs).
• Implementation of CaFe2O4 NPs at various concentrations (100 mg/L and 600 mg/L) in a dark fermentation system.
• Analysis of H2 yield, soluble metabolites (e.g., butyric acid), and microbial community structure.

Main Results:

• The highest H2 yield reached 250.1 ± 6.5 mL/g glucose at 100 mg/L CaFe2O4 NPs.
• H2 yield decreased to 208.6 ± 2.6 mL/g glucose at 600 mg/L CaFe2O4 NPs.
• CaFe2O4 NPs promoted granular sludge formation, enhanced microbial activity, increased butyric acid production, and favored the dominance of Firmicutes (up to 71.22%).

Conclusions:

• Calcium ferrite nanoparticles are effective in augmenting H2 yield during dark fermentation.
• The optimal concentration of CaFe2O4 NPs is critical for maximizing H2 production, with higher concentrations potentially being inhibitory.
• CaFe2O4 NPs enhance H2 production by improving microbial metabolism, sludge characteristics, and the abundance of key microbial populations like Firmicutes.